oxyntomodulin and Disease-Models--Animal

Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are chronic, relapsing, intestinal inflammatory disorders with complex and yet unrevealed pathogenesis in which genetic, immunological, and environmental factors play a role. Nowadays, a higher proportion of elderly IBD patients with coexisting conditions, such as cardiovascular disease and/or diabetes is recorded, who require more complex treatment and became a great challenge for gastroenterologists. Furthermore, some patients do not respond to anti-IBD therapy. These facts, together with increasing comorbidities in patients with IBD, imply that urgent, more complex, novel therapeutic strategies in the treatment are needed. Glucagon-like peptides (GLPs) possess numerous functions in the human body such as lowering blood glucose level, controlling body weight, inhibiting gastric emptying, reducing food ingestion, increasing crypt cell proliferation, and improving intestinal growth and nutrient absorption. Thus, GLPs and dipeptidyl peptidase IV (DPP-IV) inhibitors have recently gained attention in IBD research. Several animal models showed that treatment with GLPs may lead to improvement of colitis. This review presents data on the multitude effects of GLPs in the inflammatory intestinal diseases and summarizes the current knowledge on GLPs, which have the potential to become a novel therapeutic option in IBD therapy.

Topics: Animals; Anti-Inflammatory Agents; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Glucagon-Like Peptides; Humans; Inflammatory Bowel Diseases

Glucagon-like peptide 1 receptor (GLP-1R) agonists are increasingly being used as treatment for type 2 diabetes. Since the U.S. Food and Drug Administration published recommendations about the cardiovascular safety of new antidiabetes therapies for treating type 2 diabetes in 2008, the results of two outstanding clinical trials using GLP-1R agonists addressing this issue (Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results-A Long Term Evaluation [LEADER] and Trial to Evaluate Cardiovascular and Other Long-term Outcomes With Semaglutide in Subjects With Type 2 Diabetes [SUSTAIN-6]) have been published. Both studies found beneficial effects in terms of reducing the rates of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke. However, their results regarding the progression of diabetic retinopathy (DR) were neutral with liraglutide (LEADER) or worse when compared with placebo in the case of semaglutide (SUSTAIN-6). These results are surprising because of the beneficial effects of GLP-1R analogs reported in experimental models of DR. In this Perspective, an overview of the mechanisms by which GLP-1R activation exerts its effects in preventing or arresting experimental DR is given. In addition, we consider the possible reasons for the negative results regarding the progression of DR in the SUSTAIN-6 study, as well as the gaps that still need to be covered to further clarify this important issue in the management of type 2 diabetes.

Topics: Animals; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Disease Models, Animal; Disease Progression; Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptides; Humans; Hypoglycemic Agents; Liraglutide; Molecular Targeted Therapy; Myocardial Infarction; Stroke; Treatment Outcome

Topics: Animals; Colitis; Dextran Sulfate; Dipeptidyl Peptidase 4; Disease Models, Animal; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Humans; Indicators and Reagents; Inflammatory Bowel Diseases; Intestinal Mucosa; Intestines; Isoleucine; Mice; Mice, Knockout; Peptide Fragments; Serine Proteinase Inhibitors

Of the many models of intestinal adaptation, the structural and functional changes seen in the residual small bowel following jejunectomy or ileectomy are the most predictable and best studied. There are three major mechanisms for these adaptive phenomena: changes in i) luminal nutrition, ii) pancreatico-biliary secretions and iii) hormonal factors. Observations in a unique patient with an "enteroglucagon"-secreting tumor of the kidney associated with massive small bowel enlargement, provided the strongest evidence, at that time (>30 y ago), in favor of hormonal factors. When the patient's renal tumor was removed, the markedly increased circulating concentrations of the glucagon-like peptide (now presumed to be GLP-2) returned to normal-as did her intestinal anatomy. Subsequent studies showed that there are increased tissue and plasma enteroglucagon (and recently GLP-2) levels in many animal models of intestinal adaptation. This, and anecdotal evidence from three other case reports, coupled with contemporary studies of GLP-2, strongly suggest that this glucagon-like peptide is a potent, but not the sole, enterotrophin.

Topics: Adaptation, Physiological; Animals; Disease Models, Animal; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Humans; Hyperplasia; Intestinal Mucosa; Intestines; Peptides

The intestine has an inherent ability to adapt morphologically and functionally in response to internal and external environmental changes. The functional adaptations encompass modifications of the brush border membrane fluidity and permeability, as well as up- or down-regulation of carrier-mediated transport. Intestinal adaptation improves the nutritional status following the loss of a major portion of the small intestine, following chronic ingestion of ethanol, following sublethal doses of abdominal irradiation, in diabetes, in pregnancy and lactation, with ageing, and with fasting and malnutrition. Following intestinal resection, morphological and functional changes occur depending upon the extent of the intestine removed, the site studied, and the lipid content of the diet. Therefore, intestinal adaptation has important implications in the survival potential and welfare of the host. An understanding of the mechanisms of, and signals for, intestinal adaptation in the experimental setting forms the basis for the use of management strategies in humans with the short-bowel syndrome.

Topics: Animals; Biomarkers; Disease Models, Animal; Epidermal Growth Factor; Glucagon-Like Peptides; Glucocorticoids; Glutamine; Growth Hormone; Humans; Insulin-Like Growth Factor I; Intestinal Absorption; Intestinal Mucosa; Intestines; Peptides; Short Bowel Syndrome

The present article reviews the current literature on the role of diet and other trophic factors in the treatment of short-bowel syndrome. Results using glutamine, growth hormone and glucagon-like peptide 2 are reviewed. Although experimental animal data would suggest that various growth factors are of benefit in the treatment of short-bowel syndrome, only a few clinical studies have made the same claim.

Topics: Animals; Colon; Dietary Carbohydrates; Disease Models, Animal; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Glutamine; Growth Substances; Humans; Intestine, Small; Peptides; Short Bowel Syndrome

The weight loss following Semaglutide treatment, a GLP-1 receptor agonist, might be responsible for some effects observed on the nonalcoholic fatty liver disease of obese mice.. Two groups of C57BL/6 male mice (n = 30/group) were fed the diets Control (C) or high-fat (HF) for 16 weeks. Then, separated into six new groups for an additional four weeks (n = 10/group) and treated with Semaglutide (S, 40 µg/kg) or paired feeding (PF) with S groups (C; C-S; C-PF; HF; HF-S; HF-PF).. Semaglutide reduced energy consumption leading to weight loss. Simultaneously it improved glucose intolerance, glycated hemoglobin, insulin resistance/sensitivity, plasma lipids, and gastric inhibitory polypeptide. Semaglutide and paired feeding mitigated liver steatosis and adipose differentiation-related protein (Plin2) expression. Semaglutide also improved hormones and adipokines, reduced lipogenesis and inflammation, and increased beta-oxidation. Semaglutide lessened liver glucose uptake and endoplasmic reticulum (ER) stress. Among the 14 genes analyzed, 13 were modified by Semaglutide (93 %, six genes were changed exclusively by Semaglutide, and seven other genes were affected by the combination of Semaglutide and paired feeding). In seven genes, the paired diet showed no effect (50% of the genes tested). No marker was affected exclusively by paired feeding.. Semaglutide and the consequent weight loss reduced obese mice liver inflammation, insulin resistance, and ER stress. However, weight loss alone did show few or no action on some significant study findings, like liver steatosis, leptin, insulin, resistin, and amylin. Furthermore, hepatic inflammation mediated by MCP-1 and partially by TNF-alpha and IL6 were also not reduced by weight loss. Furthermore, weight loss alone did not lessen hepatic lipogenesis as determined by the findings of SREBP-1c, CHREBP, PPAR-alpha, and SIRT1. Semaglutide was implicated in improving glucose uptake and lessening ER stress by reducing GADD45, independent of weight loss.

Topics: Animals; Disease Models, Animal; Endoplasmic Reticulum; Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptides; Mice; Mice, Inbred C57BL; Non-alcoholic Fatty Liver Disease; Nutritional Support; Obesity; Weight Loss

There are significant injuries of pancreatic islets due to obesity and insulin resistance. Therefore, GLP-1 receptor agonists like Semaglutide might benefit the islet structural remodeling and its endocrine function in diet-induced obese mice. One-month-old male C57BL/6 mice were allotted into two dietary groups (n = 60/group) and fed for 16 weeks a control diet (C) or a high‒fat diet (HF). Then, for an additional four weeks, the main groups were resampled to include treatment (Semaglutide, S, 40 μg/kg), or paired feed with the treated group (PF), totaling six groups (n = 20/group): C, CS, CPF, HF, HFS, HFPF. Biochemistry, stereology, immunohistochemistry/immunofluorescence, confocal microscopy, and RT-qPCR were used in the study. The mouse model reproduced metabolism and bodily changes due to diet-induced obesity. Pancreatic islet hypertrophy was observed with alpha- and beta-cell remodeling, cell disarray, and apoptosis. Semaglutide increased islet cell proliferation and recovered islet size and alpha- and beta-cell masses. The changes include recovery of glucose and hormone levels, reduction of pro-inflammatory markers, improvement of pancreatic duodenal homeobox 1 (PDX-1), glucose transporter 2 (GLUT-2), v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MAF-A), and peroxisome proliferator-activated receptors (PPAR) -gamma. In conclusion, damage to the pancreatic islet caused by insulin resistance and the attempt to adapt the islet of obese mice involved different pathways, especially the pro-inflammatory pathway, PDX1, and PPAR-alpha and gamma. Semaglutide showed beneficial effects on these pathways, reducing the lesion on the islet. However, the weight loss influence of Semaglutide was of little relevance in the pancreatic islet.

Topics: Animals; Apoptosis; Cell Proliferation; Disease Models, Animal; Glucagon-Like Peptides; Glucagon-Secreting Cells; Insulin-Secreting Cells; Male; Mice; Obesity

Non-alcoholic steatohepatitis (NASH) has emerged as a major challenge for public health because of high global prevalence and lack of evidence-based therapies. Most animal models of NASH lack sufficient validation regarding disease progression and pharmacological treatment. The Gubra-Amylin NASH (GAN) diet-induced obese (DIO) mouse demonstrate clinical translatability with respect to disease etiology and hallmarks of NASH. This study aimed to evaluate disease progression and responsiveness to clinically effective interventions in GAN DIO-NASH mice. Disease phenotyping was performed in male C57BL/6J mice fed the GAN diet high in fat, fructose, and cholesterol for 28-88 weeks. GAN DIO-NASH mice with biopsy-confirmed NASH and fibrosis received low-caloric dietary intervention, semaglutide (30 nmol/kg/day, s.c.) or lanifibranor (30 mg/kg/day, p.o.) for 8 and 12 weeks, respectively. Within-subject change in nonalcoholic fatty liver disease (NAFLD) Activity Score (NAS) and fibrosis stage was evaluated using automated deep learning-based image analysis. GAN DIO-NASH mice showed clear and reproducible progression in NASH, fibrosis stage, and tumor burden with high incidence of hepatocellular carcinoma. Consistent with clinical trial outcomes, semaglutide and lanifibranor improved NAS, whereas only lanifibranor induced regression in the fibrosis stage. Dietary intervention also demonstrated substantial benefits on metabolic outcomes and liver histology. Differential therapeutic efficacy of semaglutide, lanifibranor, and dietary intervention was supported by quantitative histology, RNA sequencing, and blood/liver biochemistry. In conclusion, the GAN DIO-NASH mouse model recapitulates various histological stages of NASH and faithfully reproduces histological efficacy profiles of compounds in advanced clinical development for NASH. Collectively, these features highlight the utility of GAN DIO-NASH mice in preclinical drug development.

Topics: Animals; Benzothiazoles; Biopsy; Diet; Disease Models, Animal; Disease Progression; Glucagon-Like Peptides; Humans; Liver; Liver Cirrhosis; Male; Mice; Mice, Inbred C57BL; Mice, Obese; Non-alcoholic Fatty Liver Disease; Obesity; Sulfonamides

Topics: Animals; Apoptosis; Cell Line; Cognitive Dysfunction; Cytokines; Disease Models, Animal; Epilepsy; Glucagon-Like Peptides; Hippocampus; Inflammasomes; Inflammation; Male; Mice; Mice, Inbred C57BL; Microglia; Neuroprotective Agents; NLR Family, Pyrin Domain-Containing 3 Protein; Pentylenetetrazole; Seizures

To investigate the protective efficacies and potent mechanisms of combination therapy with semaglutide and rosiglitazone (RSG) on the high-glucose incubated human ARPE-19 cells and diabetic retinopathy (DR) model rats.. The CCK-8 methods were used to evaluate the protective effects of semaglutide and RSG alone or combination on the cell viability of high-glucose treated ARPE-19 cells. After the DR rat model was established, the effects of combined treatment on general indexes, retinal morphological changes, retinal Müller cells as well as PI3K/Akt/MTOR related factors of DR model rats were investigated.. The CCK-8 assay showed obviously enhanced protective efficacies of combination therapy with semaglutide and RSG on the ARPE-19 with oxidative stress induced by high-glucose with combination index all below 1.5 demonstrating obvious synergistic effects. Combined incubation could also effectively decrease the expression of inflammatory factors, including TNF-α, IL-1β, IL-6, and the increase of ROS content in ARPE cell culture supernatant induced by high-glucose. Combined use of the antioxidant, PI3K/Akt and mTOR inhibitors, we further demonstrated that combined incubation of semaglutide and RSG could effectively by reduce high glucose-induced inflammatory injury inhibiting ROS/PI3K/Akt/mTOR signaling. Furthermore, chronic combination treatment effectively improved the histopathological characteristics and down-regulated the GFAP expression in Müller cells as well as PI3K/Akt/MTOR signaling pathway-related factors in retina which was better than any monomer treatment group.. Combined semaglutide with RSG exhibited synergistically protective efficacies on retinal cells by decreasing the GFAP expression, inhibiting oxidative stress and PI3K/Akt/MTOR signaling-transduction in DR model rats.

Topics: Animals; Antioxidants; Cell Line; Cell Survival; Diabetic Retinopathy; Disease Models, Animal; Drug Therapy, Combination; Ependymoglial Cells; Glial Fibrillary Acidic Protein; Glucagon-Like Peptides; Humans; Inflammation; Male; Phosphatidylinositol 3-Kinases; Protective Agents; Proto-Oncogene Proteins c-akt; Rats, Sprague-Dawley; Rosiglitazone; Signal Transduction; TOR Serine-Threonine Kinases

The purpose of this study was to explore the effect of dulaglutide on DHEA induced PCOS rats and its mechanism, to provide new drugs and research directions for clinical treatment of PCOS.. In this study, the PCOS model was established by giving female SD rats subcutaneous injection of DHEA for 21 consecutive days. After modeling, the treatment group was injected subcutaneously with three doses of dulaglutide for 3 weeks. The model group was injected with sterile ultrapure water, and the normal group did not get any intervention. The body weight changes of rats in each group were recorded from the first day when rats received the administration of dulaglutide. Three weeks later, the rats were fasted the night after the last treatment, determined fasting insulin and fasting glucose the next day. After the rats were anesthetized by chloral hydrate, more blood was collected from the heart of the rat. The serum insulin, testosterone and sex hormone binding globulin (SHBG) levels were detected by the enzyme-linked immunoassay method. After removing the adipose tissue, the obtained rat ovary tissue was used for subsequent experimental detection, using HE staining for morphology and follicular development analysis; qRT-PCR for the detection of 3βHSD, CYP17α1, CYP19α1, and StAR gene expression in ovarian tissue; and western blotting analysis of CYP17α1, CYP19α1, StAR protein expression and insulin level to verify whether dulaglutide has a therapeutic effect on PCOS in rats.. After treated with different concentrations of dulaglutide, we found that the body weight of rats in the treatment groups were reduced. Compared with the rats in PCOS group, the serum androgen level of rats in the treatment groups was significantly decreased, and the serum sex hormone binding protein content was significantly increased, and there was statistically significant difference between these groups and PCOS group. In terms of protein expression and gene regulation, the expression of 3βHSD, CYP19α1 and StAR in the ovarian tissue of rats in treatment groups were decreased significantly after received the treatment of dulaglutide, and there was statistically significant difference between these groups and PCOS group. In addition, dulaglutide reduced the insulin content in the ovarian tissue of PCOS rats.. Dulaglutide may reduce the hyperandrogenemia of PCOS rats by regulating the content of serum SHBG and the expression of 3βHSD, CYP19α1, and StAR related genes and proteins, thereby inhibiting the excessive development of small follicles and the formation of cystic follicles in the ovaries of PCOS rats, thereby improving polycystic ovary in PCOS rats. In addition, dulaglutide may reduce the weight of PCOS rats, further reducing the level of high androgen in PCOS rats, and improving the morphology of their polycystic ovaries.

Topics: Animals; Body Weight; Dehydroepiandrosterone; Disease Models, Animal; Female; Gene Expression Regulation; Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptides; Immunoglobulin Fc Fragments; Insulin Resistance; Ovary; Ovulation; Phosphoproteins; Polycystic Ovary Syndrome; Rats, Sprague-Dawley; Recombinant Fusion Proteins; Sex Hormone-Binding Globulin; Steroid 17-alpha-Hydroxylase; Testosterone

Although diabetic polyneuropathy (DPN) is the commonest diabetic complication, its pathology remains to be clarified. As previous papers have suggested the neuroprotective effects of glucagon-like peptide-1 in DPN, the current study investigated the physiological indispensability of glucagon gene-derived peptides (GCGDPs) including glucagon-like peptide-1 in the peripheral nervous system (PNS). Neurological functions and neuropathological changes of GCGDP deficient (gcg-/-) mice were examined. The gcg-/- mice showed tactile allodynia and thermal hyperalgesia at 12-18 weeks old, followed by tactile and thermal hypoalgesia at 36 weeks old. Nerve conduction studies revealed a decrease in sensory nerve conduction velocity at 36 weeks old. Pathological findings showed a decrease in intraepidermal nerve fiber densities. Electron microscopy revealed a decrease in circularity and an increase in g-ratio of myelinated fibers and a decrease of unmyelinated fibers in the sural nerves of the gcg-/- mice. Effects of glucagon on neurite outgrowth were examined using an ex vivo culture of dorsal root ganglia. A supraphysiological concentration of glucagon promoted neurite outgrowth. In conclusion, the mice with deficiency of GCGDPs developed peripheral neuropathy with age. Furthermore, glucagon might have neuroprotective effects on the PNS of mice. GCGDPs might be involved in the pathology of DPN.

Topics: Animals; Diabetic Neuropathies; Disease Models, Animal; Ganglia, Spinal; Glucagon; Glucagon-Like Peptide 1; Glucagon-Like Peptides; Hyperalgesia; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nerve Fibers, Myelinated; Neural Conduction; Neuronal Outgrowth; Receptors, Glucagon; RNA, Messenger

Stroke is a condition with few medical treatments available. Semaglutide, a novel Glucagon-like peptide-1 (GLP-1) analogue, has been brought to the market as a treatment for diabetes. We tested the protective effects of semaglutide against middle cerebral artery occlusion injury in rats. Animals were treated with 10 nmol/kg bw ip. starting 2 h after surgery and every second day for either 1, 7, 14 or 21 days. Semaglutide-treated animals showed significantly reduced scores of neurological impairments in several motor and grip strength tasks. The cerebral infarction size was also reduced, and the loss of neurons in the hippocampal areas CA1, CA3 and the dentate gyrus was much reduced. Chronic inflammation as seen in levels of activated microglia and in the activity of the p38 MAPK - MKK - c-Jun- NF-κB p65 inflammation signaling pathway was reduced. In addition, improved growth factor signaling as shown in levels of activated ERK1 and IRS-1, and a reduction in the apoptosis signaling pathway C-raf, ERK2, Bcl-2/BAX and Caspase-3 was observed. Neurogenesis had also been normalized by the drug treatment as seen in increased neurogenesis (DCX-positive cells) in the dentate gyrus and a normalization of biomarkers for neurogenesis. In conclusion, semaglutide is a promising candidate for re-purposing as a stroke treatment.

Topics: Animals; Apoptosis; Brain; Disease Models, Animal; Doublecortin Protein; Glucagon-Like Peptide 1; Glucagon-Like Peptides; Hippocampus; Hypoglycemic Agents; Infarction, Middle Cerebral Artery; Inflammation; Insulin Receptor Substrate Proteins; Microglia; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinase Kinases; Motor Activity; Neurogenesis; Neurons; p38 Mitogen-Activated Protein Kinases; Proto-Oncogene Proteins c-jun; Rats; Stroke; Transcription Factor RelA

Patients with asthma with obesity experience severe symptoms, are unresponsive to conventional asthma treatment, and lack proper pharmacotherapy. Empagliflozin and dulaglutide, developed for diabetes, reduce weight, decrease insulin resistance, and exert additive effects. We evaluated the efficacy of empagliflozin, dulaglutide, and their combination on obesity-induced airway hyperresponsiveness (AHR) and lung fibrosis using a murine model. We assigned C57BL/6J mice to five groups: control, high-fat diet (HFD), and HFD with empagliflozin, dulaglutide, or both. Mice received a 12-week HFD, empagliflozin (5 days/week, oral gavage), and dulaglutide (once weekly, intraperitoneally). Both drugs significantly attenuated HFD-induced weight increase, abnormal glucose metabolism, and abnormal serum levels of leptin and insulin, and co-treatment was more effective. Both drugs significantly alleviated HFD-induced AHR, increased macrophages in bronchoalveolar lavage fluid (BALF), and co-treatment was more effective on AHR. HFD-induced lung fibrosis was decreased by both drugs alone and combined. HFD induced interleukin (IL)-17, transforming growth factor (TGF)-β1, and IL-1β mRNA and protein expression, which was significantly reduced by empagliflozin, dulaglutide, and their combination. Tumour necrosis factor (TNF)-α and IL-6 showed similar patterns without significant differences. HFD-enhanced T helper (Th) 1 and Th17 cell differentiation was improved by both drugs. Empagliflozin and dulaglutide could be a promising therapy for obesity-induced asthma and showed additive effects in combination.

Topics: Animals; Benzhydryl Compounds; Cell Differentiation; Cytokines; Diet, High-Fat; Disease Models, Animal; Fibrosis; Gene Expression Regulation; Glucagon-Like Peptides; Glucosides; Immunoglobulin Fc Fragments; Mice; Obesity; Recombinant Fusion Proteins; Respiratory Hypersensitivity; RNA, Messenger; Th1 Cells; Th17 Cells

A substantial number of ischaemic stroke patients who receive reperfusion therapy in the acute phase do not ever fully recover. This reveals the urgent need to develop new adjunctive neuroprotective treatment strategies alongside reperfusion therapy. Previous experimental studies demonstrated the potential of glucagon-like peptide-1 (GLP-1) to reduce acute ischaemic damage in the brain. Here, we examined the neuroprotective effects of two GLP-1 analogues, liraglutide and semaglutide.. A non-diabetic rat model of acute ischaemic stroke involved 90, 120 or 180 min of middle cerebral artery occlusion (MCAO). Liraglutide or semaglutide was administered either i.v. at the onset of reperfusion or s.c. 5 min before the onset of reperfusion. Infarct size and functional status were evaluated after 24 h or 72 h of reperfusion.. Liraglutide, administered as a bolus at the onset of reperfusion, reduced infarct size by up to 90% and improved neuroscore at 24 h in a dose-dependent manner, following 90-min, but not 120-min or 180-min ischaemia. Semaglutide and liraglutide administered s.c. reduced infarct size by 63% and 48%, respectively, and improved neuroscore at 72 h following 90-min MCAO. Neuroprotection by semaglutide was abolished by GLP1-R antagonist exendin(9-39).. Infarct-limiting and functional neuroprotective effects of liraglutide are dose-dependent. Neuroprotection by semaglutide is at least as strong as by liraglutide and is mediated by GLP-1Rs.

Topics: Animals; Brain; Disease Models, Animal; Dose-Response Relationship, Drug; Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptides; Incretins; Infarction, Middle Cerebral Artery; Liraglutide; Male; Neuroprotective Agents; Rats, Sprague-Dawley; Reperfusion; Reperfusion Injury; Time Factors

Parkinson's disease (PD) is a progressive neurological motor control disorder. A key feature is the loss of midbrain dopaminergic neurons and the accumulation of aggregated alpha-synuclein (α-syn). No current treatment is on the market that slows or halts disease progression. Previous studies have shown that glucagon-like peptide-1 (GLP-1) receptor agonists have neuroprotective effects in animal models of PD. In addition, in a phase II clinical trial, the GLP-1 receptor agonist exendin-4 has shown good protective effects in PD patients. In the present study, we have investigated the neuroprotective effects of the GLP-1 analogues semaglutide (25 nmol/kg ip. once every two days for 30 days) and liraglutide (25 nmol/kg ip. once daily for 30 days) in the chronic MPTP mouse model of PD. Both drugs are currently on the market as a treatment for Type II diabetes. Our results show that both semaglutide and liraglutide improved MPTP-induced motor impairments. In addition, both drugs rescued the decrease of tyrosine hydroxylase (TH) levels, reduced the accumulation of α-syn, alleviated the chronic inflammation response in the brain, reduced lipid peroxidation, and inhibited the mitochondrial mitophagy signaling pathway, and furthermore increased expression of the key growth factor GDNF that protects dopaminergic neurons in the substantia nigra (SN) and striatum. Moreover, the long- acting GLP-1 analogue semaglutide was more potent compared with once daily liraglutide in most parameters measured in this study. Our results demonstrate that semaglutide may be a promising treatment for PD. A clinical trial testing semaglutide in PD patients will start shortly.

Topics: alpha-Synuclein; Animals; Disease Models, Animal; Glucagon-Like Peptides; Hypoglycemic Agents; Liraglutide; Mice; MPTP Poisoning; Neuroprotective Agents; Oxidative Stress

Flap necrosis in the distal area due to the deficiency of blood circulation is a major complication in flap treatment. In many previous studies, some natural substances such as chlorogenic acid, adrenomedullin (ADM), and glucagon-like peptide-1 (GLP-1) have been used to improve flap viability via their vasodilator, angiogenic, and antioxidant effects. The aim of this study is to clarify the mechanism through the use of selective antagonists for calcitonin gene-related peptide (CGRP) receptors and GLP-1 receptors such as CGRP-(8-37), exendin-(9-39), respectively, in the flap healing effects of ADM and GLP-1. The role of nitric oxide (NO) was investigated in the mechanism as well.. Seventy adult female Wistar rats (200 g-250 g) were used in the study. The cutaneous skin flap (8 cm x 3 cm) on the abdominal wall was raised based on the superficial inferior epigastric artery (SIEA). Single-dose substance injections were administered into the SIEA. Necrosis in the flap area was evaluated on postoperative day 7. The proportion of the necrosis area (necrosis area % = [necrosis area/flap area] x 100) and vascularity (vascular number/cm2) in the distal area were calculated.. The administrations of ADM or GLP-1 increased the vascularity and decreased the necrosis area in the distal flap region. The ADM receptor antagonist, CGRP-(8-37), did not prevent the positive effects of ADM on flap healing and vascularity. A GLP-1 receptor antagonist, exendin-(9-39), prevented the effect of GLP-1 on flap healing and vascularity. Nitric oxide mediated the beneficial effects of both peptides on flap healing.. The CGRP receptors have no direct role, but NO acts as a mediator in the beneficial effect of ADM on flap healing. The GLP-1 specific receptors and NO act as important interagents for the effects of GLP-1 on flap healing.

Topics: Adrenomedullin; Animals; Antioxidants; Calcitonin Gene-Related Peptide; Disease Models, Animal; Epigastric Arteries; Female; Glucagon-Like Peptide Receptors; Glucagon-Like Peptides; Graft Survival; Immunohistochemistry; Necrosis; Nitric Oxide; Rats; Rats, Wistar; Receptors, Calcitonin Gene-Related Peptide; Surgical Flaps; Wound Healing; Wounds and Injuries

Total parenteral nutrition (TPN) is essential for patients with impaired gut function but leads to parenteral nutrition-associated liver disease (PNALD). TPN disrupts the normal enterohepatic circulation of bile acids, and we hypothesized that it would decrease intestinal expression of the newly described metabolic hormone fibroblast growth factor-19 (FGF19) and also glucagon-like peptides-1 and -2 (GLP-1 and GLP-2). We tested the effects of restoring bile acids by treating a neonatal piglet PNALD model with chenodeoxycholic acid (CDCA). Neonatal pigs received enteral feeding (EN), TPN, or TPN + CDCA for 14 days, and responses were assessed by serum markers, histology, and levels of key regulatory peptides. Cholestasis and steatosis were demonstrated in the TPN group relative to EN controls by elevated levels of serum total and direct bilirubin and also bile acids and liver triglyceride (TG) content. CDCA treatment improved direct bilirubin levels by almost fourfold compared with the TPN group and also normalized serum bile acids and liver TG. FGF19, GLP-1, and GLP-2 were decreased in plasma of the TPN group compared with the EN group but were all induced by CDCA treatment. Intestinal mucosal growth marked by weight and villus/crypt ratio was significantly reduced in the TPN group compared with the EN group, and CDCA treatment increased both parameters. These results suggest that decreased circulating FGF19 during TPN may contribute to PNALD. Moreover, we show that enteral CDCA not only resolves PNALD but acts as a potent intestinal trophic agent and secretagogue for GLP-2.

Topics: Animals; Animals, Newborn; Atrophy; Chenodeoxycholic Acid; Cholestasis; Disease Models, Animal; Fibroblast Growth Factors; Glucagon-Like Peptides; Intestinal Mucosa; Liver Diseases; Parenteral Nutrition, Total; Swine; Treatment Outcome

Glucose in the gut lumen activates gut endocrine cells to release 5-HT, glucagon-like peptide 1/2 (GLP-1/2), and glucose-dependent insulinotropic polypeptide (GIP), which act to change gastrointestinal function and regulate postprandial plasma glucose. There is evidence that both release and action of incretin hormones is reduced in type 2 diabetes (T2D). We measured cellular activation of enteroendocrine and enterochromaffin cells, enteric neurons, and vagal afferent neurons in response to intestinal glucose in a model of type 2 diabetes mellitus, the UCD-T2DM rat. Prediabetic (PD), recent-diabetic (RD, 2 wk postonset), and 3-mo diabetic (3MD) fasted UCD-T2DM rats were given an orogastric gavage of vehicle (water, 0.5 ml /100 g body wt) or glucose (330 μmol/100 g body wt); after 6 min tissue was removed and cellular activation was determined by immunohistochemistry for phosphorylated calcium calmodulin-dependent kinase II (pCaMKII). In PD rats, pCaMKII immunoreactivity was increased in duodenal 5-HT (P < 0.001), K (P < 0.01) and L (P < 0.01) cells in response to glucose; glucose-induced activation of all three cell types was significantly reduced in RD and 3MD compared with PD rats. Immunoreactivity for GLP-1, but not GIP, was significantly reduced in RD and 3MD compared with PD rats (P < 0.01). Administration of glucose significantly increased pCaMKII in enteric and vagal afferent neurons in PD rats; glucose-induced pCaMKII immunoreactivity was attenuated in enteric and vagal afferent neurons (P < 0.01, P < 0.001, respectively) in RD and 3MD. These data suggest that glucose sensing in enteroendocrine and enterochromaffin cells and activation of neural pathways is markedly impaired in UCD-T2DM rats.

Topics: Afferent Pathways; Animals; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Diabetes Mellitus, Type 2; Disease Models, Animal; Enterochromaffin Cells; Enteroendocrine Cells; Gastric Inhibitory Polypeptide; Glucagon-Like Peptides; Glucose; Insulin Resistance; Obesity; Rats; Rats, Sprague-Dawley; Rats, Zucker; Serotonin; Vagus Nerve

In chickens, retinal glucagon amacrine cells play an important role in emmetropization, since they express the transcription factor ZENK (also known as NGFI-A, zif268, tis8, cef5, Krox24) in correlation with the sign of imposed image defocus. Pharmacological studies have shown that glucagon can act as a stop signal for axial eye growth, making it a promising target for pharmacological intervention of myopia. Unfortunately, in mammalian retina, glucagon itself has not yet been detected by immunohistochemical staining. To learn more about its possible role in emmetropization in mammals, we studied the expression of different members of the glucagon hormone family in mouse retina, and whether their abundance is regulated by visual experience.. Black wildtype C57BL/6 mice, raised under a 12/12 h light/dark cycle, were studied at postnatal ages between P29 and P40. Frosted hemispherical thin plastic shells (diffusers) were placed in front of the right eyes to impose visual conditions that are known to induce myopia. The left eyes remained uncovered and served as controls. Transversal retinal cryostat sections were single- or double-labeled by indirect immunofluorescence for early growth response protein 1 (Egr-1, the mammalian ortholog of ZENK), glucagon, glucagon-like peptide-2 (GLP-2), glucose-dependent insulinotropic polypeptide (GIP), peptide histidine isoleucine (PHI), growth hormone-releasing hormone (GHRH), pituitary adenylate cyclase-activating polypeptide (PACAP), secretin, and vasoactive intestinal polypeptide (VIP). In total, retinas of 45 mice were studied, 28 treated with diffusers, and 17 serving as controls.. Glucagon itself was not detected in mouse retina. VIP, PHI, PACAP and GIP were localized. VIP was co-localized with PHI and Egr-1, which itself was strongly regulated by retinal illumination. Diffusers, applied for various durations (1, 2, 6, and 24 h) had no effect on the expression of VIP, PHI, PACAP, and GIP, at least at the protein level. Similarly, even if the analysis was confined to cells that also expressed Egr-1, no difference was found between VIP expression in eyes with diffusers and in eyes with normal vision.. Several members of the glucagon super family are expressed in mouse retina (although not glucagon itself), but their expression pattern does not seem to be regulated by visual experience.

Topics: Animals; Disease Models, Animal; Early Growth Response Protein 1; Fluorescent Antibody Technique, Indirect; Gastric Inhibitory Polypeptide; Glucagon; Glucagon-Like Peptides; Growth Hormone-Releasing Hormone; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Myopia; Peptide PHI; Pituitary Adenylate Cyclase-Activating Polypeptide; Retina; Sensory Deprivation; Vasoactive Intestinal Peptide

Parenteral nutrition is a critically important intervention for children with intestinal dysfunctions. However, total parenteral nutrition (TPN) with no enteral feeding is associated with small intestine atrophy and malabsorption, which complicate the transition to enteral nutrition. The objective of the present study was to evaluate the therapeutic potential of the intestinotrophic peptide glucagon-like peptide 2 (GLP-2), which reduces TPN-associated atrophy and maintains nutrient absorption in adult rats, for preventing nutrient malabsorption in neonates receiving TPN.. Term pigs obtained by cesarean delivery received from birth TPN alone (TPN; n = 7) or TPN with GLP-2 (25 nmol . kg(-1) . d(-1); GLP-2; n = 8) or were fed sow milk enterally (n = 7). The small intestine was removed on postnatal day 6 to measure morphological responses and absorption of glucose, leucine, lysine and proline by intact tissues and brush border membrane vesicles and to quantify the abundances of mRNA and protein for enterocyte glucose transporters (SGLT-1 and GLUT2).. Relative to TPN alone, administration of GLP-2 resulted in small intestines that were larger (P < 0.01), had greater abundances of mRNA and protein for SGLT-1, but not for GLUT2, and had higher capacities to absorb nutrients (P < 0.01). Moreover, the intestines of GLP-2 pigs were comparable in size and absorptive capacities with those of pigs fed sow milk enterally.. Providing GLP-2 to neonates receiving TPN prevents small intestine atrophy, results in small intestine absorptive capacities that are comparable to when nutrients are provided enterally and may accelerate the transition from TPN to enteral nutrition.

Topics: Animals; Animals, Newborn; Disease Models, Animal; DNA; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Intestinal Absorption; Intestine, Small; Malabsorption Syndromes; Parenteral Nutrition, Total; Random Allocation; Sodium-Glucose Transporter 1; Swine; Tissue Distribution

Glucagon-like peptide-2 (GLP-2) is an intestinal hormone that acts through unknown pathways to induce intestinal growth. We investigated the role of the insulin-like growth factors (IGF-1 and IGF-2) as mediators of GLP-2-enhanced growth in the murine intestine.. IGF-1 expression and secretion were determined in GLP-2-responsive primary intestinal cultures treated with GLP-2. Parameters of intestinal growth were assessed in wild-type (CD1, Igf1(+/+) and Igf2+), heterozygous (Igf1(+/-)), and null (Igf1(-/-) and Igf2(-P)) mice treated chronically with saline, GLP-2, IGF-1, or R-Spondin1.. GLP-2 increased IGF-1 messenger RNA expression and IGF-1 secretion in intestinal cultures and increased expression of IGF-1 messenger RNA in mouse small intestine in vivo. Igf1(+/+) and Igf2+ mice responded to .1 microg/g(-1) per day(-1) GLP-2 with increased intestinal weights, morphometric parameters, and proliferative indices. In contrast, Igf1(-/-) mice were unresponsive to the same dose of GLP-2, failing to demonstrate changes in intestinal weight, morphometry, or proliferation. However, a significant effect of 1 microg/g(-1) per day(-1) GLP-2 was observed in Igf1(-/-) mice, but only in terms of small intestinal weight when normalized for body weight. Furthermore, Igf2(-P) mice demonstrated a partially impaired response in terms of small intestinal growth. Both Igf1(-/-) and Igf2(-P) mice exhibited normal-enhanced intestinal growth in response to IGF-1 and/or R-Spondin1.. GLP-2 enhances intestinal IGF-1 expression and secretion, and IGF-1 is required for small and large intestinal growth in response to GLP-2. These findings identify IGF-1 as an essential mediator of the intestinotropic actions of GLP-2.

Topics: Animals; Blotting, Western; Cell Proliferation; Disease Models, Animal; Female; Gene Expression Regulation; Glucagon-Like Peptide 1; Glucagon-Like Peptide 2; Glucagon-Like Peptide-2 Receptor; Glucagon-Like Peptides; Immunohistochemistry; In Vitro Techniques; Insulin-Like Growth Factor I; Intestine, Small; Male; Mice; Mice, Knockout; Receptors, Glucagon; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

Glucagon-like peptide-2 (GLP-2) is an enteroendocrine hormone which is uniquely trophic for the intestine; a physiological role in regulating nutrient absorptive capacity is becoming apparent. GLP-2, independent of enteral feeding, stimulates a classical pattern of intestinal adaptation in terminal ileum following resection. Herein we investigate the effects of GLP-2 on the jejunal remant using a rat model of short bowel syndrome (SBS). Juvenile 250- to 275-g SD rats underwent 80% distal small bowel resection, leaving 20 cm of proximal jejunum and venous catheterization. Animals were maintained with total parenteral nutrition (TPN) or TPN+10 microg/kg/hr GLP-2 (n=8 per group). After 7 days, intestinal permeability was assessed by urinary recovery of gavaged carbohydrate probes. Animals were euthanized, and the intestines taken for analysis of morphology, crypt cell proliferation, apoptosis, and expression of SGLT-1 and GLUT-5 transport proteins. GLP-2 treatment reduced intestinal permeability and increased in vivo glucose absorption, small intestinal weight, surface area, villus height, crypt depth, and microvillus height. Intestinal mucosal DNA and protein content per unit length of the small bowel were increased (P < 0.05 for all comparisons). However, in contrast to previous studies examining GLP-2's effects on remnant ileum, the jejunal crypt apoptotic index was increased in GLP-2-treated animals, with no increase in SGLT-1 or GLUT 5 expression. These results show that exogenous GLP-2 treatment of animals with jejunal remnant reduces intestinal permeability, increases glucose absorption, and stimulates morphological features of intestinal adaptation including increased micovillus height and surface area. However, the pattern of changes seen is different from that in remnant ileum. This suggests that GLP-2's effects are specific to different regions of the bowel. Nonetheless, remnant jejunum is responsive to GLP-2 in the absence of enteral nutrition. Further studies are warranted to establish the mechanisms of action and therapeutic potential of GLP-2 in modulating nutrient absorptive capacity.

Topics: Adaptation, Physiological; Animals; Apoptosis; Caspase 3; Caspases; Cell Proliferation; Disease Models, Animal; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Glucose Transporter Type 5; Ileum; Intestinal Absorption; Intestinal Mucosa; Jejunum; Male; Rats; Rats, Sprague-Dawley; Short Bowel Syndrome

Glucagon-like peptide 2 (GLP-2) is an intestinal epithelium-specific growth factor. However, its protective effects and related mechanism on the small intestine injured by ischemia-reperfusion (I/R) in mice remain unclear. This study aimed to reveal the effects of GLP-2 and its functional relationship with uncoupling protein 2 (UCP2) on the small intestine after I/R injury in mice. Male Balb/c mice were given GLP-2 (250 microg/kg/day, ip) for 3 days and underwent 30 min of superior mesenteric artery occlusion followed by 1 hr of reperfusion on day 4. Histological damage, bacterial translocation, diamine oxidase, and malondialdehyde level were assessed, and UCP2 expression was measured by immunohistochemistry and Western blot. GLP-2 attenuated the intestinal histological damage caused by I/R and increased the villous height by 28% and the crypt depth by 10%, respectively. Compared to the I/R group, diamine oxidase activity was increased, the incidence of bacterial translocation and malondialdehyde level were decreased, and UCP2 expression was increased in GLP-2-treated mice. GLP-2 protected the small intestine from I/R injury and increased UCP2 expression. These results suggested that effects of GLP-2 should be related to the upregulation of mitochondrial UCP2, which antagonized reactive oxygen species production.

Topics: Animals; Biopsy, Needle; Blotting, Western; Disease Models, Animal; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Immunohistochemistry; Injections, Intraperitoneal; Intestinal Mucosa; Intestine, Small; Male; Mice; Mice, Inbred BALB C; Peptides; Probability; Random Allocation; Reference Values; Reperfusion Injury; Sensitivity and Specificity

Glucagonlike peptide-2alpha (GLP-2alpha) has been shown to be a growth factor for the small intestine. This study investigated the benefits of intravenous and intraluminal administration of GLP-2alpha using a rat model of inflammatory bowel disease (IBD).. Normal Fisher rats and HLA-B27 (IBD) rats were treated for 14 days as follows: Fisher, intravenous saline (n = 6); HLA-B27, intravenous saline (n = 6); HLA-B27, intravenous GLP-2alpha (50 microg/kg/d; n = 5); Fisher, intraluminal saline (n = 5); HLA-B27, intraluminal saline (n = 5); or intraluminal GLP-2alpha (50 microg/kg/d; n = 5). Rats were evaluated for frequency of diarrhea, and the bowel was analyzed for gross and microscopic lesions. Statistical evaluations were determined using analysis of variance (ANOVA). A P value of.05 was significant.. Intravenous GLP-2alpha decreased diarrhea and the number of bowel lesions (P <.05). Microscopic inflammation was reduced by 24% but was not statistically significant. Intraluminal GLP-2alpha decreased the number of small intestine lesions (P <.05) and the microscopic inflammation (P <.05) but did not significantly reduce diarrhea or the overall number of bowel lesions.. GLP-2alpha ameliorates the signs of IBD in HLA-B27 rats. Intravenous GLP-2alpha reduces diarrhea more effectively than intraluminal administration, and both routes are equally effective in ameliorating inflammation. GLP-2alpha potentially provides a new modality for the treatment of IBD.

Topics: Analysis of Variance; Animals; Anti-Inflammatory Agents; Defecation; Diarrhea; Disease Models, Animal; Female; Glucagon-Like Peptides; HLA-B27 Antigen; Ileum; Inflammatory Bowel Diseases; Injections, Intravenous; Intestinal Mucosa; Peptides; Rats; Rats, Inbred F344; Rats, Mutant Strains

A strategy protecting the small intestine against deleterious side effects associated with anti-cancer therapy is arresting epithelial cell cycling temporally. Since endogenous glucagon-like peptide-2 (GLP-2) is a trophic factor specific for intestinal epithelia, the possibility of inhibiting GLP-2-mediated cell proliferation by lactoferrin, thereby protecting the small intestine against deleterious side effects of anticancer therapy, was investigated. In Caco-2 cells, GLP-2-mediated proliferation was reduced in a dose-dependent manner using lactoferrin. Furthermore, in a rat model for methotrexate-induced mucositis, lactoferrin reduced BrdU incorporation in small intestinal epithelial cells, indicating inhibition of epithelial cell proliferation in vivo. Subsequently, protection against methotrexate-induced intestinal damage was found in corresponding regions. These results show, for the first time, that lactoferrin interferes with GLP-2-induced intestinal epithelial proliferation. It may therefore be hypothesized that lactoferrin protects the intestine against anticancer therapy-induced intestinal damage, via inhibition of GLP-2-induced small intestinal epithelial cell proliferation.

Topics: Animals; Antimetabolites, Antineoplastic; Bromodeoxyuridine; Caco-2 Cells; Cell Division; Cells, Cultured; Cytoprotection; Disease Models, Animal; Dose-Response Relationship, Drug; Epithelial Cells; Female; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Humans; Intestinal Mucosa; Lactoferrin; Methotrexate; Peptides; Polymerase Chain Reaction; Rats; Rats, Inbred Strains

Adaptation of the residual small bowel following resection is dependent on luminal and humoral factors. We aimed to establish if circulating levels of glucagon-like peptide (GLP-2) change under different dietary regimens following resection and to determine if there is a relationship between plasma GLP-2 levels and markers of intestinal adaptation. Four-week-old piglets underwent a 75% proximal small bowel resection (n = 31) or transection (n = 14). Postoperatively they received either pig chow (n = 14), nonpolymeric (elemental) infant formula (n = 7), or polymeric infant formula alone (n = 8) or supplemented either with fiber (n = 6) or with bovine colostrum protein concentrate (CPC; n = 10) for 8 weeks until sacrifice. Plasma GLP-2 levels were measured at weeks 0, 2, 4, and 8 postoperatively. In addition, end-stage parameters were studied at week 8 including weight gain, ileal villus height, crypt depth, and disaccharidase levels. Plasma GLP-2 levels were higher in resected animals compared to transected animals fed the same diet. Plasma GLP-2 levels were significantly increased in the colostrum protein isolate-supplemented animals following resection compared to all other diet groups. The increase in plasma GLP-2 (pM) was greatest in the first 2 weeks postresection (week 0, 15.5; week 2, 30.9), followed by a plateau at weeks 2 to 4 and a decrease in GLP-2 levels from week 4 to week 8. At week 8, no relationships were found between the plasma GLP-2 levels and the measurements of weight gain, villus height, lactase, sucrase, maltase, crypt depth, or villus/crypt ratio. Plasma GLP-2 levels increase in the first weeks following massive small intestinal resection. The increase in plasma GLP-2 levels was enhanced by supplementation of the diet with CPC. The changes in GLP-2 levels observed in this study may suggest that GLP-2 plays a role in the adaptive response in the intestine following resection in this preclinical model.

Topics: Adaptation, Physiological; Animals; Diet; Dietary Supplements; Disease Models, Animal; Energy Intake; Female; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Intestine, Small; Peptides; Postoperative Period; Short Bowel Syndrome; Swine

Penetration of the gut epithelial barrier by intact luminal antigen is necessary for immunologically mediated pathophysiology in the context of food allergy. We investigated if glucagon-like peptide-2 (GLP-2) could affect immediate hypersensitivity and late-phase allergic inflammation in a murine model. Mice were sensitized to horseradish peroxidase (HRP); studies were conducted 14 days later. Mice were treated with 5 microg GLP-2 subcutaneously 4 h before antigen challenge. For immediate hypersensitivity, jejunal segments in Ussing chambers were challenged by luminal HRP antigen. GLP-2 treatment reduced the uptake of HRP and the antigen-induced secretory response after luminal challenge. GLP-2 appears to reduce macromolecular uptake independent of the CD23-mediated enhanced antigen uptake pathway. For the late phase, mice were gavaged with antigen, and 48 h later the function and histology of the jejunum were examined. GLP-2 prevented the usual prolonged permeability defect and reduced the number of inflammatory cells in the mucosa. Our studies demonstrate that a single treatment of sensitized mice with GLP diminishes both immediate and late-phase hypersensitivity reactions characteristic of food allergy by inhibiting transepithelial uptake of antigen.

Topics: Animals; Cell Membrane Permeability; Disease Models, Animal; Endosomes; Food Hypersensitivity; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Horseradish Peroxidase; Humans; In Vitro Techniques; Jejunum; Male; Mice; Mice, Inbred BALB C; Peptides

The intestinal hormone glucagon-like peptide-2 (GLP-2) enhances bowel growth and reduces the severity of colonic injury in dextran sulfate sodium (DSS)-induced colitis in mice. In humans, ulcerative colitis is normally treated with aminosalicylates (ASAs) and corticosteroids (CSs) to reduce inflammation. However, whether the intestinotropic effects of GLP-2 are altered when combined with ASAs and/or CSs has not previously been explored. Thus, each agent [vehicle, ASA (sulfasalazine), CS (methylprednisolone), and ASA + CS] was administered alone or with GLP-2 to normal mice or mice with 3.5% DSS in the drinking water, for 10 consecutive days. GLP-2 treatment of DSS-mice increased survival and small intestinal weight (p < 0.05), and decreased body weight loss and colonic damage (p < 0.05). Furthermore, GLP-2 increased the number of proliferating cells in the colonic crypts of DSS-mice (p < 0.05). Administration of ASA, CS, or ASA + CS alone did not affect growth of the intestine in DSS-mice. However, administration of GLP-2 in combination with ASA was permissive for the beneficial effects of GLP-2 on survival and colonic damage, whereas CS treatment prevented these effects of GLP-2. Concomitant administration of GLP-2 with ASA + CS resulted in intermediate effects. No differences between colonic myeloperoxidase activity or IkappaB levels (an inhibitor of the nuclear factor-kappaB pro-inflammatory pathway) were found for any of these therapeutic agents. When taken together, the ability of GLP-2 to protect colonic mucosal architecture in DSS-colitis, and its effectiveness when given in combination with ASA, but not with CS, suggests a novel approach for the treatment of patients with colitis.

Topics: Adrenal Cortex Hormones; Aminosalicylic Acids; Animals; Colitis, Ulcerative; Colon; Disease Models, Animal; Drug Therapy, Combination; Female; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Humans; Intestine, Small; Mice; Peptide Fragments; Peptides

Gastrointestinal transit was measured in non-obese diabetic (NOD) mice, as an animal model of human diabetes type 1, and in obese diabetic mice, as an animal model of human diabetes type 2. The endocrine cells known to correlate to gastrointestinal transit, namely secretin, serotonin, Peptide YY (PYY) and enteroglucagon cells, were identified by immunocytochemistry and quantified by computer image analysis in different segments of the gut. Gastrointestinal transit was significantly accelerated in NOD mice and slower in obese diabetic mice than in controls. The density of duodenal secretin and serotonin as well as colonic PYY and enteroglucagon cells in NOD mice was significantly higher than that of control mice. On the other hand, the density of duodenal secretin and serotonin cells was significantly lower in obese diabetic mice than in controls. It was concluded that changes in duodenal secretin and colonic serotonin, PYY and enteroglucagon cells may play a role in accelerated gastrointestinal transit in NOD mice and delayed gastrointestinal transit in obese diabetic mice.

Topics: Animals; Diabetes Mellitus, Type 2; Disease Models, Animal; Enteroendocrine Cells; Gastrointestinal Transit; Glucagon-Like Peptides; Humans; Image Processing, Computer-Assisted; Mice; Mice, Inbred BALB C; Mice, Obese; Peptide YY; Secretin; Serotonin

Glucagon-like peptide-1(7-36)amide (tGLP-1) is an important insulin-releasing hormone of the enteroinsular axis which is secreted by endocrine L-cells of the small intestine following nutrient ingestion. The present study has evaluated tGLP-1 in the intestines of normal and diabetic animal models and estimated the proportion present in glycated form. Total immunoreactive tGLP-1 levels in the intestines of hyperglycaemic hydrocortisone-treated rats, streptozotocin-treated mice and ob/ob mice were similar to age-matched controls. Affinity chromatographic separation of glycated and non-glycated proteins in intestinal extracts followed by radioimmunoassay using a fully cross-reacting anti-serum demonstrated the presence of glycated tGLP-1 within the intestinal extracts of all control animals (approximately 19% of total tGLP-1 content). Chemically induced and spontaneous animal models of diabetes were found to possess significantly greater levels of glycated tGLP-1 than controls, corresponding to between 24--71% of the total content. These observations suggest that glycated tGLP-1 may be of physiological significance given that such N-terminal modification confers resistance to DPP IV inactivation and degradation, extending the very short half-life (<3 min) and bioactivity of the native peptide.

Topics: Animals; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Disease Models, Animal; Glucagon; Glucagon-Like Peptide 1; Glucagon-Like Peptides; Glycosylation; Hydrocortisone; Intestine, Small; Mice; Mice, Obese; Organ Size; Peptide Fragments; Rats

The authors' previous laboratory results have shown that rats treated for 3 days with intravenous GLP-2alpha, a synthetic protease-resistant form of glucagonlike peptide-2, showed increased mucosal mass and absorptive function when compared with saline-treated controls after intestinal ischemia/reperfusion (I/R). This study was designed to explore the temporal relationship between injury that occurs secondary to intestinal I/R and recovery of mucosal absorptive function with and without GLP-2alpha treatment.. Each of 18 male Sprague-Dawley rats (300 to 333 g) was subjected to superior mesenteric artery occlusion for 30 minutes, during which time a jugular venous catheter was placed and connected to a subcutaneous infusion pump. Rats were divided into 4 groups based on the type and duration of infusion as follows: group 1, systemic saline at 1 microL/h for 24 hours (n = 5); group 2, systemic GLP-2alpha at 100 microg/kg/d for 24 hours (n = 5); group 3, systemic saline at 1 microL/h for 72 hours (n = 4); and group 4, systemic GLP-2alpha at 100 microg/kg/d for 72 hours (n = 4). Immediately after the infusions, (14)C-galactose and (14)C-glycine absorption was measured using an in vivo, closed-recirculation technique and expressed as micromoles per square centimeter intestine +/- SEM. Statistical analysis was performed using analysis of variance.. Twenty-four hours after intestinal I/R injury, there was a decrease in substrate absorption but no significant difference between the saline and GLP-2alpha-treated groups (galactose absorption, 1.13 +/- 0.09 in group 1 v 1.35 +/- 0.11 in group 2, P =.15; glycine absorption, 1.18 +/- 0.13 in group 1 v 1.34 +/- 0.15 in group 2, P =.36). However, after the 72-hour infusion, absorption of galactose and glycine was significantly increased in the rats receiving GLP-2alpha as compared with the saline-infused control group (galactose absorption, 1.24 +/- 0.13 in group 3 v 1.88 +/- 0.10 in group 4, P <.01; glycine absorption, 1.64 +/- 0.07 in group 3 v 2.05 +/- 0.08 in group 4, P <.05). Compared with previously determined levels of absorption in normal, uninjured rat intestine (1.50 +/- 0.12 micromol/cm(2) for galactose and 1.85 +/- 0.17 micromol/cm(2) for glycine), after I/R a 72-hour infusion of GLP-2alpha increased galactose absorption 26% (P <.05) and glycine absorption 11% (P =.29) beyond baseline.. When initiated at the time of intestinal I/R, a continuous infusion of GLP-2alpha accelerated recovery of mucosal absorptive function in rats. Remarkably, carbohydrate absorption at 72 hours was increased to a level significantly greater than that in normal, uninjured rat intestine. J Pediatr Surg 36:570-572.

Topics: Analysis of Variance; Animals; Disease Models, Animal; Galactose; Glucagon-Like Peptides; Glycine; Infusions, Intravenous; Intestinal Absorption; Intestinal Mucosa; Ischemia; Male; Peptides; Probability; Rats; Rats, Sprague-Dawley; Reference Values; Reperfusion; Treatment Outcome

Glucagonlike peptide 2 (GLP-2) is trophic for the small bowel; it is produced by L cells in the distal intestine in response to luminal nutrients. This study tests the hypothesis that distal small bowel and cecal resection would decrease GLP-2 levels and reduce adaptation.. Male Sprague-Dawley rats (200 to 300 g) underwent either ileal transection (controls) or resection of the ileum and cecum, leaving 10 or 20 cm jejunal remnant anastomosed to the ascending colon. Animals were followed up for up to 21 days. Endpoints were daily weights, intestinal histology, in vivo absorption of 3-0 methylglucose (a measurement of active nutrient absorptive capacity), and serum GLP-2 levels.. The control group had a maximum 6% weight loss around day 2, and then recovered with a steady weight gain. The 10-cm jejunal remnant group lost weight continuously and never recovered postsurgery. The 20-cm jejunal remnant group of animals had a maximum of 12% weight loss by day 4 and then slowly gained weight. The average villus height increased significantly (P <.01) in the 10-cm and 20-cm jejunal remnant groups compared with controls. Absorption of 3-0 methylglucose was significantly decreased (P <.01) in both resected groups. Serum GLP-2 levels were increased significantly (P <.05) when compared with controls in both resection groups.. Increased serum GLP-2 levels were found in the ileocecal resection rat model, and these levels correlated with morphologic adaptation. However, this morphologic adaptation was not sufficient to restore nutrient absorption as shown by weight changes and 3-0 methylglucose absorption. Thus, the original hypothesis of this study is incorrect: systemic GLP-2 levels do not limit adaptation following distal ileocecal resection.

Topics: 3-O-Methylglucose; Adaptation, Physiological; Animals; Body Weight; Cecum; Disease Models, Animal; Enteroendocrine Cells; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Ileum; Intestinal Absorption; Jejunum; Male; Peptides; Rats; Rats, Sprague-Dawley; Short Bowel Syndrome

Glucagon-like peptide 2 (GLP-2) is produced in endocrine L-cells of the intestinal mucosa. Recently, GLP-2 was found to stimulate intestinal mucosal growth. Our objective was to study the content of GLP-2 in the large intestine in a murine model of T-cell-induced inflammatory bowel disease.. Inflammation was induced by adoptive transfer of CD4+ blast T cells from BALB/c mice to SCID mice. The amount of GLP-2 (1-33) was measured with a specific, NH2-terminally directed radioimmunoassay in tissue extracts from the large intestine of transplanted mice developing colitis and from BALB/c and SCID control mice.. In the middle and descending colon segments showing the most severe signs of inflammatory lesions in the CD4+ T-cell-transplanted mice, the amount of GLP-2 was significantly lower than in similar colon segments in both untransplanted SCID mice and normal BALB/c mice (P = 0.0013 and 0.0033). In the descending colon the amount of GLP-2 was 6.7 +/- 1.0 pmol/g protein in the CD4+ transplanted mice compared with 68.4 +/- 20.3 and 42.7 +/- 4.3 in the two groups of control mice. Similar findings were made with regard to the contents of the two other proglucagon-derived intestinal peptides, glicentin and GLP-1.. The amount of GLP-2 is markedly reduced in the colon of mice with a T-cell-induced inflammatory bowel disease histopathologically resembling both Crohn disease and ulcerative colitis. This observation may provide a pathophysiologic rationale for administration of GLP-2 as a trophic factor in inflammatory bowel disease.

Topics: Animals; CD4-Positive T-Lymphocytes; Colon; Disease Models, Animal; Glucagon; Glucagon-Like Peptide 2; Glucagon-Like Peptides; Growth Substances; Inflammatory Bowel Diseases; Mice; Mice, SCID; Peptide Fragments

This study was designed to explore the efficacy of a synthetic analogue of glucagonlike peptide-2 (GLP-2a) in enhancing mucosal mass and absorptive function in a rat model of intestinal ischemia-reperfusion (I-R) injury.. Each of 20 Sprague-Dawley rats underwent placement of a jugular venous catheter connected to a subcutaneous osmotic pump designed to deliver its contents over 3 days. Rats were divided into 4 groups (n = 5 per group): (1) normal intestine/saline infusion; (2) 30-minute superior mesenteric artery occlusion/saline infusion, (3) normal intestine/ GLP-2alpha infusion, and (4) 30-minute superior mesenteric artery occlusion/GLP-2alpha infusion. Subsequently, mean mucosal 14C-galactose and 14C-glycine absorption and DNA content were determined for each group.. In saline-treated rats, 30 minutes of mesenteric ischemia decreased mean mucosal galactose absorption by 29% (P < .05), glycine absorption by 22% (P = .12), and DNA content by 28% (P < .01) when compared with rats with uninjured intestine. In rats subjected to 30 minutes of intestinal ischemia, GLP-2alpha significantly improved galactose absorption by 46% (P < .05), glycine absorption by 84% (P < .01), and DNA content by 63% (P < .01) when compared with saline-treated control rats. In rats with mesenteric I-R injury treated with GLP-2a, galactose absorption was returned to normal. Glycine absorption and DNA content were increased significantly by 44% (P < .01) and 18% (P < .05), respectively, beyond the baseline for normal intestine.. Thirty minutes of intestinal ischemia followed by immediate reperfusion significantly decreased mucosal mass and absorptive function, validating this rat model of I-R injury. After mesenteric I-R, GLP-2a significantly increased mucosal DNA content and absorption of 14C-galactose and 14C-glycine when compared with untreated control rats. After I-R injury, GLP-2a restored mucosal mass and absorptive function to normal or above-normal levels.

Topics: Animals; Disease Models, Animal; DNA; Galactose; Glucagon-Like Peptides; Glycine; Infusions, Intravenous; Intestinal Absorption; Intestinal Mucosa; Male; Peptides; Probability; Rats; Rats, Sprague-Dawley; Reference Values; Reperfusion Injury

To elucidate the question of whether production of the insulinotropic gut hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) is altered by a diabetic metabolic state, their intestinal expression pattern was evaluated. Two rodent models for diabetes mellitus were used, non-obese diabetic (NOD) mice as a model for insulin-dependent diabetes and Zucker diabetic fatty (ZDF) rats for non-insulin-dependent diabetes mellitus (NIDDM). Expression of both incretin hormones followed typical patterns, which were similar in both animals and unaltered by the diabetic state. The GIP gene was greatly expressed in the duodenum, jejunum, and ileum, with a continuous decrease from the upper to lower intestines. This pattern was observed in both NOD mice and ZDF rats regardless of the diabetic state. This expression data was corroborated by radioimmunoassay (RIA) analysis of the gene product GIP. Expression of the proglucagon gene encoding GLP-1 had an opposite appearance. The highest expression was seen in the large bowel and the ileum. RIA analysis of the gene product GLP-1 mirrored these data. Although the distribution pattern was similar in both animal models, in contrast to diabetic NOD mice, a regulated expression was found in diabetic ZDF rats. Compared with lean nondiabetic controls, fatty hyperglycemic animals showed an increased expression of the proglucagon gene in the colon and a concomitant reduction in the small intestine. This was mirrored by the GLP-1 content of the colon and ileum. Overall, basal GLP-1 plasma levels were increased in ZDF rats (17.0 +/- 2.8 pmol) compared with lean Zucker rats (12.4 +/- 1.8 pmol). In conclusion, incretin hormone expression (GIP and GLP-1) follows specific patterns throughout the gut and is unaltered by the diabetic state. In ZDF rats, regulation of proglucagon expression occurs mainly in the large intestine.

Topics: Animals; Blotting, Northern; Colon; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Disease Models, Animal; Gastric Inhibitory Polypeptide; Gene Expression; Glucagon; Glucagon-Like Peptide 1; Glucagon-Like Peptides; Intestinal Mucosa; Intestine, Small; Intestines; Mice; Mice, Inbred NOD; Peptide Fragments; Proglucagon; Protein Precursors; Rats; Rats, Zucker; Rectum; RNA, Messenger; Tissue Distribution

To search if biological effects of GLP-I on glucose metabolism in extrapancreatic tissue are present in diabetic states, we have studied the action of GLP-I and insulin on glycogen-enzyme activity, glycogen synthesis, and glucose metabolism in isolated hepatocytes and soleus muscle from adult streptozotocin (STZ)- and neonatal STZ-treated diabetic rats. This work confirms the previously reported insulin-like effects of GLP-I on glucose metabolism in both muscle and liver tissue from normal rats (control). The present study extends those observations to the muscle and liver tissue of diabetic animals. In both muscle and liver tissue, the metabolism of D-glucose, in the absence of added peptides, was more severely affected in adult STZ (IDDM model) than in neonatal STZ (nSTZ; NIDDM model) rats, and the magnitude of hormonal effect on metabolic variables was lower in diabetic rats than in control rats, as a rule. Nevertheless, in liver and muscle tissue of diabetic rats, GLP-I was able to increase glycogen synthase activity, augment the net rate of D-[U-14C]glucose incorporation into glycogen, and increase D-[5-3H]glucose utilization, D-[U-14C]glucose oxidation, and lactate production. In conclusion, GLP-I exerts insulin-like effects on D-glucose metabolism in both muscle and liver tissue in IDDM or NIDDM animal models, and present observations reinforce the view that GLP-I may represent a most promising tool in the treatment of diabetic patients.

Topics: Animals; Animals, Newborn; Carbon Radioisotopes; Cells, Cultured; Cohort Studies; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Disease Models, Animal; Glucagon-Like Peptides; Glucose; Glycogen Synthase; Insulin; Liver; Muscle, Skeletal; Pancreatic Hormones; Peptides; Phosphorylases; Rats; Rats, Wistar