Abstract 438: Peripheral but Not Central Glucagon-Like Peptide-1 Receptor Agonism Regulates Fasting Dyslipidemia by Reducing VLDL Production

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Jennifer Taher ◽  
Chris Baker ◽  
Carmelle Cuizon ◽  
Mark Naples ◽  
Sarah Farr ◽  
...  

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that reduces plasma glucose levels and thus acts as an important drug target in the treatment of type 2 diabetes (T2D). Our laboratory has further shown that GLP-1 regulates intestinal lipoprotein metabolism and may also play a similar role in the liver. Hepatic lipids are packaged with apolipoprotein B-100 (apoB100) into very low density lipoproteins (VLDL) and secreted into the plasma. Dysregulation of VLDL production results in the fasting dyslipidemia that is observed in T2D. We postulate that GLP-1 receptor (GLP-1R) agonism regulates fasting dyslipidemia by decreasing VLDL production in insulin resistance through a peripheral or central pathway. To test this, experiments were conducted in fructose-fed insulin resistant Syrian golden hamsters. Hamsters were given twice daily intraperitoneal(i.p) injections of the GLP-1R agonist exendin-4 (ex4; 5nM/kg) for 7 days and placed into metabolic cages. Plasma was collected for lipid analysis following i.p poloxamer to prevent lipoprotein uptake and livers were excised. Peripheral ex4 prevented fructose-induced fasting dyslipidemia and decreased fasting plasma- and VLDL-triglyceride (TG), -cholesterol and -apoB100 accumulation. Ex4 also reduced food intake and body weight and thus pair-fed controls were added. Pair-feeding did not account for the full ex4 lipid-lowering effect. In comparison to both controls, ex4 treated hamsters had reduced respiratory exchange ratio and CO 2 production indicating a switch from glucose to fat metabolism as the main source of energy, and also decreased hepatic mRNA markers for de novo lipogenesis. To determine involvement of a central pathway, hamsters received a 4 day intracerebroventricular administration of ex4 (250ng) into the third ventricle. Central ex4 reduced body weight and food intake but did not modulate fasting plasma and VLDL-lipid or apoB100 accumulation, further suggesting that decreases in food intake cannot solely explain the changes in VLDL production. Our studies suggest that GLP-1R agonism reduces fasting dyslipidemia in insulin resistance by decreasing VLDL production through a peripheral pathway. GLP-1R agonism may be a potential therapy in the treatment of fasting dyslipidemia.

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Jeremy D. Coplan ◽  
Shariful Syed ◽  
Tarique D. Perera ◽  
Sasha L. Fulton ◽  
Mary Ann Banerji ◽  
...  

Glucagon-like peptide-1 (GLP-1) regulates carbohydrate metabolism and promotes neurogenesis. We reported an inverse correlation between adult body mass and neurogenesis in nonhuman primates. Here we examine relationships between physiological levels of the neurotrophic incretin, plasma GLP-1 (pGLP-1), and body mass index (BMI) in adolescence to adult neurogenesis and associations with a diabesity diathesis and infant stress. Morphometry, fasting pGLP-1, insulin resistance, and lipid profiles were measured in early adolescence in 10 stressed and 4 unstressed male bonnet macaques. As adults, dentate gyrus neurogenesis was assessed by doublecortin staining. High pGLP-1, low body weight, and low central adiposity, yet peripheral insulin resistance and high plasma lipids, during adolescence were associated with relatively high adult neurogenesis rates. High pGLP-1 also predicted low body weight with, paradoxically, insulin resistance and high plasma lipids. No rearing effects for neurogenesis rates were observed. We replicated an inverse relationship between BMI and neurogenesis. Adolescent pGLP-1 directly predicted adult neurogenesis. Two divergent processes relevant to human diabesity emerge—high BMI, low pGLP-1, and low neurogenesis and low BMI, high pGLP-1, high neurogenesis, insulin resistance, and lipid elevations. Diabesity markers putatively reflect high nutrient levels necessary for neurogenesis at the expense of peripheral tissues.


2002 ◽  
Vol 440 (2-3) ◽  
pp. 269-279 ◽  
Author(s):  
Juris J. Meier ◽  
Baptist Gallwitz ◽  
Wolfgang E. Schmidt ◽  
Michael A. Nauck

Endocrinology ◽  
1999 ◽  
Vol 140 (1) ◽  
pp. 244-250 ◽  
Author(s):  
Karim Meeran ◽  
Donal O’Shea ◽  
C. Mark B. Edwards ◽  
Mandy D. Turton ◽  
Melanie M. Heath ◽  
...  

Abstract Central nervous system glucagon-like peptide-1-(7–36) amide (GLP-1) administration has been reported to acutely reduce food intake in the rat. We here report that repeated intracerebroventricular (icv) injection of GLP-1 or the GLP-1 receptor antagonist, exendin-(9–39), affects food intake and body weight. Daily icv injection of 3 nmol GLP-1 to schedule-fed rats for 6 days caused a reduction in food intake and a decrease in body weight of 16 ± 5 g (P < 0.02 compared with saline-injected controls). Daily icv administration of 30 nmol exendin-(9–39) to schedule-fed rats for 3 days caused an increase in food intake and increased body weight by 7 ± 2 g (P < 0.02 compared with saline-injected controls). Twice daily icv injections of 30 nmol exendin-(9–39) with 2.4 nmol neuropeptide Y to ad libitum-fed rats for 8 days increased food intake and increased body weight by 28 ± 4 g compared with 14 ± 3 g in neuropeptide Y-injected controls (P < 0.02). There was no evidence of tachyphylaxis in response to icv GLP-1 or exendin-(9–39). GLP-1 may thus be involved in the regulation of body weight in the rat.


2004 ◽  
Vol 287 (5) ◽  
pp. R1190-R1193 ◽  
Author(s):  
Harvey J. Grill ◽  
Jill S. Carmody ◽  
L. Amanda Sadacca ◽  
Diana L. Williams ◽  
Joel M. Kaplan

The central glucagon-like peptide-1 (GLP-1) system has been implicated in the control of feeding behavior. Here we explore GLP-1 mediation of the anorexic response to administration of systemic LPS and address the relative importance of caudal brain stem and forebrain GLP-1 receptor (GLP-1-R) for the mediation of the response. Fourth-intracerebroventricular delivery of the GLP-1-R antagonist exendin-(9–39) (10 μg) did not itself affect food intake in the 24 h after injection but significantly attenuated the otherwise robust (∼60%) reduction in food intake obtained after LPS (100 μg/kg) treatment. This result highlights a role for caudal brain stem GLP-1-R in the mediation of LPS anorexia but does not rule out the possibility that forebrain receptors also contribute to the response. Forebrain contribution was addressed by delivery of the GLP-1-R antagonist to the third ventricle with the caudal flow of cerebrospinal fluid blocked by occlusion of the cerebral aqueduct. Exendin-(9–39) delivery thus limited to forebrain did not attenuate the anorexic response to LPS. These data suggest that LPS anorexia is mediated, in part, by release of the native peptide acting on GLP-1-R within the caudal brain stem.


2013 ◽  
Vol 221 (1) ◽  
pp. T1-T16 ◽  
Author(s):  
L van Bloemendaal ◽  
J S ten Kulve ◽  
S E la Fleur ◽  
R G Ijzerman ◽  
M Diamant

The delivery of nutrients to the gastrointestinal tract after food ingestion activates the secretion of several gut-derived mediators, including the incretin hormone glucagon-like peptide 1 (GLP-1). GLP-1 receptor agonists (GLP-1RA), such as exenatide and liraglutide, are currently employed successfully in the treatment of patients with type 2 diabetes mellitus. GLP-1RA improve glycaemic control and stimulate satiety, leading to reductions in food intake and body weight. Besides gastric distension and peripheral vagal nerve activation, GLP-1RA induce satiety by influencing brain regions involved in the regulation of feeding, and several routes of action have been proposed. This review summarises the evidence for a physiological role of GLP-1 in the central regulation of feeding behaviour and the different routes of action involved. Also, we provide an overview of presently available data on pharmacological stimulation of GLP-1 pathways leading to alterations in CNS activity, reductions in food intake and weight loss.


Endocrinology ◽  
2011 ◽  
Vol 152 (8) ◽  
pp. 3103-3112 ◽  
Author(s):  
Scott E. Kanoski ◽  
Samantha M. Fortin ◽  
Myrtha Arnold ◽  
Harvey J. Grill ◽  
Matthew R. Hayes

The long-acting glucagon-like peptide-1 receptor (GLP-1R) agonists, exendin-4 and liraglutide, suppress food intake and body weight. The mediating site(s) of action for the anorectic effects produced by peripheral administration of these GLP-1R agonists are not known. Experiments addressed whether food intake suppression after ip delivery of exendin-4 and liraglutide is mediated exclusively by peripheral GLP-1R or also involves direct central nervous system (CNS) GLP-1R activation. Results showed that CNS delivery [third intracerebroventricular (3rd ICV)] of the GLP-1R antagonist exendin-(9–39) (100 μg), attenuated the intake suppression by ip liraglutide (10 μg) and exendin-4 (3 μg), particularly at 6 h and 24 h. Control experiments show that these findings appear to be based neither on the GLP-1R antagonist acting as a nonspecific competing orexigenic signal nor on blockade of peripheral GLP-1R via efflux of exendin-(9–39) to the periphery. To assess the contribution of GLP-1R expressed on subdiaphragmatic vagal afferents to the anorectic effects of liraglutide and exendin-4, food intake was compared in rats with complete subdiaphragmatic vagal deafferentation and surgical controls after ip delivery of the agonists. Both liraglutide and exendin-4 suppressed food intake at 3 h, 6 h, and 24 h for controls; for subdiaphragmatic vagal deafferentation rats higher doses of the GLP-1R agonists were needed for significant food intake suppression, which was observed at 6 h and 24 h after liraglutide and at 24 h after exendin-4. Conclusion: Food intake suppression after peripheral administration of exendin-4 and liraglutide is mediated by activation of GLP-1R expressed on vagal afferents as well as direct CNS GLP-1R activation.


2013 ◽  
Vol 110 (40) ◽  
pp. 16199-16204 ◽  
Author(s):  
R. Shirazi ◽  
V. Palsdottir ◽  
J. Collander ◽  
F. Anesten ◽  
H. Vogel ◽  
...  

2014 ◽  
Vol 306 (7) ◽  
pp. R490-R498 ◽  
Author(s):  
Krystyna Tatarkiewicz ◽  
Emmanuel J. Sablan ◽  
Clara J. Polizzi ◽  
Christiane Villescaz ◽  
David G. Parkes

Glucagon-like peptide 1 receptors (GLP-1R) are expressed in multiple tissues and activation results in metabolic benefits including enhanced insulin secretion, slowed gastric emptying, suppressed food intake, and improved hepatic steatosis. Limited and inconclusive knowledge exists regarding whether the effects of chronic exposure to a GLP-1R agonist are solely mediated via this receptor. Therefore, we examined 3-mo dosing of exenatide in mice lacking a functional GLP-1R (Glp1r−/−). Exenatide (30 nmol·kg−1·day−1) was infused subcutaneously for 12 wk in Glp1r−/− and wild-type (Glp1r+/+) control mice fed a high-fat diet. Glycated hemoglobin A1c (HbA1c), plasma glucose, insulin, amylase, lipase, alanine aminotransferase (ALT), aspartate aminotransferase (AST), body weight, food intake, terminal hepatic lipid content (HLC), and plasma exenatide levels were measured. At the end of the study, oral glucose tolerance test (OGTT) and rate of gastric emptying were assessed. Exenatide produced no significant changes in Glp1r−/− mice at study end. In contrast, exenatide decreased body weight, food intake, and glucose in Glp1r+/+ mice. When compared with vehicle, exenatide reduced insulin, OGTT glucose AUC0–2h, ALT, and HLC in Glp1r+/+ mice. Exenatide had no effect on plasma amylase or lipase levels. Exenatide concentrations were approximately eightfold higher in Glp1r−/− versus Glp1r+/+ mice after 12 wk of infusion, whereas renal function was similar. These data support the concept that exenatide requires a functional GLP-1R to exert chronic metabolic effects in mice, and that novel “GLP-1” receptors may not substantially contribute to these changes. Differential exenatide plasma levels in Glp1r+/+ versus Glp1r−/− mice suggest that GLP-1R may play an important role in plasma clearance of exenatide and potentially other GLP-1-related peptides.


2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Laiyuan Li ◽  
Xiaolin Wang ◽  
Liangliang Bai ◽  
Huichuan Yu ◽  
Zenghong Huang ◽  
...  

Purpose. To investigate the effects of sleeve gastrectomy (SG) on glucose metabolism and changes in glucagon-like peptide 1 (GLP-1) in Goto-Kakizaki (GK) rats. Methods. GK rats were randomly assigned to one of three groups: SG, SG pair-fed plus sham surgery (PF-sham), and ad libitum-fed no surgery (control). Food intake, body weight, blood glucose, GLP-1 and insulin levels, and GLP-1 expression in the jejunum and ileum were compared. Results. The SG rats exhibited lower postoperative food intake, body weight, and fasting glucose than did the control rats (P<0.05). SG significantly improved glucose and insulin tolerance (P<0.05). Plasma GLP-1 levels were higher in SG rats than in control or PF-sham rats in the oral glucose tolerance test (OGTT) (P<0.05). Blood glucose levels expressed as a percentage of baseline were higher in SG rats than in control rats after exendin (9-39) administration (P<0.05). The levels of GLP-1 expression in the jejunum and ileum were higher in SG rats than in PF-sham and control rats (P<0.05). Conclusions. Improvement of glucose metabolism by SG was associated with increased GLP-1 secretion. SG contributes to an increase in plasma GLP-1 levels via increased GLP-1 expression in the mucosa of the jejunum and/or ileum.


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