glucagon-like-peptide-1-(7-36) and Disease-Models--Animal

Heart failure with preserved ejection fraction (HFpEF) has emerged as a public health burden with currently no effective medication. We assessed the treatment effects of the incretin hormone glucagon-like peptide-1 (GLP-1) on cardiac metabolism and function in a model of HFpEF. Following aortic banding, rats developed HFpEF characterized by diastolic dysfunction, pulmonary congestion, and poor survival (38%). A 4-week GLP-1 treatment via osmotic pumps significantly improved survival (70%) and reduced left ventricular stiffness, diastolic dysfunction, and pulmonary congestion. Isolated heart perfusion revealed preserved cardiac glucose oxidation (GO) and a shift in cardiac substrate utilization towards GO. While GLP-1 may boost insulin secretion and responsiveness, the protective effects were not related to cardiac insulin action. GLP-1 improves diastolic function and survival in rats with HFpEF, which was associated with a cardiac substrate switch towards GO. The therapeutic role of GLP-1 in HFpEF is new and warrants further investigation.

Topics: Animals; Cardiotonic Agents; Diastole; Disease Models, Animal; Energy Metabolism; Glucagon-Like Peptide 1; Glucose; Heart Failure; Isolated Heart Preparation; Male; Myocardium; Oxidation-Reduction; Peptide Fragments; Pulmonary Edema; Rats, Sprague-Dawley; Recovery of Function; Stroke Volume; Ventricular Function, Left

Topics: Animals; Anorexia; Appetite Regulation; Behavior, Animal; Cholecystokinin; Disease Models, Animal; Feeding Behavior; Female; Glucagon-Like Peptide 1; Mice; Peptide Fragments; Satiety Response; Signal Transduction; T-2 Toxin; Time Factors; Trichothecenes; Up-Regulation

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

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

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