Effects Of GLP-1 Research Articles

Glucagon-Like Peptide 1 and Atrial Natriuretic Peptide in a Female Mouse Model of Obstructive Pulmonary Disease.

Glucagon-like peptide-1 (GLP-1) is protective in lung disease models but the underlying mechanisms remain elusive. Because the hormone atrial natriuretic peptide (ANP) also has beneficial effects in lung disease, we hypothesized that GLP-1 effects may be mediated by ANP expression. To study this putative link, we used a mouse model of chronic obstructive pulmonary disease (COPD) and assessed lung function by unrestrained whole-body plethysmography. In 1 study, we investigated the role of endogenous GLP-1 by genetic GLP-1 receptor (GLP-1R) knockout (KO) and pharmaceutical blockade of the GLP-1R with the antagonist exendin-9 to -39 (EX-9). In another study the effects of exogenous GLP-1 were assessed. Lastly, we investigated the bronchodilatory properties of ANP and a GLP-1R agonist on isolated bronchial sections from healthy and COPD mice.Lung function did not differ between mice receiving phosphate-buffered saline (PBS) and EX-9 or between GLP-1R KO mice and their wild-type littermates. The COPD mice receiving GLP-1R agonist improved pulmonary function (P < .01) with less inflammation, but no less emphysema compared to PBS-treated mice. Compared with the PBS-treated mice, treatment with GLP-1 agonist increased ANP (nppa) gene expression by 10-fold (P < .01) and decreased endothelin-1 (P < .01), a peptide associated with bronchoconstriction. ANP had moderate bronchodilatory effects in isolated bronchial sections and GLP-1R agonist also showed bronchodilatory properties but less than ANP. Responses to both peptides were significantly increased in COPD mice (P < .05, P < .01).Taken together, our study suggests a link between GLP-1 and ANP in COPD.

Gamma-Aminobutyric Acid Requires GLP-1 Receptor to Effectively Exert Its Pancreatic Function During Streptozotocin Challenge

Background: Gamma-aminobutyric acid (GABA) administration attenuates streptozotocin (STZ) induced diabetes in rodent models, while the underlying mechanisms remain unclear. Since GABA and the incretin-based drug sitagliptin showed additive effect on pancreatic β-cells, we ask whether GLP-1 receptor (GLP-1R) is involved in mediating certain beneficial effects of GABA. Methods: Effect of GABA or GLP-1 on expression of the glucotoxicity meditator thioredoxin-interacting protein (TxNIP) was assessed in pancreatic INS-1 832/13 (INS-1) cell line, wild type (WT) and GLP-1R-/- mouse islets by qRT-PCR, Western blotting and luciferase reporter assay. GABA was orally administrated in WT or GLP-1R-/- mice received STZ injection, followed by immunohistochemistry assessment of pancreatic islets. Effect of GABA on Wnt pathway effector β-catenin was examined in INS-1 cells, WT and GLP-1R-/- mouse islets by Western blotting. Findings: We show here that GABA shares a common feature with GLP-1 on inhibiting TxNIP expression, while this function was attenuated in GLP-1R-/- islets. In WT mice with STZ challenge, GABA attenuated several “diabetic syndromes”, associated with increased β-cell mass. These features were virtually absent in GLP-1R-/- mice. Cleaved caspase-3 in pancreatic β-cells can be induced by high-glucose, dexamethasone, or STZ treatment in INS-1 cells; while GABA treatment blocked the induction. Finally, GABA treatment increased β-cat S675 phosphorylation in WT mouse islets but not in GLP-1R-/- mouse islets. Interpretation: These observations indicate that in β-cells upon STZ or other stress challenge, the GLP-1R-cAMP-β-catenin signaling cascade may also mediate the beneficial effects of GABA. Funding Statement: This study was supported by an Operating grant from the Juvenile Diabetes Research Foundation (JDRF, 2-SRA-2015-64) to QW, GP, and TJ, and a pilot grant from Banting and Best Diabetes Centre (BBDC) to TJ. Declaration of Interests: There is no conflict interests for all authors. Ethics Approval Statement: All animal work was approved by the Institutional Animal Care and Use Committee of the University Health Network.

Co-infusion of Neurotensin and GLP-1 Effects on Appetite and Food Intake.

Co-infusion of Neurotensin and GLP-1 Effects on Appetite and Food Intake.

Evaluation of cardioprotective effect of exenatide in type 2 diabetes mellitus and acute myocardial infarction in the clinic and experiment

Background. Insulin therapy is associated with the risk of hypoglycemia, high variability of glycemia. Therefore, therapy with analogues GLP1 becomes relevant for patients with myocardial infarction and diabetes mellitus type 2. These drugs can reduce glycemic variability and risk of hypoglycemia. Objective. The effects of combination therapy analogue GLP1 and insulin should be studied in rats with experimental myocardial infarction and the impact of such therapy should be studied on the level of markers of myocardial damage, BNP, dynamics of the echocardiographic parameters and level of glycemia in patients with diabetes mellitus type 2 and myocardial infarction. Design and methods . Neonatal streptozotocin diabetes mellitus was modeled in an experiment in rats. Groups of animals were formed depending on the time of the beginning of insulin therapy, analogue GLP1(exenatide) or a combination of these drugs — before or after experimental myocardial infarction. Morphological assessment of ischemia and necrosis areas was carried out and glycemic variability was assessed. Two groups of patients with type 2 diabetes mellitus and myocardial infarction were formed in the clinical part. The first group received standard insulin therapy, the second group received combination therapy with insulin and exenatide. Parameters of glycemia, markers of myocardial damage, BNP, dynamics of echocardiography were evaluated. Results. The decrease of the area of necrosis, was observed in the combination therapy group in the experiment. Troponin I and CPK MV levels did not differ initially in all groups of patients. Reducing glycemic variability, a positive trend of level BNP, and EF was noted in patients with exenatide. Conclusion. Exenatide has the most pronounced positive effect on the course of myocardial infarction at the introduction before the start of reperfusion. Exenatide had no effect on the dynamics of markers of myocardial damage, but reduced the glycemic variability, improved the dynamics of laboratory parameters in patients.

P717Glucagon-like peptide 1 (GLP-1) improves endothelial dysfunction and vascular inflammation in polymicrobial sepsis induced by cecal ligation and puncture (CLP)

Abstract Objective Sepsis causes severe hypotension, accompanied by high mortality in the setting of septic shock. LEADER, SUSTAIN-6 and other clinical trials revealed cardioprotective and anti-inflammatory properties of GLP-1 analogs like Liraglutide (Lira). We already demonstrated improved survival by amelioration of disseminated intravasal coagulation (DIC) in lipopolysaccharide (LPS)-induced endotoxemia by inhibition of the GLP-1 degrading enzyme dipeptidylpeptidase-4 (DPP-4). With the present study we aim to investigate the mechanism of protective effects of the GLP-1 analog Lira and the DPP4 inhibitor Linagliptin (Lina) in the clinically relevant sepsis model cecal ligation and puncture (CLP). Methods C57/BL6j and endothelial cell-specific GLP-1 receptor knockout mice (Cdh5crexGLP-1rfl/flmice) were used and sepsis was induced by cecal ligation and puncture (CLP). DPP4 inhibitor (Lina, 5mg/kg/d; 3 days) and GLP-1 analog (Lira, 200μg/kg/d; 3 days) were applied subcutaneously. Aortic vascular function was tested by isometric tension recording. Aorta and heart tissue was used for Western blotting, dot blot and qRT-PCR. Endogenous GLP-1 (7–36 and 9–36) and insulin was determined by ELISA. Blood samples were collected for examination of cell count, oxidative stress and glucose levels. Results Body temperature was increased by CLP and normalized by Lina and Lira. Sham- and Lira- but not Lina-treated septic mice showed low blood glucose levels compared to healthy controls. Acetylcholine-induced (endothelium-dependent) vascular relaxation in aorta was impaired by CLP. This was accompanied by vascular inflammation and elevation of IL-6, iNOS, ICAM-1, and TNF-alpha mRNA levels in aortic tissue. Vascular, cardiac and whole blood oxidative stress were increased by CLP. Furthermore, we detected higher levels of IL-6, 3-nitrotyrosine (3-NT) and 4-hydroxynonenal (4-NHE) in plasma of CLP animals. Lina and Lira reduced oxidative stress and vascular inflammation, which was accompanied by improved endothelial function. In addition, CLP treatment in endothelial specific knockout mice of the GLP-1r strongly induced mortality compared to WT mice, with the effect being strongest in the Lira-treated group. Conclusion The present study demonstrates that Lina (DPP4 inhibitor) and the GLP-1 analog Lira ameliorate sepsis-induced endothelial dysfunction by reduction of vascular inflammation and oxidative stress. Clinical trials like LEADER and SUSTAIN-6 proved that GLP-1 analogs like Lira have cardioprotective effects in T2DM patients. The present study, performed in a clinically relevant model of polymicrobial sepsis, reveals that the known cardioprotective effects of GLP-1 might be translated to other diseases which affect the cardiovascular system like sepsis, underlining the potent anti-inflammatory effects of GLP-1 analogs.

Mechanism of the Neuroprotective Effect of GLP-1 in a Rat Model of Parkinson’s with Pre-existing Diabetes

Mechanism of the Neuroprotective Effect of GLP-1 in a Rat Model of Parkinson’s with Pre-existing Diabetes

P5997GLP-1(28-36) prevents progression of ischemic heart failure in mice

Abstract Background Glucagon-like peptide-1 (GLP-1), its metabolites and related drugs have demonstrated cardioprotective benefits in several animal models of cardiovascular disease (CVD) and select clinical trials. Indeed, large cardiovascular outcome trials (CVOT) of GLP-1 analogs showed significant reductions in major adverse cardiovascular events (MACE). However, smaller studies in patients with heart failure (HF) (e.g. FIGHT), and secondary analyses of some CVOT (e.g. LEADER), have suggested that the cardiovascular benefits of GLP-1 analogs may be muted in select patients. Speculating on how this may be due to undesirable increases in heart rate caused by activation of sinoatrial GLP-1 receptors (Glp1r), we have explored the Glp1r-independent cardioprotective actions of GLP-1(28–36), a neutral endopeptidase (NEP)-derived metabolite of GLP-1. We have shown that the cardioprotective effects of GLP-1(28–36) are mediated by mitochondrial trifunctional protein-α (MTPα)-dependent metabolic shift from fatty acid- to glucose oxidation in coronary vascular cells. As metabolic perturbations are believed to contribute to the pathophysiology of HF, we hypothesized that treatment with GLP-1(28–36) may have beneficial effects on this condition. Purpose To evaluate if treatment with GLP-1(28–36) can prevent onset of HF and/or reverse established HF in a post-MI mouse model. Methods and results Permanent LAD ligation was performed in 10–12wk old male C57BL/6J wild-type mice (wt). Immediately post-MI, mice were assigned to receive either GLP-1(28–36) or scrambled peptide [Scram(28–36)] at 18.5nmol/kg/d (N=30/group) subcutaneously (s.c.) via osmotic mini-pumps for 4wk. Although, treatment with GLP-1(28–36) did not improve post-MI survival, triphenyltetrazolium chloride (TTC)-stained hearts 28d post-MI reveal smaller infarct size in GLP-1(28–36)- vs. Scram(28–36)-treated mice (35.3±1.9% vs. 41.2±1.7%, N=12–15/group, P&lt;0.05). Echocardiography at 28d post-MI showed improved LVEF in mice treated with GLP-1(2–36) (30.1±2.3% vs. 24.2±3.7%, N=12–15/group, P&lt;0.05). Similarly, treatment with GLP-1(28–36) reduced heart/body weight ratio (7.9±0.3 vs. 8.8±0.4 mg/g, N=12–15/group, P&lt;0.05). Next, we tested if GLP-1(28–36) might reverse ischemic HF in this model. After permanent LAD ligation of 10–12wk old male wt mice, only those with echocardiography-defined LVEF between 20–35% at 28d post-MI were randomized to treatment with GLP-1(28–36) or Scram(28–36) [18.5nmol/kg/d (N=15/group)] via s.c. mini-pumps for 4wk. Echocardiography at 56d post-MI (i.e. 28d post-treatment start) revealed that GLP-1(28–36) preserved LV function with no deterioration in LVEF vs. Scram(28–36)-treated controls [−3.1±4.9% vs. −22.8±4%, relative change, N=15/group, P&lt;0.001]. Conclusion In a post-MI mouse model of HF, treatment with GLP-1(28–36) prevents progression to HF, and preserves LV function after the development of established HF. Acknowledgement/Funding This study was funded by a Fellowship from Ted Rogers Centre for Heart Research and a Project Grant from Heart and Stroke Foundation, Canada

Effects of glucagon-like peptide-1 analog liraglutide on the systemic inflammation in high-fat-diet-induced mice

Metabolic syndrome is a chronic-metabolic disease caused by a variety of factors, including high peripheral blood insulin levels and insulin resistance. It has been reported that GLP-1 could regulate insulin resistance. It is not known whether and how GLP-1 protects from fat-induced inflammation and immune changes. We investigated if GLP-1 alters the populations of fat-induced inflammation and immune cells and the related mechanism. We obtained obese C57BL/6J mice by feeding them high-fat food, then treated the obese mice with GLP-1+ high-fat diet (G + Hi), normal chow diet (Nor), or high-fat diet (Hi) (n = 20 for each group) for 8 weeks. The GLP-1 receptor-/- B6 group were fed with HFD for 8 weeks (GLP-1R KO + Hi). In vivo and in vitro experiments were conducted on mice immune cells to investigate the effects of GLP-1 on the changes of the immune components and functions in obesity. We found that GLP-1 could efficiently change the CD4+ T subsets and level of cytokines in high-fat-induced mice by GLP-1 receptor. Further, these changes were correlated with a reduction in fat content and serum lipid level. Interestingly, GLP-1 could enhance the function of Tregs in vitro. Our data showed that GLP-1 has an important role in shaping the CD4+ T population in high-fat-diet-induced mice by GLP-1 receptor, possibly providing a new target for the treatment of metabolic syndrome.

Liraglutide Alleviates Hepatic Steatosis and Liver Injury in T2MD Rats via a GLP-1R Dependent AMPK Pathway

Nonalcoholic fatty liver diseases (NAFLD) ranging from nonalcoholic fatty liver to non-alcoholic steatohepatitis have a high preference in Type 2 diabetes mellitus (T2DM) patients. However, no antidiabetic drug is approved for the treatment of NAFLD in T2DM patients. Although multiple daily injection of basal-bolus insulin is the final therapeutic process for T2DM, we found that insulin treatment aggravated hepatic steatosis and oxidative stress in ZDF rats. Here, besides glycemic control, we demonstrated a stimulatory role of liraglutide in relieving hepatic steatosis and liver injury in ZDF rats. Interestingly, liraglutide could also alleviate the insulin aggravated hepatic fatty accumulation. GLP-1 agonist (liraglutide and Ex-4) activated the expression of peroxisome proliferator-activated receptor α (PPARα) via a GLP-1R dependent AMPK pathway. As a nuclear transcription factor, PPARα could mediate the effect of GLP-1 in alleviating hepatic steatosis through differentially regulating the expression of its targeting genes including acetyl CoA carboxylase (ACC) and carnitine palmitoyl transferase la (CPT1a) both in vitro and in vivo. Moreover, our results indicated that GLP-1 could relieve liver injury through decreasing the oxidative stress that stimulated by hepatic steatosis. Insulin might aggravate hepatic steatosis and liver injury through inhibiting the expression of GLP-1R. In this research, we investigated the feasibility of liraglutide treatment combined with basal insulin in attenuating hepatic steatosis and liver injury in ZDF rats, as well as the mechanism behind, which will provide a theoretical basis for the combination treatment recommended by the latest clinical practice guidelines for T2DM. Funding Statement: This work was supported by grants from the National Natural Science Foundation of China (Grant Nos. 81270966, 81500679, 81702903, 81770821), the Natural Science Foundation of Guangdong Province, China (Grant Nos. 2014A030310036, 2014A030310472, 2017A030310038, 2017A030313519 and 2018A030313609), Science and Technology Plan of Guangdong Province (Grant No. 2016A020215097, 2017A020215045) and the Guangdong Provincial Department of Education High-level University Construction Funding Southern Medical University Clinical Research Startup Program (LC2016YM007). Declaration of Interests: The authors have declared that no conflict of interest exists. Ethics Approval Statement: All animal experiments were approved by the Institutional Animal Care and Use Committee of Southern Medical University (Guangzhou, China).

The role of glucagon-like peptide-1 in reproduction: from physiology to therapeutic perspective.

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) have become firmly established in the treatment of type 2 diabetes and obesity, disorders frequently associated with diminished reproductive health. Understanding of the role of GLP-1 and GLP-1 RAs in reproduction is currently limited and largely unaddressed in clinical studies. The purpose of this narrative review is to provide a comprehensive overview of the role of GLP-1 in reproduction and to address a therapeutic perspective that can be derived from these findings. We performed a series of PubMed database systemic searches, last updated on 1 February 2019, supplemented by the authors' knowledge and research experience in the field. A search algorithm was developed incorporating the terms glucagon-like peptide-1, GLP-1, glucagon-like peptide-1 receptor, GLP-1R, or incretins, and this was combined with terms related to reproductive health. The PICO (Population, Intervention, Comparison, Outcome) framework was used to identify interventional studies including GLP-1 RAs and dipeptidyl peptidase-4 (DPP-4) inhibitors, which prevent the degradation of endogenously released GLP-1. We identified 983 potentially relevant references. At the end of the screening process, we included 6 observational (3 preclinical and 3 human) studies, 24 interventional (9 preclinical and 15 human) studies, 4 case reports, and 1 systematic and 2 narrative reviews. The anatomical distribution of GLP-1 receptor throughout the reproductive system and observed effects of GLP-1 in preclinical models and in a few clinical studies indicate that GLP-1 might be one of the important modulating signals connecting the reproductive and metabolic system. The outcomes show that there is mostly stimulating role of GLP-1 and its mimetics in mammalian reproduction that goes beyond mere weight reduction. In addition, GLP-1 seems to have anti-inflammatory and anti-fibrotic effects in the gonads and the endometrium affected by obesity, diabetes, and polycystic ovary syndrome (PCOS). It also seems that GLP-1 RAs and DPP-4 inhibitors can reverse polycystic ovary morphology in preclinical models and decrease serum concentrations of androgens and their bioavailability in women with PCOS. Preliminary data from interventional clinical studies suggest improved menstrual regularity as well as increased fertility rates in overweight and/or obese women with PCOS treated with GLP-1 RAs in the preconception period. GLP-1 RAs and DPP-4 inhibitors show promise in the treatment of diabetes and obesity-related subfertility. Larger interventional studies are needed to establish the role of preconception intervention with GLP-1 based therapies, assessing fertility outcomes in obesity, PCOS, and diabetes-related fertility problems. The potential impact of the dose- and exposure time-response of different GLP-1 RAs need further exploration. Future research should also investigate sex-specific variability of GLP-1 on reproductive outcomes, in particular on the gonads where the observations in males are most conflicting.

229-OR: GLP-1 Infusions during Postprandial Insulin Clamps Enhance Muscle Microvascular Flow, Glucose Uptake, and Protein Anabolism in Older Men

Introduction: Ageing skeletal muscle becomes insulin resistant and atrophic. This is largely due to a failure in sequestering of amino acids and glucose from dietary intake into muscle protein and glycogen. GLP-1 possesses pleiotropic multi-organ properties and its receptor is expressed and exert effects in muscle tissue(s) e.g., endothelium. We hypothesized GLP-1 infusion would enhance muscle glucose uptake and bolster the trophic effects of an anabolic stimulus i.e., feeding. Methods: Eight men (71±1y) were studied in a cross-over trial. Basal measures were taken (first 3 h) prior to insulin (i.e., postprandial (fed-state)) and glucose (euglycaemic) clamps. Participants received I.V co-infusions of octreotide, Vamin 14-EF ±GLP-1. Four muscle biopsies were taken at 90-120 min intervals. Muscle protein turnover was quantified via A-V balance and direct incorporation of 13C6 phenylalanine via mass spectrometric techniques. GLP-1 and insulin were measured using Milliplex Map, ELISA kits. Muscle microvascular blood flow (MBF) was assessed via contrast enhanced ultrasound. Glucose handling was assayed by infusion rates and leg A-V balance. Results: GLP-1 (vs. -GLP-1 condition) augmented muscle protein synthesis (basal: 0.058±0.004%.h-1 vs. fed: 0.102±0.005%.h-1, p&amp;lt;0.01), net protein balance (p&amp;lt;0.0001 and p=0.03 vs. basal at 1.5h and 3h postprandial, respectively) and MBF (5±2 vs. 1.9±0.7 fold-change from basal respectively, p&amp;lt;0.01) - while increasing whole-body glucose uptake (AUC 17.0±1.7 vs. 11.4±1.8 mg.kg-1.180 min-1, p=0.02 with and without GLP, respectively). Muscle protein breakdown was equally suppressed with and without GLP-1. Leg glucose uptake was unchanged by GLP-1. Conclusions: The beneficial effects of GLP-1 upon whole-body glycaemic control are seemingly independent of muscle under fed-conditions. The pro-anabolic effect of GLP-1 in ageing is striking and requires further clinical and mechanistic research. Disclosure H. Abdulla: None. B.E. Phillips: None. M.C. Limb: None. D.J. Wilkinson: None. T. Jandova: None. J. Cegielski: None. J.J. Bass: None. D. Rankin: None. J.S. Lewis: None. J. Williams: None. K. Smith: None. I.R. Idris: None. P.J. Atherton: None. Funding Medical Research Council UK; Arthritis Research UK

PI 3-kinase- and ERK-MAPK-dependent mechanisms underlie Glucagon-Like Peptide-1-mediated activation of Sprague Dawley colonic myenteric neurons.

Glucagon-like peptide (GLP-1) can modify colonic function, with beneficial effects reported in the functional bowel disorder, irritable bowel syndrome (IBS). IBS pathophysiology is characterized by hyper-activation of the hypothalamic-pituitary-adrenal stress axis and altered microbial profiles. This study aims to characterize the neuronal and functional effects of GLP-1 in healthy rat colons to aid understanding of its beneficial effects in moderating bowel dysfunction. Immunofluorescent and calcium imaging of myenteric neurons prepared from Sprague Dawley rat colons was carried out to elucidate the neuromodulatory actions of the GLP-1 receptor agonist, exendin-4 (Ex-4). Colonic contractile activity was assessed using organ bath physiological recordings. Ex-4 induced an elevation of intracellular calcium arising from store release and influx via voltage-gated calcium channels. Ex-4 activated both ERK-MAPK and PI 3-kinase signaling cascades. Neuronal activation was found to underlie suppression of contractile activity in colonic circular muscle. Although the stress hormone, corticotropin-releasing factor (CRF) potentiated the neuronal response to Ex-4, and the functional effects of Ex-4 on colonic circular muscle activity were not altered. Ex-4 evoked neurally regulated suppression of rat colonic circular muscle activity. In myenteric neurons, the neurostimulatory effects of Ex-4 were dependent upon activation of PI 3-kinase and ERK-MAPK signaling cascades. No further change in circular muscle function was noted in the presence of CRF suggesting that stress does not impact on colonic function in health. Further studies in a model of IBS are needed to determine whether mechanisms are modified in the context of bowel dysfunction.

Exenatide modulates visual cortex responses.

Increasing evidence suggests that metabolism affects brain physiology. Here, we examine the effect of GLP-1 on simple visual-evoked functional Magnetic Resonance Imaging (fMRI) responses in cortical areas. Lean (n=10) and nondiabetic obese (n=10) subjects received exenatide (a GLP-1 agonist) or saline infusion, and fMRI responses to visual stimuli (food and nonfood images) were recorded. We analysed the effect of exenatide on fMRI signals across the cortical surface with special reference to the visual areas. We evaluated the effects of exenatide on the raw fMRI signal and on the fMRI signal change during visual stimulation (vs rest). In line with previous studies, we find that exenatide eliminates the preference for food (over nonfood) images present under saline infusion in high-level visual cortex (temporal pole). In addition, we find that exenatide (vs saline) also modulates the response of early visual areas, enhancing responses to both food and nonfood images in several extrastriate occipital areas, similarly in obese and lean participants. Unexpectedly, exenatide increased fMRI raw signals (signal intensity during rest periods without stimulation) in a large occipital region, which were negatively correlated to BMI. In both lean and obese individuals, exenatide affects neural processing in visual cortex, both in early visual areas and in higher order areas. This effect may contribute to the known effect of GLP1 analogues on food-related behaviour.

SAT-LB013 The Effect of Select GLP1 Agonists and SGLT2 Inhibitors on the Unfolded Protein Response in Primary Human Coronary Artery Endothelial Cells

Background. GLP1R agonists and SGLT2 inhibitors are classes of medications used in diabetes management. They possess antioxidative properties and inhibit the unfolded protein response (UPR) (endoplasmic reticulum (ER) stress). Since the UPR is involved in atherogenesis, we examined the effects of the GLP1R agonists GLP1, exendin 4, liraglutide, albiglutide, and lixisenatide and the SGLT2 inhibitors canagliflozin, dapagliflozin, and empagliflozin on ER stress in primary human coronary artery endothelial cells (HCAEC). Methods. ER stress was measured in HCAEC treated with either tunicamycin (TM) or high-dextrose using the ER stress secreted alkaline phosphatase (ES-TRAP) assay. Activating transcription factor 6 (ATF6), glucose-regulated protein 78 (GRP78), inositol-requiring enzyme 1α (IRE1α), phospho-IRE1α, protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), and phospho-PERK were measured by Western blot. Results. Treatment with tunicamycin (TM) and high-dextrose increased ER stress in HCAEC. Treatment of cells exposed to TM or high-dextrose with the GLP1R agonists GLP1, exendin 4, liraglutide, albiglutide, and lixisenatide resulted in a dose-dependent decrease in ER stress. Likewise, treatment with canagliflozin, dapagliflozin, and empagliflozin inhibited ER stress. High-dextrose and TM increased IRE1α and PERK phosphorylation and ATF6 and GRP78 expression. However, treatment with liraglutide (a GLP1R agonist) and dapagliflozin (a SGLT2 inhibitor), suppressed IRE1α and PERK phosphorylation as well as ATF6 and GRP78 expression. Discussion. Treatment with select GLP1R agonists and SGLT2 inhibitors suppressed the UPR and subsequent ER stress. Conclusions. Our results suggest that GLP1R agonists and SGLT2 inhibitors may promote cardiovascular health by targeting coronary artery endothelial cells. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. s presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

SUN-165 The Largest Single-Center Experience of GLP-1 Receptor Agonists as a Safe and Effective Agent for the Management of Diabetes in Solid Organ Transplant (SOT) Recipients

Background Post-transplant diabetes mellitus is a well-recognized complication of SOT. There is a limited published data regarding the approach to management. We aim to test the efficacy and safety of a GLP-1 analog, dulaglutide, an incretin-based therapy in this population. Methods We performed a retrospective, chart review of adult SOT recipients (> 18 years) with diabetes and on dulaglutide. We identified 63 recipients and collected data at 6, 12 and 24 months post GLP1 therapy. The primary endpoint was: change in weight, BMI, and insulin requirement. Safety endpoint included hypoglycemia, GI side-effects, and cancers. Secondary endpoints were: HbA1c, renal and liver function. Results There was a sustained, statistically significant reduction in weight, BMI, and insulin requirement with Dulaglutide at each study period. The mean of paired difference for weight reduction was 2.07 (p-value < 0.003), 4.007 (p-value < 0.001), and 5.23 kgs (p-value <0.034) at 6, 12 and 24 months respectively. BMI followed a similar trend with 0.80 (p-value < 0.001), 1.35 (p-value < 0.005) and 2.015 Kg/m2 reduction (p-value <0.045) at 6, 12 and 24 months respectively. Encouragingly, the mean paired difference for insulin reduction pre, and post-GLP-1 was 5.94 units (p-value < 0.0002). 47% of recipients had a decreased insulin requirement, and 13% were able to stop all other diabetic medications. There was a trend of decrease of HbA1c throughout the follow-up, but it was statistically significant only in the first six months (mean of paired difference at six months 0.7509, p-value < 0.001). It’s likely because the A1C target was maintained with GLP1 analog while reducing the anti-diabetic therapy. Less than 3% of patient had nonsevere hypoglycemia or GI manifestations, none requiring discontinuation of medications. There was one graft failure, one anginal episode, and two mortality (one from sepsis and another was an unknown cause) throughout the follow-up. There was no increased incidence of pancreatitis, transaminitis or cancer. The eGFR was stable throughout the study including in patients with advanced kidney disease. Immunosuppressive agents remained unchanged. Conclusions Our large single-center study in SOT recipients not only demonstrated the sustained beneficial effects of GLP1 in the reduction of weight, BMI, insulin, and other hypoglycemic agents but also exhibited a favorable side-effect profile (minimal GI side-effects) without any significant organ damage (stable cardiovascular, renal, and liver function) or interference with immunosuppressant. Further prospective randomized trials in transplant patients are warranted.

The effect of glucagon-like peptide-1 and glucagon-like peptide-2 on microcirculation: A systematic review.

GLP-1 and GLP-2 are gut-derived hormones used in the treatment of diabetes type-2 and short bowel syndrome, respectively. GLP-1 attenuates insulin resistance and GLP-2 reduces enterocyte apoptosis and enhances crypt cell proliferation in the small intestine. In addition, both hormones have vasoactive effects and may be useful in situations with impaired microcirculation. The aim of this systematic review was to provide an overview of the potential effects of GLP-1 and GLP-2 on microcirculation. A systematic search was performed independently by two authors in the following databases: PubMed, EMBASE, Cochrane library, Scopus, and Web of Science. Of 1111 screened papers, 20 studies were included in this review: 16 studies in animals, three in humans, and one in humans and rats. The studies were few and heterogeneous and had a high risk of bias. However, it seems that GLP-1 regulates the pancreatic, skeletal, and cardiac muscle flow, indicating a role in the glucose homeostasis, while GLP-2 acts primarily in the regulation of the microcirculation of the mid-intestine. These findings may be useful in gastrointestinal surgery and in situations with impaired microcirculation of the gut.

Glucagon-like peptide-1 attenuates endothelial barrier injury in diabetes via cAMP/PKA mediated down-regulation of MLC phosphorylation

ObjectiveGlucagon-like peptide-1 (GLP-1) showed protective effects on endothelium-dependent dilatation. Since endothelial barrier dysfunction also plays a pivotal role in atherosclerosis, this study was designed to investigate the effects of GLP-1 on endothelial barrier function in diabetic aortic endothelium and explore the underlying mechanism. MethodsFor in vivo studies, diabetic rats were established and subjected to 12- and 24-week treatment of exenatide. The morphological changes of aortic endothelium were observed with transmission electron microscope. A permeability assay of aortic endothelium was performed using the surface biotinylation technique. Protein expression was detected by immunohistochemical analysis and Western blots. For in vitro studies, human umbilical vein endothelial cells (HUVECs) were cultured in medium enriched with advanced glycation end products (AGEs) or AGEs plus GLP-1 and other reagents. The integrity of endothelium was evaluated by endothelial monolayer permeability assay and transendothelial resistance. The in vitro expressions of relevant proteins in signaling pathways were also detected by immunofluorescence and Western blots. ResultsIn vivo, the enhanced aortic endothelial permeability in diabetic aortas were attenuated by exenatide treatment. Additionally, myosin light chain (MLC) phosphorylation, related to actomyosin contractility, and activation of its upstream targets in diabetic aorta were inhibited after administration of exenatide. In vitro, the endothelial monolayer permeability and the assembly of stress fibers were reduced by GLP-1 intervention under diabetic condition. Meanwhile, AGE-induced MLC phosphorylation mediating ECs contractility was inhibited by GLP-1. Furthermore, GLP-1 down-regulated the upstream targets of MLC phosphorylation, including RAGE, Rho/ROCK and MAPK signaling pathways. Intriguingly, the effects of GLP-1 elicited on ECs contractility and barrier function in diabetes were blunted by inhibition of GLP-1R, cAMP or PKA and stimulation of Rho/ROCK and MAPK signaling pathways. ConclusionThe findings of this study suggest that the stabilizing effect of GLP-1 on the endothelial barrier and contraction of AGE-treated ECs is caused by GLP-1R/cAMP/PKA activation and the subsequent inactivation of RAGE/Rho/ROCK as well as MAPK signaling pathways.

The effect of DPP-4-protected GLP-1 (7–36) on coronary microvascular function in obese adults

ObjectiveGlucagon-like-peptide-1 (GLP-1) receptor analogues have been shown to reduce cardiovascular events in patients with type 2 diabetes. However, the mechanism behind is still unknown. The aim of the study was to investigate the effect of intact GLP-1 (7–36) on coronary microcirculation in overweight adults. Design and methodsA double-blinded randomized cross-over study was performed, with 12 overweight participants. Effects of intact GLP-1 (7-36) infusion were compared with a saline infusion on separate days. A DPP-4 inhibitor was administered to block degradation of intact GLP-1 (7–36) to the GLP-1 metabolite (9–36). Coronary microcirculation was assessed by Doppler coronary flow velocity reserve (CFVR) before and after 2 h of infusion. Peripheral endothelial function was assessed by flow mediated dilation (FMD) before and after one hour of infusion. ResultsCFVR was 3.77 ± 1.25 during GLP-1 infusion and 3.85 ± 1.32 during saline infusion, endothelial function was 16.3 ± 15.5 % during GLP-1 infusion and 7.85 ± 7.76 % during saline infusion. When adjusting for baseline values no significant differences in CFVR (ΔCFVR 0.38 ± 0.92 vs. ΔCFVR 0.71 ± 1.03, p = 0.43) and no difference in peripheral endothelial function (ΔFMD 7.34 ± 11.5 % vs. ΔFMD –1.25 ± 9.23%, p = 0.14) was found. ConclusionsWe found no effect of intact GLP-1 (7–36), protected from DPP4 mediated degradation on coronary microcirculation in overweight adults.

Effects of GLP-1 on counter-regulatory responses during hypoglycemia after GBP surgery.

The aim of the study was to explore the role of GLP-1 receptor activation on the counter-regulation and symptoms of hypoglycemia in subjects who have undergone gastric bypass surgery (GBP). Experimental hyperinsulinemic-hypoglycemic clamp study. Twelve post-GBP subjects participated in a randomized cross-over study with two hyperinsulinemic, hypoglycemic clamps (glucose nadir 2.7 mmol/L) performed on separate days with concomitant infusions of the GLP-1 analog exenatide or with saline, respectively. Continuous measurements of metabolites and counter-regulatory hormones as well as assessments of heart rate variability and symptoms of hypoglycemia were performed throughout the clamps. No effect of GLP-1 receptor activation on counter-regulatory hormones (glucagon, catecholamines, cortisol, GH) or glucose infusion rate was seen, but we found indications of a downregulation of the sympathetic relative to the parasympathetic nerve activity, as reflected in heart rate variability. No significant differences in symptom of hypoglycemia were observed. Short-term exposure to a GLP-1 receptor agonist does not seem to impact the counter-regulatory hormonal and metabolic responses in post-GBP subjects during hypoglycemic conditions, suggesting that the improvement in symptomatic hypoglycemia post-GBP seen following treatment with GLP-1 receptor agonists may be mediated by mechanism not directly involved in counter-regulation.

Santral GLP-1'in Gastrik Mukozal Kan Akımına Etkisi; Spesifik Reseptörlerin Rolü

Amaç: İntraserebroventriküler (ICV) olarak enjekte edilen 'glucagon like peptid-1 (GLP-1)'in sıçanlarda gastrik mukozal kan akımı [gastric mucosal blood flow (GMBF)]'na etkisi, bu etkide santral spesifik reseptörlerinin rolü ve ayrıca absolu etanolün GMBF'de neden olduğu değişikliklerin üzerindeki etkisinin araştırılmasıdır. Gereç ve Yöntemler: ICV enjeksiyonlar için izofloran (%4) anestezisi altında sıçanların kafatasına orta hattın 1,5 mm sağ yanında ve bregmanın 1-1,5 mm arkasında olacak şekilde bir delik açıldı. Bu delikten sağ lateral ventriküle, dik olarak ve alt ucu kafatası yüzeyinden 4,2-4,5 mm kadar derinliğe inecek şekilde 10 mm uzunluğunda bir kanül yerleştirildi. GMBF 'Laser Doppler flowmetre' ile ölçülerek, veriler 'MP30 Data Acquisition System' aracılığıyla bilgisayara aktarıldı. Ölçümler için anestezi altındaki sıçanlarda mide hazırlandıktan sonra mide mukozasına prob yerleştirilerek kalibrasyon için 30 dk beklendi ve bazal kan akımı ölçümleri kaydedildi. GLP-1'in GMBF'deki etkisini araştırmak amacıyla, GLP-1 (3, 10 ve 30 μg/10 μL; ICV) veya serum fizyolojik (10 μL; ICV) enjekte edildi. Spesifik reseptör antagonisti exendin-(9-39) (1 μg/10 μL; ICV) enjekte edildikten 5 dk sonra 10 μg GLP- 1 enjekte edildi. Enjeksiyonları takiben gastrik çember içine serum fizyolojik (1,5 mL) uygulandı ve 30 dak süresince her 5 dk'da gastrik kan akımı kaydedildi. Absolu etanolün GMBF'de neden olduğu değişikler üzerinde GLP-1'in etkisini araştırmak için sıçanlara 10 μg GLP-1 enjeksiyonundan 5 dk sonra gastrik çember içine etanol (1,5 mL) uygulandı. Bulgular: 10 μg ICV GLP-1 GMBF'yi arttırdı ve ICV eksendin- (9-39) bu etkiyi antagonize etti. Ayrıca GLP-1 absolu etanolün GMBF'de oluşturduğu inhibisyonu azalttı. 3 ve 30 μg GLP-1 ise GMBF'yi azalttı. Sonuç: ICV olarak enjekte edilen 10 μg GLP-1'in GMBF'yi artırdığı ve bu etkide, santral spesifik reseptörlerinin rolü olduğu düşünülmektedir. Aynı zamanda santral GLP-1'in GMBF'deki etanol nedenli inhibisyonu önleyebildiği gözlenmiştir. Diğer dozlar ise GMBF'de azalmaya neden olmuştur.