exenatide and Disease-Models--Animal

Glucagon-like-peptide-1 (GLP-1)-receptor agonists have been proposed as putative treatment for substance use disorders (SUD). The objective of this systematic review is to characterize the effects of GLP-1-receptor agonists on SUD-related behavioural effects of drugs, nicotine, and alcohol. The review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A search was performed in PubMed and EMBASE on June 16, 2018. The inclusion criteria were primary studies investigating the use of GLP-1-receptor agonists on behavioural endpoints related to SUD. Seventeen studies were included, investigating the effect of the GLP-1-receptor agonists exendin-4, fluoro-exendin-4, liraglutide, AC3174 and GLP-1 (7-36) on SUD-related behavioural effects of ethanol, cocaine, amphetamine, and/or nicotine. All studies used rodents as subjects. Nine of the studies dealt with ethanol, six with cocaine, two with amphetamine, and two with nicotine. Most studies investigated acute treatment effects, finding a significant effect in all but one experiment. A few studies investigated more chronic effects on ethanol. All the studies reported sustained effects. Eleven studies tested more than one dose, finding a dose-related response in ten out of thirteen experiments. Six studies report a central effect through intra-cerebral administration or by using mice in which the central GLP-1-receptors had been inactivated. In conclusion, a solid body of evidence documents acute effects of GLP-1-receptor agonist treatment on behavioural effects of alcohol, nicotine, amphetamine and cocaine. Documentation of effect of more chronic GLP-1-receptor stimulation on these behaviours is limited.

Topics: Animals; Behavior, Animal; Disease Models, Animal; Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Liraglutide; Self Administration; Substance-Related Disorders

Experimental studies of acute myocardial infarction have revealed that up to half of the final infarct size may be due to reperfusion injury rather than the initial ischemic incident. Research over the past three decades has deepened our understanding of the molecular mechanisms underlying ischemic reperfusion injury and several therapeutic strategies to decrease the incidence and severity of reperfusion injury have been explored.. To discuss the promising therapies and future perspectives on methods to attenuate myocardial reperfusion injury.. Existing therapies that address reperfusion can be divided into two major groups comprising nonpharmacological and pharmacological interventions. Myriad pharmacological and nonpharmacological approaches to reduce lethal reperfusion injury have been employed. Although many initial clinical studies were negative, more recent proof-of-concept clinical trials are promising. To date, the most encouraging results are with ischemic postconditioning, remote ischemic preconditioning, ANP, adenosine, cyclosporine and exenatide.. Studies demonstrate that nonpharmacological and pharmacological conditioning can be used together as part of a multifaceted approach to improve clinical outcomes in patients with ischemic heart disease.

Topics: Adenosine; Animals; Atrial Natriuretic Factor; Clinical Trials as Topic; Combined Modality Therapy; Cyclosporine; Disease Models, Animal; Exenatide; Humans; Ischemic Postconditioning; Ischemic Preconditioning; Myocardial Ischemia; Myocardial Reperfusion Injury; Peptides; Venoms

Type 2 diabetes has been identified as a risk factor for Alzheimer's disease (AD) and Parkinson's disease (PD). In the brains of patients with AD and PD, insulin signaling is impaired. This finding has motivated new research that showed good effects using drugs that initially had been developed to treat diabetes. Preclinical studies showed good neuroprotective effects applying insulin or long lasting analogues of incretin peptides. In transgenic animal models of AD or PD, analogues of the incretin GLP-1 prevented neurodegenerative processes and improved neuronal and synaptic functionality and reduced the symptoms of the diseases. Amyloid plaque load and synaptic loss as well as cognitive impairment had been prevented in transgenic AD mouse models, and dopaminergic loss of transmission and motor function has been reversed in animal models of PD. On the basis of these promising findings, several clinical trials are being conducted with the first encouraging clinical results already published. In several pilot studies in AD patients, the nasal application of insulin showed encouraging effects on cognition and biomarkers. A pilot study in PD patients testing a GLP-1 receptor agonist that is currently on the market as a treatment for type 2 diabetes (exendin-4, Byetta) also showed encouraging effects. Several other clinical trials are currently ongoing in AD patients, testing another GLP-1 analogue that is on the market (liraglutide, Victoza). Recently, a third GLP-1 receptor agonist has been brought to the market in Europe (Lixisenatide, Lyxumia), which also shows very promising neuroprotective effects. This review will summarise the range of these protective effects that those drugs have demonstrated. GLP-1 analogues show promise in providing novel treatments that may be protective or even regenerative in AD and PD, something that no current drug does.

Topics: Alzheimer Disease; Animals; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Humans; Liraglutide; Mice; Mice, Transgenic; Neuroprotective Agents; Parkinson Disease; Peptides; Receptors, Glucagon; Venoms

There is a concern on the risk of thyroid cancer associated with glucagon-like peptide-1 (GLP-1) analogs including liraglutide and exenatide. In this article, we review related experimental studies, clinical trials and observational human studies currently available. In rodents, liraglutide activated the GLP-1 receptors on C-cells, causing an increased incidence of C-cell neoplasia. Animal experiments with monkeys demonstrated no increase in calcitonin release and no C-cell proliferation after long-term liraglutide administration. Longitudinal 2-year data from clinical trials do not support any significant risk for the activation or growth of C-cell cancer in humans in response to liraglutide. However, an analysis of the FDA adverse event reporting system database suggested an increased risk for thyroid cancer associated with exenatide after its marketing. Noticeably, a recent study discovered that GLP-1 receptor could also be expressed in human papillary thyroid carcinomas (PTC), but the impact of GLP-1 analogs on PTC is not known. Therefore, GLP-1 analogs might increase the risk of thyroid C-cell pathology in rodents, but its risk in humans awaits confirmation. Since GLP-1 receptor is also expressed in PTC besides C-cells, it is important to investigate the actions of GLP-1 on different subtypes of thyroid cancer in the future.

Topics: Animals; Clinical Trials as Topic; Diabetes Complications; Diabetes Mellitus; Disease Models, Animal; Exenatide; Gene Expression Regulation; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Humans; Liraglutide; Macaca fascicularis; Mice; Peptides; Rats; Receptors, Glucagon; Thyroid Neoplasms; Venoms

Type 2 diabetes is increasingly viewed as a disease of insulin deficiency due not only to intrinsic pancreatic beta-cell dysfunction but also to reduction of beta-cell mass. It is likely that, in diabetes-prone subjects, the regulated beta-cell turnover that adapts cell mass to body's insulin requirements is impaired, presumably on a genetic basis. We still have a limited knowledge of how and when this derangement occurs and what might be the most effective therapeutic strategy to preserve beta-cell mass. The animal models of type 2 diabetes with reduced beta-cell mass described in this review can be extremely helpful (a) to have insight into the mechanisms underlying the defective growth or accelerated loss of beta-cells leading to the beta-cell mass reduction; (b) to investigate in prospective studies the mechanisms of compensatory adaptation and subsequent failure of a reduced beta-cell mass. Furthermore, these models are of invaluable importance to test the effectiveness of potential therapeutic agents that either stimulate beta-cell growth or inhibit beta-cell death.

Topics: Animals; Cyclic AMP Response Element-Binding Protein; Cyclin D2; Cyclin-Dependent Kinase 4; Cyclins; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Disease Models, Animal; eIF-2 Kinase; Exenatide; Fetal Growth Retardation; Homeodomain Proteins; Insulin Receptor Substrate Proteins; Insulin-Secreting Cells; Intracellular Signaling Peptides and Proteins; Mice; Mice, Transgenic; Peptides; Phosphoproteins; Proto-Oncogene Proteins c-akt; Rats; Receptor, Insulin; Ribosomal Protein S6 Kinases, 70-kDa; Trans-Activators; Venoms

Systemic fibroblast growth factor (FGF)21 levels and hepatic FGF21 production are increased in non-alcoholic fatty liver disease patients, suggesting FGF21 resistance. We examined the effects of exenatide on FGF21 in patients with type 2 diabetes and in a diet-induced mouse model of obesity (DIO).. Type 2 diabetes mellitus patients (n = 24) on diet and/or metformin were randomised (using a table of random numbers) to receive additional treatment consisting of pioglitazone 45 mg/day or combined therapy with pioglitazone (45 mg/day) and exenatide (10 μg twice daily) for 12 months in an open label parallel study at the Baylor Clinic.. Twenty-one patients completed the entire study and were included in the analysis. Pioglitazone treatment (n = 10) reduced hepatic fat as assessed by magnetic resonance spectroscopy, despite a significant increase in body weight (Δ = 3.7 kg); plasma FGF21 levels did not change (1.9  ±  0.6 to 2.2  ±  0.6 ng/ml [mean ± SEM]). However, combined pioglitazone and exenatide therapy (n = 11) was associated with a significant reduction of FGF21 levels (2.3  ±  0.5 to 1.1  ±  0.3 ng/ml) and a greater decrease in hepatic fat. Besides weight gain observed in the pioglitazone-treated patients, lower extremity oedema was observed as a side effect in two of the ten patients. Three patients who received pioglitazone and exenatide combination therapy complained of significant nausea that was self-limiting and did not require them to leave the study. In DIO mice, exendin-4 for 4 weeks significantly reduced hepatic triacylglycerol content, decreased hepatic FGF21 protein and mRNA, and enhanced phosphorylation of hepatic AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase, although no significant difference in weight and body fat was observed. Hepatic FGF21 correlated inversely with hepatic AMPK phosphorylation. In type 2 diabetes mellitus, combined pioglitazone and exenatide therapy is associated with a reduction in plasma FGF21 levels, as well as a greater decrease in hepatic fat than that achieved with pioglitazone therapy. In DIO mice, exendin-4 treatment reduces hepatic triacylglycerol and FGF21 protein, and enhances hepatic AMPK phosphorylation, suggesting an improvement of hepatic FGF21 resistance.. ClinicalTrials.gov NCT 01432405.

Topics: Adult; Aged; Animals; Body Weight; Diabetes Mellitus, Type 2; Disease Models, Animal; Drug Therapy, Combination; Edema; Exenatide; Fatty Liver; Female; Fibroblast Growth Factors; Humans; Hypoglycemic Agents; Liver; Lower Extremity; Male; Metformin; Mice; Middle Aged; Nausea; Non-alcoholic Fatty Liver Disease; Obesity; Peptides; Pioglitazone; Thiazolidinediones; Venoms

Protective effects of exendin-4 (glucagon-like peptide-1 -GLP-1- receptor agonist) and des-fluoro-sitagliptin (dipeptidyl peptidase-4 inhibitor) on fructose-induced hepatic disturbances were evaluated in prediabetic rats. Complementary, a possible direct effect of exendin-4 in human hepatoblastoma-derived cell line HepG2 incubated with fructose in presence/absence of exendin-9-39 (GLP-1 receptor antagonist) was investigated. In vivo, after 21 days of fructose rich diet, we determined: glycemia, insulinemia, and triglyceridemia; hepatic fructokinase, AMP-deaminase, and G-6-P dehydrogenase (G-6-P DH) activities; carbohydrate-responsive element-binding protein (ChREBP) expression; triglyceride content and lipogenic gene expression (glycerol-3-phosphate acyltransferase -GPAT-, fatty acid synthase -FAS-, sterol regulatory element-binding protein-1c -SREBP-1c); oxidative stress and inflammatory markers expression. In HepG2 cells we measured fructokinase activity and triglyceride content. Hypertriglyceridemia, hyperinsulinemia, enhanced liver fructokinase, AMP-deaminase, and G-6-P DH activities, increased ChREBP and lipogenic genes expression, enhanced triglyceride level, oxidative stress and inflammatory markers recorded in fructose fed animals, were prevented by co-administration of either exendin-4 or des-fluoro-sitagliptin. Exendin-4 prevented fructose-induced increase in fructokinase activity and triglyceride contain in HepG2 cells. These effects were blunted co-incubating with exendin-9-39. The results demonstrated for the first time that exendin-4/des-fluro-sitagliptin prevented fructose-induced endocrine-metabolic oxidative stress and inflammatory changes probably acting on the purine degradation pathway. Exendin 9-39 blunted in vitro protective exendin-4 effects, thereby suggesting a direct effect of this compound on hepatocytes through GLP-1 receptor. Direct effect on fructokinase and AMP-deaminase activities, with a key role in the pathogenesis of liver dysfunction induced by fructose, suggests purine degradation pathway constitute a potential therapeutic objective for GLP-1 receptor agonists.

Topics: Animals; Disease Models, Animal; Exenatide; Fructose; Glucagon-Like Peptide-1 Receptor; Humans; Mice; Prediabetic State; Rats; Sitagliptin Phosphate; Transcription Factors; Triglycerides

Smoking cessation increases body weight. The underlying mechanisms, however, have not been fully understood. We here report an establishment of a mouse model that exhibits an augmented body weight gain after nicotine withdrawal. High fat diet-fed mice were infused with nicotine for two weeks, and then with vehicle for another two weeks using osmotic minipumps. Body weight increased immediately after nicotine cessation and was significantly higher than that of mice continued on nicotine. Mice switched to vehicle consumed more food than nicotine-continued mice during the first week of cessation, while oxygen consumption was comparable. Elevated expression of orexigenic agouti-related peptide was observed in the hypothalamic appetite center. Pair-feeding experiment revealed that the accelerated weight gain after nicotine withdrawal is explained by enhanced energy intake. As a showcase of an efficacy of pharmacologic intervention, exendin-4 was administered and showed a potent suppression of energy intake and weight gain in mice withdrawn from nicotine. Our current model provides a unique platform for the investigation of the changes of energy regulation after smoking cessation.

Topics: Agouti-Related Protein; Animals; Calorimetry; Cell Respiration; Disease Models, Animal; Energy Intake; Exenatide; Feeding Behavior; Gene Expression Regulation; Hypothalamus; Male; Mice, Inbred C57BL; Nicotine; RNA, Messenger; Substance Withdrawal Syndrome; Weight Gain

We have previously shown that diabetes causes pericyte dysfunction, leading to loss of vascular integrity and vascular cognitive impairment and dementia (VCID). Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs), used in managing type 2 diabetes mellitus, improve the cognitive function of diabetic individuals beyond glycaemic control, yet the mechanism is not fully understood. In the present study, we hypothesise that GLP-1 RAs improve VCID by preventing diabetes-induced pericyte dysfunction.. Mice with streptozotocin-induced diabetes and non-diabetic control mice received either saline (NaCl 154 mmol/l) or exendin-4, a GLP-1 RA, through an osmotic pump over 28 days. Vascular integrity was assessed by measuring cerebrovascular neovascularisation indices (vascular density, tortuosity and branching density). Cognitive function was evaluated with Barnes maze and Morris water maze. Human brain microvascular pericytes (HBMPCs), were grown in high glucose (25 mmol/l) and sodium palmitate (200 μmol/l) to mimic diabetic conditions. HBMPCs were treated with/without exendin-4 and assessed for nitrative and oxidative stress, and angiogenic and blood-brain barrier functions.. Diabetic mice treated with exendin-4 showed a significant reduction in all cerebral pathological neovascularisation indices and an improved blood-brain barrier (p<0.05). The vascular protective effects were accompanied by significant improvement in the learning and memory functions of diabetic mice compared with control mice (p<0.05). Our results showed that HBMPCs expressed the GLP-1 receptor. Diabetes increased GLP-1 receptor expression and receptor nitration in HBMPCs. Stimulation of HBMPCs with exendin-4 under diabetic conditions decreased diabetes-induced vascular inflammation and oxidative stress, and restored pericyte function (p<0.05).. This study provides novel evidence that brain pericytes express the GLP-1 receptor, which is nitrated under diabetic conditions. GLP-1 receptor activation improves brain pericyte function resulting in restoration of vascular integrity and BBB functions in diabetes. Furthermore, the GLP-1 RA exendin-4 alleviates diabetes-induced cognitive impairment in mice. Restoration of pericyte function in diabetes represents a novel therapeutic target for diabetes-induced cerebrovascular microangiopathy and VCID.

Topics: Animals; Brain; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Humans; Mice; Pericytes

Exendin-4 (Ex-4) is a glucagon-like peptide-1 receptor (GLP-1R) agonist that protects against brain injury. However, little is known about the effect of Ex-4 on kainic acid (KA)-induced seizures and hippocampal cell death. Therefore, this study evaluated the neuroprotective effects of Ex-4 pretreatment in a mouse model of KA-induced seizures. Three days before KA treatment, mice were intraperitoneally injected with Ex-4. We found that Ex-4 pretreatment reversed KA-induced reduction of GLP-1R expression in the hippocampus and attenuated KA-induced seizure score, hippocampal neuronal death, and neuroinflammation. Ex-4 pretreatment also dramatically reduced hippocampal lipocalin-2 protein in KA-treated mice. Furthermore, immunohistochemical studies showed that Ex-4 pretreatment significantly alleviated blood-brain barrier leakage. Finally, Ex-4 pretreatment stimulated hippocampal expression of phosphorylated cyclic adenosine monophosphate (cAMP) response element-binding protein (p-CREB), a known target of GLP-1/GLP-1R signaling. These findings indicate that Ex-4 pretreatment may protect against KA-induced neuronal damage by regulating GLP-1R/CREB-mediated signaling pathways.

Topics: Animals; Cell Death; Disease Models, Animal; Exenatide; Hippocampus; Male; Mice; Neuroinflammatory Diseases; Neurons; Neuroprotective Agents; Signal Transduction

This study evaluated if the cardioprotective effect of Exendin-4 against ischemia/reperfusion (I/R) injury in male rats involves modulation of AMPK and sirtuins. Adult male rats were divided into sham, sham + Exendin-4, I/R, I/R + Exendin-4, and I/R + Exendin-4 + EX-527, a sirt1 inhibitor. Exendin-4 reduced infarct size and preserved the function and structure of the left ventricles (LV) of I/R rats. It also inhibited oxidative stress and apoptosis and upregulated MnSOD and Bcl-2 in their infarcted myocardium. With no effect on SIRTs 2/6/7, Exendin-4 activated and upregulated mRNA and protein levels of SIRT1, increased levels of SIRT3 protein, activated AMPK, and reduced the acetylation of p53 and PGC-1α as well as the phosphorylation of FOXO-1. EX-527 completely abolished all beneficial effects of Exendin-4 in I/R-induced rats. In conclusion, Exendin-4 cardioprotective effect against I/R involves activation of SIRT1 and SIRT3. Graphical Abstract Exendin-4 could scavenge free radical directly, upregulate p53, and through upregulation of SIRT1 and stimulating SIRT1 nuclear accumulation. In addition, Exendin-4 also upregulates SIRT3 which plays an essential role in the upregulation of antioxidants, inhibition of reactive oxygen species (ROS) generation, and prevention of mitochondria damage. Accordingly, SIRT1 induces the deacetylation of PGC-1α and p53 and is able to bind p-FOXO-1. This results in inhibition of cardiomyocyte apoptosis through increasing Bcl-2 levels, activity, and levels of MnSOD; decreasing expression of Bax; decreasing cytochrome C release; and improving mitochondria biogenesis through upregulation of Mfn-2.

Topics: Acetylation; AMP-Activated Protein Kinases; Animals; Apoptosis; Disease Models, Animal; Enzyme Activation; Exenatide; Glucagon-Like Peptide-1 Receptor; Incretins; Male; Myocardial Reperfusion Injury; Myocytes, Cardiac; Nerve Tissue Proteins; Oxidative Stress; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Phosphorylation; Rats, Wistar; Signal Transduction; Sirtuin 1; Sirtuins; Tumor Suppressor Protein p53; Up-Regulation; Ventricular Function, Left

Random skin flaps are often used for plastic repair because they are convenient and flexible. However, necrosis of flaps is a common complication that may lead to disastrous consequences. Exenatide, a glucagon-like peptide 1 receptor agonist, can enhance angiogenesis and ameliorate ischemia/reperfusion injury. Our experiments explored random skin flap outcomes after its use.. We established modified dorsal McFarlane flaps on 54 Sprague-Dawley rats and divided the rats into three groups (control, Exe-I, and Exe-II). We intraperitoneally injected either 4 or 8 μg/kg/day exenatide into the rats of the Exe-I and Exe-II groups, respectively. On the seventh day after the operation, we measured the levels of superoxide dismutase (SOD) and malondialdehyde (MDA). Tissue sections were obtained for histopathological and immunohistochemical analyses, and we evaluated the expression of vascular endothelial growth factor (VEGF), interleukin (IL) 6, IL-1β, nuclear factor kappa beta (NF-κB), Toll-like receptor 4 (TLR4), and tumor necrosis factor α (TNF-α). We measured blood flow reconstruction and angiogenesis using laser Doppler blood flowmetry and lead oxide/gelatin angiography, respectively.. Exenatide increased the average survival area of the flap and improved microvascular density and blood flow intensity in a dose-dependent manner. Meanwhile, the SOD level was up-regulated and the MDA level down-regulated. Exenatide also enhanced the expression of VEGF and reduced the expression of inflammatory cytokines (IL-6, IL-1β, NF-κB, TLR4, and TNF-α), thereby promoting angiogenesis and inhibiting inflammation.. Exenatide potentially inhibits necrosis in our rat random skin flap model.

Topics: Angiogenesis Inducing Agents; Animals; Anti-Inflammatory Agents; Antioxidants; Cytokines; Disease Models, Animal; Exenatide; Male; Necrosis; Neovascularization, Physiologic; NF-kappa B; Oxidative Stress; Rats, Sprague-Dawley; Regional Blood Flow; Reperfusion Injury; Signal Transduction; Skin; Surgical Flaps; Toll-Like Receptor 4; Vascular Endothelial Growth Factor A

The purpose of the experiments in this study was to explore the effect of exenatide on intrauterine adhesions (IUAs) and to elucidate its mechanism to provide new ideas for the clinical treatment of IUAs.. In this study, an animal model of IUAs was established by double stimulation using mechanical curettage and inflammation. After modeling, the treatment group was injected subcutaneously with three doses of exenatide for two weeks. The model group was injected with sterile ultrapure water, and the sham operation group was treated the same as the normal group, except for the observation of abdominal wound changes. Two weeks later, all mice were sacrificed by cervical dysfunction. The obtained mouse uterine tissue was used for subsequent experimental detection, using HE and Masson staining for histomorphological and pathological analysis; qRT-PCR for the detection of TGF-β1, α-SMA, and MMP-9 gene expression in uterine tissue; and western blotting analysis of TGF-β1, α-SMA, and collagen 1 protein expression to verify whether exenatide has a therapeutic effect on IUAs in mice.. In the high-dose exenatide treatment group, the endometrial glands significantly increased in size, and the deposition area of collagen fibers in the endometrial tissue was significantly reduced. We observed that the mRNA expression of TGF-β1 and α-SMA in the endometrial tissue of IUAs mice in this group was significantly reduced, while the expression of MMP-9 was significantly increased. In addition, we found that the protein expression of TGF-β1, α-SMA, and collagen 1 remarkably decreased after treatment with exenatide.. Exenatide may reduce the deposition of collagen fibers in the uterus of IUAs mice and promote the proliferation of endometrial glands in mice.

Topics: Actins; Animals; Collagen Type I; Disease Models, Animal; Endometrium; Exenatide; Female; Gene Expression Regulation; Glucagon-Like Peptide 1; Matrix Metalloproteinase 9; Mice; Tissue Adhesions; Transforming Growth Factor beta1; Uterus

Topics: Animals; Bone and Bones; Bone Diseases; Bone Regeneration; Cell Differentiation; Cell Line; Cell Proliferation; Disease Models, Animal; Durapatite; Exenatide; Hydrogels; Mice; Osteogenesis; Polyethylene Glycols; Rats; Tomography, X-Ray Computed

Exendin-4 has been found to have hypoglycemic effect and prevent bone loss in diabetic patients, but its mechanism of preventing bone loss is still unclear. In this study, high-fat diet combined with streptozotocin was used to establish type 2 diabetes mellitus (T2DM) mice, and bone marrow mesenchyme stem cells (BMSCs) were isolated for osteogenic induction in vitro. Alizarin red staining and ALP activity detection were used to observe the effect of exendin-4 on osteogenic differentiation of BMSCs. Western blot was used to detect the proteins expression in BMSCs. In vivo, the effects of exendin-4 treatment on body weight, blood glucose, bone density and bone quality of T2DM mice were observed by treatment with exendin-4. The results showed that exendin-4 promoted osteogenic differentiation of T2DM derived BMSCs, down-regulated histone deacetylase 1 (HDAC1) and p-β-Catenin proteins expression, and up-regulated Wnt3, β-Catenin and runt-related transcription factor 2 (Runx 2) proteins expression. In vivo, exendin-4 effectively suppressed the blood glucose and increased body weight of T2DM mice, and significantly improved bone density and bone quality of the right tibia. Interestingly, by over-expression of HDAC1 in BMSCs, the effect of exendin-4 on promoting osteogenic differentiation of BMSCs was attenuated, and the regulation of Wnt3a, β-Catenin, p-β-Catenin or Runx2 proteins were reversed. By injecting adenovirus containing HDAC1 into the right tibia of mice, the effect of exendin-4 on bone density and bone quality of T2DM mice was significantly attenuated. All above results suggest that the HDAC1-Wnt/β-Catenin signal axis is involved in the anti-diabetic bone loss effect of exendin-4, and HDAC1 may be the target of exendin-4.

Topics: Animals; Cell Differentiation; Cells, Cultured; Diabetes Mellitus, Experimental; Disease Models, Animal; Exenatide; Histone Deacetylase 1; Hypoglycemic Agents; Mesenchymal Stem Cells; Mice; Mice, Inbred ICR; Osteogenesis; Wnt Signaling Pathway

Exenatide is a glucagon-like polypeptide-1 analog, whose main clinical use is to treat type 2 diabetes. However, the mechanism of exenatide in mitigating non-alcoholic steatohepatitis (NASH) remains unclear. This study aimed to investigate the. Exenatide treatment inhibited the pyroptosis signaling pathway to attenuate NASH.. To the best of our knowledge, this report provides the first evidence showing that exenatide attenuated NASH by inhibiting the pyroptosis signaling pathway. Exenatide thus has important pathophysiological functions in NASH and may represent a useful new therapeutic target.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Humans; Hypoglycemic Agents; Male; Mice; Mice, Inbred C57BL; Non-alcoholic Fatty Liver Disease; Pyroptosis; Signal Transduction

Growing evidences indicate that neuropathic pain is frequently accompanied with cognitive impairments, which aggravate the decrease in the quality of life of chronic pain patients. Furthermore, it has been shown that the activation of Glucagon-like-peptide-1receptor (GLP-1R) improved memory deficit in multiple diseases, including Alzheimer's disease (AD), stroke. However, whether GLP-1R activation could improve memory impairment induced by neuropathic pain and the mechanisms underlying the effect of the activation of GLP-1R on memory protection have not yet been established. The spared nerve injury (SNI) model was established as a kind of neuropathic pain. And novel-object recognition memory (hippocampus-dependent memory) was tested by the novel object recognition test (NORT). The expression levels of GLP-1, GLP-1R, adenosine monophosphate-activated protein kinase (AMPK), p-AMPKThr172, nuclear factor κ B p65 (NF-κB p65), interleukin-1beta (IL-1β), IL-1β p17 (mature IL-1β), tumor necrosis factor-alpha (TNF-α) and the synaptic proteins were tested in the murine hippocampus with memory deficits caused by neuropathic pain. Then, exenatide acetate (Ex-4, a GLP-1R agonist), exendin (9-39) (Ex(9-39), a GLP-1R antagonist) and Compound C dihydrochloride (CC, an AMPK inhibitor) were used to test the effects of the activation of GLP-1R in the mice with neuropathic pain. First, we uncovered that neuropathic pain could inhibit GLP-1/GLP-R axis, disturb inflammatory signaling pathway, increase the expression of IL-1β, IL-1β p17 and TNF-α, downregulate the synaptic proteins (postsynaptic density protein 95 (PSD95) and Arc). Subsequently, we reported that Ex-4 treatment could improve recognition memory impairment, increase the ratio of p-AMPKThr172/AMPK, inhibit the phosphorylation NF-κB p65 and decrease the expression of IL-1β, IL-1β p17 and TNF-α, upregulate the levels of PSD95 and Arc. Moreover, we found that Ex(9-39) and CC treatment could abrogate the memory protection of activation of GLP-1R in mice with neuropathic pain. The results indicated that the activation of GLP-1R could improve recognition memory impairment via regulating AMPK/NF-κB pathway, improving neuroinflammation, reversing the decreased level of synaptic proteins in neuropathic pain mice.

Topics: AMP-Activated Protein Kinase Kinases; Animals; Chronic Pain; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Hippocampus; Interleukin-1beta; Memory Disorders; Mice; Neuralgia; Neuroinflammatory Diseases; Open Field Test; Peptide Fragments; Peripheral Nerve Injuries; Recognition, Psychology; Sciatic Nerve; Transcription Factor RelA; Tumor Necrosis Factor-alpha

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Topics: Alstrom Syndrome; Animals; Blood Glucose; Calcium; Calcium Signaling; Diabetes Mellitus, Type 2; Disease Models, Animal; Endoplasmic Reticulum; Exenatide; Fluorescent Dyes; Fura-2; Glucagon-Like Peptide 1; Hepatocytes; Hypoglycemic Agents; Insulin; Insulin Resistance; Liver; Male; Mice; Mice, Transgenic; Non-alcoholic Fatty Liver Disease; Obesity; Palmitic Acid

Epilepsy is a neurological condition affecting millions of people worldwide. Glucagon-like peptide-1 (GLP-1) is a gut hormone, and its neuroprotective effect was investigated in previous studies. In this study, the effects of exendin-4, a GLP-1 receptor agonist, were studied in genetic absence epileptic Wistar Albino Glaxo/Rijswijk rats (WAG/Rij). WAG/Rij rat is a genetic model of the absence epilepsy and depression-like comorbidity.. We examined the effects of exendin-4 (10, 50 and 100 µg/kg) on the absence seizures (Electrocorticography [ECoG] recordings), anxiety level (open-field test [OF]), and depression-like levels (forced swimming test [FST]) in the WAG/Rij rats. Basal ECoG recording was performed for all rats. Then, exendin-4 (10, 50 or 100 µg/kg) was administered intraperitoneally and ECoG recording was made for 180 min. After ECoG recording, forced swimming test and open-field test were applied.. Administration of 10, 50, or 100 µg/kg exendin-4 increased the duration and number of spike-wave discharges (SWDs) considerably without changing the amplitude. The 100 µg/kg dose of exendin-4 was the most effective in increasing the total duration of SWDs. Additionally, all exendin-4 doses increased anxiety level in OF and depression-like level in FST.. Our results showed that exendin-4 increased SWD incidence and anxiety- and depression-like behaviors in the WAG/Rij rats. Besides, it was also found that high doses caused the most proabsence effect.

Topics: Animals; Anxiety; Depression; Disease Models, Animal; Electroencephalography; Epilepsy, Absence; Exenatide; Rats; Rats, Wistar; Seizures

Glucagon-like peptide-1 (GLP-1) is beneficial in relieving pain-related symptoms of Irritable bowel syndrome (IBS), a prevalent, multi-factorial functional bowel disorder characterized by diarrhea and/or constipation, abdominal bloating, and pain. Activation of myenteric neurons has been implicated in the inhibitory effects of GLP-1 on gastrointestinal motility; however, the mechanisms of action underlying this are not clear.. A rat model of IBS was used to examine physiological changes evoked by intraperitoneal administration of a GLP-1 receptor agonist, exendin-4. Behavioral and physiological analysis of stress-sensitive Wister Kyoto (WKY) rats was used to determine if administration of exendin-4, in the presence or absence of neutralizing interleukin-6 receptor monoclonal antibodies, modified IBS-like symptoms. Immunofluorescence, calcium imaging, and Western blotting techniques were used to investigate the potential role of enteric neural plexi and tight junction protein expression in this effect.. Consistent with the expression of GLP-1 and interleukin-6 receptors in both submucosal and myenteric ganglia, exendin-4 and interleukin-6 stimulated calcium responses in these neurons. In vivo administration of exendin-4 normalized stress-induced defecation and visceral pain sensitivity in WKY rats. No additional changes were noted in rats co-treated with exendin-4 and anti-interleukin-6 receptor antibodies. Mucosal expression of occludin, a tight junction protein, was decreased by exendin-4. Centrally regulated anxiety-like behaviors were not modified.. These data suggest that intraperitoneal injection of exendin-4 improves bowel dysfunction in WKY rats without impacting on centrally regulated anxiety-like behaviors. Modulation of enteric neuronal function and tight junction expression appear to underlie the functional benefits of this intervention.

Topics: Animals; Disease Models, Animal; Enteric Nervous System; Exenatide; Glucagon-Like Peptide 1; Interleukin-6; Irritable Bowel Syndrome; Rats; Rats, Inbred WKY

Friedreich ataxia is an autosomal recessive neurodegenerative disease associated with a high diabetes prevalence. No treatment is available to prevent or delay disease progression. Friedreich ataxia is caused by intronic GAA trinucleotide repeat expansions in the frataxin-encoding FXN gene that reduce frataxin expression, impair iron-sulfur cluster biogenesis, cause oxidative stress, and result in mitochondrial dysfunction and apoptosis. Here we examined the metabolic, neuroprotective, and frataxin-inducing effects of glucagon-like peptide-1 (GLP-1) analogs in in vivo and in vitro models and in patients with Friedreich ataxia. The GLP-1 analog exenatide improved glucose homeostasis of frataxin-deficient mice through enhanced insulin content and secretion in pancreatic β cells. Exenatide induced frataxin and iron-sulfur cluster-containing proteins in β cells and brain and was protective to sensory neurons in dorsal root ganglia. GLP-1 analogs also induced frataxin expression, reduced oxidative stress, and improved mitochondrial function in Friedreich ataxia patients' induced pluripotent stem cell-derived β cells and sensory neurons. The frataxin-inducing effect of exenatide was confirmed in a pilot trial in Friedreich ataxia patients, showing modest frataxin induction in platelets over a 5-week treatment course. Taken together, GLP-1 analogs improve mitochondrial function in frataxin-deficient cells and induce frataxin expression. Our findings identify incretin receptors as a therapeutic target in Friedreich ataxia.

Topics: Adolescent; Adult; Aged; Animals; Brain; Cerebellum; Disease Models, Animal; Exenatide; Female; Frataxin; Friedreich Ataxia; Ganglia, Spinal; Gene Expression Regulation; Gene Knock-In Techniques; Glucagon-Like Peptide 1; Humans; Insulin; Insulin-Secreting Cells; Iron; Iron-Binding Proteins; Male; Mice; Mice, Knockout; Middle Aged; Mitochondria; Oxidative Stress; Reactive Oxygen Species; Trinucleotide Repeat Expansion; Young Adult

The aim of this study was to investigate the effect of exendin-4 (Ex-4) on ventricular arrhythmias and calcium sparks-mediated calcium leak in a myocardial infarction-heart failure model.We studied the influence of exendin-4 on ventricular arrhythmogenesis in a rat myocardial infarction-heart failure model. In vivo arrhythmia studies (electrocardiogram [ECG] telemetry studies), ex vivo arrhythmia studies calcium sparks tests, and analysis of total and phosphorylated ryanodine receptor (RyR) 2 and CaMK-II were carried out in sham group, myocardial infarction (MI) group, MI + Ex-4 and MI + Ex-4 + Exendin9-39 (Ex9-39) groups.ECG telemetry studies showed an antiarrhythmic effect of exendin-4 with reduction of spontaneous ventricular arrhythmias. Exendin-4 abbreviated the APD

Topics: Animals; Arrhythmias, Cardiac; Calcium Signaling; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Disease Models, Animal; Electrocardiography; Exenatide; Heart Failure; Male; Rats; Ryanodine Receptor Calcium Release Channel; Sarcoplasmic Reticulum

Parkinson's disease (PD) is a progressive neurodegenerative disease for which there is no cure. In a clinical trial, the glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 has shown good protective effects in PD patients. The hormone glucose-dependent insulinotropic polypeptide (GIP) has also shown protective effects in animal models of PD.. We tested DA-CH5, a novel dual GLP-1/GIP receptor agonist.. DA-CH5 activity was tested on cells expressing GLP-1, GLP-2, GIP or glucagon receptors. The ability to cross the blood-brain barrier (BBB) of DA-CH5, exendin-4, liraglutide or other dual receptor agonists was tested with fluorescein-labelled peptides. DA-CH5, exendin-4 and liraglutide were tested in the MPTP mouse model of PD.. Analysing the receptor activating properties showed a balanced activation of GLP-1 and GIP receptors while not activating GLP-2 or glucagon receptors. DA-CH5 crossed the BBB better than other single or other dual receptor agonists. In a dose-response comparison, DA-CH5 was more effective than the GLP-1 receptor agonist exendin-4. When comparing the neuroprotective effect of DA-CH5 with Liraglutide, a GLP-1 analogue, both DA-CH5 and Liraglutide improved MPTP-induced motor impairments. In addition, the drugs reversed the decrease of the number of neurons expressing tyrosine hydroxylase (TH) in the SN, alleviated chronic inflammation, reduced lipid peroxidation, inhibited the apoptosis pathway (TUNEL assay) and increased autophagy -related proteins expression in the substantia nigra (SN) and striatum. Importantly, we found DA-CH5 was superior to Liraglutide in reducing microglia and astrocyte activation, improving mitochondrial activity by reducing the Bax/Bcl-2 ratio and normalising autophagy as found in abnormal expression of LC3 and p62.. The results demonstrate that the DA-CH5 is superior to liraglutide and could be a therapeutic treatment for PD.

Topics: Animals; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Liraglutide; Mice; Neuroprotective Agents; Parkinson Disease; Parkinsonian Disorders; Receptors, Gastrointestinal Hormone

The role of exendin-4 in brown adipose tissue (BAT) activation was not very clear. This study is to verify the role of BAT involved in renal benefits of exendin-4 in diabetes mellitus (DM).. In vivo, C57BL/6 mice were randomly divided into nondiabetic (control) and diabetic groups (DM). The diabetic mice were randomized into a control group (DM-Con), BAT-excision group (DM+Exc), exendin-4-treated group (DM+E4), and BAT-excision plus exendin-4-treated group (DM+Exc+E4). The weight, blood glucose and lipids, 24 h urine albumin and 8-OH-dG, and renal fibrosis were analyzed. In vitro, we investigated the role of exendin-4 in the differentiation process of 3T3-L1 and brown preadipocytes and its effect on the rat mesangial cells induced by oleate.. The expressions of UCP-1, PGC-1. Exendin-4 could decrease the renal lipid deposit and improve diabetic nephropathy via activating the renal AMPK pathway independent of BAT activation.

Topics: 3T3-L1 Cells; 8-Hydroxy-2'-Deoxyguanosine; Adenylate Kinase; Adipocytes, Brown; Adipogenesis; Adipose Tissue, Brown; Albuminuria; Animals; Blood Glucose; Blotting, Western; Body Weight; CD36 Antigens; Cholesterol, HDL; Cholesterol, LDL; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Disease Models, Animal; Exenatide; Fibrosis; Gene Expression; Incretins; Kidney; Lipase; Mesangial Cells; Mice; Mice, Inbred C57BL; Myofibroblasts; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Random Allocation; Rats; Real-Time Polymerase Chain Reaction; Triglycerides; Uncoupling Protein 1

Sirt1 is a potent inhibitor of both poly(ADP-ribose) polymerases1 (PARP1) and NF-kB. This study investigated the cardioprotective effect of exendin-4 on cardiac function and remodeling in rats after an expreimentally-induced myocardial infarction (MI) and explored if this protection involves SIRT1/PARP1 axis. Rats were divided into five groups (n = 10/each): sham, sham + exendin-4 (25 nmol/kg/day i.p.), MI (induced by LAD occlusion), MI + exendin-4, and sham + exendin-4 + EX527 (5 mg/2×/week) (a SIRT1 inhibitor). All treatments were given for 6 weeks post the induction of MI. In sham-operated and MI-induced rats, exendin-4 significantly upregulated Bcl-2 levels, enhanced activity, mRNA, and levels of SIRT1, inhibited activity, mRNA, and levels of PARP1, and reduced ROS generation and PARP1 acetylation. In MI-treated rats, these effects were associated with improved cardiac architectures and LV function, reduced collagen deposition, and reduced mRNA and total levels of TNF-α and IL-6, as well as, the activation of NF-κB p65. In addition, exendin-4 inhibited the interaction of PARP1 with p300, TGF-β1, Smad3, and NF-κB p65 and signficantly reduced mRNA and protein levels of collagen I/III and protein levels of MMP2/9. In conclusion, exendin-4 is a potent cardioprotective agent that prevents post-MI inflammation and cardiac remodeling by activating SIRT1-induced inhibition of PARP1.

Topics: Acetylation; Animals; Anti-Inflammatory Agents; Apoptosis; Disease Models, Animal; Exenatide; Fibrosis; Glucagon-Like Peptide-1 Receptor; Incretins; Male; Myocardial Infarction; Myocytes, Cardiac; NF-kappa B; Poly (ADP-Ribose) Polymerase-1; Rats, Wistar; Signal Transduction; Sirtuin 1; Ventricular Function, Left; Ventricular Remodeling

Preclinical evidence on the role of glucagon-like peptide-1 receptor (GLP-1r) agonists in the brain led to an increased interest in repurposing these compounds as a therapy for central nervous system (CNS) disorders and associated comorbidities. We aimed to investigate the neuroprotective effects of acute treatment with exendin (EX)-4, a GLP-1r agonist, in an animal model of inflammation. We evaluated the effect of different doses of EX-4 on inflammatory, neurotrophic, and oxidative stress parameters in the hippocampus and serum of lipopolysaccharide (LPS)-injected animals. Male Wistar rats were injected with LPS (0.25 mg/kg i.p.) and treated with different doses of EX-4 (0.1, 0.3, or 0.5 μg/kg i.p.). Sickness behavior was assessed by locomotor activity and body weight, and depressive-like behavior was also evaluated using forced swim test (FST). Brain-derived neurotrophic factor (BDNF), thiobarbituric acid reactive species (TBARS), and interleukin (IL)-6 were quantified in the serum and hippocampus. Glycemia was also analyzed pre- and post-EX-4 treatment. LPS groups exhibited decreased frequency of crossing and reduced body weight (p < 0.001), while alterations on FST were not observed. The higher dose of EX-4 reduced IL-6 in the hippocampus of LPS-injected animals (p = 0.018), and EX-4 per se reduced TBARS serum levels with a modest antioxidant effect in the LPS groups (p ≤ 0.005). BDNF hippocampal levels seemed to be increased in the LPS+EX-4 0.5 group compared with LPS+Saline (p > 0.05). Our study provides evidence on acute anti-inflammatory effects of EX-4 in the hippocampus of rats injected with LPS, contributing to future studies on repurposing compounds with potential neuroprotective properties.

Topics: Animals; Anti-Inflammatory Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Exenatide; Hippocampus; Inflammation; Interleukin-6; Lipopolysaccharides; Male; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Wistar

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are used as anti-diabetic drugs and are approved for obesity treatment. However, GLP-1RAs also affect heart rate (HR) and arterial blood pressure (ABP) in rodents and humans. Although the activation of GLP-1 receptors (GLP-1R) is known to increase HR, the circuits recruited are unclear, and in particular, it is unknown whether GLP-1RAs activate preproglucagon (PPG) neurons, the brain source of GLP-1, to elicit these effects.. We investigated the effect of GLP-1RAs on heart rate in anaesthetized adult mice. In a separate study, we manipulated the activity of nucleus tractus solitarius (NTS) PPG neurons (PPG. Systemic administration of the GLP-1RA Ex-4 increased resting HR in anaesthetized or conscious mice, but had no effect on ABP in conscious mice. This effect was abolished by β-adrenoceptor blockade with atenolol, but unaffected by the muscarinic antagonist atropine. Furthermore, Ex-4-induced tachycardia persisted when PPG. These results demonstrate that both systemic application of Ex-4 or GLP-1 and chemogenetic activation of PPG

Topics: Animals; Disease Models, Animal; Electrocardiography; Exenatide; Glucagon-Like Peptide-1 Receptor; Heart Rate; Mice; Mice, Transgenic; Neurons; Proglucagon; Solitary Nucleus; Spinal Cord; Sympathetic Nervous System; Tachycardia

Traumatic brain injury (TBI) can be exacerbated and prolonged for months or even years by chronic inflammatory processes with long-term consequences on neurodegeneration and neurological impairment. However, there are no clear pharmacological therapies of benefit to manage neurological dysfunctions, which, relating to the molecular mechanisms underlying the behavioral deficits after TBI, have yet to be fully identified. Recently, a glucagon-like peptide 1 (GLP-1) agonist, Exendin-4, was approved not only for the treatment of type 2 diabetes mellitus, but it also played a neurotrophic role in various CNS neurological diseases. In this study, we evaluated the neuroprotective effects of Exendin-4 on neurological outcome, cerebral blood flow, neurodegeneration, and inflammatory responses by utilizing a cortical contusion impact injury (CCI) model in rats. We found that TBI rats displayed neurological impairments, neurodegeneration, reduction of cerebral blood flow, and inflammatory responses, while Exendin-4 promoted neurological, cognitive, and cerebral blood flow recovery and attenuated neural degeneration and inflammatory cytokines after TBI. Furthermore, Exendin-4 treatment significantly diminished the TBI-induced overexpression of TNFα and IL-1β, as well as phosphorylation of p38 and ERK1/2. These data suggest a strong beneficial action of the glucagon-like peptide-1 receptor agonist Exendin-4 in improving neurological outcomes by attenuating inflammatory responses induced by traumatic brain injury, which is of therapeutic potential for TBI.

Topics: Animals; Behavior, Animal; Brain Injuries, Traumatic; Cerebrovascular Circulation; Cognition; Cytokines; Disease Models, Animal; Enzyme Activation; Exenatide; Glucagon-Like Peptide-1 Receptor; Inflammation; Interleukin-1beta; Male; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neuroglia; Neuroprotective Agents; p38 Mitogen-Activated Protein Kinases; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha

This study was designed to evaluate the protective effects of AMPKα and SIRT1 on insulin resistance in PCOS rats, and to illuminate the underlying mechanisms.. An in vitro PCOS model was established by DHEA (6 mg/(100 g•d)), and the rats were randomly divided into the metformin group (MF group, n = 11), the exenatide group (EX group, n = 11), the PCOS group (n = 10), and the normal control group (NC group, n = 10). The MF group was administered MF 300 mg/(kg•d) daily. The EX group was subcutaneously injected EX 10μg/(kg•d) daily. After 4 weeks of continuous administration, fasting blood glucose and serum androgen, luteinizing hormone and other biochemical indicators were measured. Western and Real-time PCR were used to determine the expression of AMPKα and SIRT1 in the ovaries of each group.. After 4 weeks of drug intervention, compared with untreated PCOS group, EX group and MF group had visibly decreased body weight (222.64 ± 16.57, 218.63 ± 13.18 vs 238.30 ± 12.26 g, P = 0.026), fasting blood glucose (7.71 ± 0.72, 8.17 ± 0.54 vs 8.68 ± 0.47 mmol/L, P < 0.01), HOMA-IR (8.26 ± 2.50, 7.44 ± 1.23 vs 12.66 ± 1.44, P < 0.01) and serum androgen (0.09 ± 0.03, 0.09 ± 0.03 vs 0.53 ± 0.41 ng/ml, P < 0.01) and the expressions of AMPKα and SIRT11 were increased progressively (P < 0.05).. Both metformin and exenatide can improve the reproductive and endocrine functions of rats with PCOS via the AMPKα-SIRT1 pathway, which may be the molecular mechanism for IR in PCOS and could possibly serve as a therapeutic target.

Topics: AMP-Activated Protein Kinases; Androgens; Animals; Blood Glucose; Disease Models, Animal; Exenatide; Female; Gene Expression Regulation; Humans; Insulin Resistance; Luteinizing Hormone; Metformin; Polycystic Ovary Syndrome; Rats; Sirtuin 1

The glucagon-like peptide-1 receptor agonist exenatide improves glycemic control by several and not completely understood mechanisms. Herein, we examined the effects of chronic intravenous exenatide infusion on insulin sensitivity, β cell and α cell function and relative volumes, and islet cell apoptosis and replication in nondiabetic nonhuman primates (baboons). At baseline, baboons received a 2-step hyperglycemic clamp followed by an l-arginine bolus (HC/A). After HC/A, baboons underwent a partial pancreatectomy (tail removal) and received a continuous exenatide (n = 12) or saline (n = 12) infusion for 13 weeks. At the end of treatment, HC/A was repeated, and the remnant pancreas (head-body) was harvested. Insulin sensitivity increased dramatically after exenatide treatment and was accompanied by a decrease in insulin and C-peptide secretion, while the insulin secretion/insulin resistance (disposition) index increased by about 2-fold. β, α, and δ cell relative volumes in exenatide-treated baboons were significantly increased compared with saline-treated controls, primarily as the result of increased islet cell replication. Features of cellular stress and secretory dysfunction were present in islets of saline-treated baboons and absent in islets of exenatide-treated baboons. In conclusion, chronic administration of exenatide exerts proliferative and cytoprotective effects on β, α, and δ cells and produces a robust increase in insulin sensitivity in nonhuman primates.

Topics: Animals; Apoptosis; Blood Glucose; Cell Proliferation; Cell Transdifferentiation; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Female; Glucose Clamp Technique; Humans; Hypoglycemic Agents; Infusions, Intravenous; Insulin; Insulin Resistance; Islets of Langerhans; Male; Papio

Topics: Amino Acid Sequence; Animals; Blood Glucose; CHO Cells; Cricetulus; Cyclic AMP; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide-1 Receptor; Half-Life; Hypoglycemic Agents; Maleimides; Mice; Mice, Nude; Mice, Obese; Molecular Weight; Polyethylene Glycols

Diabetes mellitus is a metabolic disorder that results in glucotoxicity and the formation of advanced glycated end products (AGEs), which mediate several systemic adverse effects, particularly in the brain tissue. Alterations in glutamatergic neurotransmission and cognitive impairment have been reported in DM. Exendin-4 (EX-4), an analogue of glucagon-like peptide-1 (GLP-1), appears to have beneficial effects on cognition in rats with chronic hyperglycemia. Herein, we investigated the ability of EX-4 to reverse changes in AGE content and glutamatergic transmission in an animal model of DM looking principally at glutamate uptake and GluN1 subunit content of the N-methyl-D-aspartate (NMDA) receptor. Additionally, we evaluated the effects of EX-4 on in vitro models and the signaling pathway involved in these effects. We found a decrease in glutamate uptake and GluN1 content in the hippocampus of diabetic rats; EX-4 was able to revert these parameters, but had no effect on the other parameters evaluated (glycemia, C-peptide, AGE levels, RAGE, and glyoxalase 1). EX-4 abrogated the decrease in glutamate uptake and GluN1 content caused by methylglyoxal (MG) in hippocampal slices, in addition to leading to an increase in glutamate uptake in astrocyte culture cells and hippocampal slices under basal conditions. The effect of EX-4 on glutamate uptake was mediated by the phosphatidylinositide 3-kinases (PI3K) signaling pathway, which could explain the protective effect of EX-4 in the brain tissue, since PI3K is involved in cell metabolism, inhibition of apoptosis, and reduces inflammatory responses. These results suggest that EX-4 could be used as an adjuvant treatment for brain impairment associated with excitotoxicity.

Topics: Animals; Astrocytes; Diabetes Mellitus, Experimental; Disease Models, Animal; Exenatide; Glutamic Acid; Glycation End Products, Advanced; Glycosylation; Hippocampus; Male; Phosphatidylinositol 3-Kinases; Pyruvaldehyde; Rats, Wistar; Receptor for Advanced Glycation End Products; Receptors, N-Methyl-D-Aspartate; Signal Transduction; Streptozocin; Synaptic Transmission

Previously, apoE-derived ABCA1 agonist peptides have been shown to possess anti-atherosclerotic and possibly antidiabetic properties. Here we assessed the in vitro and in vivo actions of a second generation of ABCA1 peptide agonists, CS6253 and T6991-2, on glucose homeostasis. The results show that these two peptides improve glucose tolerance in a prediabetic diet-induced obesity mouse model by enhancing insulin secretion. It was further demonstrated that T6991-2 also improved glucose tolerance in leptin-deficient (ob/ob) mice. CS6253 increased insulin secretion both under basal conditions and in response to high glucose stimulation in pancreatic INS-1 β-cells rendered leptin receptor deficient with specific siRNA. Additional in vitro cell studies suggest that the CS6253 agonist attenuates hepatic gluconeogenesis and glucose transport. It also potentiates insulin-stimulated glucose uptake and utilization. These observed anti-diabetic actions suggest additional benefits of the CS6253 and T6991-2 ABCA1 peptide agonists for cardiovascular disease beyond their direct anti-atherosclerosis properties previously described.

Topics: Animals; Atherosclerosis; ATP Binding Cassette Transporter 1; Cell Line; Cell Line, Tumor; Diet, High-Fat; Disease Models, Animal; Exenatide; Gluconeogenesis; Glucose; Glucose Tolerance Test; Glycated Hemoglobin; Humans; Hypoglycemic Agents; Insulin Resistance; Insulin Secretion; Leptin; Liver; Mice, Inbred C57BL; Mice, Knockout; Mice, Obese; Obesity; Peptides; Rats; Triglycerides

Traumatic brain injury (TBI) is a neurodegenerative disorder for which no effective pharmacological treatment is available. Glucagon-like peptide 1 (GLP-1) analogues such as Exenatide have previously demonstrated neurotrophic and neuroprotective effects in cellular and animal models of TBI. However, chronic or repeated administration was needed for efficacy. In this study, the pharmacokinetics and efficacy of PT302, a clinically available sustained-release Exenatide formulation (SR-Exenatide) were evaluated in a concussive mild (m)TBI mouse model. A single subcutaneous (s.c.) injection of PT302 (0.6, 0.12, and 0.024 mg/kg) was administered and plasma Exenatide concentrations were time-dependently measured over 3 weeks. An initial rapid regulated release of Exenatide in plasma was followed by a secondary phase of sustained-release in a dose-dependent manner. Short- and longer-term (7 and 30 day) cognitive impairments (visual and spatial deficits) induced by weight drop mTBI were mitigated by a single post-injury treatment with Exenatide delivered by s.c. injection of PT302 in clinically translatable doses. Immunohistochemical evaluation of neuronal cell death and inflammatory markers, likewise, cross-validated the neurotrophic and neuroprotective effects of SR-Exenatide in this mouse mTBI model. Exenatide central nervous system concentrations were 1.5% to 2.0% of concomitant plasma levels under steady-state conditions. These data demonstrate a positive beneficial action of PT302 in mTBI. This convenient single, sustained-release dosing regimen also has application for other neurological disorders, such as Alzheimer's disease, Parkinson's disease, multiple system atrophy and multiple sclerosis where prior preclinical studies, likewise, have demonstrated positive Exenatide actions.

Topics: Animals; Brain Concussion; Delayed-Action Preparations; Disease Models, Animal; Exenatide; Male; Mice; Mice, Inbred ICR; Neuroprotective Agents; Rats; Rats, Sprague-Dawley

Organ transplantation is the gold standard therapy for the majority of patients with terminal organ failure. However, it is still a limited treatment especially due to the low number of brain death (BD) donors in relation to the number of waiting list recipients. Strategies to increase the quantity and quality of donor organs have been studied, and the administration of exendin-4 (Ex-4) to the donor may be a promising approach. Male Wistar rats were randomized into 3 groups: (1) control, without central nervous system injury; (2) BD induced experimentally, and (3) BD induced experimentally + Ex-4 administered immediately after BD induction. After BD induction, animals were monitored for 6 h before blood collection and kidney biopsy. Kidney function was assessed by biochemical quantification of plasma kidney markers. Gene and protein expressions of inflammation- and stress-related genes were evaluated by RT-qPCR and immunoblot analysis. Animals treated with Ex-4 had lower creatinine and urea levels compared with controls. BD induced oxidative stress in kidney tissue through increased expression of Ucp2, Sod2 and Inos, and Ex-4 administration reduced the expression of these genes. Ex-4 also induced increased expression of the anti-apoptotic Bcl2 gene. Nlrp3 and Tnf expressions were up-regulated in the BD group compared with controls, but Ex-4 treatment had no effect on these genes. Our findings suggest that Ex-4 administration in BD rats reduces BD-induced kidney damage by decreasing the expression of oxidative stress genes and increasing the expression of Bcl2.

Topics: Animals; Apoptosis; Brain Death; Creatine; Cytokines; Disease Models, Animal; Exenatide; Genes, bcl-2; Inflammation; Kidney; Kidney Transplantation; Male; NLR Family, Pyrin Domain-Containing 3 Protein; Oxidative Stress; Rats; Rats, Wistar; Tissue Donors; Tumor Necrosis Factor-alpha; Urea

To investigate the effects of exenatide on renal injury in streptozotocin-induced diabetic rats.. Fifty SD rats were randomly divided into normal control, model, exenatide-1, exenatide-2 and exenatide-3 groups, 10 rats in each group. The diabetic nephropathy model was constructed in later 4 groups. Then, the later 3 groups were treated with 2, 4 and 8 μg/kg exenatide for 8 weeks, respectively. The serum and urine biochemical indexes and oxidative stress and inflammatory indexes in renal tissue were determined.. Compared to the model group, in exenatide-3 group the serum fasting plasma glucose and hemoglobin A1c levels were significantly decreased, the fasting insulin level was significantly increased, the renal index and blood urea nitrogen, serum creatinine and 24 h urine protein levels were significantly decreased, the renal tissue superoxide dismutase and glutathione peroxidase levels were significantly increased, the malondialdehyde level was significantly decreased, and the renal tissue tumor necrosis factor alpha, interleukin 6, hypersensitive C-reactive protein and chemokine (C-C motif) ligand 5 levels were significantly decreased P<0.05).. Exenatide can mitigate the renal injury in diabetic rats. The mechanisms may be related to its resistance of oxidative stress and inflammatory response in renal tissue.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Disease Models, Animal; Exenatide; Kidney; Male; Oxidative Stress; Random Allocation; Rats; Rats, Sprague-Dawley

In depression, excessive glucocorticoid action may cause maladaptive brain changes, including in the pathways controlling energy metabolism. Insulin and glucagon-like peptide-1 (GLP-1), besides regulation of glucose homeostasis, also possess neurotrophic properties. Current study was aimed at investigating the influence of prenatal stress (PS) on insulin, GLP-1 and their receptor (IR and GLP-1R) levels in the hypothalamus. GLP-1 and GLP-1R were assayed also in the hippocampus and frontal cortex - brain regions mainly affected in depression. The second objective was to determine the influence of exendin-4 and insulin on CRH promoter gene activity in in vitro conditions.. Adult male PS rats were subjected to acute stress and/or received orally glucose. Levels of hormones and their receptors were assayed with ELISA method. In vitro studies were performed on mHypoA-2/12 hypothalamic cell line, stably transfected with CRH promoter coupled with luciferase.. PS has reduced GLP-1 and GLP-1R levels, attenuated glucose-induced increase in insulin concentration and increased the amount of phosphorylated IR in the hypothalamus of animals subjected to additional stress stimuli, and also decreased the GLP-1R level in the hippocampus. In vitro studies demonstrated that insulin is capable of increasing CRH promoter activity in the condition of stimulation of the cAMP/PKA pathway in the applied cellular model.. Prenatal stress may act as a preconditioning factor, affecting the concentrations of hormones such as insulin and GLP-1 in the hypothalamus in response to adverse stimuli. The decreased GLP-1R level in the hippocampus could be linked with the disturbances in neuronal plasticity.

Topics: Animals; Cell Line; Corticotropin-Releasing Hormone; Depression; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Exenatide; Female; Glucagon-Like Peptide 1; Glucose; Hypothalamus; Insulin; Male; Mice; Neuronal Plasticity; Pregnancy; Prenatal Exposure Delayed Effects; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; Stress, Psychological

Hepatic ischemia/reperfusion-induced pancreatic injury (HI/RPI) is an important pathophysiological phenomenon in clinics. Exenatide is found to have hepatopancreatic protection; however, the half-life of exenatide is extremely short, which limits its clinical application. In the present study, we described an exenatide nanocarrier based on poly(L-lysine)-poly(ethylene glycol)-poly(L-lysine) (PLL-PEG-PLL) and aimed to investigate the protective effects of exenatide/PLL-PEG-PLL on HI/RPI.. PLL-PEG-PLL was synthesized and estimated by being applied as a nanocarrier for lengthening delivery of exenatide. Exenatide was loaded into PLL-PEG-PLL by electrostatic interactions at pH 7.4. The loading and release of exenatide from PLL-PEG-PLL were characterized in vitro. The pancreatic protection of exenatide/PLL-PEG-PLL was assessed using the animal model, histopathological examination, blood biochemical indices detection, antioxidant activity, and anti-inflammatory evaluation in vivo.. Exenatide/PLL-PEG-PLL displayed efficient loading and sustained release. Exenatide/PLL-PEG-PLL complex moderated HI/RPI and enlarged islet functionality compared to free exenatide.. We propose that the nanocarrier PLL-PEG-PLL may function as a potent exenatide nanocarrier for augmenting anti-HI/RPI pharmacotherapy with unprecedented clinical benefits.

Topics: Animals; Disease Models, Animal; Exenatide; Hypoglycemic Agents; Liver; Male; Nanoparticles; Pancreatic Diseases; Rats; Rats, Sprague-Dawley; Reperfusion Injury

The role of mitochondrial dysfunction has been well-documented in Alzheimer's disease (AD). Glucagon-like peptide 1 (GLP-1) receptor agonists are being utilized as neuroprotectants in the treatment of various neurological disorders, including AD. We conducted this study to explore the effects of exenatide (a GLP-1 receptor agonist) on β-amyloid plaque (Aβ)-induced cognitive impairment and mitochondrial dysfunction in 5xFAD transgenic mice. Spatial memory test showed that exenatide administration (100 μg/kg twice per day) prevented cognitive decline after 16 weeks of treatment. Aβ

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Brain; Cognitive Dysfunction; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Hippocampus; Male; Memory; Mice; Mice, Inbred Strains; Mice, Transgenic; Mitochondria; Neuroprotective Agents; Plaque, Amyloid; Synapses

Topics: Animal Feed; Animals; Copepoda; Disease Models, Animal; Energy Metabolism; Exenatide; Fatty Acids; Female; Glucose; Incretins; Isolated Heart Preparation; Mice, Inbred C57BL; Myocardial Contraction; Myocardial Reperfusion Injury; Myocardium; Obesity; Oils; Recovery of Function; Ventricular Function, Left; Ventricular Pressure

Alzheimer's disease (AD) is a multifactorial condition in which, along with amyloid-β (Aβ) and tau-related pathology, the synergistic activity of co-morbidity factors promote the onset and progression of the disease. Epidemiological evidence indicates that glucose intolerance, deficits in insulin secretion, or type-2 diabetes mellitus (T2DM) participate in increasing cognitive impairment or dementia risk. Insulin plays a pivotal role in the process as the hormone critically regulates brain functioning. GLP-1, the glucagon-like peptide 1, facilitates insulin signaling, regulates glucose homeostasis, and modulates synaptic plasticity. Exenatide is a synthetic GLP-1 analog employed in T2DM. However, exenatide has also been shown to affect the signaling of the brain-derived neurotrophic factor (BDNF), synaptic plasticity, and cognitive performances in animal models. In this study, we tested whether exenatide exerts neuroprotection in a preclinical AD model set to mimic the clinical complexity of the human disease. We investigated the effects of exenatide treatment in 3xTg-AD mice challenged with a high-fat diet (HFD). Endpoints of the study were variations in systemic metabolism, insulin and neurotrophic signaling, neuroinflammation, Aβ and tau pathology, and cognitive performances. Results of the study indicate that exenatide reverts the adverse changes of BDNF signaling and the neuroinflammation status of 3xTg-AD mice undergoing HFD without affecting systemic metabolism or promoting changes in cognitive performances.

Topics: Alzheimer Disease; Animals; Brain; Brain-Derived Neurotrophic Factor; Cognitive Dysfunction; Disease Models, Animal; Exenatide; Female; Glucagon-Like Peptide 1; Glucose Tolerance Test; Hypoglycemic Agents; Insulin; Insulin Resistance; Male; Mice; Neuroimmunomodulation; Neuronal Plasticity; Neuroprotective Agents; Signal Transduction

Therapy targeting mitochondria may provide novel ways to treat diabetes and its complications. Bone marrow-derived mesenchymal stem cells (MSCs), the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists and exendin-4; an analog of glucagon-like peptide-1 have shown cardioprotective properties in many cardiac injury models. So, we evaluated their effects in diabetic cardiomyopathy (DCM) in relation to mitochondrial dysfunction. This work included seven groups of adult male albino rats: the control group, the non-treated diabetic group, and the treated diabetic groups: one group was treated with MSCs only, the second with pioglitazone only, the third with MSCs and pioglitazone, the forth with exendin-4 only and the fifth with MSCs and exendin-4. All treatments were started after 6 weeks from induction of diabetes and continued for the next 4 weeks. Blood samples were collected for assessment of glucose, insulin, and cardiac enzymes. Hearts were removed and used for isolated heart studies, and gene expression of: myocyte enhancer factor-2 (

Topics: Animals; Cardiolipins; Diabetic Cardiomyopathies; Disease Models, Animal; Exenatide; Hypoglycemic Agents; Male; MEF2 Transcription Factors; Mesenchymal Stem Cell Transplantation; Mitochondrial Diseases; NF-kappaB-Inducing Kinase; Peptides; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Pioglitazone; PPAR gamma; Protein Serine-Threonine Kinases; Thiazolidinediones; Uncoupling Protein 2; Venoms

Exendin-4, a glucagon-like peptide-1 receptor agonist has been shown to have curative effects on hepatic steatosis in murine models.. The present study aimed to elucidate the effect of Exendin-4 on hepatic receptor for advanced glycation end products (RAGE) mRNA expression in non-alcoholic steatohepatitis (NASH) rat model induced by high-fat diet.. NASH was induced by high-fat diet intake, and Exendin-4 was given in two different doses. After 12 weeks, liver enzyme levels, hepatic triglycerides, antioxidant enzymes and malondialdehyde (MDA) levels, and mRNA RAGE was detected using RT-PCR.. Exendin-4 in high dose reduced significantly liver enzymes activity, hepatic triglycerides, MDA levels and hepatic mRNA RAGE expression levels with significantly higher antioxidant enzymes activity.. Our results give further insights into the mechanisms underlying the curative role of Exendin-4 in NASH, suggesting that interference with RAGE may be a useful therapeutic approach to NASH.

Topics: Animals; Biomarkers; Diet, High-Fat; Disease Models, Animal; Dose-Response Relationship, Drug; Down-Regulation; Enzyme Induction; Exenatide; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Insulin Resistance; Lipid Peroxidation; Liver; Male; Non-alcoholic Fatty Liver Disease; Organ Size; Oxidative Stress; Oxidoreductases; Peptides; Random Allocation; Rats, Wistar; Receptor for Advanced Glycation End Products; Triglycerides; Venoms

Neuronal apoptosis is considered to be a crucial therapeutic target against early brain injury (EBI) after subarachnoid hemorrhage (SAH). Emerging evidence indicates that Exendin-4 (Ex-4), a glucagon-like peptide 1 receptor (GLP-1R) agonist, plays a neuroprotective role in cerebrovascular disease. This study was conducted in order to verify the neuroprotective role of EX-4 in EBI after SAH in rats. The endovascular perforation model of SAH was performed in Sprague-Dawley rats (n = 153). Ex-4 was intraperitoneally injected 1 h after SAH induction in the rats (SAH + Ex-4). To elucidate the underlying molecular mechanism, small interfering ribonucleic acid (siRNA) for GLP-1R and a specific inhibitor of PI3K, LY294002, were injected intracerebroventricularly into SAH + Ex-4 rats before induction of SAH (n = 6 per group). SAH grading evaluation, immunohistochemistry, Western blots, neurobehavioral assessment, and Fluoro-Jade C (FJC) staining experiments were performed. Expression of GLP-1R was significantly increased and mainly expressed in neurons at 24 h after SAH induction. Administration of Ex-4 significantly improved both short- and long-term neurobehavior in SAH + Ex-4 group compared to SAH + Vehicle group after SAH. Ex-4 treatment significantly increased the expression of GLP-1R, PI3K, p-Akt, Bcl-xl, and Bcl-2, while at the same time was found to decrease expression of Bax in the brain. Effects of Ex-4 were reversed by the intervention of GLP-1R siRNA and LY294002 in SAH + Ex-4+GLP-1R siRNA and SAH + Ex-4+LY294002 groups, respectively. In conclusion, the neuroprotective effect of Ex-4 in EBI after SAH was mediated by attenuation of neuronal apoptosis via GLP-1R/PI3K/Akt signaling pathway, therefore EX-4 should be further investigated as a potential therapeutic agent in stroke patients.

Topics: Animals; Apoptosis; Brain Injuries; Calcium-Binding Proteins; Chromones; Disease Models, Animal; Enzyme Inhibitors; Exenatide; Glucagon-Like Peptide 1; Injections, Intraventricular; Male; Microfilament Proteins; Morpholines; Nerve Tissue Proteins; Neuroprotective Agents; Oncogene Protein v-akt; Peptides; Phosphatidylinositol 3-Kinases; Rats; Rats, Sprague-Dawley; RNA, Small Interfering; Signal Transduction; Subarachnoid Hemorrhage; Venoms

Topics: Alzheimer Disease; Amyloid beta-Protein Precursor; Animals; Cell Survival; Disease Models, Animal; Down-Regulation; Enzyme Inhibitors; Exenatide; Glucagon-Like Peptide-1 Receptor; Male; Maze Learning; Memory Disorders; Mice; Mice, Transgenic; N-Acetylglucosaminyltransferases; Oncogene Protein v-akt; PC12 Cells; Peptides; Presenilin-1; Rats; RNA, Small Interfering; Signal Transduction; Venoms

Systemic left-to-right shunting causes pulmonary arteriopathy, leading to progressive cardiopulmonary failure and a poor prognosis. In this study, we examined the extraglycemic effect of a synthetic glucagon-like peptide, exendin-4, on pulmonary arteriopathy regression and cardiopulmonary function in nondiabetic rats.. Pulmonary hypertension (PH) was induced by monocrotaline (60 mg/kg, subcutaneous) injection followed by the creation of an aortocaval fistula. After 4 weeks, exendin-4 (1 μg/kg/day) was administered intraperitoneally for 3 consecutive weeks, followed by an assessment of cardiopulmonary function, pulmonary artery vasoreactivity, tissue and blood biochemistry, and lung histology.. Exendin-4 significantly reduced right ventricle mass and pulmonary artery pressure, which improved right ventricle function and the survival rate in rats with PH. Tissue and blood interleukin-1β levels decreased, whereas pulmonary artery cyclic adenosine monophosphate levels were restored by exendin-4. Smooth muscle-myosin heavy chain-II and α-smooth muscle actin protein levels increased in the pulmonary arteries of exendin-4-treated rats. Histology showed that exendin-4 decreased the main and intra-acinar pulmonary artery medial thickness.. Exendin-4 treatment improved pulmonary artery function in flow-induced PH via its direct vasoactive properties, anti-inflammatory effects, and vascular smooth muscle cell phenotypic modulation. Mitigation of pulmonary arteriopathy further potentiated right ventricle performance and reduced overall mortality. These responses were associated with suppressed expression and activity of interleukin-1β and its downstream signaling molecules. Glucagon-like peptide analogs may possess pleiotropic therapeutic potential in flow-induced PH.

Topics: Actins; Animals; Antihypertensive Agents; Aorta; Arterial Pressure; Arteriovenous Shunt, Surgical; Cyclic AMP; Disease Models, Animal; Exenatide; Hypertension, Pulmonary; Interleukin-1beta; Male; Monocrotaline; Myosin Heavy Chains; Myosin Type II; Phosphorylation; Pulmonary Artery; Pulmonary Circulation; Rats, Sprague-Dawley; Regional Blood Flow; Vascular Remodeling; Vena Cava, Inferior; Ventricular Function, Right

Myocardial infarction (MI) is one of the main causes of morbidity and mortality in diabetic patients. The antidiabetic glucagon-like polypeptide-1 receptor (GLP-1R) agonists, such as exenatide, proved to confer cardioprotection; however, their exact mechanisms are not fully elucidated. Although the cardioprotective effect of α-estrogen receptor (ERα) activation is well established, its involvement in exenatide-induced cardioprotection has never been investigated. Moreover, modulation of insulin-like growth factor-1/2 (IGF-1/IGF-2) system by exenatide, and the consequent effect on cardiomyocyte apoptosis, is yet to be established. Current study aimed to investigate the cardioprotective potential of exenatide versus the standard cardioprotective agent, 17β-estradiol, against isoprenaline (ISO)-induced MI in rats. MI-insulted group showed electrocardiographic abnormalities, elevated serum cardiac markers, higher serum IGF-2 level along with histopathological abnormalities. Treatment with exenatide and/or 17β-estradiol, commenced 8 weeks before ISO insult, ameliorated these anomalies with maximum cardioprotection achieved with combined treatment. This was associated with upregulation of both ERα and IGF-1R, and downregulation of IGF-2R in left ventricles. Inhibition of ERs in Langendorff preparations confirmed their involvement in mediating exenatide-induced cardioprotective effect. Current study showed that the GLP-1R agonist exenatide exerted cardioprotection associated with upregulation of ERα and modulation of IGF-1/IGF-2 signaling in favor of antiapoptosis.

Topics: Animals; Apoptosis; Cytoprotection; Disease Models, Animal; Estradiol; Estrogen Receptor alpha; Exenatide; Glucagon-Like Peptide-1 Receptor; Heart Rate; Insulin-Like Growth Factor I; Insulin-Like Growth Factor II; Isolated Heart Preparation; Isoproterenol; Male; Myocardial Infarction; Myocardium; Rats, Wistar; Receptor, IGF Type 1; Signal Transduction; Ventricular Function, Left

Brain derived neurotrophic factor (BDNF) is one of the most essential neurotrophic factors in the brain. BDNF is involved in learning, memory and locomotion suggesting it as a target in type 2 diabetes mellitus (T2DM) associated cognitive changes. Visfatin; an adipokine discovered to be expressed in the brain; was found to have multiple effects including its participation in keeping energy supply to the cell and is consequentially involved in cell survival. Its role in cognitive functions in T2DM was not studied before. Recent studies point to the possible neuro-protective mechanisms of glucagon-like peptide 1 analogue: Exendin-4 (Ex-4) in many cognitive disorders, but whether BDNF or Visfatin are involved or not in its neuro-protective mechanisms; is still unknown.. to study the changes in cognitive functions in T2DM, either not treated or treated with Glucagon-like peptide 1 (GLP-1) analogue: Ex-4, and to identify the possible underlying mechanisms of these changes and whether BDNF and brain Visfatin are involved.. A total of 36 adult male wistar albino rats were divided into 4 groups; Control, Exendin-4 control, Diabetic and Exendin-4 treated groups. At the end of the study, Y-maze and open field tests were done the day before scarification to assess spatial working memory and locomotion, respectively. Fasting glucose and insulin, lipid profile and tumor necrosis factor- alpha (TNF-α) were measured in the serum. Homeostasis model assessment insulin resistance was calculated. In the brain tissue, malondialdehyde (MDA) level, gene expression and protein levels of BDNF and Visfatin, area of degenerated neurons, area of glial cells and area % of synaptophysin immunoexpression were assessed.. Compared with the control, the untreated diabetic rats showed insulin resistance, dyslipidemia and elevation of serum TNF-α. The brain tissue showed down-regulation of BDNF gene expression and reduction of its protein level, up-regulation of Visfatin gene expression and elevation of its protein level, increase in MDA, area of degenerated neurons and area of glial cells and reduction in area % of synaptophysin immunoexpression. These changes were paralleled with significant deterioration in spatial working memory and locomotion. Treatment of diabetic rats with Ex-4 reversed all these changes.. T2DM has a negative impact on cognitive functions through different pathological and subcellular mechanisms. The current study provides evidence for involvement of BDNF and brain Visfatin in T2DM- associated cognitive dysfunction. BDNF and brain Visfatin were also found to contribute to the neuro-protective effect of Ex-4 via modulation of inflammation, oxidative stress, neuro-degeneration and synaptic function.

Topics: Animals; Anti-Obesity Agents; Brain; Brain-Derived Neurotrophic Factor; Cognition Disorders; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Male; Malondialdehyde; Nicotinamide Phosphoribosyltransferase; Rats; Rats, Wistar; Tumor Necrosis Factor-alpha

The aim of this article was to observe the intracellular insulin content of islets isolated from severely scalded and Exendin-4-treated rats and to evaluate the stimulation of insulin mRNA synthesis and secretion by β cells at different glucose concentrations and during different periods of time. A 50% TBSA full-thickness scalded rat model was used. Rats were treated with Exendin-4, followed by islet isolation and functional measurements. Serum was collected for detection of serum insulin, glucose, and glucagon levels. Intracellular insulin content was determined by transmission electron microscopy. Isolated islets were incubated with different glucose concentrations for 1 or 24 hours to assess the effect of scalding with or without Exendin-4 treatment on functional parameters. Insulin secretion was analyzed by enzyme-linked immunosorbent assay. Intracellular insulin and proinsulin content were analyzed by immunoprecipitation. Islet preproinsulin mRNA expression was examined by real-time polymerase chain reaction. Transmission electron microscopy analyses showed that severe thermal injury significantly reduced the number of insulin granules per micrometer2. Insulin secretion and intracellular insulin and proinsulin levels were markedly reduced in islets stimulated with different glucose concentrations; chronic high-glucose-stimulated islet preproinsulin mRNA expression was also impaired. Exendin-4 treatment after thermal trauma improved the number of intracellular insulin granules. Exendin-4 improved both insulin secretion and intracellular insulin reserves under different glucose stimulation conditions. Islet insulin mRNA expression was also restored by Exendin-4 treatment. Exendin-4 can restore the islet β cell insulin reserve following severe scald injury and may also improve insulin secretion, insulin reserve, and mRNA expression in islet β cells.

Topics: Animals; Blood Glucose; Burns; Disease Models, Animal; Exenatide; Glucagon; Insulin; Islets of Langerhans; Male; Rats; Rats, Wistar; RNA, Messenger

Current therapies for spinal cord injury (SCI) have limited efficacy, and identifying a therapeutic target is a pressing need. Sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) plays an important role in regulating calcium homeostasis, which has been shown to inhibit apoptosis. Exendin-4 has been shown to inhibit the apoptosis of nerve cells in SCI, which can also improve SERCA2 expression. In this study, we sought to determine whether exendin-4 plays a protective role in a rat model of SCI via SERCA2.. To investigate the effects of exendin-4 on SCI, a rat model of SCI was induced by a modified version of Allen's method. Spinal cord tissue sections from rats and western blot analysis were used to examine SERCA2 expression after treatment with the long-acting glucagon-like peptide 1 receptor exendin-4 or the SERCA2 antagonist 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CE). Locomotor function was evaluated using the Basso Beattie Bresnahan locomotor rating scale and slanting board test.. Cell apoptosis was increased with CE treatment and decreased with exendin-4 treatment. Upregulation of SERCA2 in female rats with SCI resulted in an improvement of motor function scores and histological changes.. These findings suggest that exendin-4 plays a protective role in a rat model of SCI through SERCA2 via inhibition of apoptosis. Existing drugs targeting SERCA2 may be an effective therapeutic strategy for the treatment of SCI.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Disease Models, Animal; Exenatide; Locomotion; Microscopy, Fluorescence; PC12 Cells; Peptides; Protective Agents; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Recovery of Function; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Signal Transduction; Spinal Cord Injuries; Venoms

Non-alcoholic fatty liver disease (NAFLD) is a common disease associated with metabolic syndrome and can lead to life-threatening complications like hepatic carcinoma and cirrhosis. Exenatide, a glucagon-like peptide-1 (GLP-1) receptor agonist antidiabetic drug, has the capacity to overcome insulin resistance and attenuate hepatic steatosis but the specific underlying mechanism is unclear. This study was designed to investigate the underlying molecular mechanisms of exenatide therapy on NAFLD. We used in vivo and in vitro techniques to investigate the protective effects of exenatide on fatty liver via fat mass and obesity associated gene (FTO) in a high-fat (HF) diet-induced NAFLD animal model and related cell culture model. Exenatide significantly decreased body weight, serum glucose, insulin, insulin resistance, serum free fatty acid, triglyceride, total cholesterol, low-density lipoprotein, aspartate aminotransferase, and alanine aminotransferase levels in HF-induced obese rabbits. Histological analysis showed that exenatide significantly reversed HF-induced lipid accumulation and inflammatory changes accompanied by decreased FTO mRNA and protein expression, which were abrogated by PI3K inhibitor LY294002. This study indicated that pharmacological interventions with GLP-1 may represent a promising therapeutic strategy for NAFLD.

Topics: Alpha-Ketoglutarate-Dependent Dioxygenase FTO; Animals; Blood Glucose; Body Weight; Chromones; Diet, High-Fat; Disease Models, Animal; Eating; Enzyme Inhibitors; Exenatide; Fatty Liver; Gene Expression Regulation; In Vitro Techniques; Insulin; Male; Malondialdehyde; Morpholines; Non-alcoholic Fatty Liver Disease; Obesity; Oxidative Stress; Peptides; Phosphatidylinositol 3-Kinases; Protective Agents; Rabbits; Superoxide Dismutase; Venoms

Long-acting glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) agonists (GLP-1RA), such as exendin-4 (Ex4), promote weight loss. On the basis of a newly discovered interaction between GLP-1 and oleoylethanolamide (OEA), we tested whether OEA enhances GLP-1RA-mediated anorectic signaling and weight loss. We analyzed the effect of GLP-1+OEA and Ex4+OEA on canonical GLP-1R signaling and other proteins/pathways that contribute to the hypophagic action of GLP-1RA (AMPK, Akt, mTOR, and glycolysis). We demonstrate that OEA enhances canonical GLP-1R signaling when combined with GLP-1 but not with Ex4. GLP-1 and Ex4 promote phosphorylation of mTOR pathway components, but OEA does not enhance this effect. OEA synergistically enhanced GLP-1- and Ex4-stimulated glycolysis but did not augment the hypophagic action of GLP-1 or Ex4 in lean or diet-induced obese (DIO) mice. However, the combination of Ex4+OEA promoted greater weight loss in DIO mice than Ex4 or OEA alone during a 7-day treatment. This was due in part to transient hypophagia and increased energy expenditure, phenotypes also observed in Ex4-treated DIO mice. Thus, OEA augments specific GLP-1RA-stimulated signaling but appears to work in parallel with Ex4 to promote weight loss in DIO mice. Elucidating cooperative mechanisms underlying Ex4+OEA-mediated weight loss could, therefore, be leveraged toward more effective obesity therapies.

Topics: AMP-Activated Protein Kinases; Animals; Anti-Obesity Agents; CHO Cells; Cricetulus; Diet, High-Fat; Disease Models, Animal; Drug Therapy, Combination; Endocannabinoids; Exenatide; Feeding Behavior; Glucagon-Like Peptide-1 Receptor; Glycolysis; Incretins; Male; Mice, Inbred C57BL; Obesity; Oleic Acids; Phosphorylation; Proto-Oncogene Proteins c-akt; Signal Transduction; TOR Serine-Threonine Kinases; Weight Loss

Preterm birth is the leading cause of neonatal morbidity and mortality worldwide. Inflammation is causally linked to preterm birth; therefore, finding an intervention that dampens maternal and fetal inflammatory responses may provide a new strategy to prevent adverse pregnancy and neonatal outcomes. Using animal models of systemic maternal inflammation [intraperitoneal injection of lipopolysaccharide (LPS)] and fetal inflammation (intra-amniotic administration of LPS), we found that (1) systemic inflammation induced adverse pregnancy and neonatal outcomes by causing a severe maternal cytokine storm and a mild fetal cytokine response; (2) fetal inflammation induced adverse pregnancy and neonatal outcomes by causing a mild maternal cytokine response and a severe fetal cytokine storm; (3) exendin-4 (Ex4) treatment of dams with systemic inflammation or fetal inflammation improved adverse pregnancy outcomes by modestly reducing the rate of preterm birth; (4) Ex4 treatment of dams with systemic, but not local, inflammation considerably improved neonatal outcomes, and such neonates continued to thrive; (5) systemic inflammation facilitated the diffusion of Ex4 through the uterus and the maternal-fetal interface; (6) neonates born to Ex4-treated dams with systemic inflammation displayed a similar cytokine profile to healthy control neonates; and (7) treatment with Ex4 had immunomodulatory effects by inducing an M2 macrophage polarization and increasing anti-inflammatory neutrophils, as well as suppressing the expansion of CD8+ regulatory T cells, in neonates born to dams with systemic inflammation. Collectively, these results provide evidence that dampening maternal systemic inflammation through novel interventions, such as Ex4, can improve the quality of life for neonates born to women with this clinical condition.

Topics: Animals; Animals, Newborn; Cytokines; Disease Models, Animal; Exenatide; Female; Fetus; Gene Expression; Immunomodulation; Inflammation; Inflammation Mediators; Male; Mice; Neutrophils; Pregnancy; Pregnancy Complications; Pregnancy Outcome; Premature Birth; T-Lymphocyte Subsets; Tissue Distribution

We previously demonstrated that pretreatment with Exendin-4, a glucagon-like peptide-1 (GLP-1) receptor agonist, reduces 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) -mediated dopaminergic neurodegeneration. The use of GLP-1 or Exendin-4 for Parkinson's disease (PD) patients is limited by their short half-lives. The purpose of this study was to evaluate a new extended release Exendin-4 formulation, PT302, in a rat model of PD. Subcutaneous administration of PT302 resulted in sustained elevations of Exendin-4 in plasma for >20 days in adult rats. To define an efficacious dose within this range, rats were administered PT302 once every 2 weeks either before or following the unilaterally 6-hydroxydopamine lesioning. Pre- and post-treatment with PT302 significantly reduced methamphetamine-induced rotation after lesioning. For animals given PT302 post lesion, blood and brain samples were collected on day 47 for measurements of plasma Exendin-4 levels and brain tyrosine hydroxylase immunoreactivity (TH-IR). PT302 significantly increased TH-IR in the lesioned substantia nigra and striatum. There was a significant correlation between plasma Exendin-4 levels and TH-IR in the substantia nigra and striatum on the lesioned side. Our data suggest that post-treatment with PT302 provides long-lasting Exendin-4 release and reduces neurodegeneration of nigrostriatal dopaminergic neurons in a 6-hydroxydopamine rat model of PD at a clinically relevant dose.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Corpus Striatum; Delayed-Action Preparations; Disease Models, Animal; Dopaminergic Neurons; Dose-Response Relationship, Drug; Drug Administration Schedule; Exenatide; Humans; Incretins; Male; Oxidopamine; Parkinson Disease, Secondary; Rats; Rats, Sprague-Dawley; Substantia Nigra; Treatment Outcome; Tyrosine 3-Monooxygenase

The phenotype switching of vascular smooth muscle cells (VSMCs) plays a key role during development and progression of vascular remodeling diseases. Recent studies show that GLP-1 can inhibit intima thickening to delay the progression of atherosclerotic plaques. The purpose of this study was to investigate the role of Exendin-4, a GLP-1 receptor agonist, in VSMCs phenotype switching and the related mechanisms.. Immunohistochemistry and Western blot were used to detect the effect of Exendin-4 on expression of markers of contractile VSMCs. Phalloidin staining was performed to observe the effect of Exendin-4 on morphology of VSMCs.. Exendin-4 significantly increased the protein levels of contractile VSMCs markers like Calponin and SM22α. After treatment of Exendin-4, VSMCs showed more typical characteristic spindle shape. In addition, Exendin-4 significantly upregulated the phosphorylation of AMPK as well as the protein levels of Sirtuin1 (SIRT1) and FOXO3a in VSMCs. After inhibiting AMPK activity with compound C and SIRT1 activity with EX527, and knocking down FOXO3a expression through RNAi technique, Exendin-4 increased the protein levels of Calponin and SM22α and promoted the redifferentiation of VSMCs mainly through AMPK/SIRT1/FOXO3a signaling pathways.. Exendin-4 can regulate the phenotype switching of VSMCs and promote redifferentiation of VSMCs through AMPK/SIRT1/FOXO3a signaling pathways.

Topics: Actins; AMP-Activated Protein Kinases; Animals; Biomarkers; Calcium-Binding Proteins; Calponins; Carotid Artery Injuries; Cell Differentiation; Cell Plasticity; Cell Shape; Cells, Cultured; Disease Models, Animal; Exenatide; Forkhead Box Protein O3; Male; Microfilament Proteins; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phenotype; Phosphorylation; Rats, Sprague-Dawley; Signal Transduction; Sirtuin 1

There is a need for pharmaceutical agents that can reduce neuronal loss and improve functional deficits following traumatic brain injury (TBI). Previous research suggests that oxidative stress and mitochondrial dysfunction play a major role in neuronal damage after TBI. Therefore, this study aimed to investigate two drugs known to have antioxidant effects, L-carnitine and exendin-4, in rats with moderate contusive TBI. L-carnitine (1.5 mM in drinking water) or exendin-4 (15 µg/kg/day, ip) were given immediately after the injury for 2 weeks. Neurological function and brain histology were examined (24 h and 6 weeks post injury). The rats with TBI showed slight sensory, motor and memory functional deficits at 24 h, but recovered by 6 weeks. Both treatments improved sensory and motor functions at 24 h, while only exendin-4 improved memory. Both treatments reduced cortical contusion at 24 h and 6 weeks, however neither affected gliosis and inflammatory cell activation. Oxidative stress was alleviated and mitochondrial reactive oxygen species was reduced by both treatments, however only mitochondrial functional marker protein transporter translocase of outer membrane 20 was increased at 24 h post injury. In conclusion, L-carnitine and exendin-4 treatments immediately after TBI can improve neurological functional outcome and tissue integrity by reducing oxidative stress.

Topics: Animals; Antioxidants; Brain; Brain Contusion; Brain Injuries, Traumatic; Carnitine; Disease Models, Animal; Exenatide; Mitochondria; Neurons; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species

Hypoxic-ischaemic encephalopathy remains a global health burden. Despite medical advances and treatment with therapeutic hypothermia, over 50% of cooled infants are not protected and still develop lifelong neurodisabilities, including cerebral palsy. Furthermore, hypothermia is not used in preterm cases or low resource settings. Alternatives or adjunct therapies are urgently needed. Exendin-4 is a drug used to treat type 2 diabetes mellitus that has also demonstrated neuroprotective properties, and is currently being tested in clinical trials for Alzheimer's and Parkinson's diseases. Therefore, we hypothesized a neuroprotective effect for exendin-4 in neonatal neurodisorders, particularly in the treatment of neonatal hypoxic-ischaemic encephalopathy. Initially, we confirmed that the glucagon like peptide 1 receptor (GLP1R) was expressed in the human neonatal brain and in murine neurons at postnatal Day 7 (human equivalent late preterm) and postnatal Day 10 (term). Using a well characterized mouse model of neonatal hypoxic-ischaemic brain injury, we investigated the potential neuroprotective effect of exendin-4 in both postnatal Day 7 and 10 mice. An optimal exendin-4 treatment dosing regimen was identified, where four high doses (0.5 µg/g) starting at 0 h, then at 12 h, 24 h and 36 h after postnatal Day 7 hypoxic-ischaemic insult resulted in significant brain neuroprotection. Furthermore, neuroprotection was sustained even when treatment using exendin-4 was delayed by 2 h post hypoxic-ischaemic brain injury. This protective effect was observed in various histopathological markers: tissue infarction, cell death, astrogliosis, microglial and endothelial activation. Blood glucose levels were not altered by high dose exendin-4 administration when compared to controls. Exendin-4 administration did not result in adverse organ histopathology (haematoxylin and eosin) or inflammation (CD68). Despite initial reduced weight gain, animals restored weight gain following end of treatment. Overall high dose exendin-4 administration was well tolerated. To mimic the clinical scenario, postnatal Day 10 mice underwent exendin-4 and therapeutic hypothermia treatment, either alone or in combination, and brain tissue loss was assessed after 1 week. Exendin-4 treatment resulted in significant neuroprotection alone, and enhanced the cerebroprotective effect of therapeutic hypothermia. In summary, the safety and tolerance of high dose exendin-4 administrations, combined with its

Topics: Animals; Animals, Newborn; Brain; Disease Models, Animal; Exenatide; Humans; Hypothermia, Induced; Hypoxia-Ischemia, Brain; Mice; Neuroprotective Agents

Epidemiological studies have demonstrated a close association of type 2 diabetes and hepatocellular carcinoma (HCC). Exenatide (Ex-4), a potent diabetes drug targeting glucagon-like peptide-1 receptor (GLP-1R), is protective against non-alcoholic fatty liver disease (NAFLD). However, the Ex-4 function and GLP-1R status have yet been explored in HCC. Herein we investigated the effect of Ex-4 in diethylnitrosamine (DEN)-treated mice consuming control or high-fat high-carbohydrate diet. Administration of Ex-4 significantly improved obesity-induced hyperglycemia and hyperlipidemia and reduced HCC multiplicity in obese DEN-treated mice, in which suppressed proliferation and induced apoptosis were confined to tumor cells. The tumor suppression effects of Ex-4 were associated with high expression of GLP-1R and activation of cyclic AMP (cAMP) and protein kinase A (PKA). Importantly, Ex-4 also downregulated epidermal growth factor receptor (EGFR) and signal transducer and activator of transcription 3 (STAT3), which lie downstream of cAMP-PKA signaling, resulting in suppression of multiple STAT3-targeted genes including c-Myc, cyclin D1, survivin, Bcl-2 and Bcl-xl. The growth inhibitory effects of Ex-4 were consistent in GLP-1R-abundant hepatoma cell lines and xenograft mouse model, wherein both PKA and EGFR had obligatory roles in mediating Ex-4 functions. In addition, Ex-4 also effectively suppressed inflammatory and fibrotic phenotypes in mice fed with methionine-choline-deficient (MCD) diet and choline-deficient ethionine-supplemented (CDE) diet, respectively. In summary, Ex-4 elicits protective functions against NAFLD and obesity-associated HCC through cAMP-PKA-EGFR-STAT3 signaling, suggesting its administration as a novel approach to reduce HCC risk in diabetic patients.

Topics: Animals; Cyclic AMP; Diabetes Mellitus, Type 2; Disease Models, Animal; ErbB Receptors; Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Hyperglycemia; Liver Neoplasms; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred C57BL; Mice, Obese; Peptides; Risk Factors; Signal Transduction; STAT3 Transcription Factor; Venoms; Xenograft Model Antitumor Assays

Dipeptidyl peptidase-4 (DPP-4) inhibitors have various cellular effects that are associated with vascular protection. Here, we examined whether teneligliptin alters the pro-inflammatory phenotype of perivascular adipose tissue (PVAT) and inhibits atherogenesis.. Teneligliptin (60mg/kg/day) was administered orally to apolipoprotein-E-deficient (ApoE. Teneligliptin inhibited atherogenesis with attenuation of the inflammatory phenotype in PVAT. A GLP-1 analog suppressed pro-inflammatory activation of macrophages and adipocytes. Suppression of the pro-inflammatory phenotype of PVAT might contribute, at least partially, to the cardioprotective effects of teneligliptin.

Topics: 3T3-L1 Cells; Adipose Tissue; Animals; Anti-Inflammatory Agents; Aorta; Aortic Diseases; Apolipoproteins E; Atherosclerosis; Cytokines; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Exenatide; Female; Genetic Predisposition to Disease; Incretins; Inflammation Mediators; Macrophage Activation; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oxidative Stress; Peptides; Phenotype; Plaque, Atherosclerotic; Pyrazoles; RAW 264.7 Cells; Signal Transduction; Thiazolidines; Time Factors; Vasodilation; Venoms

Radiolabeled GLP-1 and its analog Exendin-4, have been employed in diabetes and insulinoma. No protocol in conventional Diet-Induced Obesity (DIO), and Diet-Restricted Obesity (DRO), has been identified. Aiming to assess pancreatic beta cell uptake in DIO and DRO, a protocol was designed.. GLP-1-βAla-HYNIC and HYNIC-βAla-Exendin-4 were labeled with technetium-99m. Four Swiss mouse models were adopted: Controls (C), Alloxan Diabetes Controls (ADC), DIO and DRO. Biodistribution and ex-vivo planar imaging were documented.. Radiolabeling yield was in the range of 97% and both agents were hydrophilic. Fasting Blood Glucose (FBG) was 79.2±8.2mg/dl in C, 590.4±23.3mg/dl in ADC, 234.3±66.7mg/dl in DIO, and 96.6±9.3 in DRO (p=0.010). Biodistribution confirmed predominantly urinary excretion. DIO mice exhibited depressed uptake in liver and pancreas, for both radiomarkers, in the range of ADC. DRO only partially restored such values.. 1) Diet-induced obesity remarkably depressed beta cell uptake; 2) Restriction of obesity failed to normalize uptake, despite robust improvement of FBG; 3) HYNIC-βAla-Exendin-4 was the most useful marker; 4) Further studies are recommended in obesity and dieting, including bariatric surgery.

Topics: Amino Acid Sequence; Animals; Biological Transport; Diet; Disease Models, Animal; Exenatide; Female; Glucagon-Like Peptide 1; Isotope Labeling; Liver; Mice; Obesity; Pancreas; Peptides; Tissue Distribution; Venoms

Recent studies have indicated that lipid-induced endoplasmic reticulum (ER) stress is a major contributor to the progression of hepatic steatosis. Exenatide (exendin-4), a glucagon-like peptide-1 receptor agonist, is known to improve hepatic steatosis, with accumulating evidence. In this study, we investigated whether exenatide could alleviate lipid-induced hepatic ER stress through mammal sirtuin 1 (SIRT1) and illustrated the detailed mechanisms. Male C57BL/6J mice challenged with a high-fat diet (HFD) were treated with exenatide or normal saline by intraperitoneal injection for 4 weeks. We observed that HFD feeding induced hepatic ER stress as indicated by increased expression of glucose-regulated protein 78, phosphorylated protein kinase-like ER kinase, and phosphorylated eukaryotic initiation factor 2α, while these increases were significantly inhibited by exenatide. Exenatide notably decreased the liver weight and hepatic steatosis induced by HFD challenge. Consistently, in human HepG2 cells and primary murine hepatocytes, exendin-4 also significantly alleviated the ER stress and lipid accumulation induced by palmitate. Importantly, further studies showed that exendin-4 enhanced the binding of heat shock factor 1 to the promoter of heat shock protein (HSP) genes through SIRT1-mediated deacetylation, which then increased the expression of molecular chaperones HSP70 and HSP40 to alleviate hepatic ER stress. Finally, inhibition of SIRT1 by genetic whole-body heterozygous knockout or by lentiviral short hairpin RNA knockdown greatly diminished the effect of exenatide on deacetylating heat shock factor 1, increasing HSP expression and alleviating ER stress and hepatic steatosis in HFD-fed mice.. The SIRT1/heat shock factor 1/HSP pathway is essential for exenatide-alleviated, lipid-induced ER stress and hepatic steatosis, which provides evidence for a molecular mechanism to support exenatide and incretin mimetics as promising therapeutics for obesity-induced hepatic steatosis. (Hepatology 2017;66:809-824).

Topics: Animals; Blood Glucose; Cells, Cultured; Diet, High-Fat; Disease Models, Animal; Endoplasmic Reticulum Stress; Exenatide; Fatty Liver; Heat-Shock Proteins; Hepatocytes; Humans; Lipid Metabolism; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Peptides; Random Allocation; Sensitivity and Specificity; Signal Transduction; Sirtuin 1; Venoms

Mild blast traumatic brain injury (B-TBI) induced lasting cognitive impairments in novel object recognition and less severe deficits in Y-maze behaviors. B-TBI significantly reduced the levels of synaptophysin (SYP) protein staining in cortical (CTX) and hippocampal (HIPP) tissues. Treatment with exendin-4 (Ex-4) delivered by subcutaneous micro-osmotic pumps 48 hours prior to or 2 hours immediately after B-TBI prevented the induction of both cognitive deficits and B-TBI induced changes in SYP staining. The effects of a series of biaxial stretch injuries (BSI) on a neuronal derived cell line, HT22 cells, were assessed in an in vitro model of TBI. Biaxial stretch damage induced shrunken neurites and cell death. Treatment of HT22 cultures with Ex-4 (25 to 100 nM), prior to injury, attenuated the cytotoxic effects of BSI and preserved neurite length similar to sham treated cells. These data imply that treatment with Ex-4 may represent a viable option for the management of secondary events triggered by blast-induced, mild traumatic brain injury that is commonly observed in militarized zones.

Topics: Animals; Blast Injuries; Brain Injuries, Traumatic; Cell Line; Cognitive Dysfunction; Disease Models, Animal; Exenatide; Hippocampus; Male; Mice; Synaptophysin

Exenatide and cyclosporine A have been shown to moderately protect against myocardial reperfusion injury leading to reduction of infarct size in patients. Our objective was to investigate whether the combined treatment with exenatide (glucagon-like peptide 1 receptor agonist) and cyclosporine A or parstatin 1-26 (inhibitors of mitochondrial permeability transition pore and/or inflammation) is more beneficial than either agent alone. Rabbits underwent 40 minutes of ischemia and 120 minutes of reperfusion. Intravenous bolus administration of exenatide or cyclosporine A, 10 minutes before reperfusion, reduced infarct size by 38% (P < 0.05) and 40% (P < 0.05), and cardiac troponin I (cTnI) plasma levels by 48% (P < 0.05) and 36% (P < 0.05), respectively, compared with control. The combined administration of both agents resulted in an additive decrease of infarct size by 55% (P < 0.05) and cTnI release by 61% (P < 0.05). Also, combined treatment of exenatide and parstatin 1-26 enhanced infarct size reduction (62%, P < 0.05), compared with monotherapies (41% for parstatin 1-26, P < 0.05; 43% for exenatide, P < 0.05). In contrast, the combined administration of parstatin 1-26 and cyclosporine A canceled out the cardioprotective effects observed by monotherapies. These results suggest that, for the therapy of myocardial reperfusion injury the combined administration of exenatide and cyclosporine A or parstatin 1-26 is more effective than monotherapies and may provide advantageous clinical outcome.

Topics: Animals; Cyclosporine; Disease Models, Animal; Drug Therapy, Combination; Exenatide; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Peptide Fragments; Peptides; Rabbits; Receptor, PAR-1; Venoms

Exposure to psychosocial stress is a risk factor for cardiovascular disorders. Because the glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) agonist prevents cardiovascular injury, we investigated the beneficial effects and mechanism of the GLP-1 analogue exenatide on stress-related vascular senescence and atherosclerosis in apolipoprotein E-deficient (ApoE. ApoE. Chronic stress enhanced vascular endothelial senescence and atherosclerotic plaque growth. The stress increased the levels of plasma depeptidyl peptidase-4 activity and decreased the levels of plasma GLP-1 and both plasma and adipose adiponectin (APN). As compared with the mice subjected to stress alone, the exenatide-treated mice had decreased plaque microvessel density, macrophage accumulation, broken elastin, and enhanced plaque collagen volume, and lowered levels of peroxisome proliferator-activated receptor-α, gp91phox osteopontin, C-X-C chemokine receptor-4, toll-like receptor-2 (TLR2), TLR4, and cathepsins K, L, and S mRNAs and/or proteins. Exenatide reduced aortic matrix metalloproteinase-9 (MMP-9) and MMP-2 gene expression and activities. Exenatide also stimulated APN expression of preadipocytes and inhibited ox-low density lipoprotein-induced foam cell formation of monocytes in stressed mice.. These results indicate that the exenatide-mediated beneficial vascular actions are likely attributable, at least in part, to the enhancement of APN production and the attenuation of plaque oxidative stress, inflammation, and proteolysis in ApoE

Topics: Adiponectin; Age Factors; Animals; Aorta; Aortic Diseases; Atherosclerosis; Cells, Cultured; Cellular Senescence; Chronic Disease; Diet, High-Fat; Dipeptidyl Peptidase 4; Disease Models, Animal; Endothelial Cells; Exenatide; Foam Cells; Genetic Predisposition to Disease; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Incretins; Inflammation Mediators; Male; Mice, Knockout, ApoE; Oxidative Stress; Peptide Hydrolases; Peptides; Phenotype; Plaque, Atherosclerotic; Proteolysis; Signal Transduction; Stress, Psychological; Venoms

Current therapies for reducing raised intracranial pressure (ICP) under conditions such as idiopathic intracranial hypertension or hydrocephalus have limited efficacy and tolerability. Thus, there is a pressing need to identify alternative drugs. Glucagon-like peptide-1 receptor (GLP-1R) agonists are used to treat diabetes and promote weight loss but have also been shown to affect fluid homeostasis in the kidney. We investigated whether exendin-4, a GLP-1R agonist, is able to modulate cerebrospinal fluid (CSF) secretion at the choroid plexus and subsequently reduce ICP in rats. We used tissue sections and cell cultures to demonstrate expression of GLP-1R in the choroid plexus and its activation by exendin-4, an effect blocked by the GLP-1R antagonist exendin 9-39. Acute treatment with exendin-4 reduced Na

Topics: Animals; Choroid Plexus; Consciousness; Cyclic AMP; Disease Models, Animal; Exenatide; Female; Glucagon-Like Peptide-1 Receptor; Humans; Hydrocephalus; Intracranial Pressure; Peptides; Postmortem Changes; Rats, Sprague-Dawley; RNA, Messenger; Sodium-Potassium-Exchanging ATPase; Venoms

Perturbations in hepatic lipid and very-low-density lipoprotein (VLDL) metabolism are involved in the pathogenesis of obesity and hepatic insulin resistance. The objective of this study is to delineate the mechanism of subdiaphragmatic vagotomy in preventing obesity, hyperlipidemia, and insulin resistance.. By subjecting the complete subdiaphragmatic vagotomized mice to various nutritional conditions and investigating hepatic de novo lipogenesis pathway, we found that complete disruption of subdiaphragmatic vagal signaling resulted in a significant decrease of circulating VLDL-triglyceride compared with the mice obtained sham procedure. Vagotomy further prevented overproduction of VLDL-triglyceride induced by an acute fat load and a high-fat diet-induced obesity, hyperlipidemia, hepatic steatosis, and glucose intolerance. Mechanistic studies revealed that plasma glucagon-like peptide-1 was significantly raised in the vagotomized mice, which was associated with significant reductions in mRNA and protein expression of SREBP-1c (sterol regulatory element-binding protein 1c), SCD-1 (stearoyl-CoA desaturase-1), and FASN (fatty acid synthase), as well as enhanced hepatic insulin sensitivity. In vitro, treating mouse primary hepatocytes with a glucagon-like peptide-1 receptor agonist, exendin-4, for 48 hours inhibited free fatty acid, palmitic acid treatment induced de novo lipid synthesis, and VLDL secretion from hepatocytes.. Elevation of glucagon-like peptide-1 in vagotomized mice may prevent VLDL overproduction and insulin resistance induced by high-fat diet. These novel findings, for the first time, delineate an intrinsic gut-liver regulatory circuit that is mediated by glucagon-like peptide-1 in regulating hepatic energy metabolism.

Topics: Animals; Biomarkers; Blood Glucose; Cells, Cultured; Diet, High-Fat; Disease Models, Animal; Exenatide; Fatty Acid Synthase, Type I; Fatty Liver; Gene Expression Regulation; Glucagon-Like Peptide 1; Hepatocytes; Hyperlipidemias; Incretins; Insulin; Insulin Resistance; Intestinal Mucosa; Intestines; Lipoproteins, VLDL; Liver; Male; Mice, Inbred C57BL; Obesity; Peptides; RNA, Messenger; Signal Transduction; Stearoyl-CoA Desaturase; Sterol Regulatory Element Binding Protein 1; Time Factors; Triglycerides; Up-Regulation; Vagotomy; Vagus Nerve; Venoms

Enhancement of glucagon-like peptide-1 (GLP-1) reduces glucose levels and preserves pancreatic β-cell function, but its effect against restenosis is unknown.. We investigated the effect of subcutaneous injection of exenatide or local delivery of a recombinant adenovirus expressing GLP-1 (rAd-GLP-1) into carotid artery, in reducing the occurrence of restenosis following balloon injury. As a control, we inserted β-galactosidase cDNA in the same vector (rAd-βGAL). Otsuka Long-Evans Tokushima rats were assigned to three groups (n = 12 each): (1) normal saline plus rAd-βGAL delivery (NS + rAd-βGAL), (2) exenatide plus rAd-βGAL delivery (Exenatide + rAd-βGAL), and (3) normal saline plus rAd-GLP-1 delivery (NS + rAd-GLP-1). Normal saline or exenatide were administered subcutaneously from 1 week before to 2 weeks after carotid injury. After 3 weeks, the NS + rAd-βGAL group showed the highest intima-media ratio (IMR; 3.73 ± 0.90), the exenatide + rAd-βGAL treatment was the next highest (2.80 ± 0.51), and NS + rAd-GLP-1 treatment showed the lowest IMR (1.58 ± 0.48, P < 0.05 vs. others). The proliferation and migration of vascular smooth muscle cells and monocyte adhesion were decreased significantly after rAd-GLP-1 treatment, showing the same overall patterns as the IMR. In injured vessels, the apoptosis was greater and MMP2 expression was less in the NS + rAd-GLP-1 than in the exenatide or rAd-βGAL groups. In vitro expressions of matrix metalloproteinases-2 and monocyte chemoattractant protein-1 and nuclear factor-kappa-B-p65 translocation were decreased more in the NS + rAd-GLP-1 group than in the other two groups (all P < 0.05).. Direct GLP-1 overexpression showed better protection against restenosis after balloon injury via suppression of vascular smooth muscle cell migration, increased apoptosis, and decreased inflammatory processes than systemic exenatide treatment. This has potential therapeutic implications for treating macrovascular complications in diabetes.

Topics: Adenoviridae; Animals; Apoptosis; Carotid Artery Injuries; Carotid Artery, External; Cell Adhesion; Cell Movement; Cell Proliferation; Cells, Cultured; Coronary Stenosis; Diabetes Mellitus; Disease Models, Animal; Exenatide; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Glucagon-Like Peptide 1; Human Umbilical Vein Endothelial Cells; Hypoglycemic Agents; Incretins; Male; Matrix Metalloproteinase 2; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neointima; Peptides; Rats, Inbred OLETF; Transcription Factor RelA; Transfection; Venoms

Exenatide exerts cardioprotective effects by attenuating ischaemic reperfusion (IR) injury, possibly through activating the opening of mitochondrial ATP-sensitive potassium channels. We used atomic force microscopy (AFM) to investigate changes in mitochondrial morphology and properties in order to assess exenatide-mediated cardioprotection in IR injury.. We used an in vivo Sprague-Dawley rat IR model and ex vivo Langendorff injury model. In the left anterior descending artery (LAD) occlusion model, animals were randomly divided into three groups: sham-operated rats (Sham, n=5), IR-injured rats treated with placebo (IR, n=6), and IR-injured treated with exenatide (IR + EXE, n=6). For the Langendorff model, rats were randomly divided into two groups: IR injury with placebo (IR, n=4) and IR injury with exenatide (IR+EXE, n=4). Morphological and mechanical changes of mitochondria were analysed by AFM.. Exenatide pre-treatment improved cardiac function as evidenced by improvement in echocardiographic results. The ratio of infarct area (IA) to risk area (RA) was significantly reduced in exenatide-treated rats. According to AFM, IR significantly increased the area of isolated mitochondria, indicative of mitochondrial swelling. Treatment with exenatide reduced the mitochondrial area and ameliorated the adhesion force of mitochondrial surfaces.. Exenatide pre-treatment improves morphological and mechanical characteristics of mitochondria in response to IR injury in a rat model. These alterations in mitochondrial characteristics appear to play a cardioprotective role against IR injury.

Topics: Animals; Disease Models, Animal; Echocardiography; Exenatide; Male; Microscopy, Atomic Force; Mitochondria, Heart; Myocardial Reperfusion Injury; Peptides; Rats; Rats, Sprague-Dawley; Venoms

We have demonstrated that glucagon like peptide-1 (GLP-1) protects the heart against ischemic injury. However, the physiological mechanism by which GLP-1 receptor (GLP-1R) initiates cardioprotection remains to be determined. The objective of this study is to elucidate the functional roles of MAPK kinase 3 (MKK3) and Akt-1 in mediating exendin-4-elicited protection in the infarcted hearts. Adult mouse myocardial infarction (MI) was created by ligation of the left descending artery. Wild-type, MKK3(-/-), Akt-1(-/-), and Akt-1(-/-);MKK3(-/-) mice were divided into one of several groups: 1) sham: animals underwent thoracotomy without ligation; 2) MI: animals underwent MI and received a daily dose of intraperitoneal injection of vehicle (saline); 3) MI + exendin-4: infarcted mice received daily injections of exendin-4, a GLP-1R agonist (0.1 mg/kg, ip). Echocardiographic measurements indicate that exendin-4 treatment resulted in the preservation of ventricular function and increases in the survival rate, but these effects were diminished in MKK3(-/-), Akt-1(-/-), and Akt-1(-/-);MKK3(-/-) mice. Exendin-4 treatments suppressed cardiac hypotrophy and reduced scar size and cardiac interstitial fibrosis, respectively, but these beneficial effects were lost in genetic elimination of MKK3, Akt-1, or Akt-1(-/-);MKK3(-/-) mice. GLP-1R stimulation stimulated angiogenic responses, which were also mitigated by deletion of MKK3 and Akt-1. Exendin-4 treatment increased phosphorylation of MKK3, p38, and Akt-1 at Ser129 but decreased levels of active caspase-3 and cleaved poly (ADP-ribose) polymerase; these proteins were diminished in MKK3(-/-), Akt-1(-/-), and Akt-1(-/-);MKK3(-/-) mice. These results reveal that exendin-4 treatment improves cardiac function, attenuates cardiac remodeling, and promotes angiogenesis in the infarcted myocardium through MKK3 and Akt-1 pathway.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Cardiomegaly; Cardiotonic Agents; Disease Models, Animal; Enzyme Activation; Exenatide; Fibrosis; MAP Kinase Kinase 3; Mice, Inbred C57BL; Mice, Knockout; Myocardial Infarction; Myocardium; Neovascularization, Physiologic; Peptides; Phosphorylation; Proto-Oncogene Proteins c-akt; Signal Transduction; Stroke Volume; Time Factors; Venoms; Ventricular Function, Left; Ventricular Remodeling

Insulin resistance and hyperandrogenism are the main features of polycystic ovarian syndrome (PCOS). Low-grade inflammation is also involved in PCOS. This study was performed to evaluate the effect of exenatide on metabolic changes, sexual hormones, inflammatory cytokines, adipokines, and weight changes in a dehydroepiandrosterone (DHEA)-treated rat model. After the model was produced by daily subcutaneous injections of DHEA, rats were given metformin (265 mg/kg), exenatide (10 μg/kg), and saline (1 mL). One group served as a control group. Blood samples and ovarian tissues were removed and prepared for biochemical and hormonal analyses. Exenatide significantly reduced body weight and insulin, testosterone, interleukin 6 (IL-6), PEDF, and visfatin levels. Exenatide also ameliorated changes in ovarian morphology, as evidenced by decreased numbers of cystic follicles and various follicles and elevated numbers of granular cell layers. The effects observed with exenatide were comparable to those observed with metformin. This study has provided evidence that exenatide may be efficient in the treatment of PCOS.

Topics: Adipokines; Animals; Body Weight; Cytokines; Dehydroepiandrosterone; Disease Models, Animal; Exenatide; Female; Gonadal Steroid Hormones; Inflammation Mediators; Metformin; Ovary; Peptides; Polycystic Ovary Syndrome; Rats; Rats, Sprague-Dawley; Venoms

To investigate whether a glucagon-like peptide-1 (GLP-1) analogue inhibits nonalcoholic steatohepatitis (NASH), which is being increasingly recognized in Asia, in non-obese mice.. A methionine-choline-deficient diet (MCD) along with exendin-4 (20 μg/kg per day, ip), a GLP-1 analogue, or saline was administered to male db/db mice (non-obese NASH model). Four or eight weeks after commencement of the diet, the mice were sacrificed and their livers were excised. The excised livers were examined by histochemistry for evidence of hepatic steatosis and inflammation. Hepatic triglyceride (TG) and free fatty acid (FFA) content was measured, and the expression of hepatic fat metabolism- and inflammation-related genes was evaluated. Oxidative stress-related parameters and macrophage recruitment were also examined using immunohistochemistry.. Four weeks of MCD feeding induced hepatic steatosis and inflammation and increased the hepatic TG and FFA content. The expression of fatty acid transport protein 4 (FATP4), a hepatic FFA influx-related gene; macrophage recruitment; and the level of malondialdehyde (MDA), an oxidative stress marker, were significantly augmented by a 4-wk MCD. The levels of hepatic sterol regulatory element-binding protein-1c (SREBP-1c) mRNA (lipogenesis-related gene) and acyl-coenzyme A oxidase 1 (ACOX1) mRNA (β-oxidation-related gene) had decreased at 4 wk and further decreased at 8 wk. However, the level of microsomal triglyceride transfer protein mRNA (a lipid excretion-related gene) remained unchanged. The administration of exendin-4 significantly attenuated the MCD-induced increase in hepatic steatosis, hepatic TG and FFA content, and FATP4 expression as well as the MCD-induced augmentation of hepatic inflammation, macrophage recruitment, and MDA levels. Additionally, it further decreased the hepatic SREBP-1c level and alleviated the MCD-mediated inhibition of the ACOX1 mRNA level.. These results suggest that GLP-1 inhibits hepatic steatosis and inflammation through the inhibition of hepatic FFA influx and oxidative stress in a non-obese NASH model.

Topics: Acyl-CoA Oxidase; Animals; Biomarkers; Disease Models, Animal; Exenatide; Fatty Acid Transport Proteins; Fatty Acids, Nonesterified; Gene Expression Regulation; Glucagon-Like Peptide 1; Inflammation Mediators; Liver; Macrophages; Male; Mice, Inbred NOD; Non-alcoholic Fatty Liver Disease; Oxidative Stress; Peptides; Sterol Regulatory Element Binding Protein 1; Time Factors; Triglycerides; Venoms

Admission hyperglycemia is an independent risk factor for poor outcome of ischemic stroke. Amelioration of hyperglycemia by insulin has not been shown to improve the poststroke outcome. Glucagon-like peptide 1 receptor agonists, which modulate glucose levels by stimulating insulin secretion, have been shown to exert cytoprotective effects by inhibiting inflammation and oxidative stress. This study aimed to evaluate whether the glucagon-like peptide 1 receptor agonist exendin-4 could reduce glucose levels and exert protective effects after acute focal ischemia in hyperglycemic mice.. Hyperglycemia was induced by intraperitoneal injection of dextrose 15 minutes before transient middle cerebral artery occlusion was performed for 60 minutes using an intraluminal thread. We assessed 4 groups: (1) normal glucose (vehicle control), (2) induced hyperglycemia, (3) induced hyperglycemia with insulin treatment, and (4) induced hyperglycemia with exendin-4 treatment. Neurovascular injuries in brains from each group were evaluated 24 hours and 7 days post ischemia.. Hyperglycemia significantly increased infarct volume (36.3±1.20 versus 26.9±1.28; P<0.001), brain edema (P<0.05), and hemorrhagic transformation compared with control (P<0.001). This increase in infarct volume was associated with increased blood-brain barrier disruption and matrix metalloproteinase-9 activation. Exendin-4, but not insulin, attenuated matrix metalloproteinase-9 activation, proinflammatory cytokine (tumor necrosis factor-α) release, and biomarkers of oxidative stress and showed significant inhibition of infarct growth at 24 hours (23.6±0.97 versus 36.3±1.20; P<0.001) and at 7 days after ischemia (21.0±0.92 versus 29.3±1.41; P<0.001).. Treatment with exendin-4 could be a potentially useful therapeutic option for treatment of acute ischemic stroke with transient hyperglycemia.

Topics: Animals; Blood-Brain Barrier; Brain Ischemia; Disease Models, Animal; Exenatide; Hyperglycemia; Hypoglycemic Agents; Infarction, Middle Cerebral Artery; Male; Matrix Metalloproteinase 9; Mice, Inbred C57BL; Peptides; Venoms

Maternal obesity is associated with an increased risk of chronic disease in offspring, including type 2 diabetes (T2D). Exendin-4 (Exd-4) activates the glucagon like peptide-1 (GLP-1) receptor thereby decreasing serum glucose levels and body weight. In addition, Exd-4 has been shown to reduce renal and cardiac complications in experimental models of T2D. We hypothesized that treatment with Exd-4 would ameliorate the detrimental effects of maternal and diet-induced obesity on renal characteristics in offspring. Female Sprague-Dawley rats were fed either normal or high-fat diet (HFD) for 6 weeks prior to pregnancy, during pregnancy and lactation, and their offspring were weaned to normal or HFD. The offspring were randomized to Exd-4 or placebo from weaning and their kidneys harvested at Week 9. We found that the kidneys of offspring from obese mothers, regardless of postnatal diet, had significantly increased markers of inflammation, oxidative stress and fibrosis. Exd-4 ameliorated the negative renal effects of maternal obesity and in particular, reduced renal inflammation, oxidative stress and fibrosis. In conclusion, maternal obesity has persisting effects on renal structure in the offspring. GLP-1 analogues are potentially useful for protecting against the deleterious effects of maternal obesity on renal physiology in offspring.

Topics: Animals; Animals, Newborn; Body Weight; Diet, High-Fat; Disease Models, Animal; Exenatide; Female; Glucagon-Like Peptide-1 Receptor; Humans; Kidney; Kidney Diseases; Maternal Nutritional Physiological Phenomena; Obesity; Oxidative Stress; Peptides; Pregnancy; Random Allocation; Rats; Rats, Sprague-Dawley; Treatment Outcome; Venoms; Weaning

The guideline for the management of new-onset diabetes after transplantation recommends metformin (MET) as a first-line drug, and addition of a second-line drug is needed to better control of hyperglycemia. We tested the effect of addition of a dipeptidyl peptidase IV (DPP IV) inhibitor to MET on sirolimus (SRL)-induced diabetes mellitus (DM). In animal model of SRL-induced DM, MET treatment improved pancreatic islet function (blood glucose level and insulin secretion) and attenuated oxidative stress and apoptotic cell death. Addition of a DPP IV inhibitor to MET improved these parameters more than MET alone. An in vitro study showed that SRL treatment increased pancreas beta cell death and production of reactive oxygen species (ROS), and pretreatment of ROS inhibitor, or p38MAPK inhibitor effectively decreased SRL-induced islet cell death. Exendin-4 (EXD), a substrate of DPP IV or MET significantly improved cell viability and decreased ROS production compared with SRL treatment, and combined treatment with the 2 drugs improved both parameters. At the subcellular level, impaired mitochondrial respiration by SRL were partially improved by MET or EXD and much improved further after addition of EXD to MET. Our data suggest that addition of a DPP IV inhibitor to MET decreases SRL-induced oxidative stress and improves mitochondrial respiration. This finding provides a rationale for the combined use of a DPP IV inhibitor and MET in treating SRL-induced DM.

Topics: Animals; Apoptosis; Cell Survival; Diabetes Mellitus, Experimental; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Drug Therapy, Combination; Exenatide; Hyperglycemia; Islets of Langerhans; Male; Metformin; Mitochondria; Oxidative Stress; Peptides; Piperidones; Pyrimidines; Rats, Sprague-Dawley; Reactive Oxygen Species; Sirolimus; Venoms

Wolfram syndrome 1 is a very rare monogenic disease resulting in a complex of disorders including diabetes mellitus. Up to now, insulin has been used to treat these patients. Some of the monogenic forms of diabetes respond preferentially to sulphonylurea preparations. The aim of the current study was to elucidate whether exenatide, a GLP-1 receptor agonist, and glipizide, a sulphonylurea, are effective in a mouse model of Wolfram syndrome 1. Wolframin-deficient mice were used to test the effect of insulin secretagogues. Wolframin-deficient mice had nearly normal fasting glucose levels but developed hyperglycaemia after glucose challenge. Exenatide in a dose of 10 μg/kg lowered the blood glucose level in both wild-type and wolframin-deficient mice when administered during a nonfasted state and during the intraperitoneal glucose tolerance test. Glipizide (0.6 or 2 mg/kg) was not able to reduce the glucose level in wolframin-deficient animals. In contrast to other groups, wolframin-deficient mice had a lower insulin-to-glucose ratio during the intraperitoneal glucose tolerance test, indicating impaired insulin secretion. Exenatide increased the insulin-to-glucose ratio irrespective of genotype, demonstrating the ability to correct the impaired insulin secretion caused by wolframin deficiency. We conclude that GLP-1 agonists may have potential in the treatment of Wolfram syndrome-related diabetes.

Topics: Animals; Biomarkers; Blood Glucose; Disease Models, Animal; Exenatide; Genetic Predisposition to Disease; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Insulin; Membrane Proteins; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Peptides; Time Factors; Venoms; Wolfram Syndrome

Recent data implicate glucagon-like peptide-1 (GLP-1), a potent anorexigenic peptide released in response to nutrient intake, as a regulator for the reinforcing properties of food, alcohol and psychostimulants. While, both central and peripheral mechanisms mediate effects of GLP-1R signaling on food intake, the extent to which central or peripheral GLP-1R signaling regulates reinforcing properties of drugs of abuse is unknown. Here, we examined amphetamine reinforcement, alcohol intake and hedonic feeding following peripheral administration of EX-4 (a GLP-1 analog) in FLOX and GLP-1R KD(Nestin) (GLP-1R selectively ablated from the central nervous system) mice (n=13/group). First, the effect of EX-4 pretreatment on the expression of amphetamine-induced conditioned place preference (Amp-CPP) was examined in the FLOX and GLP-1R KD(Nestin) mice. Next, alcohol intake (10% v/v) was evaluated in FLOX and GLP-1R KD(Nestin) mice following saline or EX-4 injections. Finally, we assessed the effects of EX-4 pretreatment on hedonic feeding behavior. Results indicate that Amp-CPP was completely blocked in the FLOX mice, but not in the GLP-1R KD(Nestin) mice following EX-4 pretreatment. Ex-4 pretreatment selectively blocked alcohol consumption in the FLOX mice, but was ineffective in altering alcohol intake in the GLP-1R KD(Nestin) mice. Notably, hedonic feeding was partially blocked in the GLP-1R KD(Nestin) mice, whereas it was abolished in the FLOX mice. The present study provides critical insights regarding the nature by which GLP-1 signaling controls reinforced behaviors and underscores the importance of both peripheral and central GLP-1R signaling for the regulation of addictive disorders.

Topics: Alcohol Drinking; Amphetamine; Animals; Behavior, Addictive; Central Nervous System Stimulants; Conditioning, Operant; Diet; Disease Models, Animal; Exenatide; Feeding Behavior; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nestin; Peptides; Signal Transduction; Venoms

Inflammation associated with blood-retinal barrier (BRB) breakdown is a common feature of several retinal diseases. Therefore, the development of novel nonsteroidal anti-inflammatory approaches may provide important therapeutic options. Previous studies demonstrated that inhibition of dipeptidyl peptidase-IV, the enzyme responsible for the degradation of glucagon-like peptide-1 (GLP-1), led to insulin-independent prevention of diabetes-induced increases in BRB permeability, suggesting that incretin-based drugs may have beneficial pleiotropic effects in the retina. In the current study, the barrier protective and anti-inflammatory properties of exendin-4 (Ex-4), an analog of GLP-1, after ischemia-reperfusion (IR) injury were examined.. Ischemia-reperfusion injury was induced in rat retinas by increasing the intraocular pressure for 45 minutes followed by 48 hours of reperfusion. Rats were treated with Ex-4 prior to and following IR. Blood-retinal barrier permeability was assessed by Evans blue dye leakage. Retinal inflammatory gene expression and leukocytic infiltration were measured by qRT-PCR and immunofluorescence, respectively. A microglial cell line was used to determine the effects of Ex-4 on lipopolysaccharide (LPS)-induced inflammatory response.. Exendin-4 dramatically reduced the BRB permeability induced by IR injury, which was associated with suppression of inflammatory gene expression. Moreover, in vitro studies showed that Ex-4 also reduced the inflammatory response to LPS and inhibited NF-κB activation.. The present work suggests that Ex-4 can prevent IR injury-induced BRB breakdown and inflammation through inhibition of inflammatory cytokine production by activated microglia and may provide a novel option for therapeutic intervention in diseases involving retinal inflammation.

Topics: Animals; Blood-Retinal Barrier; Cattle; Cells, Cultured; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Immunoblotting; Immunohistochemistry; Incretins; Inflammation; Ischemia; Male; Peptides; Rats; Rats, Long-Evans; Reperfusion Injury; Retinal Diseases; Venoms

The CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP), a major transcriptional regulator of endoplasmic reticulum (ER) stress-mediated apoptosis, is implicated in lipotoxicity-induced ER stress and hepatocyte apoptosis in non-alcoholic fatty liver disease (NAFLD). We have previously demonstrated that the glucagon-like peptide-1 (GLP-1) agonist, liraglutide, protects steatotic hepatocytes from lipotoxicity-induced apoptosis by improved handling of free fatty acid (FFA)-induced ER stress. In the present study, we investigated whether CHOP is critical for GLP-1-mediated restoration of ER homeostasis and mitigation of hepatocyte apoptosis in a murine model of NASH (non-alcoholic steatohepatitis). Our data show that despite similar caloric intake, CHOP KO (CHOP(-/-)) mice fed a diet high in fat, fructose, and cholesterol (HFCD) for 16 weeks developed more severe histological features of NASH compared with wild-type (WT) controls. Severity of NASH in HFCD-fed CHOP(-/-) mice correlated with significant decrease in peroxisomal β-oxidation, and increased de novo lipogenesis and ER stress-mediated hepatocyte apoptosis. Four weeks of liraglutide treatment markedly attenuated steatohepatitis in HFCD-fed WT mice by improving insulin sensitivity, and suppressing de novo lipogenesis and ER stress-mediated hepatocyte apoptosis. However, in the absence of CHOP, liraglutide did not improve insulin sensitivity, nor suppress peroxisomal β-oxidation or ER stress-mediated hepatocyte apoptosis. Taken together, these data indicate that CHOP protects hepatocytes from HFCD-induced ER stress, and has a significant role in the mechanism of liraglutide-mediated protection against NASH pathogenesis.

Topics: Animals; Apoptosis; Blood Glucose; Cells, Cultured; Cholesterol; Diet, High-Fat; Dietary Carbohydrates; Disease Models, Animal; Endoplasmic Reticulum Stress; Exenatide; Hepatocytes; Insulin Resistance; Lipid Metabolism; Liraglutide; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Non-alcoholic Fatty Liver Disease; Peptides; Protective Agents; Transcription Factor CHOP; Venoms

Exenatide's effects on glucose metabolism have been studied extensively in diabetes but not in pre-diabetes.. We examined the chronic effects of exenatide alone on glucose metabolism in pre-diabetic canines.. After 10 weeks of high-fat diet (HFD), adult dogs received one injection of streptozotocin (STZ, 18.5 mg/kg). After induction of pre-diabetes, while maintained on HFD, animals were randomized to receive either exenatide (n = 7) or placebo (n = 7) for 12 weeks. β-Cell function was calculated from the intravenous glucose tolerance test (IVGTT, expressed as the acute insulin response, AIRG), the oral glucose tolerance test (OGTT, insulinogenic index) and the graded-hyperglycemic clamp (clamp insulinogenic index). Whole-body insulin sensitivity was assessed by the IVGTT. At the end of the study, pancreatic islets were isolated to assess β-cell function in vitro.. OGTT: STZ caused an increase in glycemia at 120 min by 22.0% (interquartile range, IQR, 31.5%) (P = 0.011). IVGTT: This protocol also showed a reduction in glucose tolerance by 48.8% (IQR, 36.9%) (P = 0.002). AIRG decreased by 54.0% (IQR, 40.7%) (P = 0.010), leading to mild fasting hyperglycemia (P = 0.039). Exenatide, compared with placebo, decreased body weight (P<0.001) without altering food intake, fasting glycemia, insulinemia, glycated hemoglobin A1c, or glucose tolerance. Exenatide, compared with placebo, increased both OGTT- (P = 0.040) and clamp-based insulinogenic indexes (P = 0.016), improved insulin secretion in vitro (P = 0.041), but had no noticeable effect on insulin sensitivity (P = 0.405).. In pre-diabetic canines, 12-week exenatide treatment improved β-cell function but not glucose tolerance or insulin sensitivity. These findings demonstrate partial beneficial metabolic effects of exenatide alone on an animal model of pre-diabetes.

Topics: Animals; Blood Glucose; Body Composition; Disease Models, Animal; Dogs; Eating; Energy Metabolism; Exenatide; Fasting; Glucagon; Glucose Tolerance Test; Glycated Hemoglobin; Hypoglycemic Agents; Insulin; Insulin Resistance; Insulin-Secreting Cells; Liver; Male; Peptides; Prediabetic State; Venoms

Exercise capacity is reduced in heart failure (HF) patients, due mostly to skeletal muscle abnormalities including impaired energy metabolism, mitochondrial dysfunction, fibre type transition, and atrophy. Glucagon-like peptide-1 (GLP-1) has been shown to improve exercise capacity in HF patients. We investigated the effects of the administration of a dipeptidyl peptidase (DPP)-4 inhibitor on the exercise capacity and skeletal muscle abnormalities in an HF mouse model after myocardial infarction (MI).. MI was created in male C57BL/6J mice by ligating the left coronary artery, and a sham operation was performed in other mice. The mice were then divided into two groups according to the treatment with or without a DPP-4 inhibitor, MK-0626 [1 mg/kg body weight (BW)/day] provided in the diet. Four weeks later, the exercise capacity evaluated by treadmill test was revealed to be limited in the MI mice, and it was ameliorated in the MI + MK-0626 group without affecting the infarct size or cardiac function. The citrate synthase activity, mitochondrial oxidative phosphorylation capacity, supercomplex formation, and their quantity were reduced in the skeletal muscle from the MI mice, and these decreases were normalized in the MI + MK-0626 group, in association with the improvement of mitochondrial biogenesis. Immunohistochemical staining also revealed that a shift toward the fast-twitch fibre type in the MI mice was also reversed by MK-0626. Favourable effects of MK-0626 were significantly inhibited by treatment of GLP-1 antagonist, Exendin-(9-39) (150 pmol/kg BW/min, subcutaneous osmotic pumps) in MI + MK-0626 mice. Similarly, exercise capacity and mitochondrial function were significantly improved by treatment of GLP-1 agonist, Exendin-4 (1 nmol/kg/BW/h, subcutaneous osmotic pumps).. A DPP-4 inhibitor may be a novel therapeutic agent against the exercise intolerance seen in HF patients by improving the mitochondrial biogenesis in their skeletal muscle.

Topics: Animals; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Male; Mice, Inbred C57BL; Mitochondria; Muscle, Skeletal; Myocardial Infarction; Organelle Biogenesis; Peptides; Triazoles; Venoms

As the number of patients with cardioembolic ischemic stroke is predicted to be double by 2030, increased burden of warfarin-associated hemorrhagic transformation (HT) after cerebral ischemia is an expected consequence. However, thus far, no effective treatment strategy is available for HT prevention in routine clinical practice. While the glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 (Ex-4) is known to protect against oxidative stress and neuronal cell death caused by ischemic brain damage, its effect on preventing warfarin-associated HT after cerebral ischemia is yet unknown. Therefore, we hypothesized that Ex-4 would stabilize the blood-brain barrier (BBB) and suppress neuroinflammation through PI3K-Akt-induced inhibition of glycogen synthase kinase-3β (GSK-3β) after warfarin-associated HT post-cerebral ischemia.. We used male C57BL/6 mice for all experiments. A 5-mg warfarin sodium tablet was dissolved in animals' drinking water (effective warfarin uptake 0.04 mg (2 mg/kg) per mouse). The mice were fed for 0, 6, 12, and 24 h with ad libitum access to the treated water. To study the effects of Ex-4, temporary middle cerebral artery occlusion (MCAO) was performed. Then, either Ex-4 (10 mg/kg) or saline was injected through the tail vein, and in the Ex-4 + wortmannin group, PI3K inhibitor wortmannin was intravenously injected, after reperfusion. The infarct volume, neurological deficits, and integrity of the BBB were assessed 72 h post MCAO. One- or two-way ANOVA was used to test the difference between means followed by Newman-Keuls post hoc testing for pair-wise comparison.. We observed that Ex-4 ameliorated warfarin-associated HT and preserved the integrity of the BBB after cerebral ischemia through the PI3K/Akt/GSK-3β pathway. Furthermore, Ex-4 suppressed oxidative DNA damage and lipid peroxidation, attenuated pro-inflammatory cytokine expression levels, and suppressed microglial activation and neutrophil infiltration in warfarin-associated HT post-cerebral ischemia. However, these effects were totally abolished in the mice treated with Ex-4 + the PI3K inhibitor-wortmannin. The PI3K/Akt-GSK-3β signaling pathway appeared to contribute to the protection afforded by Ex-4 in the warfarin-associated HT model.. GLP-1 administration could reduce warfarin-associated HT in mice. This beneficial effect of GLP-1 is associated with attenuating neuroinflammation and BBB disruption by inactivating GSK-3β through the PI3K/Akt pathway.

Topics: Animals; Anticoagulants; Blood-Brain Barrier; Brain; Brain Infarction; Brain Ischemia; Cytokines; Disease Models, Animal; Exenatide; Gene Expression Regulation; Glucagon-Like Peptide-1 Receptor; Hemorrhage; Hypoglycemic Agents; Infarction, Middle Cerebral Artery; Male; Mice; Mice, Inbred C57BL; Microglia; Nervous System Diseases; Peptides; Signal Transduction; Venoms; Warfarin

Although the nature of the humoral factor which mediates cardioprotection established by remote ischaemic conditioning (RIc) remains unknown, parasympathetic (vagal) mechanisms appear to play a critical role. As the production and release of many gut hormones is modulated by the vagus nerve, here we tested the hypothesis that RIc cardioprotection is mediated by the actions of glucagon-like peptide-1 (GLP-1).. A rat model of myocardial infarction (coronary artery occlusion followed by reperfusion) was used. Remote ischaemic pre- (RIPre) or perconditioning (RIPer) was induced by 15 min occlusion of femoral arteries applied prior to or during the myocardial ischaemia. The degree of RIPre and RIPer cardioprotection was determined in conditions of cervical or subdiaphragmatic vagotomy, or following blockade of GLP-1 receptors (GLP-1R) using specific antagonist Exendin(9-39). Phosphorylation of PI3K/AKT and STAT3 was assessed. RIPre and RIPer reduced infarct size by ∼50%. In conditions of bilateral cervical or subdiaphragmatic vagotomy RIPer failed to establish cardioprotection. GLP-1R blockade abolished cardioprotection induced by either RIPre or RIPer. Exendin(9-39) also prevented RIPre-induced AKT phosphorylation. Cardioprotection induced by GLP-1R agonist Exendin-4 was preserved following cervical vagotomy, but was abolished in conditions of M3 muscarinic receptor blockade.. These data strongly suggest that GLP-1 functions as a humoral factor of remote ischaemic conditioning cardioprotection. This phenomenon requires intact vagal innervation of the visceral organs and recruitment of GLP-1R-mediated signalling. Cardioprotection induced by GLP-1R activation is mediated by a mechanism involving M3 muscarinic receptors.

Topics: Animals; Disease Models, Animal; Exenatide; Femoral Artery; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Hormone Antagonists; Ischemic Preconditioning; Ligation; Male; Muscarinic Antagonists; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Peptide Fragments; Peptides; Phosphatidylinositol 3-Kinase; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats, Sprague-Dawley; Receptor, Muscarinic M3; Signal Transduction; STAT3 Transcription Factor; Vagotomy; Vagus Nerve; Venoms

To provide selectable microRNA for intervening diabetes mellitus diseases, NOD mice's expression of microRNA in pancreas tissues and blood under the exendin-4 intervention of was observed and the difference of microRNA target gene was screened.. Forty clean NOD mice were randomly divided into four groups (in each group, n = 10): One is blank control group D which is intervened with normal saline, and the other three groups were divided into low-dose group A, middle-dose group B, and high-dose group C according to the different exendin-4 dosage 2, 4, and 8 μg/kg·d. After the 8-week intervention, these four groups were killed, and the pancreatic tissue and blood were left to prepare specimens for morphology and molecular biology analysis. The specimen with differential expression microRNA in pancreas tissue and blood should be screened out after detected with the locked nucleic acid array system (LNATM) microRNA expression profile chip. The primers should be designed, and the ABI7500 real-time fluorescent quantitative PCR should be applied to amplify, analyze, and verify according to the screen results of the microRNA chip in order to screen out the significant differentially expressed microRNA.. Histological detection showed that the pancreas of the mice in control group D was fibrosis gradually and the islet frame was relatively disordered and significantly atrophied. Groups A, B, and C have no islet hypertrophy or atrophy and the degree of fibrosis of the pancreas has reduced. According to the gene chip detection, there are four significantly differently expressed microRNAs in pancreas tissue and blood among the group A, B, and C, among which miR-19a, miR-19b, and miR-22 were downregulated expressed while the miRNA-1 was upregulated expressed. Bioinformatics analysis showed that the target genes of 4 differentially regulated microRNA genes were related to cell proliferation, apoptosis, glucose metabolism, and angiogenesis. The expression of microRNA in pancreatic tissue and blood of NOD rats was highly consistent.. MicroRNA expression file of pancreatic tissue and blood can be changed during the intervention of the NOD rat model with exendin-4. MicroRNA that indicates the differential expression may take part in the recovering process of the NOD pancreatic trauma. At the same time, the administration of exendin-4 can protect NOD mice, reduce its pancreatic tissue fibrosis, and regulate molecular markers of pancreatic cells in size and pancreatic mast cells. This may be one of the main mechanisms of pancreatic injury in diabetes prevention.

Topics: Animals; Diabetes Mellitus; Disease Models, Animal; Exenatide; Mice; Mice, Inbred NOD; MicroRNAs; Pancreas; Peptides; Rats; Venoms

Benign prostatic hyperplasia (BPH) is a prevalent disease globally, and accumulating evidence has indicated an association between BPH, insulin resistance (IR) and diabetes. Exendin-4 is widely used in clinics, which could enhance the proliferation of pancreatic β cells. The ability of exendin-4 to promote tumorigenesis has been of concern, and whether exendin-4 would enhance the propagation of BPH is not fully understood. We aimed to determine whether glucagon-like peptide-1 receptors (GLP-1Rs) were expressed in rat prostate and to determine the effect of exendin-4 on prostate of BPH. Male Wistar rats were used and assigned to six groups: normal diet (ND), high-fat diet (HFD), HFD + exendin-4, HFD + BPH, HFD + BPH + exendin-4 and HFD + BPH + rosiglitazone group. After castration, steroids were injected subcutaneously for 4 weeks to induce BPH. Rats were kept on high-fat diet to induce IR. Treatment groups were treated with exendin-4 and rosiglitazone. Prostatic index and HOMA-IR index were used to evaluate the prostatic hyperplasia status and the degree of IR respectively. The expression of GLP-1R was indicated not only by immunohistochemistry, but also by Western blot analysis. The expression of GLP-1R was significantly higher, and HOMA-IR index and body weight significantly decreased after administration of exendin-4. However, no significant differences in the prostatic index were observed between exendin-4 treatment groups and non-exendin-4 treatment groups. Prostatic index was not influenced by exendin-4 maybe by improving IR and weight loss.

Topics: Animals; Body Weight; Diet, High-Fat; Disease Models, Animal; Dose-Response Relationship, Drug; Exenatide; Glucagon-Like Peptide-1 Receptor; Insulin Resistance; Male; Peptides; Prostate; Prostatic Hyperplasia; Rats; Rats, Wistar; Receptors, Glucagon; Rosiglitazone; Severity of Illness Index; Thiazolidinediones; Venoms

A Site-specifically PEGylated exendin-4 (denoted as PEG-Ex4) is an exendin-4 (denoted as Ex4) analog we developed by site-specific PEGylation of exendin-4 with a high molecular weight trimeric poly(ethylene glycol) (tPEG). It has been shown to possess prolonged half-life in vivo with similar receptor binding affinity compared to unmodified exendin-4 by our previous work. This study is sought to test whether PEG-Ex4 is suitable for treating myocardial infarction (MI). In the MI model, PEG-Ex4 was administered every 3 days while equivalent amount of Ex4 was administered every 3 days or twice daily. Animal survival rate, heart function, remodeling and neoangiogenesis were evaluated and compared. Tube formation was examined in endothelial cells. In addition, Western blotting and histology were performed to determine the markers of cardiac hypertrophy and angiogenesis and to explore the possible molecular mechanism involved. PEG-Ex4 and Ex4 showed comparable binding affinity to GLP-1 receptor. In MI mice, PEG-Ex4 given at 3 days interval achieved similar extent of protection as Ex4 given twice daily, while Ex4 given at 3 days interval failed to produce protection. PEG-Ex4 elevated endothelial tube formation in vitro and capillary density in the border area of MI. PEG-Ex4 increased Akt activity and VEGF production in a GLP-1R dependent manner in endothelial cells and antagonism of GLP-1R, Akt or VEGF abolished the protection of PEG-Ex4 in the MI model. PEG-Ex4 is a potent long-acting GLP-1 receptor agonist for the treatment of chronic heart disease. Its protection might be attributed to enhanced angiogenesis mediated by the activation of Akt and VEGF.

Topics: Aminophylline; Animals; Atropine; Blotting, Western; Cardiovascular Agents; Disease Models, Animal; Drug Combinations; Exenatide; Glucagon-Like Peptide 1; Heart; Heart Function Tests; Histocytochemistry; Male; Mice, Inbred C57BL; Myocardial Infarction; Myocardium; Neovascularization, Physiologic; Nitroglycerin; Papaverine; Peptides; Phenobarbital; Survival Analysis; Treatment Outcome; Venoms

Dipeptidyl peptidase (DPP)-4 is an enzyme that cleaves and inactivates incretin hormones capable of stimulating insulin secretion from pancreatic β-cells. DPP-4 inhibitors are now widely used for the treatment of type 2 diabetes. Experimental studies have suggested a renoprotective role of DPP-4 inhibitors in various models of diabetic kidney disease, which may be independent of lowering blood glucose levels. In the present study, we examined the effect of DPP-4 inhibitors in the rat Thy-1 glomerulonephritis model, a nondiabetic glomerular injury model. Rats were injected with OX-7 (1.2 mg/kg iv) and treated with the DPP-4 inhibitor alogliptin (20 mg·kg(-1)·day(-1)) or vehicle for 7 days orally by gavage. Alogliptin significantly reduced the number of CD68-positive inflammatory macrophages in the kidney, which was associated with a nonsignificant tendency to ameliorate glomerular injury and reduce proteinuria. Another DPP-4 inhibitor, anagliptin (300 mg·kg(-1)·day(-1) mixed with food) and a glucagon-like peptide-1 receptor agonist, exendin-4 (10 mg/kg sc), similarly reduced CD68-positive macrophage infiltration to the kidney. Furthermore, ex vivo transmigration assays using peritoneal macrophages revealed that exendin-4, but not alogliptin, dose dependently reduced monocyte chemotactic protein-1-stimulated macrophage infiltration. These data suggest that DPP-4 inhibitors reduced macrophage infiltration directly via glucagon-like peptide-1-dependent signaling in the rat Thy-1 nephritis model and indicate that the control of inflammation by DPP-4 inhibitors is useful for the treatment of nondiabetic kidney disease models.

Topics: Animals; Anti-Inflammatory Agents; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Antilymphocyte Serum; Cell Line; Chemokine CCL2; Chemotaxis; Cytoprotection; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Exenatide; Glomerulonephritis; Glucagon-Like Peptide-1 Receptor; Kidney Glomerulus; Macrophages, Peritoneal; Male; Mice, Inbred C57BL; Peptides; Piperidines; Proteinuria; Pyrimidines; Rats, Sprague-Dawley; Receptors, Glucagon; Signal Transduction; Uracil; Venoms

Although mitochondrial oxidative phosphorylation (OxPhos) dysfunction is believed to be responsible for beta cell dysfunction in insulin resistance and mitochondrial diabetes, the mechanisms underlying progressive beta cell failure caused by defective mitochondrial OxPhos are largely unknown.. We examined the in vivo phenotypes of beta cell dysfunction in beta cell-specific Crif1 (also known as Gadd45gip1)-deficient mice. CR6-interacting factor-1 (CRIF1) is a mitochondrial protein essential for the synthesis and formation of the OxPhos complex in the inner mitochondrial membrane.. Crif1(beta-/-) mice exhibited impaired glucose tolerance with defective insulin secretion as early as 4 weeks of age without defects in islet structure. At 11 weeks of age, Crif1(beta-/-) mice displayed characteristic ultrastructural mitochondrial abnormalities as well as severe glucose intolerance. Furthermore, islet area and insulin content was decreased by approximately 50% compared with wild-type mice. Treatment with the glucoregulatory drug exenatide, a glucagon-like peptide-1 (GLP-1) agonist, was not sufficient to preserve beta cell function in Crif1(beta-/-) mice.. Our results indicate that mitochondrial OxPhos dysfunction triggers progressive beta cell failure that is not halted by treatment with a GLP-1 agonist. The Crif1(beta-/-) mouse is a useful model for the study of beta cell failure caused by mitochondrial OxPhos dysfunction.

Topics: Age Factors; Animals; Autophagy; Blood Glucose; Cell Cycle Proteins; Cell Line; Diabetes Mellitus; Disease Models, Animal; Disease Progression; Exenatide; Genotype; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Incretins; Insulin; Insulin-Secreting Cells; Mice, Inbred C57BL; Mice, Knockout; Mitochondria; Oxidative Phosphorylation; Peptides; Phenotype; Time Factors; Venoms

Intestinal overproduction of atherogenic chylomicron particles postprandially is an important component of diabetic dyslipidemia in insulin-resistant states. In addition to enhancing insulin secretion, peripheral glucagon-like peptide-1 (GLP-1) receptor stimulation has the added benefit of reducing this chylomicron overproduction in patients with type 2 diabetes mellitus. Given the presence of central GLP-1 receptors and GLP-1-producing neurons, we assessed whether central GLP-1 exerts an integral layer of neuronal control during the production of these potentially atherogenic particles.. Postprandial production of triglyceride-rich lipoproteins was assessed in Syrian hamsters administered a single intracerebroventricular injection of the GLP-1 receptor agonist exendin-4. Intracerebroventricular exendin-4 reduced triglyceride-rich lipoprotein-triglyceride and -apolipoprotein B48 accumulation relative to vehicle-treated controls. This was mirrored by intracerebroventricular MK-0626, an inhibitor of endogenous GLP-1 degradation, and prevented by central exendin9-39, a GLP-1 receptor antagonist. The effects of intracerebroventricular exendin-4 were also lost during peripheral adrenergic receptor and central melanocortin-4 receptor inhibition, achieved using intravenous propranolol and phentolamine and intracerebroventricular HS014, respectively. However, central exendin9-39 did not preclude the effects of peripheral exendin-4 treatment on chylomicron output.. Central GLP-1 is a novel regulator of chylomicron production via melanocortin-4 receptors. Our findings point to the relative importance of central accessibility of GLP-1-based therapies and compel further studies examining the status of this brain-gut axis in the development of diabetic dyslipidemia and chylomicron overproduction.

Topics: Animals; Central Nervous System; Chylomicrons; Cricetinae; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Intestinal Mucosa; Intestines; Lipid Metabolism; Lipoproteins; Peptides; Random Allocation; Receptors, Glucagon; Venoms

Glucagon-like peptide-1 (GLP-1) is an insulin-releasing hormone clinically exploited for glycaemic control in diabetes, which also confers acute cardioprotection and benefits in experimental/clinical heart failure. We specifically investigated the role of the GLP-1 mimetic, exendin-4, in post-myocardial infarction (MI) remodelling, which is a key contributor to heart failure. Adult female normoglycaemic mice underwent coronary artery ligation/sham surgery prior to infusion with exendin-4/vehicle for 4 weeks. Metabolic parameters and infarct sizes were comparable between groups. Exendin-4 protected against cardiac dysfunction and chamber dilatation post-MI and improved survival. Furthermore, exendin-4 modestly decreased cardiomyocyte hypertrophy/apoptosis but markedly attenuated interstitial fibrosis and myocardial inflammation post-MI. This was associated with altered extracellular matrix (procollagen IαI/IIIαI, connective tissue growth factor, fibronectin, TGF-β3) and inflammatory (IL-10, IL-1β, IL-6) gene expression in exendin-4-treated mice, together with modulation of both Akt/GSK-3β and Smad2/3 signalling. Exendin-4 also altered macrophage response gene expression in the absence of direct actions on cardiac fibroblast differentiation, suggesting cardioprotective effects occurring secondary to modulation of inflammation. Our findings indicate that exendin-4 protects against post-MI remodelling via preferential actions on inflammation and the extracellular matrix independently of its established actions on glycaemic control, thereby suggesting that selective targeting of GLP-1 signalling may be required to realise its clear therapeutic potential for post-MI heart failure.

Topics: Animals; Blotting, Western; Disease Models, Animal; Exenatide; Extracellular Matrix; Female; Immunohistochemistry; In Situ Nick-End Labeling; Inflammation; Mice; Mice, Inbred C57BL; Myocardial Infarction; Peptides; Rats; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Venoms; Ventricular Remodeling

In the nervous system, NMDA receptors (NMDARs) participate in neurotransmission and modulate the viability of neurons. In contrast, little is known about the role of NMDARs in pancreatic islets and the insulin-secreting beta cells whose functional impairment contributes to diabetes mellitus. Here we found that inhibition of NMDARs in mouse and human islets enhanced their glucose-stimulated insulin secretion (GSIS) and survival of islet cells. Further, NMDAR inhibition prolonged the amount of time that glucose-stimulated beta cells spent in a depolarized state with high cytosolic Ca(2+) concentrations. We also noticed that, in vivo, the NMDAR antagonist dextromethorphan (DXM) enhanced glucose tolerance in mice, and that in vitro dextrorphan, the main metabolite of DXM, amplified the stimulatory effect of exendin-4 on GSIS. In a mouse model of type 2 diabetes mellitus (T2DM), long-term treatment with DXM improved islet insulin content, islet cell mass and blood glucose control. Further, in a small clinical trial we found that individuals with T2DM treated with DXM showed enhanced serum insulin concentrations and glucose tolerance. Our data highlight the possibility that antagonists of NMDARs may provide a useful adjunct treatment for diabetes.

Topics: Adult; Animals; Calcium; Cell Line; Cell Survival; Dextromethorphan; Diabetes Mellitus, Type 2; Disease Models, Animal; Drug Design; Exenatide; Female; Glucose; Glucose Tolerance Test; Humans; Insulin; Insulin-Secreting Cells; Islets of Langerhans; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Nerve Tissue Proteins; Pancreas; Peptides; Receptors, N-Methyl-D-Aspartate; Venoms

Diabetic patients have an increased risk of restenosis and late stent thrombosis after angioplasty, i.e. complications that are related to a defective re-endothelialization. Exendin-4, a stable glucagon-like peptide (GLP)-1 receptor agonist, has been suggested to influence the formation of intimal hyperplasia and to increase endothelial cell proliferation in vitro. Thus, the aim of this study was to investigate the mechanisms by which treatment with exendin-4 could influence re-endothelialization and intimal hyperplasia after vascular injury.. Sprague-Dawley rats were subjected to balloon injury of the left common carotid artery and treated for 4 weeks with exendin-4 or vehicle. Intimal hyperplasia and vessel wall elasticity were monitored noninvasively by high-frequency ultrasound, and re-endothelialization was evaluated upon sacrifice using Evans blue dye.. Exendin-4 selectively reduced the proliferation of smooth muscle cells (SMCs) and intimal hyperplasia in vivo without affecting the re-endothelialization process, but treatment with exendin-4 improved arterial wall elasticity. Our data also show that exendin-4 significantly decreased the proliferation and increased the apoptosis of SMCs in vitro, effects that appear to be mediated through cAMP signaling and endothelial nitric oxide synthase following GLP-1 receptor activation. Together, these effects of exendin-4 are highly desirable and may lead to an improved outcome for patients undergoing vascular interventions.

Topics: Animals; Blood Glucose; Carotid Artery Injuries; Carotid Artery, Common; Cell Division; Cells, Cultured; Cyclic AMP; Disease Models, Animal; Endothelium, Vascular; Exenatide; Fatty Acids, Nonesterified; Glucagon-Like Peptide-1 Receptor; Hyperplasia; Insulin; Male; Myocytes, Smooth Muscle; Nitric Oxide Synthase Type III; Peptides; Random Allocation; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Regeneration; Tunica Intima; Vascular Stiffness; Venoms

Traumatic brain injury (TBI), a brain dysfunction for which there is no present effective treatment, is often caused by a concussive impact to the head and affects an estimated 1.7 million Americans annually. Our laboratory previously demonstrated that exendin-4, a long-lasting glucagon-like peptide 1 receptor (GLP-1R) agonist, has neuroprotective effects in cellular and animal models of TBI. Here, we demonstrate neurotrophic and neuroprotective effects of a different GLP-1R agonist, liraglutide, in neuronal cultures and a mouse model of mild TBI (mTBI). Liraglutide promoted dose-dependent proliferation in SH-SY5Y cells and in a GLP-1R over-expressing cell line at reduced concentrations. Pre-treatment with liraglutide rescued neuronal cells from oxidative stress- and glutamate excitotoxicity-induced cell death. Liraglutide produced neurotrophic and neuroprotective effects similar to those of exendin-4 in vitro. The cAMP/PKA/pCREB pathway appears to play an important role in this neuroprotective activity of liraglutide. Furthermore, our findings in cell culture were well-translated in a weight drop mTBI mouse model. Post-treatment with a clinically relevant dose of liraglutide for 7 days in mice ameliorated memory impairments caused by mTBI when evaluated 7 and 30 days post trauma. These data cross-validate former studies of exendin-4 and suggest that liraglutide holds therapeutic potential for the treatment of mTBI. Exendin-4, a long-lasting glucagon-like peptide 1 receptor (GLP-1R) agonist, has neuroprotective effects in cellular and animal models of traumatic brain injury (TBI). Here, we demonstrate neurotrophic and neuroprotective effects of a different GLP-1R agonist, liraglutide, in neuronal cultures and a mouse model of mild TBI (mTBI). Liraglutide promoted dose-dependent proliferation in SH-SY5Y cells and in a GLP-1R over-expressing cell line at reduced concentrations. Pretreatment with liraglutide rescued neuronal cells from oxidative stress- and glutamate excitotoxicity-induced cell death. Liraglutide produced neurotrophic and neuroprotective effects similar to those of exendin-4 in vitro, likely involving the cAMP/PKA/pCREB pathway. Our findings in cell culture were well-translated in a weight-drop mTBI mouse model. Post-treatment with a clinically relevant dose of liraglutide for 7 days in mice ameliorated memory impairments caused by mTBI.

Topics: Animals; Brain Concussion; Brain Injuries; Cell Death; Cell Line; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Hypoglycemic Agents; Liraglutide; Mice; Neurons; Neuroprotective Agents; Peptides; Receptors, Glucagon; Venoms

Glucagon-like peptide 1 (GLP-1) is a growth factor. GLP-1 mimetics are on the market as treatments for type 2 diabetes and are well tolerated. These drugs have shown neuroprotective properties in animal models of neurodegenerative disorders. In addition, the GLP-1 mimetic exendin-4 has shown protective effects in animal models of Parkinson's disease (PD), and a clinical trial in PD patients showed promising first results. Liraglutide and lixisenatide are two newer GLP-1 mimetics which have a longer biological half-life than exendin-4. We previously showed that these drugs have neuroprotective properties in an animal model of Alzheimer's disease. Here we demonstrate the neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. MPTP was injected once-daily (20mg/kg i.p.) for 7 days, and drugs were injected once-daily for 14 days i.p. When comparing exendin-4 (10 nmol/kg), liraglutide (25 nmol/kg) and lixisenatide (10 nmol/kg), it was found that exendin-4 showed no protective effects at the dose chosen. Both liraglutide and lixisenatide showed effects in preventing the MPTP-induced motor impairment (Rotarod, open-field locomotion, catalepsy test), reduction in tyrosine hydroxylase (TH) levels (dopamine synthesis) in the substantia nigra and basal ganglia, a reduction of the pro-apoptotic signaling molecule BAX and an increase in the anti-apoptotic signaling molecule B-cell lymphoma-2. The results demonstrate that in this study, both liraglutide and lixisenatide are superior to exendin-4, and both drugs show promise as a novel treatment of PD.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Apoptosis; Basal Ganglia; Catalepsy; Disease Models, Animal; Dopaminergic Neurons; Exenatide; Liraglutide; Male; Mice; Mice, Inbred C57BL; Motor Activity; Neuroprotective Agents; Parkinsonian Disorders; Peptides; Rotarod Performance Test; Substantia Nigra; Tyrosine 3-Monooxygenase; Venoms

Experimental evidence suggested that Exendin-4 (Exe4), an agonist at glucagon like receptor-1 (GLP-1R), promoted tissue regeneration. We aimed to verify the effect of Exe4, in the absence or in the presence of Exendin-4(9-39), an antagonist at GLP-1R, on the healing of abraded skin. Two wounds (approximately 1.1×1.1 cm(2); namely "upper" and "lower" in respect of the head) were produced by abrasion on the back of 12 mice, which were then randomly assigned to receive an intradermal injection (20 μl) of Group 1: saline (NT) or Exe4 (62 ng) in the upper and lower wound respectively; Group 2: Exendin-4(9-39) (70 ng) in the upper and Exendin-4(9-39) (70 ng) and, after 15 min, Exe4 (62 ng) in the lower wound. Wounds were measured at the time of abrasion (T0) and 144 h (T3) afterward taking pictures with a ruler and by using a software. The inflammatory cell infiltrate, fibroblasts/myofibroblasts, endothelial cells and GLP-1R expression, were each labeled by immunofluorescence in each wound, pERK1/2 was evaluated by Western-blot in wound lysates. At T3, the percentage of healing surface was 53% and 92% for NT and Exe4 wounds respectively and 68% and 79% for those treated with Exendin-4(9-39) and Exendin-4(9-39)+Exe4 respectively. Exe4, but not Exendin-4(9-39) induced quantitative increase in fibroblasts/myofibroblasts and vessel density when compared to NT wounds. This increase was not evident in wounds treated with Exendin-4(9-39)+Exe4. Exe4 promotes wound healing opening to the possible dermatological use of this incretin analogue.

Topics: Animals; Cell Proliferation; Cell Transdifferentiation; Dermatologic Agents; Disease Models, Animal; Endothelial Cells; Enzyme Activation; Exenatide; Fibroblasts; Glucagon-Like Peptide-1 Receptor; Incretins; Male; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Myofibroblasts; Peptide Fragments; Peptides; Phosphorylation; Skin; Time Factors; Venoms; Wound Healing; Wounds and Injuries

Intrauterine growth restriction (IUGR) increases the risk of adult type 2 diabetes (T2D) and obesity. Neonatal exendin-4 treatment can prevent diabetes in the IUGR rat, but whether this will be effective in a species where the pancreas is more mature at birth is unknown. Therefore, we evaluated the effects of neonatal exendin-4 administration after experimental restriction of placental and fetal growth on growth and adult metabolic outcomes in sheep. Body composition, glucose tolerance, and insulin secretion and sensitivity were assessed in singleton-born adult sheep from control (CON; n = 6 females and 4 males) and placentally restricted pregnancies (PR; n = 13 females and 7 males) and in sheep from PR pregnancies that were treated with exendin-4 as neonates (daily sc injections of 1 nmol/kg exendin-4; PR + exendin-4; n = 11 females and 7 males). Placental restriction reduced birth weight (by 29%) and impaired glucose tolerance in the adult but did not affect adult adiposity, insulin secretion, or insulin sensitivity. Neonatal exendin-4 suppressed growth during treatment, followed by delayed catchup growth and unchanged adult adiposity. Neonatal exendin-4 partially restored glucose tolerance in PR progeny but did not affect insulin secretion or sensitivity. Although the effects on glucose tolerance are promising, the lack of effects on adult body composition, insulin secretion, and insulin sensitivity suggest that the neonatal period may be too late to fully reprogram the metabolic consequences of IUGR in species that are more mature at birth than rodents.

Topics: Adiposity; Animals; Animals, Newborn; Blood Glucose; Body Composition; Diabetes Mellitus, Type 2; Disease Models, Animal; Endometrium; Exenatide; Female; Fetal Growth Retardation; Hypoglycemic Agents; Insulin; Insulin Resistance; Insulin Secretion; Peptides; Pregnancy; Random Allocation; Sheep; Venoms

Exendin-4, an analog of glucagon-like peptide-1, has shown to have beneficial effects on endothelial function, and was recently approved for the treatment of diabetes. In previous studies, we showed that exendin-4 induces angiogenesis in in vitro and ex vivo assays; in this study, we assessed the proangiogenic effects of exendin-4 in vivo using a mouse hindlimb ischemia model. Treatment with exendin-4 for three days mitigated hindlimb and gastrocnemius muscle fiber necrosis. Hindlimb perfusion was determined using indocyanine green fluorescence dynamics that showed, significantly higher blood flow rate to the ischemic hindlimbs in an exendin-4-treated group. Immunohistochemistry assay showed that exendin-4 increased CD31-positive areas in the gastrocnemius muscle of ischemic limbs. Furthermore, treatment of the hindlimbs of ischemic mice with exendin-4 increased vascular endothelial growth factor (VEGF) and phospho-extracellular signal-related kinase (ERK) on western blot analysis. Our data demonstrate that exendin-4 prevents hindlimb ischemic injury by inducing vessels via VEGF angiogenic-related pathways. These findings suggest that exendin-4 has potential as a therapeutic agent for vascular diseases that stimulate angiogenesis.

Topics: Angiogenesis Inducing Agents; Animals; Disease Models, Animal; Exenatide; Hemodynamics; Hindlimb; Ischemia; Male; MAP Kinase Signaling System; Mice; Mice, Inbred BALB C; Neovascularization, Physiologic; Peptides; Vascular Endothelial Growth Factor A; Venoms

Some anti-diabetic therapies can have adverse effects on bone health and increase fracture risk. In this study, we tested the skeletal effects of chronic administration of two Glucagon-like peptide-1 receptor agonists (GLP-1RA), increasingly used for type 2 diabetes treatment, in a model of osteoporosis associated bone loss and examined the expression and activation of GLP-1R in bone cells. Mice were ovariectomised (OVX) to induce bone loss and four weeks later they were treated with Liraglutide (LIR) 0.3mg/kg/day, Exenatide (Ex-4) 10 μg/kg/day or saline for four weeks. Mice were injected with calcein and alizarin red prior to euthanasia, to label bone-mineralising surfaces. Tibial micro-architecture was determined by micro-CT and bone formation and resorption parameters measured by histomorphometric analysis. Serum was collected to measure calcitonin and sclerostin levels, inhibitors of bone resorption and formation, respectively. GLP-1R mRNA and protein expression were evaluated in the bone, bone marrow and bone cells using RT-PCR and immunohistochemistry. Primary osteoclasts and osteoblasts were cultured to evaluate the effect of GLP-1RA on bone resorption and formation in vitro. GLP-1RA significantly increased trabecular bone mass, connectivity and structure parameters but had no effect on cortical bone. There was no effect of GLP-1RA on bone formation in vivo but an increase in osteoclast number and osteoclast surfaces was observed with Ex-4. GLP-1R was expressed in bone marrow cells, primary osteoclasts and osteoblasts and in late osteocytic cell line. Both Ex-4 and LIR stimulated osteoclastic differentiation in vitro but slightly reduced the area resorbed per osteoclast. They had no effect on bone nodule formation in vitro. Serum calcitonin levels were increased and sclerostin levels decreased by Ex-4 but not by LIR. Thus, GLP-1RA can have beneficial effects on bone and the expression of GLP-1R in bone cells may imply that these effects are exerted directly on the tissue.

Topics: Adaptor Proteins, Signal Transducing; Animals; Bone and Bones; Bone Resorption; Calcitonin; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Female; Glucagon-Like Peptide-1 Receptor; Glycoproteins; Immunohistochemistry; Intercellular Signaling Peptides and Proteins; Liraglutide; Mice; Mice, Inbred C57BL; Osteoblasts; Osteoclasts; Osteocytes; Osteogenesis; Osteoporosis; Ovariectomy; Peptides; RNA, Messenger; Tibia; Venoms; X-Ray Microtomography

The majority of liver grafts destined for transplantation originate from brain dead donors. However, significantly better posttransplantation outcomes are achieved when organs from living donors are used, suggesting that brain death (BD) causes irreversible damage to the liver tissue. Recently, glucagon-like peptide-1 (GLP1) analogues were shown to possess interesting hepatic protection effects in different liver disease models. We hypothesized that donor treatment with the GLP1 analogue exendin-4 (Ex-4) could alleviate BD-induced liver damage. A rat model of BD was employed in order to estimate BD-induced liver damage and Ex-4's potential protective effects. Liver damage was assessed by biochemical determination of circulating hepatic markers. Apoptosis in the hepatic tissue was assessed by immunoblot and immunohistochemistry using an antibody that only recognizes the active form of caspase-3. Gene expression changes in inflammation and stress response genes were monitored by quantitative real-time polymerase chain reaction. Here, we show that Ex-4 administration to the brain dead liver donors significantly reduces levels of circulating aspartate aminotransferase and lactate dehydrogenase. This was accompanied by a remarkable reduction in hepatocyte apoptosis. In this model, BD caused up-regulation of tumor necrosis factor and stress-related genes, confirming previous findings in clinical and animal studies. In conclusion, treatment of brain dead rats with Ex-4 reduced BD-induced liver damage. Further investigation is needed to determine the molecular basis of the observed liver protection. After testing in a randomized clinical trial, the inclusion of GLP1 analogues in organ donor management might help to improve organ quality, maximize organ donation, and possibly increase liver transplantation success rates.

Topics: Animals; Apoptosis; Brain Death; Caspase 3; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Exenatide; Gene Expression Regulation; Glucagon-Like Peptide 1; Hypoglycemic Agents; Immunoblotting; Immunohistochemistry; Liver; Liver Diseases; Liver Transplantation; Male; Peptides; Rats; Rats, Wistar; Real-Time Polymerase Chain Reaction; Venoms

To investigate the expression of silent information regulator 1 (SIRT1) in rats with polycystic ovary syndrome (PCOS) and its alteration after exenatide treatment.. PCOS rat model was established by dehydroepiandrosterone induction. The animals were randomly divided into exenatide treatment group (EX group, n = 10), metformin treatment group (MF group, n = 10), PCOS group (PCOS group, n = 9) and normal control group (NC group, n = 10). Histological changes of the ovarian tissues were examined by HE staining. SIRT1 expression in the ovarian tissue was detected by RT-PCR and immunohistochemistry.. Rats in the PCOS group lost their estrous cycle. Histological observation of the ovary showed saccular dilatation of the follicle, decreased number of corpora lutea, fewer layers of granulosa cells aligned loosely, and thickened layer of theca cells. The changes in reproductive hormones and the development of insulin resistance suggested the successful establishment of the animal models. Immunohistochemistry and Q-PCR detected the mRNA and protein expressions of SIRT1 in the ovary tissues of rats in the normal control group. The SIRT1 expression was significantly lower in PCOS group than in control group (P < 0.05); after drug intervention, the SIRT1 expression significantly increased in EX and MF groups (compared with the PCOS group), whereas no significant difference was noted between the EX group and MF group.. The SIRT1 expression in the ovary tissue decreases in PCOS rats (compare with the normal rats) but can be up-regulated after Ex or MF treatment. These drugs may affect the process and development of PCOS by regulating the SIRT1 expression. Exenatide may be therapeutic for PCOS by up-regulating the SITR1 expression.

Topics: Animals; Dehydroepiandrosterone; Disease Models, Animal; Exenatide; Female; Gene Expression Regulation, Enzymologic; Immunohistochemistry; Metformin; Ovary; Peptides; Polycystic Ovary Syndrome; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; RNA, Messenger; Sirtuin 1; Up-Regulation; Venoms

Cardiovascular complications of obesity and diabetes are major health problems. Assessing their development, their link with ectopic fat deposition and their flexibility with therapeutic intervention is essential. The aim of this study was to longitudinally investigate cardiac alterations and ectopic fat accumulation associated with diet-induced obesity using multimodal cardiovascular magnetic resonance (CMR) in mice. The second objective was to monitor cardiac response to exendin-4 (GLP-1 receptor agonist).. Male C57BL6R mice subjected to a high fat (35 %) high sucrose (34 %) (HFHSD) or a standard diet (SD) during 4 months were explored every month with multimodal CMR to determine hepatic and myocardial triglyceride content (HTGC, MTGC) using proton MR spectroscopy, cardiac function with cine cardiac MR (CMR) and myocardial perfusion with arterial spin labeling CMR. Furthermore, mice treated with exendin-4 (30 μg/kg SC BID) after 4 months of diet were explored before and 14 days post-treatment with multimodal CMR.. HFHSD mice became significantly heavier (+33 %) and displayed glucose homeostasis impairment (1-month) as compared to SD mice, and developed early increase in HTGC (1 month, +59 %) and MTGC (2-month, +63 %). After 3 months, HFHSD mice developed cardiac dysfunction with significantly higher diastolic septum wall thickness (sWtnD) (1.28 ± 0.03 mm vs. 1.12 ± 0.03 mm) and lower cardiac index (0.45 ± 0.06 mL/min/g vs. 0.68 ± 0.07 mL/min/g, p = 0.02) compared to SD mice. A significantly lower cardiac perfusion was also observed (4 months:7.5 ± 0.8 mL/g/min vs. 10.0 ± 0.7 mL/g/min, p = 0.03). Cardiac function at 4 months was negatively correlated to both HTGC and MTGC (p < 0.05). 14-day treatment with Exendin-4 (Ex-4) dramatically reversed all these alterations in comparison with placebo-treated HFHSD. Ex-4 diminished myocardial triglyceride content (-57.8 ± 4.1 %), improved cardiac index (+38.9 ± 10.9 %) and restored myocardial perfusion (+52.8 ± 16.4 %) under isoflurane anesthesia. Interestingly, increased wall thickness and hepatic steatosis reductions were independent of weight loss and glycemia decrease in multivariate analysis (p < 0.05).. CMR longitudinal follow-up of cardiac consequences of obesity and diabetes showed early accumulation of ectopic fat in mice before the occurrence of microvascular and contractile dysfunction. This study also supports a cardioprotective effect of glucagon-like peptide-1 receptor agonist.

Topics: Adiposity; Animals; Blood Glucose; Coronary Circulation; Diabetes Mellitus; Diet, High-Fat; Dietary Sucrose; Disease Models, Animal; Exenatide; Fatty Liver; Glucagon-Like Peptide 1; Heart Diseases; Liver; Magnetic Resonance Imaging, Cine; Male; Mice, Inbred C57BL; Multimodal Imaging; Multivariate Analysis; Myocardial Contraction; Myocardial Perfusion Imaging; Myocardium; Obesity; Peptides; Predictive Value of Tests; Proton Magnetic Resonance Spectroscopy; Recovery of Function; Time Factors; Triglycerides; Venoms; Ventricular Function; Weight Gain

The arcuate nucleus (ARC) of the hypothalamus plays a key role in sensing metabolic feedback and regulating energy homeostasis. Recent studies revealed activation of microglia in mice with high-fat diet (HFD)-induced obesity (DIO), suggesting a potential pathophysiological role for inflammatory processes within the hypothalamus. To further investigate the metabolic causes and molecular underpinnings of such glial activation, we analyzed the microglial activity in wild-type (WT), monogenic obese ob/ob (leptin deficient), db/db (leptin-receptor mutation), and Type-4 melanocortin receptor knockout (MC4R KO) mice on either a HFD or on standardized chow (SC) diet. Following HFD exposure, we observed a significant increase in the total number of ARC microglia, immunoreactivity of ionized calcium binding adaptor molecule 1 (iba1-ir), cluster of differentiation 68 (CD68-ir), and ramification of microglial processes. The ob/ob mice had significantly less iba1-ir and ramifications. Leptin replacement rescued these phenomena. The db/db mice had similar iba1-ir comparable with WT mice but had significantly lower CD68-ir and more ramifications than WT mice. After 2 weeks of HFD, ob/ob mice showed an increase of iba1-ir, and db/db mice showed increase of CD68-ir. Obese MC4R KO mice fed a SC diet had comparable iba1-ir and CD68-ir with WT mice but had significantly more ramifications than WT mice. Intriguingly, treatment of DIO mice with glucagon-like peptide-1 receptor agonists reduced microglial activation independent of body weight. Our results show that diet type, adipokines, and gut signals, but not body weight, affect the presence and activity levels of hypothalamic microglia in obesity.

Topics: Animals; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Body Weight; Cytokinins; Diet, High-Fat; Disease Models, Animal; Exenatide; Hormones; Leptin; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microglia; Obesity; Peptides; Receptor, Melanocortin, Type 4; Receptors, Interleukin-8A; Receptors, Leptin; Signal Transduction; Supraoptic Nucleus; Venoms

Although uncoupling protein 2 (UCP2) negatively regulates intracellular reactive oxygen species (ROS) production and protects vascular function, its participation in vascular benefits of drugs used to treat cardiometabolic diseases is largely unknown. This study investigated whether UCP2 and associated oxidative stress reduction contribute to the improvement of endothelial function by a dipeptidyl peptidase-4 inhibitor, sitagliptin, in hypertension.. Pharmacological inhibition of cyclooxygenase-2 (COX-2) but not COX-1 prevented endothelial dysfunction, and ROS scavengers reduced COX-2 mRNA and protein expression in spontaneously hypertensive rats (SHR) renal arteries. Angiotensin II (Ang II) evoked endothelium-dependent contractions (EDCs) in C57BL/6 and UCP2 knockout (UCP2KO) mouse aortae. Chronic sitagliptin administration attenuated EDCs in SHR arteries and Ang II-infused C57BL/6 mouse aortae and eliminated ROS overproduction in SHR arteries, which were reversed by glucagon-like peptide 1 receptor (GLP-1R) antagonist exendin 9-39, AMP-activated protein kinase (AMPK)α inhibitor compound C, and UCP2 inhibitor genipin. By contrast, sitagliptin unaffected EDCs in Ang II-infused UCP2KO mice. Sitagliptin increased AMPKα phosphorylation, upregulated UCP2, and downregulated COX-2 expression in arteries from SHR and Ang II-infused C57BL/6 mice. Importantly, exendin 9-39, compound C, and genipin reversed the inhibitory effect of GLP-1R agonist exendin-4 on Ang II-stimulated mitochondrial ROS rises in SHR endothelial cells. Moreover, exendin-4 improved the endothelial function of renal arteries from SHR and hypertensive patients.. We elucidate for the first time that UCP2 serves as an important signal molecule in endothelial protection conferred by GLP-1-related agents. UCP2 could be a useful target in treating hypertension-related vascular events.. UCP2 inhibits oxidative stress and downregulates COX-2 expression through GLP-1/GLP-1R/AMPKα cascade.

Topics: Animals; Cyclooxygenase 2; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Endothelium, Vascular; Exenatide; Gene Expression Regulation; Humans; Hypertension; Ion Channels; Male; Mice; Mitochondria; Mitochondrial Proteins; Models, Biological; Oxidative Stress; Peptides; Pyrazines; Rats; Rats, Inbred SHR; Reactive Oxygen Species; Renal Artery; Sitagliptin Phosphate; Triazoles; Uncoupling Protein 2; Vasoconstriction; Venoms

Exendin-4 (Ex-4) is an agonist of the glucagon-like peptide 1 (GLP-1) receptor, approved for the treatment of type 2 diabetes (T2DM). Several strategies have been tried to develop stable and efficacious Ex-4 expression systems. The purpose of the current study was to determine whether double-stranded adeno-associated virus (dsAAV)-mediated in vivo expression of exendin-4 in salivary glands (SG), improves pathology in the Sprague-Dawley (SD) rat model of diabetes mellitus (DM).. The effects of Ex-4 expression by recombinant dsAAV-NT4-Ex-4 were evaluated in vitro compared with a single-strand (ss) AAV. The dsAAV was delivered into SGs and the blood glucose and insulin levels were assessed in a rat model of DM.. DsAAV-NT4-Ex-4 virus induces significant exendin-4 expression in vitro. Furthermore, Ex-4 expressed from dsAAV virus in SGs enhances insulins secretion in vivo and significantly controls the onset of hyperglycemia in rat model of DM.. Results suggest that sustained secretion of Ex-4 following dsAAV-mediated gene therapy is feasible. SGs appear to be promising targets with potential clinical applicability for the treatment of DM. This represents the example of a successful use of Ex-4 for diabetes therapy, providing support for direct AAV-mediated in vivo as an easy, safe and efficient therapeutic strategy.

Topics: Animals; Blood Glucose; Dependovirus; Diabetes Mellitus, Experimental; Disease Models, Animal; Exenatide; Genetic Therapy; Genetic Vectors; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; HEK293 Cells; Humans; Hypoglycemic Agents; Immunoenzyme Techniques; Insulin; Mice; NIH 3T3 Cells; Peptides; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Salivary Glands; Venoms

The aetiology of inflammation in the liver and vessel wall, leading to non-alcoholic steatohepatitis (NASH) and atherosclerosis, respectively, shares common mechanisms including macrophage infiltration. To treat both disorders simultaneously, it is highly important to tackle the inflammatory status. Exendin-4, a glucagon-like peptide-1 (GLP-1) receptor agonist, reduces hepatic steatosis and has been suggested to reduce atherosclerosis; however, its effects on liver inflammation are underexplored. Here, we tested the hypothesis that exendin-4 reduces inflammation in both the liver and vessel wall, and investigated the common underlying mechanism.. Female APOE*3-Leiden.CETP mice, a model with human-like lipoprotein metabolism, were fed a cholesterol-containing Western-type diet for 5 weeks to induce atherosclerosis and subsequently treated for 4 weeks with exendin-4.. Exendin-4 modestly improved dyslipidaemia, but markedly decreased atherosclerotic lesion severity and area (-33%), accompanied by a reduction in monocyte adhesion to the vessel wall (-42%) and macrophage content in the plaque (-44%). Furthermore, exendin-4 reduced hepatic lipid content and inflammation as well as hepatic CD68⁺ (-18%) and F4/80⁺ (-25%) macrophage content. This was accompanied by less monocyte recruitment from the circulation as the Mac-1⁺ macrophage content was decreased (-36%). Finally, exendin-4 reduced hepatic chemokine expression in vivo and suppressed oxidized low-density lipoprotein accumulation in peritoneal macrophages in vitro, effects dependent on the GLP-1 receptor.. Exendin-4 reduces inflammation in both the liver and vessel wall by reducing macrophage recruitment and activation. These data suggest that exendin-4 could be a valuable strategy to treat NASH and atherosclerosis simultaneously.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Apolipoprotein E3; Atherosclerosis; Cholesterol Ester Transfer Proteins; Diet, Atherogenic; Disease Models, Animal; Drug Implants; Dyslipidemias; Endothelium, Vascular; Exenatide; Fatty Liver; Female; Glucagon-Like Peptide-1 Receptor; Humans; Hypolipidemic Agents; Liver; Macrophage Activation; Macrophages; Mice; Mice, Transgenic; Non-alcoholic Fatty Liver Disease; Peptides; Random Allocation; Receptors, Glucagon; Venoms

The design, synthesis and pharmacology of novel long-acting exenatide analogs for the treatment of metabolic diseases are described. These molecules display enhanced pharmacokinetic profile and potent glucoregulatory and weight lowering actions compared to native exenatide. [Leu(14)]exenatide-ABD is an 88 residue peptide amide incorporating an Albumin Binding Domain (ABD) scaffold. [Leu(14)]exenatide-ABP is a 53 residue peptide incorporating a short Albumin Binding Peptide (ABP). [Leu(14)]exenatide-ABD and [Leu(14)]exenatide-ABP exhibited nanomolar functional GLP-1 receptor potency and were metabolically stable in vitro in human plasma and in a pancreatic digestive enzyme mixture. Both molecules displayed picomolar and nanomolar binding association with albumin across multiple species and circulating half lives of 16 and 11 hours, respectively, post a single IV dose in rats. Unlike exenatide, both molecules elicited robust glucose lowering when injected 1 day prior to an oral glucose tolerance test, indicative of their extended duration of action. [Leu(14)]exenatide-ABD was compared to exenatide in a Lep (ob/ob) mouse model of diabetes. Twice-weekly subcutaneously dosed [Leu(14)]exenatide-ABD displayed superior glucose lowering and weight loss in diabetic mice when compared to continuously infused exenatide at the same total weekly dose. A single oral administration of each molecule via an enteric coated capsule to cynomolgus monkeys showed superior pharmacokinetics for [Leu(14)]exenatide-ABD as compared to [Leu(14)]exenatide-ABP with detectable exposure longer than 14 days. These studies support the potential use of these novel long acting exenatide analogs with different routes of administration for the treatment of type 2 diabetes.

Topics: Administration, Oral; Albumins; Animals; Binding Sites; Diabetes Mellitus, Experimental; Disease Models, Animal; Drug Stability; Exenatide; Glucagon-Like Peptide-1 Receptor; Glucose Tolerance Test; Humans; Hypoglycemic Agents; Kinetics; Macaca fascicularis; Male; Mice; Peptides; Protein Binding; Protein Interaction Domains and Motifs; Rats; Receptors, Glucagon; Venoms

To investigate the metabolic changes in skeletal muscle and/or adipose tissue in glucagon-like peptide-1-induced improvement of nonalcoholic fatty liver disease (NAFLD).. Male Wistar rats were fed either a control diet (control group) or a high-fat diet (HFD). After 4 wk, the HFD-fed rats were subdivided into two groups; one group was injected with exenatide [HFD-Ex(+) group] and the other with saline [HFD-Ex(-) group] every day for 12 wk. The control group received saline and were fed a control diet. Changes in weight gain, energy intake, and oxygen consumption were analyzed. Glucose tolerance tests were performed after 8 wk of treatment. Histological assessments were performed in liver and adipose tissue. RNA expression levels of lipid metabolism related genes were evaluated in liver, skeletal muscle, and adipose tissue.. Exenatide attenuated weight gain [HFD-Ex(-) vs HFD-Ex(+)] and reduced energy intake, which was accompanied by an increase in oxygen consumption and a decrease in the respiratory exchange ratio [HFD-Ex(-) vs HFD-Ex(+)]. However, exenatide did not affect glucose tolerance. Exenatide reduced lipid content in the liver and adipose tissue. Exenatide did not affect the expression of lipid metabolism-related genes in the liver or skeletal muscle. In adipose tissue, exenatide significantly upregulated lipolytic genes, including hormone-sensitive lipase, carnitine palmitoyltransferase-1, long-chain acyl-CoA dehydrogenase, and acyl-CoA oxidase 1 [HFD-Ex(-) vs HFD-Ex(+)]. Exenatide also upregulated catalase and superoxide dismutase 2 [HFD-Ex(-) vs HFD-Ex(+)].. In addition to reducing appetite, enhanced lipid use by exenatide in adipose tissue may reduce hepatic lipid content in NAFLD, most likely by decreasing lipid influx into the liver.

Topics: Adipose Tissue; Animals; Appetite Regulation; Blood Glucose; Diet, High-Fat; Disease Models, Animal; Energy Intake; Energy Metabolism; Exenatide; Gene Expression Regulation, Enzymologic; Lipolysis; Liver; Male; Mitochondria; Muscle, Skeletal; Non-alcoholic Fatty Liver Disease; Oxygen Consumption; Peptides; Rats, Wistar; Time Factors; Up-Regulation; Venoms; Weight Gain

Prader-Willi syndrome (PWS) is a genetic disease characterized by persistent hunger and hyperphagia. The lack of the Snord116 small nucleolar RNA cluster has been identified as the major contributor to PWS symptoms. The Snord116 deletion (Snord116del) mouse model manifested a subset of PWS symptoms including hyperphagia and hyperghrelinemia. In this study, male Snord116del mice were characterized and tested for their acute and chronic responses to anorexic substances related to the ghrelin pathway. In comparison with their wild-type littermates, the food intake rate of Snord116del mice was 14% higher when fed ad libitum, and 32% to 49% higher within 12 hours after fasting. Fasted Snord116del mice were less sensitive to the acute anorexic effect of competitive antagonist [d-Lys(3)]-GHRP6, YIL-781, and reverse agonist [d-Arg(1),d-Phe(5),d-Trp(7,9),Leu(11)]-substance P (SPA) of ghrelin receptor GHS-R. All 3 GHS-R inhibitors failed to inhibit chronic food intake of either Snord116del or wild-type mice due to rapid adaptation. Although fasted Snord116del mice had normal sensitivity to the acute anorexic effect of glucagon-like peptide 1 receptor agonist exenatide, those fed ad libitum required a higher dose and more frequent delivery to achieve ∼15% suppression of long-term food intake in comparison with wild-type mice. Ghrelin, however, is unlikely to be essential for the anorexic effect of exenatide in fed mice, as shown by the fact that exenatide did not reduce ghrelin levels in fed mice and food intake of ghrelin(-/-) mice fed ad libitum could be suppressed by exenatide. In conclusion, this study suggests that GHS-R may not be an effective therapeutic target, and in contrast, exenatide may produce anorexic effect in PWS individuals.

Topics: Analysis of Variance; Animals; Anorexia; Disease Models, Animal; Eating; Exenatide; Fasting; Ghrelin; Humans; Hyperphagia; Hypoglycemic Agents; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oligopeptides; Peptides; Piperidines; Prader-Willi Syndrome; Quinazolinones; Receptors, Ghrelin; RNA, Small Nucleolar; Substance P; Venoms

The aims of the study were to evaluate (1) detection of cognitive function changing in rat with hepatosteatosis model and (2) evaluate the effect of GLP-1 analog (exenatide) on cognitive function in hepatosteatosis. In the study group, 30% fructose was given in nutrition water to perform hepatosteatosis for 8 weeks to 18 male rats. Six male rats were chosen as control group and had normal nutrition. Fructose nutrition group were stratified into 3 groups. In first group (n = 6), intracerebroventricular (ICV) infusion of exenatide (n = 6) was given. ICV infusion of NaCl (n = 6) was given to second group. And also, the third group had no treatment. And also, rats were evaluated for passive avoidance learning (PAL) and liver histopathology. Mean levels of latency time were statistically significantly decreased in rats with hepatosteatosis than those of normal rats (P < 0.00001). However, mean level of latency time in rats with hepatosteatosis treated with ICV exenatide was statistically significantly increased than that of rats treated with ICV NaCl (P < 0.001). Memory performance falls off in rats with hepatosteatosis feeding on fructose (decreased latency time). However, GLP-1 ameliorates cognitive functions (increased latency time) in rats with hepatosteatosis and releated metabolic syndrome.

Topics: Animals; Cognition; Disease Models, Animal; Exenatide; Fatty Liver; Glucagon-Like Peptide 1; Hypoglycemic Agents; Male; Peptides; Rats; Venoms

The breakdown of the inner endothelial blood-retinal barrier (BRB) and subsequent retinal vascular leakage are the main causes of vision loss due to diabetic retinopathy (DR). Exendin-4 (E4) is a long-acting agonist of the glucagon-like peptide 1 hormone receptor (GLP-1R) that is widely used in clinics and has shown a neuroprotective effect. Our previous studies demonstrated the protective effect of E4 in early experimental DR; however, the molecular and cellular mechanisms that mediate this protective effect are not fully known. The BRB plays a key role in DR. We speculated that E4 may exert its protective effects on the BRB. To test this hypothesis, E4 (0.1 μg/2 μL/eye) or vehicle were intravitreally injected into diabetic Goto-Kakizaki(GK) rats and control animals. The results revealed that E4 significantly inhibited the reductions in electroretinogram (ERG) amplitudes in the GK rats, particularly in the b-wave and oscillatory potentials (OPs). E4 upregulated retinal GLP-1R expression and downregulated the expressions of placental growth factor (PLGF) and vascular endothelial growth factor (VEGF) via the ERK and AKT/PKB pathways. Decreases in tight junction protein (i.e., claudin-5 and occludin) expression and increases in Evans blue permeation (EBP) were inhibited by E4. Similar results were also found in primary rat Müller cells in high glucose concentration cultures in vitro. We conclude that E4 may protect the BRB from diabetic insults by decreasing PLGF and ICAM-1 expression and maintaining the integrity of the BRB. Thus, E4 treatment may be an effective therapeutic approach for DR.

Topics: Animals; Blood-Retinal Barrier; Capillary Permeability; Claudin-5; Diabetic Retinopathy; Disease Models, Animal; Electroretinography; Exenatide; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Intercellular Adhesion Molecule-1; Intravitreal Injections; Male; MAP Kinase Signaling System; Occludin; Peptides; Placenta Growth Factor; Pregnancy Proteins; Rats; Rats, Wistar; Receptors, Glucagon; Retinal Vessels; Vascular Endothelial Growth Factor A; Venoms

The activation of the biliary stem-cell signaling pathway hairy and enhancer of split 1/pancreatic duodenal homeobox-1 (Hes-1/PDX-1) in mature cholangiocytes determines cell proliferation. Neurogenin-3 (Ngn-3) is required for pancreas development and ductal cell neogenesis. PDX-1-dependent activation of Ngn-3 initiates the differentiation program by inducing microRNA (miR)-7 expression. Here we investigated the role Ngn-3 on cholangiocyte proliferation. Expression levels of Ngn-3 and miR-7 isoforms were tested in cholangiocytes from normal and cholestatic human livers. Ngn-3 was knocked-down in vitro in normal rat cholangiocytes by short interfering RNA (siRNA). In vivo, wild-type and Ngn-3-heterozygous (+/-) mice were subjected to 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding (a model of sclerosing cholangitis) or bile duct ligation (BDL). In the liver, Ngn-3 is expressed specifically in cholangiocytes of primary sclerosing cholangitis (PSC) patients and in mice subjected to DDC or BDL, but not in normal human and mouse livers. Expression of miR-7a-1 and miR-7a-2 isoforms, but not miR-7b, was increased in DDC cholangiocytes compared to normal ones. In normal rat cholangiocytes, siRNA against Ngn-3 blocked the proliferation stimulated by exendin-4. In addition, Ngn-3 knockdown neutralized the overexpression of insulin growth factor-1 (IGF1; promitotic effector) observed after exposure to exendin-4, but not that of PDX-1 or VEGF-A/C. Oligonucleotides anti-miR-7 inhibited the exendin-4-induced proliferation in normal rat cholangiocytes, but did not affect Ngn-3 synthesis. Biliary hyperplasia and collagen deposition induced by DDC or BDL were significantly reduced in Ngn-3(+/-) mice compared to wild-type.. Ngn-3-dependent activation of miR-7a is a determinant of cholangiocyte proliferation. These findings indicate that the reacquisition of a molecular profile typical of organ development is essential for the biological response to injury by mature cholangiocytes.

Topics: Acute Lung Injury; Animals; Basic Helix-Loop-Helix Transcription Factors; Bile Ducts; Cell Proliferation; Cholestasis; Collagen; Disease Models, Animal; Exenatide; Humans; In Vitro Techniques; Insulin-Like Growth Factor I; Mice; Mice, Inbred Strains; MicroRNAs; Nerve Tissue Proteins; Oligonucleotides; Peptides; Rats; RNA, Small Interfering; Signal Transduction; Venoms

Glucagon‑like peptide‑1 (GLP‑1) is involved in the development of non‑alcoholic steatohepatitis (NASH), which is characterized by fatty acid imbalance. The aim of this study was to investigate the effects of the GLP‑1 receptor (GLP‑1R) agonist, exendin‑4 (Ex‑4), on hepatic fatty acid metabolism and its key enzyme, Δ‑5‑desaturase, in a murine model of NASH. NASH was induced in db/db mice fed a methionine‑choline deficient (MCD) diet. Ex‑4 (n=4) or saline [control (CON); n=4] was administered intraperitoneally for 8 weeks. Steatohepatitis activity was evaluated by non‑alcoholic fatty liver disease (NAFLD) activity score. Hepatic fatty acid composition and Δ‑5‑desaturase index were analyzed by gas chromatography. Ex‑4 treatment significantly reduced body weight and the NAFLD activity score. Hepatic concentrations of long‑chain saturated fatty acids (SFAs) were significantly higher in the Ex‑4 group compared to the CON group (23240±955 vs. 31710±8436 µg/g•liver, P<0.05).Ex‑4 significantly reduced hepatic n‑3 polyunsaturated fatty acid (PUFA)/n‑6 PUFA ratio compared to the CON group (13.83±3.15 vs. 8.73±1.95, P<0.05). In addition, the hepatic Δ‑5‑desaturase index was significantly reduced in the Ex‑4 group compared to the CON group (31.1±12.4 vs. 10.5±3.1, P<0.05). In conclusion, the results showed that Ex‑4 improved steatohepatitis in a murine model of NASH. Furthermore, Ex‑4 altered hepatic long‑chain saturated and PUFA composition and reduced the Δ‑5‑desaturase index. Thus, Ex‑4 may improve NASH by regulating hepatic fatty acid metabolism.

Topics: Animals; Body Weight; Delta-5 Fatty Acid Desaturase; Disease Models, Animal; Exenatide; Fatty Acid Desaturases; Fatty Acids; Glucagon-Like Peptide-1 Receptor; Liver; Male; Mice; Models, Biological; Non-alcoholic Fatty Liver Disease; Peptides; Receptors, Glucagon; Triglycerides; Venoms

The short biological half-life limits the therapeutic use of glucagon-like peptide-1 (GLP-1) and chemical modification to improve the interaction of peptides with serum albumin represents an effective strategy to develop long-acting peptide analogues. Coumarin, a natural product, is known to bind tightly to plasma proteins and possesses many biological activities. Therefore, we designed and synthesized a series of coumarin-modified GLP-1 derivatives, hypothesizing that conjugation with coumarin would retain the therapeutic effects and prolong the biological half-life of the conjugates.. Four cysteine-modified GLP-1 analogues (1-4) were prepared using Gly8 -GLP-1(7-36)-NH2 peptide as a starting point. These analogues were conjugated with two coumarin maleimides to yield eight compounds (conjugates 6-13) for testing. Activation of human GLP-1 receptors, stability to enzymic inactivation in plasma and binding to human albumin were assessed in vitro. In vivo, effects on oral glucose tolerance tests (OGTT) in rats and on blood glucose levels in db/db mice were studied.. Most conjugates showed well preserved receptor activation efficacy, enhanced albumin-binding properties and improved in vitro plasma stability and conjugate 7 was selected to undergo further assessment. In rats, conjugate 7 had a longer circulating t1/2 than exendin-4 or liraglutide. A prolonged antidiabetic effect of conjugate 7 was observed after OGTT in rats and a prolonged hypoglycaemic effect in db/db mice.. Cysteine-specific coumarin conjugation with GLP-1 offers a useful approach to the development of long-acting incretin-based antidiabetic agents. Conjugate 7 is a promising long-lasting GLP-1 derivative deserving further investigation.

Topics: Animals; Coumarins; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Glucose; Glucose Tolerance Test; HEK293 Cells; Humans; Hypoglycemic Agents; Insulin; Insulin Secretion; Liraglutide; Male; Mice, Inbred C57BL; Peptides; Rats, Sprague-Dawley; Receptors, Glucagon; Serum Albumin; Venoms

Comorbid neurobehavioral disturbances and type-2 diabetes mellitus (T2DM) warrant immediate research attention. Exenatide, which is a potent and selective agonist for the glucagon-like peptide-1 (GLP-1), is used in the treatment of T2DM. Exenatide displays a multitude of effects in the central nervous system. The aim of this study was to investigate the anxiolytic- and antidepressant-like effects and analgesic effects of exenatide in a type-2 diabetic mouse model.. Modified elevated plus-maze test for anxiolytic-like, forced swimming test for depression-like behavior and hotplate test for neuropathy were used as behavioral tasks. Behavioral parameters were investigated in a streptozocin--(100 mg/kg, i.p.) and nicotinamide--(240 mg/kg, i.p.) induced type-2 diabetic mouse model. Exenatide (0.1 µg/kg, s.c., twice daily) was administered for 2 weeks. Vehicle (control), diabetic, and exenatide-treated diabetic mice were tested.. Our results confirm that exenatide exerts anxiolytic- and antidepressant-like effects and might be effective in diabetic neuropathy in a diabetic mouse model.. Exenatide may be a good candidate as a treatment option for depression, anxiety, and neuropathy in patients with type-2 diabetes.

Topics: Animals; Anti-Anxiety Agents; Antidepressive Agents; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Disease Models, Animal; Exenatide; Immobilization; Male; Maze Learning; Mice, Inbred BALB C; Motor Activity; Peptides; Reaction Time; Time Factors; Venoms

We have demonstrated that GLP-1 improved myocardial functional recovery in acute myocardial ischemic injury. However, whether stimulation of the GLP-1 receptor (GLP-1R) with exendin-4, a selective GLP-1R agonist, could initiate a protective effect in the heart remains to be determined. Mouse myocardial infarction (MI) was created by ligation of the left descending artery. After 48 h of MI, animals were divided into the following groups (n = 5-7/group): 1) sham (animals that underwent thoracotomy without ligation), 2) MI [animals that underwent MI and received a daily dose of intraperitoneal injection (ip) of saline]; and 3) MI + exendin-4 [infarcted mice that received injections of exendin-4 (0.1 mg/kg ip)]. Two weeks later, cardiac function was assessed by echocardiography and an isovolumetrically perfused heart. Compared with control MI hearts, stimulation of GLP-1R improved cardiac function, which was associated with attenuation of myocardial hypertrophy, the mitigation of interstitial fibrosis, and an increase in survival rate in post-MI hearts. Furthermore, H9c2 cardiomyoblasts were preconditioned with exendin-4 at a dose of 100 nmol/l and then subjected to hydrogen peroxide exposure at concentrations of 50 and 100 μmol/l. The exendin-4 treatment decreased lactate dehydrogenase leakage and increased cell survival. Notably, this event was also associated with the reduction of cleaved caspase-3 and caspase-9 and attenuation of reactive oxygen species production. Exendin-4 treatments improved mitochondrial respiration and suppressed the opening of mitochondrial permeability transition pore and protected mitochondria function. Our results indicate that GLP-1R serves as a novel approach to eliciting cardioprotection and mitigating oxidative stress-induced injury.

Topics: Animals; Antioxidants; Apoptosis; Cardiotonic Agents; Cell Line; Cell Survival; Disease Models, Animal; Exenatide; Glucagon-Like Peptide-1 Receptor; Heart Ventricles; Hypertrophy, Left Ventricular; Kaplan-Meier Estimate; Male; Mice, Inbred ICR; Mitochondria, Heart; Molecular Targeted Therapy; Myoblasts, Cardiac; Myocardial Infarction; Oxidative Stress; Peptides; Rats; Receptors, Glucagon; Ultrasonography; Venoms; Ventricular Dysfunction, Left; Ventricular Remodeling

Leptin may reduce pancreatic lipid deposition, which increases with progression of obesity and can impair β-cell function. The insulinotropic effect of glucagon-like peptide-1 (GLP-1) and the efficacy of GLP-1 receptor agonist are reduced associated with impaired β-cell function. In this study, we examined whether leptin could restore the efficacy of exenatide, a GLP-1 receptor agonist, in type 2 diabetes with increased adiposity. We chronically administered leptin (500 μg·kg⁻¹·day⁻¹) and/or exenatide (20 μg·kg⁻¹·day⁻¹) for 2 wk in a mouse model of type 2 diabetes with increased adiposity induced by streptozotocin and high-fat diet (STZ/HFD mice). The STZ/HFD mice exhibited hyperglycemia, overweight, increased pancreatic triglyceride level, and reduced glucose-stimulated insulin secretion (GSIS); moreover, the insulinotropic effect of exenatide was reduced. However, leptin significantly reduced pancreatic triglyceride level, and adding leptin to exenatide (LEP/EX) remarkably enhanced GSIS. These results suggested that the leptin treatment restored the insulinotropic effect of exenatide in the mice. In addition, LEP/EX reduced food intake, body weight, and triglyceride levels in the skeletal muscle and liver, and corrected hyperglycemia to a greater extent than either monotherapy. The pair-feeding experiment indicated that the marked reduction of pancreatic triglyceride level and enhancement of GSIS by LEP/EX occurred via mechanisms other than calorie restriction. These results suggest that leptin treatment may restore the insulinotropic effect of exenatide associated with the reduction of pancreatic lipid deposition in type 2 diabetes with increased adiposity. Combination therapy with leptin and exenatide could be an effective treatment for patients with type 2 diabetes with increased adiposity.

Topics: Adiposity; Animals; Anti-Obesity Agents; Diabetes Mellitus, Type 2; Diet, High-Fat; Disease Models, Animal; Drug Implants; Drug Synergism; Drug Therapy, Combination; Exenatide; Glucagon-Like Peptide 1; Hyperglycemia; Hypoglycemic Agents; Insulin; Insulin Secretion; Leptin; Male; Mice, Inbred C57BL; Overweight; Pancreas; Peptides; Recombinant Proteins; Streptozocin; Triglycerides; Venoms

Exendin-4 (E4), a long-acting agonist of the hormone glucagon-like peptide 1 receptor (GLP-1R), is administered to treat type II diabetes in the clinical setting and also shows a neuroprotective effect. Our previous studies demonstrated its protective effect in early experimental diabetic retinopathy (DR), but the molecular and cellular mechanisms are largely unknown. This study aimed to investigate the protective mechanism of a GLP-1R agonist E4 against early DR in Goto-Kakizaki (GK) rats.. Diabetic GK rats and control animals were randomly assigned to receive E4 or vehicle by intravitreal injection. The retinal function and retinal cell counts were evaluated using an electroretinogram and light microscopy. The expressions of retinal GLP-1R, mitochondria-dependent apoptosis-associated genes, reactive gliosis markers, and endoplasmic reticulum stress-related pathway genes were studied by western blotting and immunohistochemistry in vivo and in vitro.. E4 significantly prevented the reduction of the b-wave and oscillatory potential amplitudes and retinal cell loss and maintained the Bcl-2/Bax and Bcl-xL/Bax ratio balances in GK rats. It also downregulated the expression of glial fibrillary acidic protein and reduced retinal reactive gliosis. Similar results were found in primary rat Müller cells under high glucose culture in vitro.. E4 may protect retinal cells from diabetic attacks by activating GLP-1R, decreasing retinal cell apoptosis, and reducing retinal reactive gliosis. Thus, E4 treatment may be a novel approach for early DR.

Topics: Animals; Apoptosis; Diabetes Mellitus, Type 2; Disease Models, Animal; Electroretinography; Ependymoglial Cells; Exenatide; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Gliosis; Glucagon-Like Peptide-1 Receptor; Glucose; Hypoglycemic Agents; Intravitreal Injections; Male; Peptides; Primary Cell Culture; Protective Agents; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Transgenic; Receptors, Glucagon; Retina; Venoms

Twelve novel dicoumarol glucagon-like peptide 1 (GLP-1) conjugates were designed, synthesized, and tested for biological activity. All derivatives retained receptor activation efficacy, and exhibited improved albumin affinity and in vitro stability in rat plasma. The in vivo elimination half-lives of 13c and 13 l (22.07 and 18.78 h, respectively) were much longer than those of the GLP-1 receptor agonists exendin-4 (2.82 h) and liraglutide (12.53 h). The prolonged in vivo antidiabetic effects of 13c and 13 l on db/db mice were confirmed by the hypoglycemic efficacy test and the multiple intraperitoneal glucose tolerance test. Importantly, a once daily administration of 13c to db/db mice for 7 weeks provided long-term beneficial effects by lowering glycated hemoglobin (HbA1c) levels to 5.05%, which was lower than with liraglutide treatment (5.41%). These results suggest that 13c is a promising long-lasting GLP-1 mimetic that may be suitable for clinical use following further research.

Topics: Animals; Coumarins; Diabetes Mellitus, Experimental; Disease Models, Animal; Drug Design; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Glucose Tolerance Test; Glycated Hemoglobin; Half-Life; HEK293 Cells; Humans; Hypoglycemic Agents; Male; Mice; Mice, Obese; Molecular Structure; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Serum Albumin

Oxidative stress produced during pancreatic islet isolation leads to significant β-cell damage. Homeostatic cytokines secreted subsequently to islet transplantation damage β-cells by generating oxygen free radicals. In this study, exendin-4, a glucagon-like peptide-1 analog improved islet transplantation outcome by increasing the survival of diabetic recipient mice from 58% to 100%. We hypothesized that this beneficial effect was due to the ability of exendin-4 to reduce oxidative stress. Further experiments showed that it significantly reduced the apoptotic rate of cultured β-cells subjected to hypoxia or to IL-1β. Reduction of apoptotic events was confirmed in pancreatic islet grafts of exendin-4-treated mice. Exendin-4 enhanced Akt phosphorylation of β-cells and insulin released from them. It even augmented insulin secretion from islets cultivated at hypoxic conditions. Exposure to hypoxia led to a decrease in the activation of Akt, which was reversed when β-cells were pretreated with exendin-4. Moreover, exendin-4 increased the activity of redox enzymes in a hypoxia-treated β-cell line and reduced reactive oxygen species production in isolated pancreatic islets. Recovery from diabetes in mice transplanted with hypoxic islets was more efficient when they received exendin-4. In conclusion, exendin-4 rescued islets from oxidative stress caused by hypoxia or due to cytokine exposure. It improved the outcome of syngenic and xenogenic islet transplantation.

Topics: Animals; Apoptosis; Cell Hypoxia; Cells, Cultured; Diabetes Mellitus, Experimental; Disease Models, Animal; Exenatide; Graft Survival; Hypoglycemic Agents; Insulin-Secreting Cells; Islets of Langerhans; Islets of Langerhans Transplantation; Mice; Mice, Inbred C57BL; Oxidative Stress; Peptides; Reactive Oxygen Species; Swine; Venoms

Glucagon-like peptide-1 and its receptor agonist-exendin-4 (Ex-4) have been shown to provide beneficial effects for cardiovascular diseases. This study investigated the effects of Ex-4 on ischemia-induced ventricular arrhythmias in rats.. Anesthetized male rats were once treated with Ex-4 (5 μg/kg, i.v.) 1 h before ischemia in the absence and/or presence of 5-hydroxydecanoic acid (5-HD, 10 mg/kg, i.v., a specific inhibitor of mitochondrial ATP-sensitive potassium [KATP] channels) which were once injected 10 min before ischemia. And then subjected to ischemia for 30 min. Ventricular arrhythmias were assessed.. During the 30-min ischemia, Ex-4 significantly reduced the incidence of ventricular fibrillation (VF) (p < 0.05). The duration of ventricular tachycardia (VT) + VF, the number of VT + VF episodes and the severity of arrhythmias were all significantly reduced by Ex-4 compared to those in myocardial ischemia group (p < 0.05 for all). Administration of 5-HD abolished the protective effects of Ex-4 on VF incidence, the duration of VT + VF, the number of VT + VF episodes and the severity of arrhythmias (p < 0.05 for all).. This study suggested that Ex-4 could attenuate ischemia-induced ventricular arrhythmias in rats in which mitochondrial KATP channels may be involved.

Topics: Animals; Anti-Arrhythmia Agents; Blood Pressure; Decanoic Acids; Disease Models, Animal; Exenatide; Heart Rate; Hydroxy Acids; Hypoglycemic Agents; Male; Myocardial Ischemia; Peptides; Potassium Channel Blockers; Potassium Channels; Rats; Rats, Sprague-Dawley; Tachycardia, Ventricular; Venoms; Ventricular Fibrillation

Recent studies have shown that type 2 diabetes mellitus (T2DM) is a risk factor for cognitive dysfunction or dementia. Insulin resistance is often associated with T2DM and can induce defective insulin signaling in the central nervous system as well as increase the risk of cognitive impairment in the elderly. Glucagone like peptide-1 (GLP-1) is an incretin hormone and, like GLP-1 analogs, stimulates insulin secretion and has been employed in the treatment of T2DM. GLP-1 and GLP-1 analogs also enhance synaptic plasticity and counteract cognitive deficits in mouse models of neuronal dysfunction and/or degeneration. In this study, we investigated the potential neuroprotective effects of long-term treatment with exenatide, a GLP-1 analog, in two animal models of neuronal dysfunction: the PS1-KI and 3xTg-AD mice. We found that exenatide promoted beneficial effects on short- and long-term memory performances in PS1-KI but not in 3xTg-AD animals. In PS1-KI mice, the drug increased brain lactate dehydrogenase activity leading to a net increase in lactate levels, while no effects were observed on mitochondrial respiration. On the contrary, exenatide had no effects on brain metabolism of 3xTg-AD mice. In summary, our data indicate that exenatide improves cognition in PS1-KI mice, an effect likely driven by increasing the brain anaerobic glycolysis rate.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Brain; Cognition Disorders; Diabetes Mellitus, Experimental; Disease Models, Animal; Electron Transport Complex IV; Exenatide; Female; Hypoglycemic Agents; L-Lactate Dehydrogenase; Lactic Acid; Male; Memory, Long-Term; Memory, Short-Term; Mice; Mice, Transgenic; Mitochondria; Peptides; tau Proteins; Venoms

Glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 (Ex-4) is a remedy for type 2 diabetes mellitus (T2DM). Ex-4 ameliorates cardiac dysfunction induced by myocardial infarction in preclinical and clinical settings. However, it remains unclear whether Ex-4 may modulate diabetic cardiomyopathy. We tested the impact of Ex-4 on two types of diabetic cardiomyopathy models, genetic (KK) and acquired T2DM induced by high-fat diet [diet-induced obesity (DIO)], to clarify whether Ex-4 may combat independently of etiology. Each type of mice was divided into Ex-4 (24 nmol·kg(-1)·day(-1) for 40 days; KK-ex4 and DIO-ex4) and vehicle (KK-v and DIO-v) groups. Ex-4 ameliorated systemic and cardiac insulin resistance and dyslipidemia in both T2DM models. T2DM mice exhibited systolic (DIO-v) and diastolic (DIO-v and KK-v) left ventricular dysfunctions, which were restored by Ex-4 with reduction in left ventricular hypertrophy. DIO-v and KK-v exhibited increased myocardial fibrosis and steatosis (lipid accumulation), in which were observed cardiac mitochondrial remodeling and enhanced mitochondrial oxidative damage. Ex-4 treatment reversed these cardiac remodeling and oxidative stress. Cytokine array revealed that Ex-4-sensitive inflammatory cytokines were ICAM-1 and macrophage colony-stimulating factor. Ex-4 ameliorated myocardial oxidative stress via suppression of NADPH oxidase 4 with concomitant elevation of antioxidants (SOD-1 and glutathione peroxidase). In conclusion, GLP-1R agonism reverses cardiac remodeling and dysfunction observed in T2DM via normalizing imbalance of lipid metabolism and related inflammation/oxidative stress.

Topics: Animals; Diabetes Mellitus, Type 2; Diabetic Cardiomyopathies; Diet, High-Fat; Disease Models, Animal; Dyslipidemias; Echocardiography, Doppler; Exenatide; Fibrosis; Glucagon-Like Peptide-1 Receptor; Glutathione Peroxidase; Hypertrophy, Left Ventricular; Hypoglycemic Agents; Inflammation Mediators; Infusions, Subcutaneous; Insulin Resistance; Intercellular Adhesion Molecule-1; Lipid Metabolism; Macrophage Colony-Stimulating Factor; Male; Mice; Mitochondria, Heart; Myocardium; NADPH Oxidase 4; NADPH Oxidases; Oxidative Stress; Peptides; Receptors, Glucagon; Superoxide Dismutase; Superoxide Dismutase-1; Time Factors; Venoms; Ventricular Dysfunction, Left; Ventricular Function, Left; Ventricular Remodeling

Glucagon-like peptide-1 receptor (GLP-1R) activation exerts protective effects against reactive oxygen species by inducing the oxidative defense gene heme oxygenase-1 (HO-1), and provides protection in mice against transient focal cerebral ischemia and ischemia-reperfusion injury in the rat heart. GLP-1R is also expressed in the kidney, but it is unknown whether GLP-1R activation is able to protect against ischemia-reperfusion injury in the rat kidney.. We used a rat model of renal ischemia-reperfusion injury. The rats were pretreated with the GLP-1R agonist, exendin-4 before reperfusion. We used real-time polymerase chain reaction to evaluate expression of the oxidative defense gene HO-1 and Western blot analysis for HO-1 and GLP-1R. Renal function was assessed at baseline and 24 and 72 h after reperfusion. The kidneys were processed for histologic and morphometric analysis, caspase-3, and ED1 immunohistochemistry at 72 h. The degree of apoptosis of the renal tubular cells was determined using terminal deoxynucleotidyl transferase deoxyuridine triphosphate-biotin nick end labeling assays.. Exendin-4 pretreatment resulted in GLP-1R activation and upregulation of HO-1. Preconditional activation of GLP-1R significantly improved the serum creatinine levels compared with vehicle (P < 0.05). Furthermore, tissue injury, caspase-3 and ED1 expression, and apoptosis were less severe, as quantified by application of a standardized histologic scoring system in a blinded manner.. These results have demonstrated that preconditional activation of the GLP-1R with exendin-4 in the kidney significantly protected against ischemia-reperfusion injury in rats by increasing HO-1 expression.

Topics: Animals; Apoptosis; Creatinine; Disease Models, Animal; Exenatide; Glucagon-Like Peptide-1 Receptor; Heme Oxygenase-1; Hypoglycemic Agents; Kidney Diseases; Macrophages; Male; Peptides; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Reperfusion Injury; RNA, Messenger; Venoms

Glucagon-like peptide-1 (GLP-1) and its mimetics reduce infarct size in the setting of acute myocardial ischemia/reperfusion (I/R) injury. However, the short serum half-life of GLP-1 and its mimetics may limit their therapeutic use in acute myocardial ischemia. Domain antibodies to serum albumin (AlbudAbs) have been developed to extend the serum half-life of short lived therapeutic proteins, peptides and small molecules. In this study, we compared the effect of a long acting GLP-1 agonist, DPP-IV resistant GLP-1 (7-36, A8G) fused to an AlbudAb (GAlbudAb), with the effect of the GLP-1 mimetic, exendin-4 (short half-life GLP-1 agonist) on infarct size following acute myocardial I/R injury.. Male Sprague-Dawley rats (8-week-old) were treated with vehicle, GAlbudAb or exendin-4. Myocardial ischemia was induced 2 h following the final dose for GAlbudAb and 30 min post the final dose for exendin-4. In a subgroup of animals, the final dose of exendin-4 was administered (1 μg/kg, SC, bid for 2 days) 6 h prior to myocardial ischemia when plasma exendin-4 was at its minimum concentration (C(min)). Myocardial infarct size, area at risk and cardiac function were determined 24 h after myocardial I/R injury.. GAlbudAb and exendin-4 significantly reduced myocardial infarct size by 28% and 23% respectively, compared to vehicle (both p < 0.01 vs. vehicle) after I/R injury. Moreover, both GAlbudAb and exendin-4 markedly improved post-ischemic cardiac contractile function. Body weight loss and reduced food intake consistent with the activation of GLP-1 receptors was observed in all treatment groups. However, exendin-4 failed to reduce infarct size when administered 6 h prior to myocardial ischemia, suggesting continuous activation of the GLP-1 receptors is needed for cardioprotection.. Cardioprotection provided by GAlbudAb, a long acting GLP-1 mimetic, following myocardial I/R injury was comparable in magnitude, but more sustained in duration than that produced by short-acting exendin-4. Very low plasma concentrations of exendin-4 failed to protect the heart from myocardial I/R injury, suggesting that sustained GLP-1 receptor activation plays an important role in providing cardioprotection in the setting of acute myocardial I/R injury. Long-acting GLP-1 agonists such as GAlbudAb may warrant additional evaluation as novel therapeutic agents to reduce myocardial I/R injury during acute coronary syndrome.

Topics: Animals; Cardiotonic Agents; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Immunoconjugates; Injections, Subcutaneous; Male; Myocardial Contraction; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Peptide Fragments; Peptides; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Serum Albumin; Single-Domain Antibodies; Venoms; Ventricular Function, Left

High mobility group box 1 protein (HMGB1) plays an important role in myocardial ischemia and reperfusion (I/R) injury. Exendin-4 (Ex-4), glucagon-like peptide-1 receptor agonist, has been reported to attenuate myocardial I/R injury. This study was to investigate the potential mechanism by which Ex-4 attenuates myocardial I/R injury in rats.. Anesthetized male rats were once treated with Ex-4 (5 μg/kg, i.v.) 1 h before ischemiain the absence and/or presence of exendin (9-39) (an antagonist for glucagon-like peptide-1 receptor, 5 μg/kg, i.v.), and then subjected to ischemia for 30 min followed by reperfusion for 4 h. Lactate dehydrogenase (LDH), creatine kinase (CK), malondialdehyde (MDA), superoxide dismutase (SOD) activity and infarct size were measured. HMGB1 expression was assessed by immunoblotting.. The results showed that pretreatment of Ex-4 could significantly decrease the infarct size and the levels of LDH and CK after 4 h reperfusion (all p < 0.05). Ex-4 could also significantly inhibit the increase of the MDA level, the decrease of the SOD level (both p < 0.05). Meanwhile, Ex-4 could significantly inhibit HMGB1 expression induced by I/R. Administration of exendin (9-39) could abolish the protective effect of Ex-4 (all p < 0.05).. The present study suggested that Ex-4 could attenuate myocardial I/R injury which may be associated with inhibiting HMGB1 expression.

Topics: Animals; Creatine Kinase; Cytoprotection; Disease Models, Animal; Down-Regulation; Exenatide; Glucagon-Like Peptide-1 Receptor; HMGB1 Protein; L-Lactate Dehydrogenase; Male; Malondialdehyde; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Peptide Fragments; Peptides; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Superoxide Dismutase; Time Factors; Venoms

The influence of Glucagon-like peptide-1 (GLP-1) and Exendin-4 on development of intrahepatic cholangiocarcinoma (ICC) is evaluated in the study. In vitro tests, including acute toxicity test, cell colony formation assays, cells proliferation and apoptosis, transwell assay, were performed. An ICC in situ tumor animal model was established. Then, animals were randomly divided into four groups (n = 6): control, Exendin-4 treatment, oxaliplatin treatment and Exendin-4-oxaliplatin treatment. Animals in the Exendin-4 treatment and Exendin-4-oxaliplatin treatment groups received a subcutaneous injection of Exendin-4 (100 μg/kg/day) for 1 week, and then received oxaliplatin (10 mg/kg/week) by tail vein injection. Animals in the control group received PBS. Immunohistochemistry tests were used for PCNA, Ki67, Caspase 3 expression in tumor tissue. Results show that that, after incubation of human cholangiocarcinoma cell lines, HuCCTI and GLP-1, or HuCCTI and Exendin-4, colony formation number was sharply decreased. However, GLP-1, HuCCTI or Exendin-4 did not affect the colony of normal cells. Combination treatment with oxaliplatin and Exendin-4 can significantly inhibit tumor cells' proliferation and promote apoptosis. The combined effect is stronger than that of oxaliplatin or Exendin-4. Combination treatment with oxaliplatin and Exendin4 can significantly decrease Ki67 and PCNA proteins' expression in subcutaneous tumors of nude mice. The inhibitory effect of Combination treatment with oxaliplatin and Exendin4 is clearly stronger than that of oxaliplatin. In addition, Combination treatment with oxaliplatin and Exendin4 can significantly increase Caspase3 protein positive expression. In short, these results show that combination treatment with oxaliplatin and Exendin4 can inhibit tumor cells' proliferation, and promote apoptosis.

Topics: Animals; Apoptosis; Bile Duct Neoplasms; Bile Ducts, Intrahepatic; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cholangiocarcinoma; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Humans; Ki-67 Antigen; Liver Neoplasms; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Organoplatinum Compounds; Oxaliplatin; Peptides; Proliferating Cell Nuclear Antigen; Toxicity Tests, Acute; Transplantation, Heterologous; Venoms

Mild traumatic brain injury (mTBI) represents a major and increasing public health concern and is both the most frequent cause of mortality and disability in young adults and a chief cause of morbidity in the elderly. Albeit mTBI patients do not show clear structural brain defects and, generally, do not require hospitalization, they frequently suffer from long-lasting cognitive, behavioral, and emotional problems. No effective pharmaceutical therapy is available, and existing treatment chiefly involves intensive care management after injury. The diffuse neural cell death evident after mTBI is considered mediated by oxidative stress and glutamate-induced excitotoxicity. Prior studies of the long-acting GLP-1 receptor agonist, exendin-4 (Ex-4), an incretin mimetic approved for type 2 diabetes mellitus treatment, demonstrated its neurotrophic/protective activity in cellular and animal models of stroke, Alzheimer's and Parkinson's diseases, and, consequent to commonalities in mechanisms underpinning these disorders, Ex-4 was assessed in a mouse mTBI model. In neuronal cultures in this study, Ex-4 ameliorated H2O2-induced oxidative stress and glutamate toxicity. To evaluate in vivo translation, we administered steady-state Ex-4 (3.5 pM/kg/min) or saline to control and mTBI mice over 7 days starting 48 h prior to or 1 h post-sham or mTBI (30 g weight drop under anesthesia). Ex-4 proved well-tolerated and fully ameliorated mTBI-induced deficits in novel object recognition 7 and 30 days post-trauma. Less mTBI-induced impairment was evident in Y-maze, elevated plus maze, and passive avoidance paradigms, but when impairment was apparent Ex-4 induced amelioration. Together, these results suggest that Ex-4 may act as a neurotrophic/neuroprotective drug to minimize mTBI impairment.

Topics: Alzheimer Disease; Animals; Behavior, Animal; Brain; Brain Injuries; Cell Line; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Humans; Incretins; Male; Memory; Mice; Neuroprotective Agents; Oxidative Stress; Peptides; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Recognition, Psychology; Trauma Severity Indices; Venoms

Topics: Animals; Brain; Cocaine-Related Disorders; Conditioning, Operant; Disease Models, Animal; Dose-Response Relationship, Drug; Exenatide; Exploratory Behavior; Glucagon-Like Peptide 1; Male; Mice; Mice, Inbred C57BL; Peptides; Reward; Venoms

Glucagon-like peptide (GLP)-1 receptor activation increases intracellular cAMP with downstream activation of PKA. Cilostazol (CIL), a phosphodiesterase-3 inhibitor, prevents cAMP degradation. We assessed whether CIL amplifies the exenatide (EX)-induced increase in myocardial cAMP levels and PKA activity and augments the infarct size (IS)-limiting effects of EX in db/db mice. Mice fed a Western diet received oral CIL (10 mg/kg) or vehicle by oral gavage 24 h before surgery. One hour before surgery, mice received EX (1 μg/kg sc) or vehicle. Additional mice received H-89, a PKA inhibitor, alone or with CIL + EX. Mice underwent 30 min of coronary artery occlusion and 24 h of reperfusion. Both EX and CIL increased myocardial cAMP levels and PKA activity. Levels were significantly higher in the EX + CIL group. Both EX and CIL reduced IS. IS was the smallest in the CIL + EX group. H-89 completely blocked the IS-limiting effects of EX + CIL. EX + CIL decreased phosphatase and tensin homolog on chromosome 10 upregulation and increased Akt and ERK1/2 phosphorylation after ischemia-reperfusion. These effects were blocked by H-89. In conclusion, EX and CIL have additive effects on IS limitation in diabetic mice. The additive effects are related to cAMP-induced PKA activation, as H-89 blocked the protective effect of CIL + EX.

Topics: Animals; Blood Glucose; Blotting, Western; Cholesterol; Cilostazol; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Diabetes Mellitus, Type 2; Disease Models, Animal; Enzyme Activation; Exenatide; Glucagon-Like Peptide-1 Receptor; Glycated Hemoglobin; Hypoglycemic Agents; Isoquinolines; Lipoxins; Male; Mice; Myocardial Infarction; Myocardium; Peptides; Phosphodiesterase 3 Inhibitors; Phosphorylation; Protein Kinase Inhibitors; PTEN Phosphohydrolase; Receptors, Glucagon; Signal Transduction; Sulfonamides; Tetrazoles; Triglycerides; Up-Regulation; Venoms

Alterations in gut motility and visceral hypersensitivity are two major features of irritable bowel syndrome (IBS). The aim of this study was to investigate the roles of glucagon-like peptide-1 (GLP-1) in the pathogenesis of experimental IBS. Rat models of constipation-predominant IBS (IBS-C) and diarrhea-predominant IBS (IBS-D) were established. Fecal water content and behavioral responses to colorectal distention (CRD), using electromyography (EMG), were measured. The expression of glucagon-like peptide-1 receptor (GLP-1R) in the colon was detected by immunohistochemistry, and the serum concentration of GLP-1 was measured by ELISA assay. The movement of circular and longitudinal colonic muscle was detected using an organ bath recording technique. Compared to controls, the fecal water contents were lower in the IBS-C group, while they were higher in the IBS-D group (P<0.05). EMG response to CRD in the experimental IBS groups was increased compared with their respective controls (P<0.05). GLP-1R was localized in the mucosa layer, circular muscle and myenteric nerve plexus of the colon. Notably, the expression of GLP-1R in the IBS-C group was higher, but in the IBS-D group, it was lower compared with controls. The serum levels of GLP-1 in the IBS-C group were higher compared to those in the IBS-D group (P<0.05). In addition, administration of exogenous GLP-1 and exendin-4 inhibited colonic circular muscle contraction, particularly in the IBS-C group, while there was no significant effect on longitudinal muscle contraction. In conclusion, these results indicated that GLP-1 and GLP-1R are implicated in the pathogenesis of IBS-C and IBS-D.

Topics: Animals; Colon; Constipation; Diarrhea; Disease Models, Animal; Exenatide; Feces; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Irritable Bowel Syndrome; Male; Muscle Contraction; Peptides; Peristalsis; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Venoms; Water

Impaired cardiac microvascular function contributes to cardiovascular complications in diabetes. Glucagon-like peptide-1 (GLP-1) exhibits potential cardioprotective properties in addition to its glucose-lowering effect. This study was designed to evaluate the impact of GLP-1 on cardiac microvascular injury in diabetes and the underlying mechanism involved. Experimental diabetes was induced using streptozotocin in rats. Cohorts of diabetic rats received a 12-week treatment of vildagliptin (dipeptidyl peptidase-4 inhibitor) or exenatide (GLP-1 analog). Experimental diabetes attenuated cardiac function, glucose uptake, and microvascular barrier function, which were significantly improved by vildagliptin or exenatide treatment. Cardiac microvascular endothelial cells (CMECs) were isolated and cultured in normal or high glucose medium with or without GLP-1. GLP-1 decreased high-glucose-induced reactive oxygen species production and apoptotic index, as well as the levels of NADPH oxidase such as p47(phox) and gp91(phox). Furthermore, cAMP/PKA (cAMP-dependent protein kinase activity) was increased and Rho-expression was decreased in high-glucose-induced CMECs after GLP-1 treatment. In conclusion, GLP-1 could protect the cardiac microvessels against oxidative stress, apoptosis, and the resultant microvascular barrier dysfunction in diabetes, which may contribute to the improvement of cardiac function and cardiac glucose metabolism in diabetes. The protective effects of GLP-1 are dependent on downstream inhibition of Rho through a cAMP/PKA-mediated pathway.

Topics: AMP-Activated Protein Kinases; Animals; Cardiotonic Agents; Cells, Cultured; Cyclic AMP; Diabetic Angiopathies; Diabetic Cardiomyopathies; Disease Models, Animal; Endothelium, Vascular; Exenatide; Glucagon-Like Peptide 1; Heart Ventricles; Hyperglycemia; Hypoglycemic Agents; Male; Microvessels; Oxidative Stress; Peptides; Random Allocation; Rats; Rats, Sprague-Dawley; rho GTP-Binding Proteins; Second Messenger Systems; Venoms

Exendin-4 is a GLP-1 agonist that is clinically used for the treatment of diabetes mellitus and may also have neuroprotective effect. We explored the effect of repeated administration of exendin-4 (0.5 μg/kg, intraperitoneal twice a day for 7 days) on infarct volume, neurological deficit (neurological score, grip test, foot fault and rota rod tests), oxidative stress parameters (malondialdehyde, reduced glutathione, and superoxide dismutase) and expression of endothelin (ET) ET(A) and ET(B) receptors following cerebral ischemia produced in rats by permanent middle cerebral artery occlusion (MCAO). Since ET(A) receptors in the central nervous system (CNS) are involved in cerebral ischemia, we determined the effect of a specific ET(A) receptor antagonist, BQ123 (1mg/kg, intravenously administered thrice: 30 min, 2h and 4h after MCAO for a total dose of 3 mg/kg) on cerebral ischemia in control and exendin-4 treated rats. Results indicate that exendin-4 treated rats had significant protection following MCAO induced cerebral ischemia. The infarct volume was 27% less compared to vehicle treated rats. The neurological deficit following MCAO was lower and oxidative stress parameters were improved in exendin-4 treated rats compared to control. BQ123 significantly improved infarct volume, oxidative stress parameters and neurological deficit in ischemic rats treated with vehicle or exendin-4. BQ123 induced protection from cerebral ischemia was similar in vehicle or exendin-4 treated rats. Expression of ET(A) receptors was significantly increased following cerebral ischemia which was not affected by exendin-4 treatment or by BQ123 administration. No change in expression of ET(B) receptors was observed following cerebral ischemia or any treatment. It is concluded that exendin-4 protects the CNS from damage due to cerebral ischemia by reducing oxidative stress and is independent of ET receptor involvement.

Topics: Animals; Brain Infarction; Brain Ischemia; Disease Models, Animal; Down-Regulation; Drug Administration Schedule; Exenatide; Male; Neuroprotective Agents; Peptides; Rats; Rats, Sprague-Dawley; Venoms

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by a progressive loss of lower motor neurons in the spinal cord. The incretin hormone, glucagon-like peptide-1 (GLP-1), facilitates insulin signaling, and the long acting GLP-1 receptor agonist exendin-4 (Ex-4) is currently used as an anti-diabetic drug. GLP-1 receptors are widely expressed in the brain and spinal cord, and our prior studies have shown that Ex-4 is neuroprotective in several neurodegenerative disease rodent models, including stroke, Parkinson's disease and Alzheimer's disease. Here we hypothesized that Ex-4 may provide neuroprotective activity in ALS, and hence characterized Ex-4 actions in both cell culture (NSC-19 neuroblastoma cells) and in vivo (SOD1 G93A mutant mice) models of ALS. Ex-4 proved to be neurotrophic in NSC-19 cells, elevating choline acetyltransferase (ChAT) activity, as well as neuroprotective, protecting cells from hydrogen peroxide-induced oxidative stress and staurosporine-induced apoptosis. Additionally, in both wild-type SOD1 and mutant SOD1 (G37R) stably transfected NSC-19 cell lines, Ex-4 protected against trophic factor withdrawal-induced toxicity. To assess in vivo translation, SOD1 mutant mice were administered vehicle or Ex-4 at 6-weeks of age onwards to end-stage disease via subcutaneous osmotic pump to provide steady-state infusion. ALS mice treated with Ex-4 showed improved glucose tolerance and normalization of behavior, as assessed by running wheel, compared to control ALS mice. Furthermore, Ex-4 treatment attenuated neuronal cell death in the lumbar spinal cord; immunohistochemical analysis demonstrated the rescue of neuronal markers, such as ChAT, associated with motor neurons. Together, our results suggest that GLP-1 receptor agonists warrant further evaluation to assess whether their neuroprotective potential is of therapeutic relevance in ALS.

Topics: Amyotrophic Lateral Sclerosis; Animals; Apoptosis; Cell Line; Choline O-Acetyltransferase; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucose Tolerance Test; Hydrogen Peroxide; Hypoglycemic Agents; Insulin; Male; Mice; Motor Neurons; Oxidative Stress; Peptides; Spinal Cord; Staurosporine; Superoxide Dismutase; Superoxide Dismutase-1; Venoms

Topics: Alzheimer Disease; Animals; Disease Models, Animal; Exenatide; Humans; Hypoglycemic Agents; Insulin Resistance; Peptides; Venoms

BACKGROUND AND PURPOSE Parkinson's disease (PD) is characterized by progressive dopaminergic cell loss; however, the noradrenergic system exhibits degeneration as well. Noradrenergic deficit in PD may be responsible for certain non-motor symptoms of the pathology, including psychiatric disorders and cognitive decline. The aim of this study was to generate a pre-motor rodent model of PD with noradrenergic denervation, and to assess whether treatment with exendin-4 (EX-4), a glucagon-like peptide 1 receptor agonist, could reverse impairment exhibited by our model. EXPERIMENTAL APPROACH We generated a model of PD utilizing N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine and 6-hydroxydopamine to create partial lesions of both the noradrenergic and dopaminergic systems respectively. We then assessed the validity of our model using an array of behavioural paradigms and biochemical techniques. Finally, we administered EX-4 over a 1 week period to determine therapeutic efficacy. KEY RESULTS Our model exhibits anhedonia and decreased object recognition as indicated by a decrease in sucrose preference, increased immobility in the forced swim test and reduced novel object exploration. Tissue and extracellular dopamine and noradrenaline were reduced in the frontal cortex and striatum. TH+ cell counts decreased in the locus coeruleus and substantia nigra. Treatment with EX-4 reversed behavioural impairment and restored extracellular/tissue levels of both dopamine and noradrenaline and TH+ cell counts. CONCLUSION AND IMPLICATIONS We conclude that early treatment with EX-4 may reverse certain neuropsychiatric dysfunction and restore dopamine and noradrenaline content.

Topics: Animals; Behavior, Animal; Benzylamines; Cerebrum; Disease Models, Animal; Dopamine; Exenatide; Male; Neuroprotective Agents; Norepinephrine; Oxidopamine; Parkinson Disease; Peptides; Rats; Rats, Wistar; Venoms

Exendin-4 (Ex-4) is a Glucagon-like peptide 1 (GLP-1) receptor agonist approved for the treatment of Type 2 Diabetes (T2DM), which requires daily subcutaneous administration. In T2DM patients, GLP-1 administration is reported to reduce glycaemia and HbA1c in association with a modest, but significant weight loss. The aim of present study was to characterize the site-specific profile and metabolic effects of Ex-4 levels expressed from salivary glands (SG) in vivo, following adeno-associated virus-mediated (AAV) gene therapy in two different animal models of obesity prone to impaired glucose tolerance and T2DM, specifically, Zucker fa/fa rats and high fed diet (HFD) mice. Following percutaneous injection of AAV5 into the salivary glands, biologically active Ex-4 was detected in the blood of both animal models and expression persisted in salivary gland ductal cell until the end of the study. In treated mice, Ex-4 levels averaged 138.9±42.3 pmol/L on week 6 and in treated rats, mean circulating Ex-4 levels were 238.2±72 pmol/L on week 4 and continued to increase through week 8. Expression of Ex-4 resulted in a significant decreased weight gain in both mice and rats, significant improvement in glycemic control and/or insulin sensitivity as well as visceral adipose tissue adipokine profile. In conclusion, these results suggest that sustained site-specific expression of Ex-4 following AAV5-mediated gene therapy is feasible and may be useful in the treatment of obesity as well as trigger improved metabolic profile.

Topics: Animals; Blood Glucose; Dependovirus; Diabetes Mellitus, Type 2; Diet, High-Fat; Disease Models, Animal; Exenatide; Gene Expression; Genetic Therapy; Genetic Vectors; Glucagon-Like Peptide-1 Receptor; Glucose Tolerance Test; Humans; Male; Mice; Obesity; Peptides; Rats; Rats, Zucker; Receptors, Glucagon; Salivary Glands; Venoms; Weight Gain

Hypothalamic obesity caused by damage of medial hypothalamic nuclei presents a therapeutic challenge. Glucagon-like peptide-1 agonist exenatide (synthetic version of exendin-4 (Ex4)), used for treatment of diabetes, causes weight loss via hindbrain signaling.. We tested Ex4 in an established rat model of medial hypothalamic lesions. Lesion and control animals were administered either daily intraperitoneal injections of 1 µg·kg(-1) Ex4 or saline for 9 days.. In our rat model, a significant difference in percent baseline food intake (lesion -20.8%, control -13.6%; p < 0.001) and percent change in body weight (lesion -4.9%/9 days, control -3.2%/9 days; p < 0.05) was observed during Ex4 treatment compared with saline.. Ex4 resulted in reduction of food intake and body weight. Follow-up studies are required to further elucidate its effects on energy homeostasis and to establish Ex4 as a potential drug for treatment of hypothalamic obesity.

Topics: Animals; Body Weight; Disease Models, Animal; Down-Regulation; Drug Evaluation, Preclinical; Energy Intake; Exenatide; Glucagon-Like Peptide 1; Hypoglycemic Agents; Hypothalamic Diseases; Male; Obesity; Peptides; Rats; Rats, Sprague-Dawley; Venoms; Weight Loss

Sitagliptin, a selective dipeptidyl peptidase 4 inhibitor, inhibits the inactivation and degradation of glucagon like peptide 1 (GLP-1), which is used for the treatment of type 2 diabetes mellitus. However, little is known about the role of GLP-1 in hypertension. This study investigated whether the activation of GLP-1 signaling protects endothelial function in hypertension. Two-week sitagliptin treatment (10 mg/kg per day, oral gavage) improved endothelium-dependent relaxation in renal arteries, restored renal blood flow, and reduced systolic blood pressure in spontaneously hypertensive rats. In vivo sitagliptin treatment elevated GLP-1 and GLP-1 receptor expressions, increased cAMP level, and subsequently activated protein kinase A, liver kinase B1, AMP-activated protein kinase-α and endothelial NO synthase in spontaneously hypertensive rat renal arteries. Inhibition of GLP-1 receptor, adenylyl cyclase, protein kinase A, AMP-activated protein kinase-α, or NO synthase reversed the protective effects of sitagliptin. We also demonstrate that GLP-1 receptor agonist exendin 4 in vitro treatment had similar vasoprotective effects in spontaneously hypertensive rat renal arteries and increased NO production in spontaneously hypertensive rat aortic endothelial cells. Studies using transient expressions of wild-type and dominant-negative AMP-activated protein kinase-α2 support the critical role of AMP-activated protein kinase-α in mediating the effect of GLP-1 in endothelial cells. Ex vivo exendin 4 treatment also improved endothelial function of renal arteries from hypertensive patients. Our results elucidate that upregulation of GLP-1 and related agents improve endothelial function in hypertension by restoring NO bioavailability, suggesting that GLP-1 signaling could be a therapeutic target in hypertension-related vascular events.

Topics: Aged; Aged, 80 and over; Animals; Blood Pressure; Cells, Cultured; Cyclic AMP; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Endothelium, Vascular; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Humans; Hypertension; In Vitro Techniques; Kidney; Magnetic Resonance Imaging; Male; Middle Aged; Nitric Oxide; Peptides; Pyrazines; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptors, Glucagon; Regional Blood Flow; Renal Artery; Signal Transduction; Sitagliptin Phosphate; Triazoles; Venoms

Viral infection is one of the important factors for the pathogenesis of type 1 diabetes. Particularly, in fulminant type 1 diabetes, rapid β-cell destruction is suggested to be triggered by viral infection. Recently, glucagon-like peptide 1 (GLP-1) receptor agonists have been reported to have direct beneficial effects on β-cells, such as anti-apoptotic effect, increasing β-cell mass, and improvement of β-cell function. However, their effects on β-cell destruction induced by viral infections have not been elucidated. In this study, we used an encephalomyocarditis virus (EMCV)-induced diabetic model mouse to show that a GLP-1 receptor agonist, exendin-4, prevents β-cell destruction. Nine-week-old male DBA/2 mice were intraperitoneally injected with EMCV (200 plaque forming units (PFU)mouse(-1)). Low (20 nmolkg(-1)d(-1)) or high (40 nmolkg(-1)d(-1)) doses of exendin-4 were administered for 10d, starting from 2d before the infection, and the rate of diabetic onset was evaluated. In addition, the number of infiltrating macrophage per islet and the ratio of β-cell area to islet area were determined. The effects of exendin-4 on infected β-cells and macrophages were investigated by using MIN6 and RAW264 mouse macrophages. The incidence of diabetes was significantly lower in the high-dose exendin-4-treated group than in the control group. Furthermore, the β-cell area was significantly more preserved in the high-dose exendin-4-treated group than in the control. In addition, the number of macrophages infiltrating into the islets was significantly less in the high-dose exendin-4-treated group than in the control group. In vitro, exendin-4 reduced β-cell apoptosis, and tumor necrosis factor α (TNFα), interleukin β (IL-β), and inducible nitric oxide synthase (iNOS) production of infected or lipopolysaccharide (LPS)-stimulated macrophages. These results suggested that exendin-4 limits β-cell destruction by protecting β cells and reducing the inflammatory response of macrophages.

Topics: Animals; Apoptosis; Cardiovirus Infections; Diabetes Mellitus, Type 1; Disease Models, Animal; Encephalomyocarditis virus; Exenatide; Glucagon-Like Peptide-1 Receptor; Insulin-Secreting Cells; Macrophages; Male; Mice; Peptides; Receptors, Glucagon; Venoms

One of the symptoms of diabetes is the progressive development of neuropathies. One mechanism to replace neurons in the CNS is through the activation of stem cells and neuronal progenitor cells. We have tested the effects of the novel GLP-1 mimetics exenatide (exendin-4; Byetta) and liraglutide (NN2211; Victoza), which are already on the market as treatments for type 2 diabetes, on the proliferation rate of progenitor cells and differentiation into neurons in the dentate gyrus of brains of mouse models of diabetes. GLP-1 analogues were injected subcutaneously for 4, 6, or 10 weeks once daily in three mouse models of diabetes: ob/ob mice, db/db mice, or high-fat-diet-fed mice. Twenty-four hours before perfusion, animals were injected with 5'-bromo-2'-deoxyuridine (BrdU) to mark dividing progenitor cells. By using immunohistochemistry and stereological methods, the number of progenitor cells or doublecortin-positive young neurons in the dentate gyrus was estimated. We found that, in all three mouse models, progenitor cell division was enhanced compared with nondiabetic controls after chronic i.p. injection of either liraglutide or exendin-4 by 100-150% (P < 0.001). We also found an increase in young neurons in the DG of high-fat-diet-fed mice after drug treatment (P < 0.001). The GLP-1 receptor antagonist exendin(9-36) reduced progenitor cell proliferation in these mice. The results demonstrate that GLP-1 mimetics show promise as a treatment for neurodegenerative diseases such as Alzheimer's disease, because these novel drugs cross the blood-brain barrier and increase neuroneogenesis.

Topics: Animals; Brain; Cell Differentiation; Cell Proliferation; Dentate Gyrus; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Hypoglycemic Agents; Immunohistochemistry; Liraglutide; Male; Mice; Neural Stem Cells; Neurogenesis; Neurons; Peptides; Venoms

There is growing awareness of secondary insulin resistance and alterations in myocardial glucose utilization in congestive heart failure. Whether therapies that directly target these changes would be beneficial is unclear. We previously demonstrated that acute blockade of the insulin responsive facilitative glucose transporter GLUT4 precipitates acute decompensated heart failure in mice with advanced dilated cardiomyopathy. Our current objective was to determine whether pharmacologic enhancement of insulin sensitivity and myocardial glucose uptake preserves cardiac function and survival in the setting of primary heart failure.. The GLP-1 agonist exenatide was administered twice daily to a murine model of dilated cardiomyopathy (TG9) starting at 56 days of life. TG9 mice develop congestive heart failure and secondary insulin resistance in a highly predictable manner with death by 12 weeks of age. Glucose homeostasis was assessed by measuring glucose tolerance at 8 and 10 weeks and tissue 2-deoxyglucose uptake at 75 days. Exenatide treatment improved glucose tolerance, myocardial GLUT4 expression and 2-deoxyglucose uptake, cardiac contractility, and survival over control vehicle-treated TG9 mice. Phosphorylation of AMP kinase and AKT was also increased in exenatide-treated animals. Total myocardial GLUT1 levels were not different between groups. Exenatide also abrogated the detrimental effect of the GLUT4 antagonist ritonavir on survival in TG9 mice.. In heart failure secondary insulin resistance is maladaptive and myocardial glucose uptake is suboptimal. An incretin-based therapy, which addresses these changes, appears beneficial.

Topics: Animals; Blood Glucose; Cardiomyopathy, Dilated; Disease Models, Animal; Drug Administration Schedule; Drug Evaluation, Preclinical; Exenatide; Female; Homeostasis; Hypoglycemic Agents; Mice; Mice, Transgenic; Peptides; Survival Analysis; Time Factors; Venoms

Dimerization is viewed as the most effective means of increasing receptor binding affinity, and both dimerization and PEGylation effectively prolong the life spans of short-lived peptides and proteins in vivo by delaying excretion via the renal route. Here, we describe the high binding affinities of two long-acting exendin-4 (Ex4) conjugates, dimerized Ex4 (Di-Ex4) and PEGylated Di-Ex-4 (PEG-Di-Ex4). Di-Ex4 and PEG-Di-Ex4 were prepared using cysteine and amine residue specific coupling reactions using Ex4-Cys, bisMal-NH(2), and activated PEG. The Ex4 conjugates produced were of high purity (>98.5%), as determined by size-exclusion chromatography and MALDI-TOF mass spectrometry. The receptor binding affinity of Di-Ex4 on RIN-m5F cells was 3.5-fold higher than that of Ex4, and the in vivo antihyperglycemic efficacy of Di-Ex4 was also greater than that of native Ex4 in type 2 diabetic db/db mice. Furthermore, Di-Ex4 and PEG-Di-Ex4 were found to have greater blood circulating t(1/2) and AUC(inf) values than native Ex4 by 2.7- and 13.7-fold, and by 4.0- and 17.3-fold, respectively. Accordingly, hypoglycemic durations were greatly increased to 15.0 and 40.1 h, respectively, at a dose of 25 nmol/kg (native Ex4 7.3 h). The results of this study show that combined dimerization and PEGylation are effective when applied to Ex4, and suggest that PEG-Di-Ex4 has considerable potential as a type 2 anti-diabetic agent.

Topics: Animals; Binding Sites; Diabetes Mellitus, Experimental; Dimerization; Disease Models, Animal; Exenatide; Hypoglycemic Agents; Male; Mice; Mice, Inbred C57BL; Peptides; Polyethylene Glycols; Tissue Distribution; Venoms

Glucagon-like peptide-1 receptor (GLP-1R) protects against neuronal damages in the brain. In the present study, ischemia-induced changes in GLP-1R immunoreactivity in the gerbil hippocampal CA1 region were evaluated after transient cerebral ischemia; in addition, the neuroprotective effect of the GLP-1R agonist exendin-4 (EX-4) against ischemic damage was studied. GLP-1R immunoreactivity and its protein levels in the ischemic CA1 region were highest at 1 day after ischemia/reperfusion (I/R). At 4 days after I/R, GLP-1R immunoreactivity was hardly detected in CA1 pyramidal neurons, and its protein level was lowest. GLP-1R protein level was increased again at 10 days after I/R, and GLP-1R immunoreactivity was found in astrocytes and GABAergic interneurons. In addition, EX-4 treatment attenuated ischemia-induced hyperactivity, neuronal damage, and microglial activation in the ischemic CA1 region in a dose-dependent manner. EX-4 treatment also induced the elevation of GLP-1R immunoreactivity and protein levels in the ischemic CA1 region. These results indicate that GLP-1R is altered in the ischemic region after an ischemic insult and that EX-4 protects against ischemia-induced neuronal death possibly by increasing GLP-1R expression and attenuating microglial activation against transient cerebral ischemic damage.

Topics: Animals; Brain Infarction; Brain Ischemia; Disease Models, Animal; Exenatide; Gerbillinae; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Male; Neuroprotective Agents; Peptides; Receptors, Glucagon; Reperfusion Injury; Venoms

High-fat dietary intake and low physical activity lead to insulin resistance, nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Recent studies have shown an effect of glucagon-like peptide-1 (GLP-1) on hepatic glucose metabolism, although GLP-1 receptors (GLP-1r) have not been found in human livers. The aim of this study was to investigate the presence of hepatic GLP-1r and the effect of exenatide, a GLP-1 analogue, on hepatic signalling.. The expression of GLP-1r was evaluated in human liver biopsies and in the livers of high-fat diet-treated rats. The effect of exenatide (100 nM) was evaluated in hepatic cells of rats fed 3 months with the high-fat diet.. GLP-1r is expressed in human hepatocytes, although reduced in patients with NASH. Similarly, in rats with NASH resulted from 3 months of the high-fat diet, we found a decreased expression of GLP-1r and peroxisome proliferator-activated receptor γ (PPARγ), and reduced peroxisome proliferator-activated receptor α (PPARα) activity. Incubation of hepatocytes with exenatide increased PPARγ expression, which also exerted an insulin-sensitizing action by reducing JNK phosphorylation. Moreover, exenatide increased protein kinase A (PKA) activity, Akt and AMPK phosphorylation and determined a PKA-dependent increase of PPARα activity.. GLP-1 has a direct effect on hepatocytes, by activating genes involved in fatty acid β-oxidation and insulin sensitivity. GLP-1 analogues could be a promising treatment approach to improve hepatic insulin resistance in patients with NAFLD/NASH.

Topics: AMP-Activated Protein Kinases; Animals; Biopsy; Cyclic AMP-Dependent Protein Kinases; Dietary Fats; Disease Models, Animal; Exenatide; Fatty Acids; Fatty Liver; Gene Expression Regulation; Glucagon-Like Peptide-1 Receptor; Hep G2 Cells; Hepatocytes; Humans; Hypoglycemic Agents; Insulin Resistance; JNK Mitogen-Activated Protein Kinases; Liver; Male; Non-alcoholic Fatty Liver Disease; Oxidation-Reduction; Peptides; Phosphorylation; PPAR alpha; PPAR gamma; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Signal Transduction; Time Factors; Venoms

Exendin-4, a glucagon-like peptide 1 receptor agonist, is a potent therapeutic xenopeptide hormone for the treatment of type 2 diabetes. In order to further improve in vivo activity, we examined the introduction of sialyl N-acetyllactosamine (sialyl LacNAc) to exendin-4. The glycosylated analogue having sialyl LacNAc at position 28 was found to have improved in vivo activity with prolonged glucose-lowering activity.

Topics: Amino Acid Sequence; Animals; Blood Glucose; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glycosylation; Hypoglycemic Agents; Mice; Molecular Sequence Data; Peptides; Venoms

In autoimmune type 1 diabetes mellitus, proinflammatory cytokine-mediated apoptosis of beta-cells has been considered to be the first event directly responsible for beta-cell mass reduction. In the Bio-Breeding (BB) rat, an in vivo model used in the study of autoimmune diabetes, beta-cell apoptosis is observed from 9 wk of age and takes place after an insulitis period that begins at an earlier age. Previous studies by our group have shown an antiproliferative effect of proinflammatory cytokines on cultured beta-cells in Wistar rats, an effect that was partially reversed by Exendin-4, an analogue of glucagon-like peptide-1. In the current study, the changes in beta-cell apoptosis and proliferation during insulitis stage were also determined in pancreatic tissue sections in normal and thymectomized BB rats, as well as in Wistar rats of 5, 7, 9, and 11 wk of age. Although stable beta-cell proliferation in Wistar and thymectomized BB rats was observed along the course of the study, a decrease in beta-cell proliferation and beta-cell mass from the age of 5 wk, and prior to the commencement of apoptosis, was noted in BB rats. Exendin-4, in combination with anti-interferon-gamma antibody, induced a near-total recovery of beta-cell proliferation during the initial stages of insulitis. This highlights the importance of early intervention and, as well, the possibilities of new therapeutic approaches in preventing autoimmune diabetes by acting, initially, in the insulitis stage and, subsequently, on beta-cell regeneration and on beta-cell apoptosis.

Topics: Animals; Antibodies; Apoptosis; Cell Proliferation; Diabetes Mellitus, Type 1; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucose Tolerance Test; Hypoglycemic Agents; Immunohistochemistry; Insulin-Secreting Cells; Interferon-gamma; Peptides; Random Allocation; Rats; Rats, Wistar; Venoms

Endothelial cell senescence is an important contributor to vascular aging and is increased under diabetic conditions. Here we investigated whether the antidiabetic hormone glucagon-like peptide 1 (GLP-1) could prevent oxidative stress-induced cellular senescence in endothelial cells.. In Zucker diabetic fatty rats, a significant 2-fold higher level of vascular senescence was observed compared with control lean rats. Dipeptidyl-peptidase 4 (DPP-4) inhibition significantly increased GLP-1 levels in these animals and reduced senescence almost to lean animal levels. In vitro studies with human umbilical vein endothelial cells showed that GLP-1 had a direct protective effect on oxidative stress (H(2)O(2))-induced senescence and was able to attenuate oxidative stress-induced DNA damage and cellular senescence. The GLP-1 analogue exendin-4 provided similar results, whereas exendin fragment 9-39, a GLP-1 receptor antagonist, abolished this effect. Intracellular signaling by the phosphoinositide 3-kinase (PI3K)/Akt survival pathway did not appear to be involved. Further analysis revealed that GLP-1 activates the cAMP response element-binding (CREB) transcription factor in a cAMP/protein kinase A (PKA)-dependent manner, and inhibition of the cAMP/PKA pathway abolished the GLP-1 protective effect. Expression analysis revealed that GLP-1 can induce the oxidative defense genes HO-1 and NQO1.. Dipeptidyl-peptidase 4 inhibition protects against vascular senescence in a diabetic rat model. In vitro studies with human umbilical vein endothelial cells showed that reactive oxygen species-induced senescence was attenuated by GLP-1 in a receptor-dependent manner involving downstream PKA signaling and induction of antioxidant genes.

Topics: Adamantane; Animals; Cells, Cultured; Cellular Senescence; Cyclic AMP; Cyclic AMP Response Element-Binding Protein; Cyclic AMP-Dependent Protein Kinases; Diabetes Mellitus; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; DNA Damage; Dose-Response Relationship, Drug; Endothelial Cells; Enzyme Activation; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Heme Oxygenase-1; Humans; Hydrogen Peroxide; Hypoglycemic Agents; Male; NAD(P)H Dehydrogenase (Quinone); Nitriles; Oxidants; Oxidative Stress; Peptides; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Pyrrolidines; Rats; Rats, Zucker; Reactive Oxygen Species; Receptors, Glucagon; Signal Transduction; Venoms; Vildagliptin

Topics: Animals; Combined Modality Therapy; Diabetes Mellitus, Type 1; Disease Models, Animal; Drug Therapy; Drug Therapy, Combination; Exenatide; Humans; Hypoglycemic Agents; Immunologic Factors; Immunotherapy, Active; Peptides; Venoms

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease in the Western world. The aim of this study was to evaluate the biochemical and histological effects of omega-3 fatty acid and exendin-4 treatment on NAFLD in an animal model.. Sixty-three 8-week-old outbred Sprague-Dawley male rats were used for this study. Three animals were used as procedure controls, and 30 rats were fed a methionine and choline deficient (MCD) diet and 30 were fed a regular chow diet. In each group of 30 animals, 10 served as controls, 10 received exendin-4, and 10 received omega-3 fatty acids. After 75 days of treatment, the animals were euthanized, the tissues and serum were harvested, and the livers were formalin-fixed for histology.. The MCD diet was exceptionally efficient at producing fatty livers. The MCD control animals had a liver steatosis score of 38+/-6.7 (of 50 possible); treatment with exendin-4 was not associated with a significant reduction of steatosis (44+/-5.16, P=0.07) and the omega-3 fatty acid treatment was associated with a significant decrease in the liver steatosis score (15.6+/-13.46, P<0.001) compared with both the controls and the exendin-4 groups. The omega-3 fatty acid treatment increased serum aspartate aminotransferase significantly, whereas exendin-4 had no effect.. In an animal model of NAFLD, the omega-3 fatty acid therapy was associated with significant improvement in hepatic steatosis compared with exendin-4. These data suggest that omega-3 fatty acid supplements may have a potential therapeutic role in patients with NAFLD.

Topics: Adipokines; Animals; Body Weight; Corn Oil; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP4A; Dietary Supplements; Disease Models, Animal; Exenatide; Fatty Acids, Omega-3; Fatty Liver; Fish Oils; Hypoglycemic Agents; Insulin Resistance; Liver; Male; Peptides; Rats; Rats, Sprague-Dawley; Venoms

The aim of this study was to find an effective treatment for the genetic form of diabetes that is present in some Huntington's disease patients and in Huntington's disease mouse models. Huntington's disease is a neurodegenerative disorder caused by a polyglutamine expansion within the huntingtin protein. Huntington's disease patients exhibit neuronal dysfunction/degeneration, chorea, and progressive weight loss. Additionally, they suffer from abnormalities in energy metabolism affecting both the brain and periphery. Similarly to Huntington's disease patients, mice expressing the mutated human huntingtin protein also exhibit neurodegenerative changes, motor dysfunction, perturbed energy metabolism, and elevated blood glucose levels.. Huntington's disease mice were treated with an FDA-approved antidiabetic glucagon-like peptide 1 receptor agonist, exendin-4 (Ex-4), to test whether euglycemia could be achieved, whether pancreatic dysfunction could be alleviated, and whether the mice showed any neurological benefit. Blood glucose and insulin levels and various appetite hormone concentrations were measured during the study. Additionally, motor performance and life span were quantified and mutant huntingtin (mhtt) aggregates were measured in both the pancreas and brain.. Ex-4 treatment ameliorated abnormalities in peripheral glucose regulation and suppressed cellular pathology in both brain and pancreas in a mouse model of Huntington's disease. The treatment also improved motor function and extended the survival time of the Huntington's disease mice. These clinical improvements were correlated with reduced accumulation of mhtt protein aggregates in both islet and brain cells.. Targeting both peripheral and neuronal deficits, Ex-4 is an attractive agent for therapeutic intervention in Huntington's disease patients suffering from diabetes.

Topics: Adipokines; Animals; Blood Glucose; Blotting, Western; Brain; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Exenatide; Ghrelin; Huntington Disease; Immunohistochemistry; Insulin; Male; Mice; Pancreas; Peptides; Radioimmunoassay; Survival Rate; Venoms

Immunotherapy with Complete Freund's adjuvant (CFA) is effective in ameliorating autoimmunity in diabetic nonobese diabetic (NOD) mice. We investigated whether CFA treatment up-regulates CD4+CD25+Foxp3+ regulatory T cells and increases transforming growth factor (TGF)-beta1 production in diabetic NOD mice.. New-onset diabetic NOD mice were treated with CFA and exendin-4, a potent analog of glucagon-like peptide-1. Reversal of diabetes was determined by monitoring blood glucose level. Ameliorating autoimmunity through immunoregulation was assessed by adoptive transfer. Regulatory T cells in the peripheral blood, spleen, thymus, and pancreatic nodes were measured. TGF-beta1 in plasma and the insulin content in the pancreas were also measured. Immunostainings for insulin and BrdU were performed.. New-onset diabetes could be reversed in 38% of NOD mice treated with CFA alone and in 86% of NOD mice treated with both CFA and exendin-4. Diabetes adoptive transfer by splenocytes from CFA-treated NOD mice was delayed. The percentage of CD4+CD25+Foxp3+ regulatory T cells in the pancreatic lymph nodes of CFA-treated NOD mice was significantly increased at 1, 5, and 15 to 17 weeks after treatment. TGF-beta1 in the plasma of CFA-treated NOD mice was also significantly increased. Combining CFA with exendin-4 treatment significantly increased the insulin content and the numbers of insulin and BrdU double-labeled beta cells in the islets.. Our results demonstrated that CFA treatment ameliorates autoimmunity in diabetic NOD mice by up-regulating CD4=CD25+Foxp3+ regulatory T cells and increasing TGF-beta1 production. Exendin-4 enhanced the effect of CFA on reversing diabetes in NOD mice by stimulating beta-cell replication.

Topics: Adjuvants, Immunologic; Adoptive Transfer; Animals; Autoimmunity; Blood Glucose; CD4-Positive T-Lymphocytes; Cell Proliferation; Diabetes Mellitus, Type 1; Disease Models, Animal; Drug Therapy, Combination; Exenatide; Female; Forkhead Transcription Factors; Freund's Adjuvant; Hypoglycemic Agents; Insulin; Insulin-Secreting Cells; Interleukin-2 Receptor alpha Subunit; Lymph Nodes; Male; Mice; Mice, Inbred NOD; Mice, SCID; Pancreas; Peptides; T-Lymphocytes, Regulatory; Time Factors; Transforming Growth Factor beta1; Up-Regulation; Venoms

Glucagon-like peptide-1 (GLP-1) is an endogenous insulinotropic peptide secreted from the gastrointestinal tract in response to food intake. It enhances pancreatic islet beta-cell proliferation and glucose-dependent insulin secretion, and lowers blood glucose and food intake in patients with type 2 diabetes mellitus (T2DM). A long-acting GLP-1 receptor (GLP-1R) agonist, exendin-4 (Ex-4), is the first of this new class of antihyperglycemia drugs approved to treat T2DM. GLP-1Rs are coupled to the cAMP second messenger pathway and, along with pancreatic cells, are expressed within the nervous system of rodents and humans, where receptor activation elicits neurotrophic actions. We detected GLP-1R mRNA expression in both cultured embryonic primary cerebral cortical and ventral mesencephalic (dopaminergic) neurons. These cells are vulnerable to hypoxia- and 6-hydroxydopamine-induced cell death, respectively. We found that GLP-1 and Ex-4 conferred protection in these cells, but not in cells from Glp1r knockout (-/-) mice. Administration of Ex-4 reduced brain damage and improved functional outcome in a transient middle cerebral artery occlusion stroke model. Ex-4 treatment also protected dopaminergic neurons against degeneration, preserved dopamine levels, and improved motor function in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease (PD). Our findings demonstrate that Ex-4 can protect neurons against metabolic and oxidative insults, and they provide preclinical support for the therapeutic potential for Ex-4 in the treatment of stroke and PD.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Brain Infarction; Cell Death; Cell Hypoxia; Cells, Cultured; Cerebral Cortex; Cytoprotection; Disease Models, Animal; Dopamine; Embryo, Mammalian; Exenatide; Gene Expression Regulation; Glucagon-Like Peptide-1 Receptor; Humans; Mesencephalon; Mice; Neurons; Parkinson Disease; Peptides; Rats; Receptors, Glucagon; Stroke; Treatment Outcome; Venoms

This study sought to examine whether exenatide is capable of reducing myocardial infarct size.. Exenatide is a glucagon-like peptide (GLP)-1 analogue with insulinotropic and insulinomimetic properties. Because insulin and GLP-1 have been described as reducing apoptosis, exenatide might confer cardioprotection after acute myocardial infarction (MI).. Pigs were randomized to exenatide or phosphate-buffered saline (PBS) treatment after 75 min of coronary artery ligation and subsequent reperfusion. Infarct size was assessed with Evans Blue (Sigma-Aldrich, St. Louis, Missouri) and triphenyltetrazolium chloride. Cardiac function was measured with epicardial ultrasound and conductance catheter-based pressure-volume loops. Western blotting, histology, and activity assays were performed to determine markers of apoptosis/survival and oxidative stress.. Exenatide reduced myocardial infarct size (32.7 +/- 6.4% vs. 53.6 +/- 3.9%; p = 0.031) and prevented deterioration of systolic and diastolic cardiac function (systolic wall thickening: 47.3 +/- 6.3% vs. 8.1 +/- 1.9%, p < 0.001; myocardial stiffness: 0.12 +/- 0.06 mm Hg/ml vs. 0.22 +/- 0.07 mm Hg/ml; p = 0.004). After exenatide treatment, myocardial phosphorylated Akt and Bcl-2 expression levels were higher compared with those after PBS treatment, and active caspase 3 expression was lower. In addition, fewer cells were terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling-positive. In addition, nuclear oxidative stress as assessed with an 8-hydroxydeoxyguanosine staining was reduced in the exenatide treatment arm, and superoxide dismutase activity and catalase activity were increased. Serum insulin levels increased after exenatide treatment, without affecting glucose levels.. These data identify exenatide as a potentially effective compound to reduce infarct size in adjunction to reperfusion therapy in patients with acute MI.

Topics: Animals; Disease Models, Animal; Exenatide; Hypoglycemic Agents; Myocardial Infarction; Myocardial Reperfusion Injury; Peptides; Swine; Venoms

Exenatide is a peptide incretin mimetic that has glucoregulatory actions associated with weight reduction. Previous reports demonstrated acute increases in blood pressure after systemic or intracerebroventricular administration of exenatide or glucagon like peptide 1 (GLP 1) in rats. However, there are limited studies testing the chronic effects of these peptides on arterial pressure and no reports showing the effects of these peptides to reverse hypertension in the context of the metabolic syndrome.. Thus, we examined the response to peripheral exenatide using telemetry in conscious, unrestrained rats under normotensive conditions and in a model of hypertension/metabolic syndrome induced by corticosterone. Rats were implanted with either corticosterone or wax (control) pellets, followed 14 days later by the additional implantation of pumps to deliver exenatide (1 microg/kg per day) or vehicle for 7 days.. The 21-day corticosterone treatment produced hypertriglyceridemia, visceral fat deposition, hyperglycemia, insulin resistance, and an elevation of mean arterial blood pressure (MAP) by 14 +/- 1 mmHg. Exenatide significantly reversed corticosterone-induced increases in blood pressure and this normalization occurred independently from change in body weight. Additionally, exenatide reduced MAP by 5 +/- 3 mmHg in normotensive control rats.. These results are the first demonstration of a durable antihypertensive effect of exenatide in a glucocorticoid-induced model of the metabolic syndrome.

Topics: Animals; Blood Pressure; Body Weight; Corticosterone; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Hypertension; Hypoglycemic Agents; Injections, Intraventricular; Male; Metabolic Syndrome; Peptides; Rats; Rats, Sprague-Dawley; Telemetry; Time Factors; Venoms

The glucagon-like peptide-1 (GLP-1) receptor agonist, exendin-4, has previously been shown to delay the onset of diabetes when administered to Goto-Kakizaki (GK) rats in the prediabetic period. The present study aimed to evaluate whether long-term administration of exendin-4 to GK rats in the diabetic period would improve their diabetes and how glycaemic control was affected following drug wash-out.. Glycaemic control was assessed in diabetic GK rats during 12 weeks of exendin-4 or vehicle treatment. Moreover, some animals were followed for an additional 9 weeks without treatment.. Glycaemic control was seen to deteriorate in vehicle-treated animals, as assessed by increased glycated haemoglobin A1c (HbA1c), whereas HbA1c improved in exendin-4-treated animals. Following an additional 9 weeks without treatment, glycaemic control in exendin-4-treated animals remained below baseline value and thus remained significantly lower than that of vehicle-treated animals. Following exendin-4 administration, oral glucose tolerance tests revealed greatly reduced glucose and insulin excursions compared with vehicle-treated animals, whereas following overnight drug wash-out, only little difference was seen, suggesting that the improvement in glycaemic control may have been obtained primarily by increased postprandial control. No significant differences were observed in pancreatic islet morphology or islet hormone content.. Exendin-4 treatment improved glycaemic control in diabetic GK rats, independent of changes in beta-cell mass. Additionally, progression of the disease seemed to be delayed because the improvement in HbA1c was still apparent 9 weeks after cessation of treatment.

Topics: Animals; Area Under Curve; Blood Glucose; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide-1 Receptor; Glycated Hemoglobin; Hypoglycemic Agents; Insulin; Pancreas; Peptides; Rats; Rats, Mutant Strains; Rats, Wistar; Receptors, Glucagon; Venoms

Clinical reports link use of the glucagon-like peptide-1 receptor (GLP-1R) agonists exenatide and liraglutide to pancreatitis. However, whether these agents act on the exocrine pancreas is poorly understood.. We assessed whether the antidiabetic agents exendin (Ex)-4, liraglutide, the dipeptidyl peptidase-4 inhibitor sitagliptin, or the biguanide metformin were associated with changes in expression of genes associated with the development of experimental pancreatitis. The effects of Ex-4 when administered before or after the initiation of caerulein-induced experimental pancreatitis were determined. The importance of endogenous GLP-1R signaling for gene expression in the exocrine pancreas and the severity of pancreatitis was assessed in Glp1r(-/-) mice.. Acute administration of Ex-4 increased expression of egr-1 and c-fos in the exocrine pancreas. Administration of Ex-4 or liraglutide for 1 week increased pancreas weight and induced expression of mRNA transcripts encoding the anti-inflammatory proteins pancreatitis-associated protein (PAP) (RegIIIbeta) and RegIIIalpha. Chronic Ex-4 treatment of high-fat-fed mice increased expression of PAP and reduced pancreatic expression of mRNA transcripts encoding for the proinflammatory monocyte chemotactic protein-1, tumor necrosis factor-alpha, and signal transducer and activator of transcription-3. Sitagliptin and metformin did not significantly change pancreatic gene expression profiles. Ex-4 administered before or after caerulein did not modify the severity of experimental pancreatitis, and levels of pancreatic edema and serum amylase were comparable in caerulein-treated Glp1r(-/-) versus Glp1r(+/+) mice.. These findings demonstrate that GLP-1 receptor activation increases pancreatic mass and selectively modulates the expression of genes associated with pancreatitis. However, activation or genetic elimination of GLP-1R signaling does not modify the severity of experimental pancreatitis in mice.

Topics: Animals; Ceruletide; Dietary Fats; Disease Models, Animal; Early Growth Response Protein 1; Exenatide; Gene Expression; Genes, fos; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Liraglutide; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Pancreas, Exocrine; Pancreatitis; Pancreatitis-Associated Proteins; Peptides; Receptors, Glucagon; Severity of Illness Index; Signal Transduction; Venoms

Exendin-4 is a naturally occurring more potent and stable analog of glucagon-like peptide-1 (GLP-1) that selectively binds at the GLP-1 receptor. It has been recently demonstrated that GLP-1 receptor stimulation preserves dopaminergic neurons in cellular and rodent models of Parkinson's disease (PD). 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes nigrostriatal dopaminergic neurotoxicity in rodents; previous studies suggest that activated microglia actively participate in the pathogenesis of PD neurodegeneration. However, the role of microglia in the neuroprotective properties of exendin-4 is still unknown. Here, we show that, in the mouse MPTP PD model, systemic administration of exendin-4 significantly attenuates the loss of substantia nigra pars compacta (SNpc) neurons and the striatal dopaminergic fibers. Exendin-4 prevents MPTP-induced microglial activation in the SNpc and striatum, and the expression of matrix metalloproteinase-3. In addition, exendin-4 also suppressed MPTP-induced expression of pro-inflammatory molecules and tumor necrosis factor alpha and interleukin-1 beta. Our data indicate that exendin-4 may act as a survival factor for dopaminergic neurons by functioning as a microglia-deactivating factor and suggest that exendin-4 may be a valuable therapeutic agent for neurodegenerative diseases such as PD.

Topics: Animals; Corpus Striatum; Disease Models, Animal; Dopamine; Exenatide; Gene Expression Regulation, Enzymologic; Gliosis; Hypoglycemic Agents; Inflammation Mediators; Male; Matrix Metalloproteinase 3; Matrix Metalloproteinase Inhibitors; Mice; Mice, Inbred C57BL; Microglia; Neuroprotective Agents; Parkinsonian Disorders; Peptides; Substantia Nigra; Venoms

Second generation antipsychotic drug (SGA) treatment is associated with detrimental effects on glucose metabolism which is often attributed to the development of obesity and insulin resistance. However, we have recently demonstrated that clozapine and quetiapine also have direct effects of glucose metabolism in animals. This study compares clozapine and quetiapine and investigates the effects of these on the development of obesity and the direct effects of these drugs on glucose metabolism compared with those caused by the obesity per se.. Three groups of male Sprague-Dawley rats were fed a high fat/high sugar diet to induce obesity while another three groups were fed a chow diet. One group on each diet was injected daily with vehicle, clozapine or quetiapine and effects on glucose metabolism were monitored.. Clozapine and quetiapine treatment did not directly cause obesity or potentiate diet induced obesity but did induce a preference for the high fat/high sugar diet. Neither drug caused a impairment in insulin tolerance over that caused by obesity but both drugs acutely induced impairments in glucose tolerance that were additive with the effects induced by the diet induced obesity. Both drugs caused increases in glucagon levels and a suppression of GLP-1. We investigated two strategies for restoring GLP-1 signalling. The DPP-IV inhibitor sitagliptin only partially restored GLP-1 levels and did not overcome the deleterious effects on glucose tolerance whereas the GLP-1 receptor agonist exendin-4 normalised both glucagon levels and glucose metabolism.. Our findings indicate that the clozapine and quetiapine induced impairments in glucose tolerance in rats are independent of insulin resistance caused by obesity and that these defects are linked with a suppression of GLP-1 levels. These studies suggest the need to perform follow up studies in humans to determine whether clozapine and quetiapine induce acute derangements in glucose metabolism and whether GLP-1 replacement therapy might be the most appropriate therapeutic strategy for treating derangements in glucose metabolism in subjects taking these drugs.

Topics: Analysis of Variance; Animals; Antipsychotic Agents; Body Composition; Body Weight; Clozapine; Dibenzothiazepines; Dietary Fats; Disease Models, Animal; Eating; Exenatide; Food Preferences; Gene Expression Regulation; Glucagon; Glucagon-Like Peptide 1; Glucose; Glucose Tolerance Test; Hypoglycemic Agents; Insulin Resistance; Male; Obesity; Peptides; Pyrazines; Quetiapine Fumarate; Rats; Rats, Sprague-Dawley; Sitagliptin Phosphate; Triazoles; Venoms

Intrauterine growth retardation (IUGR) has been linked to the development of type 2 diabetes in adulthood. We have developed an IUGR model in the rat whereby the animals develop diabetes later in life. Previous studies demonstrate that administration of the long-acting glucagon-like-peptide-1 agonist, exendin-4, during the neonatal period prevents the development of diabetes in IUGR rats. IUGR animals exhibit hepatic insulin resistance early in life (prior to the onset of hyperglycemia), characterized by blunted suppression of hepatic glucose production (HGP) in response to insulin. Basal HGP is also significantly higher in IUGR rats. We hypothesized that neonatal administration of exendin-4 would prevent the development of hepatic insulin resistance. IUGR and control rats were given exendin-4 on days 1-6 of life. Hyperinsulinemic-euglycemic clamp studies showed that Ex-4 significantly reduced basal HGP by 20% and normalized insulin suppression of HGP in IUGR rats. While Ex-4 decreased body weight and fat content in both Control and IUGR animals, these differences were only statistically significant in Controls. Exendin-4 prevented development of oxidative stress in liver and reversed insulin-signaling defects in vivo, thereby preventing the development of hepatic insulin resistance. Defects in glucose disposal and suppression of hepatic glucose production in response to insulin were reversed. Similar results were obtained in isolated Ex-4-treated neonatal hepatocytes. These results indicate that exposure to exendin-4 in the newborn period reverses the adverse consequences of fetal programming and prevents the development of hepatic insulin resistance.

Topics: Age Factors; Aging; Animals; Animals, Newborn; Biomarkers; Blood Glucose; Body Composition; Body Weight; Cells, Cultured; Diabetes Mellitus, Type 2; Disease Models, Animal; Drug Administration Schedule; Exenatide; Female; Fetal Growth Retardation; Gene Expression Regulation, Enzymologic; Glucokinase; Glucose-6-Phosphatase; Hypoglycemic Agents; Injections, Subcutaneous; Insulin; Insulin Resistance; Liver; Oxidative Stress; Peptides; Phosphoenolpyruvate Carboxykinase (GTP); Pregnancy; Rats; Rats, Sprague-Dawley; RNA, Messenger; Signal Transduction; Venoms

We investigated the effects of exendin-4 on neural stem/progenitor cells in the subventricular zone of the adult rodent brain and its functional effects in an animal model of Parkinson's disease. Our results showed expression of GLP-1 receptor mRNA or protein in the subventricular zone and cultured neural stem/progenitor cells isolated from this region. In vitro, exendin-4 increased the number of neural stem/progenitor cells, and the number of cells expressing the neuronal markers microtubule-associated protein 2, beta-III-tubulin, and neuron-specific enolase. When exendin-4 was given intraperitoneally to naïve rodents together with bromodeoxyuridine, a marker for DNA synthesis, both the number of bromodeoxyuridine-positive cells and the number of neuronal precursor cells expressing doublecortin were increased. Exendin-4 was tested in the 6-hydroxydopamine model of Parkinson's disease to investigate its possible functional effects in an animal model with neuronal loss. After unilateral lesion and a 5-week stabilization period, the rats were treated for 3 weeks with exendin-4. We found a reduction of amphetamine-induced rotations in animals receiving exendin-4 that persisted for several weeks after drug administration had been terminated. Histological analysis showed that exendin-4 significantly increased the number of both tyrosine hydroxylase- and vesicular monoamine transporter 2-positive neurons in the substantia nigra. In conclusion, our results show that exendin-4 is able to promote adult neurogenesis in vitro and in vivo, normalize dopamine imbalance, and increase the number of cells positive for markers of dopaminergic neurons in the substantia nigra in a model of Parkinson's disease.

Topics: Animals; Cell Differentiation; Cell Proliferation; Disease Models, Animal; Doublecortin Protein; Exenatide; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Immunohistochemistry; Mice; Motor Activity; Neurons; Parkinsonian Disorders; Peptides; Rats; Receptors, Glucagon; Recovery of Function; Reverse Transcriptase Polymerase Chain Reaction; Stem Cells; Substantia Nigra; Venoms

Activation of the glucagon-like peptide-1 receptor (GLP-1R) is associated with expansion of beta-cell mass due to stimulation of cell proliferation and induction of antiapoptotic pathways coupled to beta-cell survival. Although the GLP-1R agonist Exenatide (exendin-4) is currently being evaluated in subjects with type 1 diabetes, there is little information available about the efficacy of GLP-1R activation for prevention of experimental type 1 diabetes. We examined the consequences of exendin-4 (Ex-4) administration (100 ng once daily and 2 microg twice daily) on diabetes onset in nonobese diabetic mice beginning at either 4 or 9 wk of age prior to the onset of diabetes. Ex-4 treatment for 26 wk (2 microg twice daily) initiated at 4 wk of age delayed the onset of diabetes (P = 0.007). Ex-4-treated mice also exhibited a significant reduction in insulitis scores, enhanced beta-cell mass, and improved glucose tolerance. Although GLP-1R mRNA transcripts were detected in spleen, thymus, and lymph nodes from nonobese diabetic mice, Ex-4 treatment was not associated with significant changes in the numbers of CD4+ or CD8+ T cells or B cells in the spleen. However, Ex-4 treatment resulted in an increase in the number of CD4+ and CD8+ T cells in the lymph nodes and a reduction in the numbers of CD4+CD25+Foxp3+ regulatory T cells in the thymus but not in lymph nodes. These findings demonstrate that sustained GLP-1R activation in the absence of concomitant immune intervention may be associated with modest but significant delay in diabetes onset in a murine model of type 1 diabetes.

Topics: Animals; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Diabetes Mellitus, Experimental; Disease Models, Animal; Disease Progression; Dose-Response Relationship, Drug; Exenatide; Female; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Insulin-Secreting Cells; Lymph Nodes; Mice; Mice, Inbred NOD; Peptides; Receptors, Glucagon; Spleen; Venoms

Islet transplantations have been performed clinically, but their practical applications are limited. An extensive effort has been made toward the identification of pancreatic beta-cell stem cells that has yielded many insights to date, yet targeted reconstitution of beta-cell mass remains elusive. Here, we present a mouse model for inducible and reversible ablation of pancreatic beta-cells named the PANIC-ATTAC (pancreatic islet beta-cell apoptosis through targeted activation of caspase 8) mouse.. We efficiently induce beta-cell death through apoptosis and concomitant hyperglycemia by administration of a chemical dimerizer to the transgenic mice. In contrast to animals administered streptozotocin, the diabetes phenotype and beta-cell loss are fully reversible in the PANIC-ATTAC mice, and we find significant beta-cell recovery with normalization of glucose levels after 2 months.. The rate of recovery can be enhanced by various pharmacological interventions with agents acting on the glucagon-like peptide 1 axis and agonists of peroxisome proliferator-activated receptor-gamma. During recovery, we find an increased population of GLUT2(+)/insulin(-) cells in the islets of PANIC-ATTAC mice, which may represent a novel pool of potential beta-cell precursors.. The PANIC-ATTAC mouse may be used as an animal model of inducible and reversible beta-cell ablation and therefore has applications in many areas of diabetes research that include identification of beta-cell precursors, evaluation of glucotoxicity effects in diabetes, and examination of pharmacological interventions.

Topics: Animals; Apoptosis; Caspase 8; Caspases; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Exenatide; Glucose Tolerance Test; Insulin-Secreting Cells; Male; Mice; Mice, Transgenic; Peptides; Reverse Transcriptase Polymerase Chain Reaction; Tacrolimus; Tacrolimus Binding Proteins; Transgenes; Venoms

Exenatide (exendin-4) injected subcutaneously twice daily reduces glycaemic deterioration in diabetic fatty Zucker (ZDF) rats and reduces HbA1c in humans with type 2 diabetes. Because tachyphylaxis may develop with continuous peptide exposure, we examined the activity of a long-acting-release (LAR) formulation of exenatide on HbA1c, insulin sensitivity and beta cell secretion in ZDF rats.. Single subcutaneous injections of a poly-lactide-glycolide microsphere suspension (3% peptide) containing 0, 1, 10, 100, 1,000, 3,000 or 9,000 mug exenatide were administered to 9-week-old ZDF rats with matched initial HbA1c values (n=7 rats/group).. In contrast to the progressive 3.22+/-0.42% increase in HbA1c in control ZDF rats observed over 28 days, single exenatide-LAR injections dose-proportionally prevented such glycaemic deterioration (median effective dose 74 microg+/-0.1 log per rat; median effective concentration 52 pmol/l+/-0.06 log). Hyperinsulinaemic-euglycaemic clamp procedures incorporating an intraclamp glucose challenge performed 28 days after treatment revealed increases in beta cell response to the glucose challenge at lower exenatide-LAR doses, and up to a 2.1-fold increase in insulin sensitivity at higher exenatide-LAR doses.. The finding that a single dose of exenatide-LAR enhanced glucose control for 28 days in the ZDF rat model of type 2 diabetes suggests that tachyphylaxis is unlikely to be a feature of exenatide-LAR preparations, and supports further clinical exploration.

Topics: Animals; Blood Glucose; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucose Clamp Technique; Glycated Hemoglobin; Hyperinsulinism; Infusions, Intravenous; Insulin; Male; Peptides; Rats; Rats, Zucker; Venoms

In the Goto-Kakizaki (GK) rat, a genetic model of type 2 diabetes, the neonatal beta-cell mass deficit is considered to be the primary defect leading to basal hyperglycemia, which is detectable for the first time 3 weeks after birth. We investigated in GK females the short- and the long-term effects of a treatment with glucagon-like peptide-1 (GLP-1) or its long-acting analog exendin-4 (Ex-4) during the first postnatal week (during the prediabetic period). GK rats were treated with daily injections of glucagon-like peptide-1 (400 microg x kg(-1) x day(-1)) or Ex-4 (3 microg x kg(-1) x day(-1)) from day 2 to day 6 after birth and were evaluated against Wistar and untreated GK rats. Under these conditions, on day 7 both treatments enhanced pancreatic insulin content and total beta-cell mass by stimulating beta-cell neogenesis and regeneration. Follow-up of biological characteristics from day 7 to adult age (2 months) showed that such a GLP-1 or Ex-4 treatment exerted long-term favorable influences on beta-cell mass and glycemic control at adult age. As compared to untreated GK rats, 2-month-old treated rats exhibited significantly decreased basal plasma glucose. Their glucose-stimulated insulin secretion, in vivo after intravenous glucose load or in vitro using isolated perfused pancreas, was slightly improved. This contributed at least partly to improve the in vivo plasma glucose disappearance rate, which was found to be increased in both treated GK groups compared to the untreated GK group. These findings in the GK model indicated, for the first time, that GLP-1 or Ex-4 treatment limited to the prediabetic period delays the installation and limits the severity of type 2 diabetes. Under these conditions, GLP-1 represents a unique tool because of its beta-cell replenishing effect in spontaneously diabetic rodents. It may prove to be an invaluable agent for the prevention of human type 2 diabetes.

Topics: Age Factors; Animals; Animals, Newborn; Blood Glucose; Body Weight; Cell Division; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Female; Glucagon; Glucagon-Like Peptide 1; Insulin; Insulin Secretion; Islets of Langerhans; Longitudinal Studies; Peptide Fragments; Peptides; Protein Precursors; Rats; Rats, Mutant Strains; Rats, Wistar; Venoms