exenatide and Reperfusion-Injury

The purpose of this study was to evaluate whether exenatide administration can prevent impairment in endothelium-dependent vasodilatation induced by ischemia-reperfusion (IR) injury and whether this effect is mediated by K(ATP) channel opening.. In a double-blind, placebo-controlled, crossover design, 20 volunteers were randomly assigned to 2 groups: subcutaneous exenatide (10 μg) or placebo administration. At 30 minutes after the study drug administration, endothelium-dependent flow-mediated dilatation (FMD) of the radial artery was measured before and after IR (15 minutes of ischemia at the level of the brachial artery followed by 15 minutes of reperfusion) injury. Seven days later, both groups were crossed over and received the other treatment (ie, placebo or exenatide) and underwent the same protocol. Pre-IR radial artery diameter, FMD, and baseline radial artery diameter after IR injury were similar between 2 groups (P=no significant difference). After placebo administration, IR significantly blunted FMD (before IR: 12.0±6.23%; after IR: 4.6±3.57%, P=0.02). Exenatide prevented this impairment (FMD before IR: 15.0±7.14%; FMD after IR: 15.0±5.96%, P=no significant difference; P<0.001 compared with placebo). In a separate protocol, this protective effect was completely abolished by pretreatment with glibenclamide (glyburide, 5 mg), a blocker of K(ATP) channels (n=7; FMD before IR: 12.0±2.2%; after IR: 3.2±2.1%, P<0.001).. The present study demonstrates that subcutaneous exenatide protects IR-induced endothelial dysfunction through opening of K(ATP) channels in human IR injury model.

Topics: Adult; Brachial Artery; Cross-Over Studies; Double-Blind Method; Endothelium, Vascular; Exenatide; Forearm; Glyburide; Humans; Hypoglycemic Agents; Injections, Subcutaneous; KATP Channels; Peptides; Potassium Channel Blockers; Reperfusion Injury; Vasodilation; Venoms

Exenatide has been demonstrated to be cardioprotective as an adjunct to primary percutaneous coronary intervention in patients with ST-segment-elevation myocardial infarction (STEMI). The aim of the post hoc analysis study was to evaluate the effect of exenatide in relation to system delay, defined as time from first medical contact to first balloon.. Patients with STEMI and Thrombolysis In Myocardial Infarction flow 0/1 were randomly assigned to intravenous exenatide or placebo continuous infusion. Study treatment was commenced 15 minutes before intervention and maintained for 6 hours after the procedure. The patients were stratified according to median system delay (132 minutes). Final infarct size and myocardial area at risk were measured by cardiovascular magnetic resonance. Among patients with a system delay ≤132 minutes (n=74), treatment with exenatide resulted in a smaller infarct size (9 grams [interquartile range (IQR), 4-13] versus 13 grams [IQR, 8-24], P=0.008, corresponding to 8% [IQR, 4-12] versus 11% [IQR, 7-17] of the left ventricle, P=0.015). In a regression analysis adjusting for myocardial area at risk the data points of the exenatide group lay significantly lower than for the placebo group (P=0.006). In the patients with system delay >132 minutes (n=74) no difference was observed in infarct size expressed as grams (P=0.49) or percentage (P=0.46). There was significant interaction between system delay (less than or equal to median versus greater than median) and treatment allocation in terms of infarct size (P=0.018).. In this post hoc analysis, exenatide treatment was associated with a 30% decrease in final infarct size in patients with short system delay, whereas no cardioprotective effect in patients with long system delay was seen. However, this finding must be confirmed in larger studies.. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00835848.

Topics: Aged; Angioplasty; Chemotherapy, Adjuvant; Coronary Vessels; Disease-Free Survival; Electrocardiography; Exenatide; Female; Heart; Humans; Hypoglycemic Agents; Magnetic Resonance Imaging; Male; Middle Aged; Myocardial Infarction; Myocardium; Peptides; Radiography; Reperfusion Injury; Venoms; Warm Ischemia

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 aim of this study is to investigate the vasorelaxant effect of exendin-4, a GLP-1 receptor agonist on retinal capillaries under normal and ischaemia-reperfusion (I/R) conditions.. Capillary diameters in the whole-mounted retina were directly observed using infrared differential interference contrast microscopy. A model of retinal I/R was established inraats,using high perfusion pressure in an anterior chamber. To assess the effects of exendin-4, it was administered through subcutaneous injection, intravitreal injection, or eye drops. The underlying mechanism was explored by immunofluorescence, qPCR, and capillary western blots.. Immunofluorescence staining showed that GLP-1 receptors were expressed in endothelial cells of retinal capillaries. Exendin-4 relaxed the capillaries precontracted by noradrenaline, an effect abolished by denuding endothelium with CHAPS and inhibited by GLP-1 receptor antagonist exendin-9-39, endothelial NOS (eNOS) inhibitor l-NAME, and the guanylate cyclase blocker ODQ but not by a COX inhibitor, indomethacin. Retinal capillaries were constricted in I/R injury, an effect reversed by perfusion of exendin-4. Expression of PI3K and Akt, phosphorylation level of eNOS and NO production after I/R were lower than that in the normal control group. Administration of exendin-4 improved the changes.. Exendin-4 can restore injured microvascular patency in I/R. Exendin-4 may regulate retinal capillaries through the GLP-1 receptor-PI3K/Akt-eNOS/NO-cGMP pathway. Therefore, exendin-4 may be an effective treatment for improving tissue perfusion in I/R-related conditions.

Topics: Capillaries; Endothelial Cells; Exenatide; Glucagon-Like Peptide-1 Receptor; Humans; Phosphatidylinositol 3-Kinases; Reperfusion Injury; Retina; Venoms

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

Diabetes is a major risk factor for the development of stroke. Glucagon-like peptide-1 receptor (GLP-1R) agonists have been in clinical use for the treatment of diabetes and also been reported to be neuroprotective in ischemic stroke. The quinoxaline 6,7-dichloro-2-methylsulfonyl-3-N-tert- butylaminoquinoxaline (DMB) is an agonist and allosteric modulator of the GLP-1R with the potential to increase the affinity of GLP-1 for its receptor. The aim of this study was to evaluate the neuroprotective effects of DMB on transient focal cerebral ischemia. In cultured cortical neurons, DMB activated the GLP-1R, leading to increased intracellular cAMP levels with an EC50 value about 100 fold that of exendin-4. Pretreatment of neurons with DMB protected against necrotic and apoptotic cell death was induced by oxygen-glucose deprivation (OGD). The neuroprotective effects of DMB were blocked by GLP-1R knockdown with shRNA but not by GLP-1R antagonism. In C57BL/6 mice, DMB was orally administered 30 min prior to middle cerebral artery occlusion (MCAO) surgery. DMB markedly reduced the cerebral infarct size and neurological deficits caused by MCAO and reperfusion. The neuroprotective effects were mediated by activation of the GLP-1R through the cAMP-PKA-CREB signaling pathway. DMB exhibited anti-apoptotic effects by modulating Bcl-2 family members. These results provide evidence that DMB, a small molecular GLP-1R agonist, attenuates transient focal cerebral ischemia injury and inhibits neuronal apoptosis induced by MCAO. Taken together, these data suggest that DMB is a potential neuroprotective agent against cerebral ischemia.

Topics: Administration, Oral; Allosteric Regulation; Animals; Apoptosis; Blood Glucose; Brain; Cell Survival; Cells, Cultured; Drug Evaluation, Preclinical; Exenatide; Glucagon-Like Peptide-1 Receptor; Infarction, Middle Cerebral Artery; Inhibitory Concentration 50; Insulin; Male; Mice, Inbred C57BL; Neurons; Neuroprotective Agents; Peptides; Primary Cell Culture; Quinoxalines; Reperfusion Injury; Sulfones; Venoms

Donor organ shortages have led to an increased interest in finding new approaches to recover organs from extended criteria donors (ECD). Normothermic extracorporeal liver perfusion (NELP) has been proposed as a superior preservation method to reduce ischemia/reperfusion injury (IRI), precondition suboptimal grafts, and treat ECD livers so that they can be successfully used for transplantation. The aim of this study was to investigate the beneficial effects of a modified NELP circuit on discarded human livers. Seven human livers that were rejected for transplantation were placed on a modified NELP circuit for 8 hours. Perfusate samples and needle core biopsies were obtained at hourly intervals. A defatting solution that contained exendin-4 (50 nM) and L-carnitine (10 mM) was added to the perfusate for 2 steatotic livers. NELP provided normal temperature, electrolytes, and pH and glucose levels in the perfusate along with physiological vascular flows and pressures. Functional, biochemical, and microscopic evaluation revealed no additional injuries to the grafts during NELP with an improved oxygen extraction ratio (>0.5) and stabilized markers of hepatic injury. All livers synthesized adequate amounts of bile and coagulation factors. We also demonstrated a mild reduction (10%) of macroglobular steatosis with the use of the defatting solution. Histology demonstrated normal parenchymal architecture and a minimal to complete lack of IRI at the end of NELP. In conclusion, a modified NELP circuit preserved hepatocyte architecture, recovered synthetic functions, and hepatobiliary parameters of ECD livers without additional injuries to the grafts. This approach has the potential to increase the donor pool for clinical transplantation. Liver Transplantation 22 979-993 2016 AASLD.

Topics: Adult; Aged; Allografts; Biopsy, Large-Core Needle; Carnitine; Donor Selection; Exenatide; Fatty Liver; Female; Humans; Liver; Liver Transplantation; Male; Middle Aged; Organ Preservation; Organ Preservation Solutions; Peptides; Perfusion; Reperfusion Injury; Temperature; Tissue Survival; Venoms; Warm Ischemia

We tested the hypothesis that combined treatment with melatonin, an anti-oxidant, and exendin-4, an anti-inflammatory agent, was superior to either alone for protecting the kidney from ischemia-reperfusion (IR) injury. Male adult Sprague-Dawley rats (n=40) were equally divided into group 1 (sham-operated control), group 2 (IR only, IR=1h/72h), group 3 (IR-exendin-4, 10 µg/kg at 30 min, 24 h, 48 h after IR procedure), group 4 (IR-melatonin, i.p. 50 mg at 30 min, then 20 mg at 6 and 18 h after IR procedure), and group 5 (combined IR-exendin-4-melatonin). All animals were sacrificed by 72 h after IR/sham procedure. The results showed that the kidney injury score, plasma creatinine, and blood urea nitrogen (BUN) levels were highest in group 2 and lowest in group 1, significantly higher in groups 3 and 4 than those in group 5 and significantly higher in group 3 than those in group 4 (all p < 0.001). The protein expressions of inflammatory (toll-like receptor 4, inducible nitric oxide synthase, interleukin-1β), apoptotic (mitochondrial Bax, cleaved caspase-3 and poly(ADP-ribose) polymerase, p53), podocyte integrity (E-cadherin, P-cadherin), and cell survival (phosphatidylinositol-3-kinase/AKT/mammalian target of rapamycin) biomarkers, as well the podocyte dysfunction biomarkers (Wnt1/Wnt4/β-catenin) displayed a pattern identical to that of creatinine level among the five groups (all p < 0.001). Microscopic findings demonstrated that podocyte dysfunction (Wnt1/Wnt4/β-catenin expression) and inflammatory (CD14 and F4/80-positively stained cells) biomarkers exhibited an identical pattern, whereas that of antioxidant (HO-1(+), NQO-1(+) cells) biomarkers showed an opposite pattern compared to that of creatinine level among the five groups (all p < 0.001). Combined melatonin-exendin-4 therapy offered an additional benefit in protecting the kidney from acute IR injury.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Apoptosis; Biomarkers; Blood Urea Nitrogen; Creatinine; Exenatide; Kidney; Male; Melatonin; Oxidative Stress; Peptides; Proteinuria; Rats, Sprague-Dawley; Reperfusion Injury; 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

Glucagon-like peptide-1 (GLP-1) receptor activation in the brain provides neuroprotection. Exendin-4 (Ex-4), a GLP-1 analog, has seen limited clinical usage because of its short half-life. We developed long-lasting Ex-4-loaded poly(D,L-lactide-co-glycolide) microspheres (PEx-4) and explored its neuroprotective potential against cerebral ischemia in diabetic rats. Compared with Ex-4, PEx-4 in the gradually degraded microspheres sustained higher Ex-4 levels in the plasma and cerebrospinal fluid for at least 2 weeks and improved diabetes-induced glycemia after a single subcutaneous administration (20 μg/day). Ten minutes of bilateral carotid artery occlusion (CAO) combined with hemorrhage-induced hypotension (around 30 mm Hg) significantly decreased cerebral blood flow and microcirculation in male Wistar rats subjected to streptozotocin-induced diabetes. CAO increased cortical O2(-) levels by chemiluminescence amplification and prefrontal cortex edema by T2-weighted magnetic resonance imaging analysis. CAO significantly increased aquaporin 4 and glial fibrillary acidic protein expression and led to cognition deficits. CAO downregulated phosphorylated Akt/endothelial nitric oxide synthase (p-Akt/p-eNOS) signaling and enhanced nuclear factor (NF)-κBp65/intercellular adhesion molecule-1 (ICAM-1) expression, endoplasmic reticulum (ER) stress, and apoptosis in the cerebral cortex. PEx-4 was more effective than Ex-4 to improve CAO-induced oxidative injury and cognitive deficits. The neuroprotection provided by PEx-4 was through p-Akt/p-eNOS pathways, which suppressed CAO-enhanced NF-κB/ICAM-1 signaling, ER stress, and apoptosis.

Topics: Animals; Brain Ischemia; Carotid Arteries; Carotid Stenosis; Cerebrovascular Circulation; Cognition Disorders; Diabetes Mellitus, Experimental; Drug Carriers; Exenatide; Injections, Subcutaneous; Lactic Acid; Magnetic Resonance Imaging; Male; Microcirculation; Microspheres; Neuroprotective Agents; Nitric Oxide Synthase Type III; Oncogene Protein v-akt; Peptides; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rats; Rats, Wistar; Reperfusion Injury; Signal Transduction; Venoms

We tested whether combined melatonin (Mel) and exendin-4 (Ex4) treatment can better preserve glomerular structural integrity after ischemia-reperfusion (IR) injury compared with either alone. Adult male Sprague Dawley rats (n = 50) were equally divided into sham control (SC), IR, IR-Ex4 (10 μg/kg subcutaneously 30 min after reperfusion and daily for 5 days), IR-Mel (20 mg/kg intraperitoneally at 30 min postreperfusion and 50 mg/kg at 6 and 18 hr), and IR-Ex4-Mel were euthanized at day 14. Serum creatinine level and urine protein-to-creatinine ratio at days 3 and 14 were highest in IR group and lowest in SC, significantly higher in IR-Ex4 and IR-Mel groups than in IR-Ex4-Mel group (all P < 0.001) without significant difference between IR-Ex4 and IR-Mel groups. Changes in podocyte injury score (PIS) and kidney injury score were highest in IR group and lowest in SC, significantly higher in IR-Ex4 and IR-Mel groups than in IR-Ex4-Mel, and significantly higher in IR-Mel group than in IR-Ex4 group (all P < 0.001). Immunohistochemical microscopic findings of the expressions of FSP-1 and WT-1 (two glomerular damage indicators) and KIM-1 and snail (two renal tubular-damaged indicators) showed an identical pattern, whereas the expressions of ZO-1, p-cadherin, podocin, dystroglycan, fibronectin, and synaptopodin (six indices of glomerular integrity) demonstrated an opposite pattern compared to that of PIS among five groups (all P < 0.001). Protein expressions of inflammatory (TNF-α/NF-κB/MMP-9) and oxidative stress (NOX-1, NOX-2, oxidized protein) biomarkers exhibited an identical pattern to that of PIS among five groups (all P < 0.001). Combined melatonin-exednin-4 therapy further protected glomerulus from IR injury.

Topics: Animals; Cadherins; Calcium-Binding Proteins; Cell Adhesion Molecules; Exenatide; Kidney; Male; Matrix Metalloproteinase 9; Melatonin; NF-kappa B; Oxidative Stress; Peptides; Podocytes; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Tumor Necrosis Factor-alpha; Venoms; WT1 Proteins

Ischemia-reperfusion injury (IRI) is a common clinical consequence of hepatic surgery, cardiogenic shock, and liver transplantation. A steatotic liver is particularly vulnerable to IRI, responding with extensive hepatocellular injury. Autophagy, a lysosomal pathway balancing cell survival and cell death, is engaged in IRI, although its role in IRI of a steatotic liver is unclear. The role of autophagy was investigated in high-fat diet (HFD)-fed mice exposed to IRI in vivo and in steatotic hepatocytes exposed to hypoxic IRI (HIRI) in vitro. Two inhibitors of autophagy, 3-methyladenine and bafilomycin A1, protected the steatotic hepatocytes from HIRI. Exendin 4 (Ex4), a glucagon-like peptide 1 analog, also led to suppression of autophagy, as evidenced by decreased autophagy-associated proteins [microtubule-associated protein 1A/1B-light chain 3 (LC3) II, p62, high-mobility group protein B1, beclin-1, and autophagy-related protein 7], reduced hepatocellular damage, and improved mitochondrial structure and function in HFD-fed mice exposed to IRI. Decreased autophagy was further demonstrated by reversal of a punctate pattern of LC3 and decreased autophagic flux after IRI in HFD-fed mice. Under the same conditions, the effects of Ex4 were reversed by the competitive antagonist exendin 9-39. The present study suggests that, in IRI of hepatic steatosis, treatment of hepatocytes with Ex4 mitigates autophagy, ameliorates hepatocellular injury, and preserves mitochondrial integrity. These data suggest that therapies targeting autophagy, by Ex4 treatment in particular, may ameliorate the effects of IRI in highly prevalent steatotic liver.

Topics: Adenine; Animals; Autophagy; Cells, Cultured; Exenatide; Hepatocytes; Humans; Macrolides; Male; Mice; Mice, Inbred C57BL; Mitochondria, Liver; Non-alcoholic Fatty Liver Disease; Peptides; Reperfusion Injury; Venoms

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

Accumulating evidence of the beyond-glucose lowering effects of a gut-released hormone, glucagon-like peptide-1 (GLP-1), has been reported in the context of remote organ connections of the cardiovascular system. Specifically, GLP-1 appears to prevent apoptosis, and inhibition of dipeptidyl peptidase-4 (DPP-4), which cleaves GLP-1, is renoprotective in rodent ischemia-reperfusion injury models. Whether this renoprotection involves enhanced GLP-1 signaling is unclear, however, because DPP-4 cleaves other molecules as well. Thus, we investigated whether modulation of GLP-1 signaling attenuates cisplatin (CP)-induced AKI. Mice injected with 15 mg/kg CP had increased BUN and serum creatinine and CP caused remarkable pathologic renal injury, including tubular necrosis. Apoptosis was also detected in the tubular epithelial cells of CP-treated mice using immunoassays for single-stranded DNA and activated caspase-3. Treatment with a DPP-4 inhibitor, alogliptin (AG), significantly reduced CP-induced renal injury and reduced the renal mRNA expression ratios of Bax/Bcl-2 and Bim/Bcl-2. AG treatment increased the blood levels of GLP-1, but reversed the CP-induced increase in the levels of other DPP-4 substrates such as stromal cell-derived factor-1 and neuropeptide Y. Furthermore, the GLP-1 receptor agonist exendin-4 reduced CP-induced renal injury and apoptosis, and suppression of renal GLP-1 receptor expression in vivo by small interfering RNA reversed the renoprotective effects of AG. These data suggest that enhancing GLP-1 signaling ameliorates CP-induced AKI via antiapoptotic effects and that this gut-kidney axis could be a new therapeutic target in AKI.

Topics: Acute Kidney Injury; Animals; Antineoplastic Agents; Apoptosis; Cisplatin; Dipeptidyl-Peptidase IV Inhibitors; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Intestinal Mucosa; Male; Mice; Mice, Inbred C57BL; Oxidative Stress; Peptides; Piperidines; Receptors, Glucagon; Reperfusion Injury; RNA, Small Interfering; Uracil; Venoms

This study tested the hypothesis that exendin-4 and sitagliptin can effectively protect kidney from acute ischemia-reperfusion (IR) injury.. Adult SD-rats (n = 48) equally divided into group 1 (sham control), group 2 (IR injury), group 3 [IR + sitagliptin 600 mg/kg at post-IR 1, 24, 48 hr)], and group 4 [IR + exendin-4 10 μm/kg at 1 hr after procedure] were sacrificed after 24 and 72 hrs (n = 6 at each time from each group) following clamping of bilateral renal pedicles for 60 minutes (groups 2-4).. Serum creatinine level and urine protein to creatinine ratio were highest in group 2 and lowest in group 1 (all p < 0.001) without notable differences between groups 3 and 4. Kidney injury score, expressions of inflammatory biomarkers at mRNA (MMP-9, TNF-α, IL-1β, PAI-1), protein (TNF-α, NF-κB and VCAM-1), and cellular (CD68+) levels in injured kidneys at 24 and 72 hr showed an identical pattern compared to that of creatinine level in all groups (all p < 0.0001). Expressions of oxidized protein, reactive oxygen species (NOX-1, NOX-2), apoptosis (Bax, caspase-3 and PARP), and DNA damage marker (γH2AX+) of IR kidney at 24 and 72 hrs exhibited a pattern similar to that of inflammatory mediators among all groups (all p < 0.01). Renal expression of glucagon-like peptide-1 receptor, and anti-oxidant biomarkers at cellular (GPx, GR) and protein (NQO-1, HO-1, GPx) levels at 24 and 72 hr were lowest in group 1, significantly lower in group 2 than in groups 3 and 4 (all p < 0.01).. Exendin-4 and sitagliptin provided significant protection for the kidneys against acute IR injury.

Topics: Animals; Biomarkers; Creatinine; Exenatide; Inflammation; Kidney; Male; Oxidative Stress; Peptides; Proteinuria; Pyrazines; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Reperfusion Injury; Sitagliptin Phosphate; Triazoles; Venoms

Islets isolated from cadaveric donor pancreas are functionally viable and can be transplanted in diabetic patients to reduce insulin requirements. This therapeutic approach is less efficient because a significant portion of functional islets is lost due to oxidative stress, inflammation, and hypoxia. Exendin-4, a glucagon-like peptide-1 receptor agonist, is known to improve islet survival through activation of the transcription factor, cAMP response element binding protein (CREB). However, isolated human islets are exposed to several stresses known to down-regulate CREB. The objective of the present study was to determine whether the cytoprotective actions of exendin-4 in human islets can be augmented by increasing the levels of CREB. Simulation of ischemia/reperfusion injury and exposure to hypoxic conditions in cultured human islets resulted in decreased CREB activation and induction of apoptosis. Islets were transduced with adenoviral CREB followed by exposure to exendin-4 as a strategy for improving their survival. This combination increased the levels of several proteins needed for β-cell survival and function, including insulin receptor substrate-2, Bcl-2, and baculoviral IAP repeat-containing 3, and suppressed the expression of proapoptotic and inflammatory genes. A combination of CREB and exendin-4 exerted enhanced antiapoptotic action in cultured islets against hypoxia and cytokines. More significantly, transplantation of human islets transduced with adenoviral CREB and treated with exendin-4 showed improved glycemic control over a 30-d period in diabetic athymic nude mice. These observations have significant implications in the therapeutic potential of exendin-4 and CREB in the islet transplantation setting as well as in preserving β-cell mass of diabetic patients.

Topics: Animals; Apoptosis; Cell Line; Cells, Cultured; Computer Simulation; Cyclic AMP Response Element-Binding Protein; Cytokines; Exenatide; Humans; Hypoxia; Insulin Receptor Substrate Proteins; Insulin-Secreting Cells; Islets of Langerhans; Male; Mice; Mice, Nude; Pancreas; Peptides; Reperfusion Injury; Signal Transduction; Venoms

Nonalcoholic fatty liver disease is an increasingly prevalent spectrum of conditions characterized by excess fat deposition within hepatocytes. Affected hepatocytes are known to be highly susceptible to ischemic insults, responding to injury with increased cell death, and commensurate liver dysfunction. Numerous clinical circumstances lead to hepatic ischemia. Mechanistically, specific means of reducing hepatic vulnerability to ischemia are of increasing clinical importance. In this study, we demonstrate that the glucagon-like peptide-1 receptor agonist Exendin 4 (Ex4) protects hepatocytes from ischemia reperfusion injury by mitigating necrosis and apoptosis. Importantly, this effect is more pronounced in steatotic livers, with significantly reducing cell death and facilitating the initiation of lipolysis. Ex4 treatment leads to increased lipid droplet fission, and phosphorylation of perilipin and hormone sensitive lipase - all hallmarks of lipolysis. Importantly, the protective effects of Ex4 are seen after a short course of perioperative treatment, potentially making this clinically relevant. Thus, we conclude that Ex4 has a role in protecting lean and fatty livers from ischemic injury. The rapidity of the effect and the clinical availability of Ex4 make this an attractive new therapeutic approach for treating fatty livers at the time of an ischemic insult.

Topics: 3T3-L1 Cells; Adiposity; Animals; Apoptosis; Carrier Proteins; Cell Line, Tumor; Exenatide; Fatty Liver; Glucagon-Like Peptide-1 Receptor; Hepatocytes; Humans; Lipolysis; Liver; Male; Mice; Mice, Inbred C57BL; Necrosis; Peptides; Perilipin-1; Phosphoproteins; Phosphorylation; Protective Agents; Receptors, Glucagon; Reperfusion Injury; Sterol Esterase; Thinness; 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

The widely expressed dipeptidyl peptidase-4 enzyme rapidly cleaves the gut hormone glucagon-like peptide-1 [GLP-1(7-36)amide] at the N terminus to generate GLP-1(9-36)amide. Both intact GLP-1(7-36)amide and GLP-1(9-36)amide exert cardioprotective actions in rodent hearts; however, the mechanisms underlying the actions of GLP-1(9-36)amide remain poorly understood. We used mass spectrometry of coronary effluents to demonstrate that isolated mouse hearts rapidly convert infused GLP-1(7-36)amide to GLP-1(9-36)amide. After ischemia-reperfusion (I/R) injury of isolated mouse hearts, administration of GLP-1(9-36)amide or exendin-4 improved functional recovery and reduced infarct size. The direct actions of these peptides were studied in cultured neonatal mouse cardiomyocytes. Both GLP-1(9-36)amide and exendin-4 increased levels of cAMP and phosphorylation of ERK1/2 and the phosphoinositide 3-kinase target protein kinase B/Akt. In I/R injury models in vitro, both peptides improved mouse cardiomyocyte viability and reduced lactate dehydrogenase release and caspase-3 activation. These effects were attenuated by inhibitors of ERK1/2 and phosphoinositide 3-kinase. Unexpectedly, the cardioprotective actions of GLP-1(9-36)amide were blocked by exendin(9-39) yet preserved in Glp1r(-/-) cardiomyocytes. Furthermore, GLP-1(9-36)amide, but not exendin-4, improved the survival of human aortic endothelial cells undergoing I/R injury, actions sensitive to the nitric oxide synthase inhibitor, N(G)-nitro-l-arginine methyl ester (L-NAME). In summary, our findings demonstrate separate actions for GLP-1(9-36)amide vs. the GLP-1R agonist exendin-4 and reveal the existence of a GLP-1(9-36)amide-responsive, exendin(9-39)-sensitive, cardioprotective signaling pathway distinct from that associated with the classical GLP-1 receptor.

Topics: Analysis of Variance; Animals; Blotting, Western; Cells, Cultured; Cytoprotection; Dose-Response Relationship, Drug; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Heart; Male; Mass Spectrometry; Mice; Mice, Knockout; Myocardium; Peptide Fragments; Peptides; Receptors, Glucagon; Recovery of Function; Reperfusion Injury; Signal Transduction; Time Factors; Venoms