Differential Effects of Intra-Ventral Tegmental Area Ghrelin and Glucagon-like Peptide-1 on the Stimulatory Action of D-Amphetamine and Cocaine-Induced Ethanol Intake in Male Sprague Dawley Rats

2021 ◽  
pp. 113726
Author(s):  
Kayla J. Colvin ◽  
Henry S. Killen ◽  
Maxwell J. Kanter ◽  
Maximilian C. Halperin ◽  
Liv Engel ◽  
...  
Keyword(s):  
Ventral Tegmental Area ◽  
Ethanol Intake ◽  
Sprague Dawley ◽  
Stimulatory Action ◽  
Differential Effects ◽  
Sprague Dawley Rats ◽  
Glucagon Like Peptide ◽  
Ventral Tegmental ◽  
Glucagon Like Peptide 1

scholarly journals Glucagon-Like Peptide-1 (GLP-1) and 5-Hydroxytryptamine 2c (5-HT2c) Receptor Agonists in the Ventral Tegmental Area (VTA) Inhibit Ghrelin-Stimulated Appetitive Reward

2019 ◽  
Vol 20 (4) ◽  
pp. 889 ◽  
Author(s):  
Erin Howell ◽  
Hannah Baumgartner ◽  
Lia Zallar ◽  
Joaquín Selva ◽  
Liv Engel ◽  
...  
Keyword(s):  
Ventral Tegmental Area ◽  
Receptor Agonist ◽  
Food Reinforcement ◽  
Progressive Ratio ◽  
Sprague Dawley ◽  
Operant Responding ◽  
Orexigenic Peptide ◽  
Glucagon Like Peptide ◽  
Ventral Tegmental ◽  
Glucagon Like Peptide 1

Current literature indicates that the orexigenic peptide ghrelin increases appetitive motivation via signaling in the mesolimbic reward system. Another gastric peptide, glucagon-like peptide-1 (GLP-1), and the neurotransmitter 5-hydroxytryptamine (5-HT), are both known to suppress operant responding for food by acting on key mesolimbic nuclei, including the ventral tegmental area (VTA). In order to investigate the interaction effects of ghrelin, GLP-1, and 5-HT within the VTA, we measured operant responding for sucrose pellets after the administration of ghrelin, the GLP-1 receptor agonist exendin-4 (Ex-4), and the 5-HT2c receptor agonist Ro60-0175 in male Sprague-Dawley rats. Following training on a progressive ratio 3 (PR3) schedule, animals were first injected with ghrelin into the VTA at doses of 3 to 300 pmol. In subsequent testing, separate rats were administered intraperitoneal (IP) Ex-4 (0.1–1.0 µg/kg) or VTA Ex-4 (0.01–0.1 µg) paired with 300 pmol ghrelin. In a final group of rats, the 5-HT2c agonist Ro60-0175 was injected IP (0.25–1.0 mg/kg) or into the VTA (1.5–3.0 µg), and under both conditions paired with 300 pmol ghrelin delivered into the VTA. Our results indicated that ghrelin administration increased operant responding for food reward and that this effect was attenuated by IP and VTA Ex-4 pretreatment as well as pre-administration of IP or VTA Ro60-0175. These data provide compelling evidence that mesolimbic GLP-1 and serotonergic circuitry interact with the ghrelinergic system to suppress ghrelin’s effects on the mediation of food reinforcement.

Glucagon-like peptide-1 response to whey protein is less diminished by dipeptidyl peptidase-4 in comparison with responses to dextrin, a lipid and casein in rats

2020 ◽  
pp. 1-10 ◽  
Author(s):  
Yuki Shimizu ◽  
Hiroshi Hara ◽  
Tohru Hira
Keyword(s):  
Whey Protein ◽  
Dipeptidyl Peptidase ◽  
Dietary Proteins ◽  
Sprague Dawley ◽  
Dipeptidyl Peptidase 4 ◽  
Sprague Dawley Rats ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Abstract Although glucose is the best-known nutrient to stimulate glucagon-like peptide-1 (GLP-1) secretion, dietary peptides also potently stimulate GLP-1 secretion. Certain peptide fragments derived from dietary proteins possess dipeptidyl peptidase-4 (DPP-4) inhibitory activity in vitro. Hence, we hypothesised that dietary peptides protect GLP-1 from degradation through attenuating DPP-4 activity in vivo. Here, we compared GLP-1 responses with dietary proteins, a carbohydrate and a lipid (Intralipos) in rats having or not having plasma DPP-4 activity. Plasma GLP-1 concentrations clearly increased by oral administration of whey protein (2–4 g/kg), but not by that of dextrin (2–4 g/kg), in control rats (untreated Sprague–Dawley rats and F344/Jcl rats), having DPP-4 activity. In contrast, dextrin administration increased the plasma GLP-1 concentrations as the whey protein administration did, in rats having reduced or no DPP-4 activity (a DPP-4 inhibitor, sitagliptin-treated Sprague–Dawley rats or DPP-4-deficient F344/DuCrl/Crlj rats). DPP-4 inhibition by sitagliptin treatment also enhanced GLP-1 response to Intralipos, and casein, but the treatment did not further enhance GLP-1 response to whey protein. Intestinal GLP-1 content and gastric emptying rate were not associated with differences in GLP-1 responses to test nutrients. The luminal contents from rats administered whey protein decreased DPP-4 activity in vitro. These results suggest that GLP-1 released by dextrin, Intralipos and casein was immediately degraded by DPP-4, while GLP-1 released by whey protein was less degraded. Our study provides novel in vivo evidence supporting the hypothesis that dietary peptides not only stimulate GLP-1 secretion but also inhibit DPP-4 activity to potentiate GLP-1 response.

scholarly journals The food intake-suppressive effects of glucagon-like peptide-1 receptor signaling in the ventral tegmental area are mediated by AMPA/kainate receptors

2013 ◽  
Vol 305 (11) ◽  
pp. E1367-E1374 ◽  
Author(s):  
Elizabeth G. Mietlicki-Baase ◽  
Pavel I. Ortinski ◽  
Laura E. Rupprecht ◽  
Diana R. Olivos ◽  
Amber L. Alhadeff ◽  
...  
Keyword(s):  
Food Intake ◽  
Ventral Tegmental Area ◽  
Dopamine Neurons ◽  
Kainate Receptors ◽  
System Control ◽  
Receptor Signaling ◽  
Palatable Food ◽  
Glucagon Like Peptide ◽  
Ventral Tegmental ◽  
Glucagon Like Peptide 1

Glucagon-like peptide-1 receptor (GLP-1R) activation in the ventral tegmental area (VTA) is physiologically relevant for the control of palatable food intake. Here, we tested whether the food intake-suppressive effects of VTA GLP-1R activation are mediated by glutamatergic signaling within the VTA. Intra-VTA injections of the GLP-1R agonist exendin-4 (Ex-4) reduced palatable high-fat food intake in rats primarily by reducing meal size; these effects were mediated in part via glutamatergic AMPA/kainate but not NMDA receptor signaling. Additional behavioral data indicated that GLP-1R expressed specifically within the VTA can partially mediate the intake- and body weight-suppressive effects of systemically administered Ex-4, offering the intriguing possibility that this receptor population may be clinically relevant for food intake control. Intra-VTA Ex-4 rapidly increased tyrosine hydroxylase levels within the VTA, suggesting that GLP-1R activation modulates VTA dopaminergic signaling. Further evidence for this hypothesis was provided by electrophysiological data showing that Ex-4 increased the frequency of AMPA-mediated currents and reduced the paired/pulse ratio in VTA dopamine neurons. Together, these data provide novel mechanisms by which GLP-1R agonists in the mesolimbic reward system control for palatable food intake.

scholarly journals Glucagon-Like Peptide-1 Receptor Activation in the Ventral Tegmental Area Decreases the Reinforcing Efficacy of Cocaine

2015 ◽  
Vol 41 (7) ◽  
pp. 1917-1928 ◽  
Author(s):  
Heath D Schmidt ◽  
Elizabeth G Mietlicki-Baase ◽  
Kelsey Y Ige ◽  
John J Maurer ◽  
David J Reiner ◽  
...  
Keyword(s):  
Ventral Tegmental Area ◽  
Receptor Activation ◽  
Reinforcing Efficacy ◽  
Glucagon Like Peptide ◽  
Ventral Tegmental ◽  
Glucagon Like Peptide 1

scholarly journals The Effects of Mutual Interaction of Orexin-A and Glucagon-Like Peptide-1 on Reflex Swallowing Induced by SLN Afferents in Rats

2020 ◽  
Vol 21 (12) ◽  
pp. 4422
Author(s):  
Motoi Kobashi ◽  
Yuichi Shimatani ◽  
Masako Fujita ◽  
Yoshihiro Mitoh ◽  
Ryusuke Yoshida ◽  
...  
Keyword(s):  
Receptor Antagonist ◽  
Nucleus Tractus Solitarius ◽  
Superior Laryngeal Nerve ◽  
Mutual Interaction ◽  
Sprague Dawley ◽  
Orexin A ◽  
Medial Nucleus ◽  
Sprague Dawley Rats ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

(1) Background: Our previous studies revealed that orexin-A, an appetite-increasing peptide, suppressed reflex swallowing via the commissural part of the nucleus tractus solitarius (cNTS), and that glucagon-like peptide-1 (GLP-1), an appetite-reducing peptide, also suppressed reflex swallowing via the medial nucleus of the NTS (mNTS). In this study, we examined the mutual interaction between orexin-A and GLP-1 in reflex swallowing. (2) Methods: Sprague–Dawley rats under urethane–chloralose anesthesia were used. Swallowing was induced by electrical stimulation of the superior laryngeal nerve (SLN) and was identified by the electromyographic (EMG) signals obtained from the mylohyoid muscle. (3) Results: The injection of GLP-1 (20 pmol) into the mNTS reduced the swallowing frequency and extended the latency of the first swallow. These suppressive effects of GLP-1 were not observed after the fourth ventricular administration of orexin-A. After the injection of an orexin-1 receptor antagonist (SB334867) into the cNTS, an ineffective dose of GLP-1 (6 pmol) into the mNTS suppressed reflex swallowing. Similarly, the suppressive effects of orexin-A (1 nmol) were not observed after the injection of GLP-1 (6 pmol) into the mNTS. After the administration of a GLP-1 receptor antagonist (exendin-4(5-39)), an ineffective dose of orexin-A (0.3 nmol) suppressed reflex swallowing. (4) Conclusions: The presence of reciprocal inhibitory connections between GLP-1 receptive neurons and orexin-A receptive neurons in the NTS was strongly suggested.

scholarly journals Glucagon-like peptide-1 receptor activation in the ventral tegmental area attenuates cocaine seeking in rats

2018 ◽  
Vol 43 (10) ◽  
pp. 2000-2008 ◽  
Author(s):  
Nicole S. Hernandez ◽  
Kelsey Y. Ige ◽  
Elizabeth G. Mietlicki-Baase ◽  
Gian Carlo Molina-Castro ◽  
Christopher A. Turner ◽  
...  
Keyword(s):  
Ventral Tegmental Area ◽  
Receptor Activation ◽  
Cocaine Seeking ◽  
Glucagon Like Peptide ◽  
Ventral Tegmental ◽  
Glucagon Like Peptide 1

A functional role for central glucagon-like peptide-1 receptors in lithium chloride-induced anorexia

1999 ◽  
Vol 277 (5) ◽  
pp. R1537-R1540 ◽  
Author(s):  
Linda Rinaman
Keyword(s):  
Food Intake ◽  
Receptor Antagonist ◽  
Lithium Chloride ◽  
Neural Pathways ◽  
Sprague Dawley ◽  
Receptor Signalling ◽  
Sprague Dawley Rats ◽  
Licl Treatment ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

The present study sought to determine whether central glucagon-like peptide-1 (GLP-1)-receptor signalling contributes to the anorexigenic effects of systemically administered lithium chloride (LiCl). Male Sprague-Dawley rats with chronic intracerebroventricular (ICV) cannulas were acclimated to a feeding schedule that included daily 30-min access to palatable mash. In the first experiment, ICV infusion of a GLP-1-receptor antagonist [exendin-4-(3—39)] significantly attenuated (10 μg dose) or completely blocked (20 μg dose) the inhibition of food intake produced by subsequent ICV infusion of GLP-1-(7—36) amide (5 μg). In the second experiment, rats were infused with 0, 10, or 20 μg of the GLP-1-receptor antagonist ICV, followed by injection of 0.15 M LiCl (50 mg/kg ip) or the same volume of 0.15 M NaCl. The ability of LiCl treatment to suppress food intake was significantly attenuated in rats that were pretreated with the GLP-1-receptor antagonist. These results support the view that central mechanisms underlying LiCl-induced anorexia include a prominent role for endogenous GLP-1 neural pathways.

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