scholarly journals Glucagon-Like Peptide-1 (GLP-1) in the Integration of Neural and Endocrine Responses to Stress

Nutrients ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3304
Author(s):  
Yolanda Diz-Chaves ◽  
Salvador Herrera-Pérez ◽  
Lucas C. González-Matías ◽  
José Antonio Lamas ◽  
Federico Mallo

Glucagon like-peptide 1 (GLP-1) within the brain is produced by a population of preproglucagon neurons located in the caudal nucleus of the solitary tract. These neurons project to the hypothalamus and another forebrain, hindbrain, and mesolimbic brain areas control the autonomic function, feeding, and the motivation to feed or regulate the stress response and the hypothalamic-pituitary-adrenal axis. GLP-1 receptor (GLP-1R) controls both food intake and feeding behavior (hunger-driven feeding, the hedonic value of food, and food motivation). The activation of GLP-1 receptors involves second messenger pathways and ionic events in the autonomic nervous system, which are very relevant to explain the essential central actions of GLP-1 as neuromodulator coordinating food intake in response to a physiological and stress-related stimulus to maintain homeostasis. Alterations in GLP-1 signaling associated with obesity or chronic stress induce the dysregulation of eating behavior. This review summarized the experimental shreds of evidence from studies using GLP-1R agonists to describe the neural and endocrine integration of stress responses and feeding behavior.

Author(s):  
David J. Nutt ◽  
Liam J. Nestor

Many of the same behavioural and brain disturbances observed in addiction are also seen in obesity and binge-eating disorder. This suggests that there are shared neural substrates between substance addiction and compulsive food consumption. Food intake and appetite are regulated by numerous appetite hormones that exert their effects through brain systems involved in reward sensitivity, stress, impulsivity, and compulsivity. There is now emerging evidence that appetite hormones (e.g. ghrelin, glucagon-like peptide-1, orexin) can modulate addictive behaviours (e.g. craving) and the intake of alcohol and drugs. Therefore, there is an emerging shift into a new field of testing drugs that affect appetite hormones and their receptors in the brain, and their use in regulating the brain mechanisms that lead to relapse in addiction disorders.


2016 ◽  
Vol 311 (1) ◽  
pp. R115-R123 ◽  
Author(s):  
Fredrik Anesten ◽  
Marie K. Holt ◽  
Erik Schéle ◽  
Vilborg Pálsdóttir ◽  
Frank Reimann ◽  
...  

Neuronal circuits in the hypothalamus and hindbrain are of importance for control of food intake, energy expenditure, and fat mass. We have recently shown that treatment with exendin-4 (Ex-4), an analog of the proglucagon-derived molecule glucagon-like peptide 1 (GLP-1), markedly increases mRNA expression of the cytokine interleukin-6 (IL-6) in the hypothalamus and hindbrain and that this increase partly mediates the suppression of food intake and body weight by Ex-4. Endogenous GLP-1 in the central nervous system (CNS) is produced by preproglucagon (PPG) neurons of the nucleus of the solitary tract (NTS) in the hindbrain. These neurons project to various parts of the brain, including the hypothalamus. Outside the brain, IL-6 stimulates GLP-1 secretion from the gut and pancreas. In this study, we aim to investigate whether IL-6 can affect GLP-1-producing PPG neurons in the nucleus of the solitary tract (NTS) in mouse hindbrain via the ligand binding part of the IL-6 receptor, IL-6 receptor-α (IL-6Rα). Using immunohistochemistry, we found that IL-6Rα was localized on PPG neurons of the NTS. Recordings of these neurons in GCaMP3/GLP-1 reporter mice showed that IL-6 enhances cytosolic Ca2+ concentration in neurons capable of expressing PPG. We also show that the Ca2+ increase originates from the extracellular space. Furthermore, we found that IL-6Rα was localized on cells in the caudal hindbrain expressing immunoreactive NeuN (a neuronal marker) or CNP:ase (an oligodendrocyte marker). In summary, IL-6Rα is present on PPG neurons in the NTS, and IL-6 can stimulate these cells by increasing influx of Ca2+ to the cytosol from the extracellular space.


2003 ◽  
Vol 284 (6) ◽  
pp. R1427-R1435 ◽  
Author(s):  
Rafael R. Schick ◽  
Jens P. Zimmermann ◽  
Thomas vorm Walde ◽  
Volker Schusdziarra

Glucagon-like peptide 1-(7–36) amide (GLP-1) potently inhibits rat feeding behavior after central administration. Because third ventricular injection of GLP-1 appeared to be less effective than lateral ventricular injection, we have reexamined this issue. In addition, we attempted to identify brain regions other than the paraventricular nucleus of the hypothalamus that are sensitive toward GLP-1-induced feeding suppression. Finally, we examined the local role of endogenous GLP-1 by specific GLP-1 receptor blockade. After lateral ventricular injection, GLP-1 significantly inhibited food intake of 24-h-fasted rats in a dose-dependent fashion with a minimal effective dose of 1 μg. After third ventricular injection, GLP-1 (1 μg) was similarly effective in suppressing food intake, which extends previous findings. Intracerebral microinjections of GLP-1 significantly suppressed food intake in the lateral (LH), dorsomedial (DMH), and ventromedial hypothalamus (VMH), but not in the medial nucleus of the amygdala. The minimal effective dose of GLP-1 was 0.3 μg at LH sites and 1 μg at DMH or VMH sites. LH microinjections of exendin-(9–39) amide, a GLP-1 receptor antagonist, at 1 or 2.5 μg did not alter feeding behavior in 24-h-fasted rats. In satiated animals, however, a single LH injection of 1 μg exendin-(9–39) amide significantly augmented food intake, but only during the first 20 min (0.6 vs. 0.1 g). With three repeated injections of 2.5 μg exendin-(9–39) amide every 20 min, 1-h food intake was significantly increased by 300%. These data strongly support and extend the concept of GLP-1 as a physiological regulator of food intake in the hypothalamus.


Endocrinology ◽  
2009 ◽  
Vol 150 (7) ◽  
pp. 2997-3001 ◽  
Author(s):  
Diana L. Williams

Glucagon-like peptide 1 (GLP-1) is both a gut-derived hormone and a neurotransmitter synthesized in the brain. Early reports suggested that GLP-1 acts in the periphery to promote insulin secretion and affect glucose homeostasis, whereas central GLP-1 reduces food intake and body weight. However, current research indicates that in fact, GLP-1 in each location plays a role in these functions. This review summarizes the evidence for involvement of peripheral and brain GLP-1 in food intake regulation and glucose homeostasis and proposes a model for the coordinated actions of GLP-1 at multiple sites.


Antioxidants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1118
Author(s):  
Jan Homolak ◽  
Ana Babic Perhoc ◽  
Ana Knezovic ◽  
Jelena Osmanovic Barilar ◽  
Melita Salkovic-Petrisic

The gastrointestinal system may be involved in the etiopathogenesis of the insulin-resistant brain state (IRBS) and Alzheimer’s disease (AD). Gastrointestinal hormone glucagon-like peptide-1 (GLP-1) is being explored as a potential therapy as activation of brain GLP-1 receptors (GLP-1R) exerts neuroprotection and controls peripheral metabolism. Intracerebroventricular administration of streptozotocin (STZ-icv) is used to model IRBS and GLP-1 dyshomeostasis seems to be involved in the development of neuropathological changes. The aim was to explore (i) gastrointestinal homeostasis in the STZ-icv model (ii) assess whether the brain GLP-1 is involved in the regulation of gastrointestinal redox homeostasis and (iii) analyze whether brain-gut GLP-1 axis is functional in the STZ-icv animals. Acute intracerebroventricular treatment with exendin-3(9-39)amide was used for pharmacological inhibition of brain GLP-1R in the control and STZ-icv rats, and oxidative stress was assessed in plasma, duodenum and ileum. Acute inhibition of brain GLP-1R increased plasma oxidative stress. TBARS were increased, and low molecular weight thiols (LMWT), protein sulfhydryls (SH), and superoxide dismutase (SOD) were decreased in the duodenum, but not in the ileum of the controls. In the STZ-icv, TBARS and CAT were increased, LMWT and SH were decreased at baseline, and no further increment of oxidative stress was observed upon central GLP-1R inhibition. The presented results indicate that (i) oxidative stress is increased in the duodenum of the STZ-icv rat model of AD, (ii) brain GLP-1R signaling is involved in systemic redox regulation, (iii) brain-gut GLP-1 axis regulates duodenal, but not ileal redox homeostasis, and iv) brain-gut GLP-1 axis is dysfunctional in the STZ-icv model.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu Liu ◽  
Lizhen Wang ◽  
Donghui Pan ◽  
Mingzhu Li ◽  
Yaoqi Li ◽  
...  

AbstractLight therapy has been accepted as a promising therapeutic choice for depression. Positron emission tomography (PET) combined with specific radiotracers has great benefits for revealing pathogenesis and developing therapeutics. This study aimed to investigate the influences of light therapy on microglial activation and glucagon-like peptide-1 receptor (GLP-1R) expression in the brain of depressive rats using [18F]DPA-714 and [18F]exendin-4 PET. The results showed that chronic unpredictable mild stress (CUMS)-induced depressive rats had poorer performance in behavioral tests compared to normal rats (p < 0.05) and the depressive-like behavior could be ameliorated by light therapy. Besides, depressive rats had significantly higher [18F]DPA-714 uptake and lower [18F]FDG uptake compare to normal rats in 11 and 9 regions of interest (ROIs) of the brain, respectively (p < 0.05). After 5 weeks of light therapy, higher [18F]FDG and [18F]exendin-4 uptake was observed in most ROIs of light therapy-treated depressive rats compared to untreated depressive rats (p < 0.05) and no significant differences existed in [18F]DPA-714 uptake between the two groups. This study demonstrated that light therapy can ameliorate depressive-like behavior, improve glucose metabolism, and halt the decline of brain GLP-1R expression of depressive rats, but have no effects on microglial activation caused by CUMS. Besides, this study validated that [18F]DPA-714 and [18F]exendin-4 PET have the potential for noninvasive evaluation of microglial activation and GLP-1R expression in the brain of depression.


2013 ◽  
Vol 304 (7) ◽  
pp. E677-E685 ◽  
Author(s):  
Melissa A. Burmeister ◽  
Jennifer Ayala ◽  
Daniel J. Drucker ◽  
Julio E. Ayala

Glucagon-like peptide-1 (GLP-1) suppresses food intake via activation of a central (i.e., brain) GLP-1 receptor (GLP-1R). Central AMP-activated protein kinase (AMPK) is a nutrient-sensitive regulator of food intake that is inhibited by anorectic signals. The anorectic effect elicited by hindbrain GLP-1R activation is attenuated by the AMPK stimulator AICAR. This suggests that central GLP-1R activation suppresses food intake via inhibition of central AMPK. The present studies examined the mechanism(s) by which central GLP-1R activation inhibits AMPK. Supporting previous findings, AICAR attenuated the anorectic effect elicited by intracerebroventricular (icv) administration of the GLP-1R agonist exendin-4 (Ex-4). We demonstrate that Ex-4 stimulates glycolysis and suppresses AMPK phosphorylation in a glucose-dependent manner in hypothalamic GT1-7 cells. This suggests that inhibition of AMPK and food intake by Ex-4 requires central glucose metabolism. Supporting this, the glycolytic inhibitor 2-deoxyglucose (2-DG) attenuated the anorectic effect of Ex-4. However, icv glucose did not enhance the suppression of food intake by Ex-4. AICAR had no effect on Ex-4-mediated reduction in locomotor activity. We also tested whether other carbohydrates affect the anorectic response to Ex-4. Intracerebroventricular pretreatment with the sucrose metabolite fructose, an AMPK activator, attenuated the anorectic effect of Ex-4. This potentially explains the increased food intake observed in sucrose-fed mice. In summary, we propose a model whereby activation of the central GLP-1R reduces food intake via glucose metabolism-dependent inhibition of central AMPK. We also suggest that fructose stimulates food intake by impairing central GLP-1R action. This has significant implications given the correlation between sugar consumption and obesity.


2016 ◽  
Vol 310 (10) ◽  
pp. R906-R916 ◽  
Author(s):  
Alison D. Kreisler ◽  
Linda Rinaman

Published research supports a role for central glucagon-like peptide 1 (GLP-1) signaling in suppressing food intake in rodent species. However, it is unclear whether GLP-1 neurons track food intake and contribute to satiety, and/or whether GLP-1 signaling contributes to stress-induced hypophagia. To examine whether GLP-1 neurons track intake volume, rats were trained to consume liquid diet (LD) for 1 h daily until baseline intake stabilized. On test day, schedule-fed rats consumed unrestricted or limited volumes of LD or unrestricted volumes of diluted (calorically matched to LD) or undiluted Ensure. Rats were perfused after the test meal, and brains processed for immunolocalization of cFos and GLP-1. The large majority of GLP-1 neurons expressed cFos in rats that consumed satiating volumes, regardless of diet type, with GLP-1 activation proportional to intake volume. Since GLP-1 signaling may limit intake only when such large proportions of GLP-1 neurons are activated, a second experiment examined the effect of central GLP-1 receptor (R) antagonism on 2 h intake in schedule-fed rats. Compared with baseline, intracerebroventricular vehicle (saline) suppressed Ensure intake by ∼11%. Conversely, intracerebroventricular injection of vehicle containing GLP-1R antagonist increased intake by ∼14% compared with baseline, partly due to larger second meals. We conclude that GLP-1 neural activation effectively tracks liquid diet intake, that intracerebroventricular injection suppresses intake, and that central GLP-1 signaling contributes to this hypophagic effect. GLP-1 signaling also may contribute to satiety after large volumes have been consumed, but this potential role is difficult to separate from a role in the hypophagic response to intracerebroventricular injection.


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