Loss of cholecystokinin and glucagon-like peptide-1-induced satiation in mice lacking serotonin 2C receptors

2009 ◽  
Vol 296 (1) ◽  
pp. R51-R56 ◽  
Author(s):  
Lori Asarian
Keyword(s):  
Neural Mechanisms ◽  
Wild Type ◽  
Gut Peptides ◽  
Serotonin Signaling ◽  
The Central Nervous System ◽  
Fos Expression ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
The Brain

To investigate the role of serotonin 2C receptors (2CR), which are expressed only in the central nervous system, in the satiating actions of the gut peptides CCK and glucagon-like peptide 1 (GLP-1), we examined 1) the effect of null mutations of serotonin 2CR (2CR KO) on the eating-inhibitory potencies of dark-onset intraperitoneal injections of 0.9, 1.7, or 3.5 nmol/kg (1, 2, or 4 μg/kg) CCK and 100, 200, and 400 nmol/kg (33, 66, or 132 μg/kg) GLP-1, and 2) the effects of intraperitoneal injections of 1.7 nmol//kg CCK and 100 nmol/kg GLP-1 on neuronal activation in the brain, as measured by c-Fos expression. All CCK and GLP-1 doses decreased 30-min food intake in wild-type (WT) mice, but none of them did in 2CR KO mice. CCK increased the number of cells expressing c-Fos in the nucleus tractus solitarii (NTS) of WT, but not 2CR KO mice. CCK induced similar degrees of c-Fos expression in the paraventricular (PVN) and arcuate (Arc) nuclei of the hypothalamus of both genotypes. GLP-1, on the other hand, increased c-Fos expression similarly in the NTS of both genotypes and increased c-Fos expression more in the PVN and Arc of 2CR KO mice, but not WT mice. These results indicate that serotonin signaling via serotonin 2CR is necessary for the full satiating effects of CCK and GLP-1. In addition, they suggest that the satiating effects of the two peptides are mediated by different neural mechanisms.

scholarly journals The Role of Central Glucagon-Like Peptide-1 in Mediating the Effects of Visceral Illness: Differential Effects in Rats and Mice

Endocrinology ◽  
2005 ◽  
Vol 146 (1) ◽  
pp. 458-462 ◽  
Author(s):  
Jennifer L. Lachey ◽  
David A. D’Alessio ◽  
Linda Rinaman ◽  
Joel K. Elmquist ◽  
Daniel J. Drucker ◽  
...  
Keyword(s):  
Neural Activation ◽  
Central Administration ◽  
Wild Type ◽  
Targeted Disruption ◽  
The Central Nervous System ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Rats And Mice ◽  
Do So

In rats, central administration of glucagon-like peptide-1 (GLP-1) elicits symptoms of visceral illness like those caused by the toxin lithium chloride (LiCl), including anorexia, conditioned taste aversion (CTA) formation, and neural activation in the hypothalamus and hindbrain including activation of brainstem preproglucagon cells. Most compellingly, pharmacological antagonists of the GLP-1 receptor (GLP-1R) block several effects of LiCl in rat. The major goal of these experiments was to further test the hypothesis that the central nervous system GLP-1 system is critical to the visceral illness actions of LiCl by using mice with a targeted disruption of the only described GLP-1R. First, we observed that, like the rat, LiCl activates preproglucagon neurons in wild-type mice. Second, GLP-1R −/− mice demonstrated normal anorexic and CTA responses to LiCl. To test the possibility that alternate GLP-1Rs mediate aversive effects, we examined the ability of GLP-1 to produce a CTA in GLP1R −/− mice. Although lateral ventricular GLP-1 produced a CTA in wild-type mice, it did not produce a CTA in GLP-1R −/− mice. Furthermore, the same GLP-1R antagonist that can block the aversive effects of LiCl in the rat failed to do so in the mouse. These results support the conclusion that in mouse, unlike in rat, GLP-1R signaling is not required for the visceral illness response to LiCl. Such species differences are an important consideration when comparing results from rat and mouse studies.

scholarly journals Effects of glucose and insulin on glucokinase activity in rat hypothalamus

2007 ◽  
Vol 193 (2) ◽  
pp. 259-267 ◽  
Author(s):  
Carmen Sanz ◽  
Isabel Roncero ◽  
Patricia Vázquez ◽  
M Angeles Navas ◽  
Enrique Blázquez
Keyword(s):  
Enzyme Activities ◽  
Physiological Model ◽  
Ventromedial Hypothalamus ◽  
Glucose Sensing ◽  
Biological Models ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
The Brain ◽  
Hypothalamic Slices

In an attempt to study the role of glucokinase (GK) and the effects of glucose and peptides on GK gene expression and on the activity of this enzyme in the hypothalamus, we used two kinds of biological models: hypothalamic GT1-7 cells and rat hypothalamic slices. The expression of the GK gene in GT1-7 cells was reduced by insulin (INS) and was not modified by different glucose concentrations, while GK enzyme activities were significantly reduced by the different peptides. Interestingly, a distinctive pattern of GK activities between the ventromedial hypothalamus (VMH) and lateral hypothalamus (LH) were found, with higher enzyme activities in the VMH as the glucose concentrations rose, while LH enzyme activities decreased at 2.8 and 20 mM glucose, the latter effect being prevented by incubation with INS. These effects were produced only by d-glucose and the modifications found were due to GK, but not to other hexokinases. In addition, GK activities in the VMH and the LH were reduced by glucagon-like peptide 1, leptin, orexin B, INS, and neuropeptide Y (NPY), but this effect was only statistically significant for NPY in LH. Our results indicate that the effects of both glucose and peptides occur on GK enzyme activities rather than on GK gene transcription. Moreover, the effects of glucose and INS on GK activity suggest that in the brain GK behaves in a manner opposite to that in the liver, which might facilitate its role in glucose sensing. Finally, hypothalamic slices seem to offer a good physiological model to discriminate the effects between different areas.

scholarly journals Preproglucagon neurons in the hindbrain have IL-6 receptor-α and show Ca2+ influx in response to IL-6

2016 ◽  
Vol 311 (1) ◽  
pp. R115-R123 ◽  
Author(s):  
Fredrik Anesten ◽  
Marie K. Holt ◽  
Erik Schéle ◽  
Vilborg Pálsdóttir ◽  
Frank Reimann ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Food Intake ◽  
Extracellular Space ◽  
Solitary Tract ◽  
Neuronal Marker ◽  
Reporter Mice ◽  
The Central Nervous System ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
The Brain

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.

scholarly journals Nutrient sensing and signalling by the gut

2012 ◽  
Vol 71 (4) ◽  
pp. 446-455 ◽  
Author(s):  
Rojo Rasoamanana ◽  
Nicolas Darcel ◽  
Gilles Fromentin ◽  
Daniel Tomé
Keyword(s):  
Peptide Yy ◽  
Nutrient Sensing ◽  
Vagal Afferents ◽  
Adaptive Responses ◽  
Gut Peptides ◽  
Intestinal Peptides ◽  
Nutrient Transporter ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
The Brain

Recent advances highlight that nutrient receptors (such as T1R1/T1R3 heterodimer, Ca sensing receptor and GPR93 for amino acids and protein, GPR40, GPR41, GPR43 and GPR120 for fatty acids, T1R2/T1R3 heterodimer for monosaccharides) are expressed in the apical face of the gut and sense nutrients in the lumen. They transduce signals for the regulation of nutrient transporter expressions in the apical face. Interestingly, they are also localised in enteroendocrine cells (EEC) and mainly exert a direct control on the secretion in the lamina propria of gastro-intestinal peptides such as cholecystokinin, glucagon-like peptide-1 and peptide YY in response to energy nutrient transit and absorption in the gut. This informs central nuclei involved in the control of feeding such as the hypothalamus and nucleus of the solitary tract of the availability of these nutrients and thus triggers adaptive responses to maintain energy homoeostasis. These nutrient receptors then have a prominent position since they manage nutrient absorption and are principally the generator of the first signal of satiation mechanisms mainly transmitted to the brain by vagal afferents. Moreover, tastants are also able to elicit gut peptides secretion via chemosensory receptors expressed in EEC. Targeting these nutrient and tastant receptors in EEC may thus be helpful to promote satiation and so to fight overfeeding and its consequences.

scholarly journals Pathogenesis of Chimeric MHV4/MHV-A59 Recombinant Viruses: the Murine Coronavirus Spike Protein Is a Major Determinant of Neurovirulence

1999 ◽  
Vol 73 (9) ◽  
pp. 7752-7760 ◽  
Author(s):  
Joanna J. Phillips ◽  
Ming Ming Chua ◽  
Ehud Lavi ◽  
Susan R. Weiss
Keyword(s):  
Hepatitis Virus ◽  
Major Determinant ◽  
Rna Recombination ◽  
Wild Type ◽  
Recombinant Viruses ◽  
S Gene ◽  
The Central Nervous System ◽  
Plaque Phenotype ◽  
The Brain

ABSTRACT The mouse hepatitis virus (MHV) spike glycoprotein, S, has been implicated as a major determinant of viral pathogenesis. In the absence of a full-length molecular clone, however, it has been difficult to address the role of individual viral genes in pathogenesis. By using targeted RNA recombination to introduce the S gene of MHV4, a highly neurovirulent strain, into the genome of MHV-A59, a mildly neurovirulent strain, we have been able to directly address the role of the S gene in neurovirulence. In cell culture, the recombinants containing the MHV4 S gene, S4R22 and S4R21, exhibited a small-plaque phenotype and replicated to low levels, similar to wild-type MHV4. Intracranial inoculation of C57BL/6 mice with S4R22 and S4R21 revealed a marked alteration in pathogenesis. Relative to wild-type control recombinant viruses (wtR13 and wtR9), containing the MHV-A59 S gene, the MHV4 S gene recombinants exhibited a dramatic increase in virulence and an increase in both viral antigen staining and inflammation in the central nervous system. There was not, however, an increase in the level of viral replication in the brain. These studies demonstrate that the MHV4 S gene alone is sufficient to confer a highly neurovirulent phenotype to a recombinant virus deriving the remainder of its genome from a mildly neurovirulent virus, MHV-A59. This definitively confirms previous findings, suggesting that the spike is a major determinant of pathogenesis.

scholarly journals GLP-1(7-36)-amide and Exendin-4 Stimulate the HPA Axis in Rodents and Humans

Endocrinology ◽  
2010 ◽  
Vol 151 (6) ◽  
pp. 2629-2640 ◽  
Author(s):  
Manuel Gil-Lozano ◽  
Diego Pérez-Tilve ◽  
Mayte Alvarez-Crespo ◽  
Aurelio Martís ◽  
Ana M. Fernandez ◽  
...  
Keyword(s):  
Hpa Axis ◽  
Dependent Manner ◽  
Igf I ◽  
Anaesthetized Rats ◽  
The Central Nervous System ◽  
Ad Libitum ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Insulinotropic Peptide ◽  
The Brain

Glucagon-like peptide-1 (GLP-1) is a potent insulinotropic peptide expressed in the gut and brain, which is secreted in response to food intake. The levels of GLP-1 within the brain have been related to the activity of the hypothalamic-pituitary-adrenal (HPA) axis, and hence, this peptide might mediate some responses to stress. Nevertheless, there is little information regarding the effects of circulating GLP-1 on the neuroendocrine control of HPA activity. Here, we have studied the response of corticoadrenal steroids to the peripheral administration of GLP-1 (7-36)-amide and related peptides [exendin (Ex)-3, Ex-4, and Ex-4(3-39)] in rats, mice, and humans. GLP-1 increases circulating corticosterone levels in a time-dependent manner, both in conscious and anaesthetized rats, and it has also increased aldosterone levels. Moreover, GLP-1 augmented cortisol levels in healthy subjects and diabetes mellitus (DM)-1 patients. The effects of GLP-1/Ex-4 on the HPA axis are very consistent after distinct means of administration (intracerebroventricular, iv, and ip), irrespective of the metabolic state of the animals (fasting or fed ad libitum), and they were reproduced by different peptides in this family, independent of glycaemic changes and their insulinotropic properties. Indeed, these effects were also observed in diabetic subjects (DM-1 patients) and in the DM-1 streptozotocin-rat or DM-2 muscle IGF-I receptor-lysine-arginine transgenic mouse animal models. The mechanisms whereby circulating GLP-1 activates the HPA axis remain to be elucidated, although an increase in ACTH after Ex-4 and GLP-1 administration implicates the central nervous system or a direct effect on the pituitary. Together, these findings suggest that GLP-1 may play an important role in regulating the HPA axis.

scholarly journals Potential for Gut Peptide-Based Therapy in Postprandial Hypotension

Nutrients ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 2826
Author(s):  
Malcolm J. Borg ◽  
Cong Xie ◽  
Christopher K. Rayner ◽  
Michael Horowitz ◽  
Karen L. Jones ◽  
...  
Keyword(s):  
Cardiovascular Response ◽  
Cardiovascular Responses ◽  
Caloric Content ◽  
Gut Peptides ◽  
Small Intestinal Transit ◽  
Postprandial Hypotension ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Insulinotropic Peptide

Postprandial hypotension (PPH) is an important and under-recognised disorder resulting from inadequate compensatory cardiovascular responses to meal-induced splanchnic blood pooling. Current approaches to management are suboptimal. Recent studies have established that the cardiovascular response to a meal is modulated profoundly by gastrointestinal factors, including the type and caloric content of ingested meals, rate of gastric emptying, and small intestinal transit and absorption of nutrients. The small intestine represents the major site of nutrient-gut interactions and associated neurohormonal responses, including secretion of glucagon-like peptide-1, glucose-dependent insulinotropic peptide and somatostatin, which exert pleotropic actions relevant to the postprandial haemodynamic profile. This review summarises knowledge relating to the role of these gut peptides in the cardiovascular response to a meal and their potential application to the management of PPH.

scholarly journals Intestinal NAPE-PLD contributes to short-term regulation of food intake via gut-to-brain axis

2020 ◽  
Vol 319 (3) ◽  
pp. E647-E657
Author(s):  
Marialetizia Rastelli ◽  
Matthias Van Hul ◽  
Romano Terrasi ◽  
Charlotte Lefort ◽  
Marion Régnier ◽  
...  
Keyword(s):  
High Fat Diet ◽  
Physiological Role ◽  
Intestinal Epithelial ◽  
Wild Type ◽  
Short Term ◽  
Physiological Mechanisms ◽  
Short Term Exposure ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Our objective was to explore the physiological role of the intestinal endocannabinoids in the regulation of appetite upon short-term exposure to high-fat-diet (HFD) and understand the mechanisms responsible for aberrant gut-brain signaling leading to hyperphagia in mice lacking Napepld in the intestinal epithelial cells (IECs). We generated a murine model harboring an inducible NAPE-PLD deletion in IECs ( NapepldΔIEC). After an overnight fast, we exposed wild-type (WT) and NapepldΔIEC mice to different forms of lipid challenge (HFD or gavage), and we compared the modification occurring in the hypothalamus, in the vagus nerve, and at endocrine level 30 and 60 min after the stimulation. NapepldΔIEC mice displayed lower hypothalamic levels of N-oleoylethanolamine (OEA) in response to HFD. Lower mRNA expression of anorexigenic Pomc occurred in the hypothalamus of NapepldΔIEC mice after lipid challenge. This early hypothalamic alteration was not the consequence of impaired vagal signaling in NapepldΔIEC mice. Following lipid administration, WT and NapepldΔIEC mice had similar portal levels of glucagon-like peptide-1 (GLP-1) and similar rates of GLP-1 inactivation. Administration of exendin-4, a full agonist of GLP-1 receptor (GLP-1R), prevented the hyperphagia of NapepldΔIEC mice upon HFD. We conclude that in response to lipid, NapepldΔIEC mice displayed reduced OEA in brain and intestine, suggesting an impairment of the gut-brain axis in this model. We speculated that decreased levels of OEA likely contributes to reduce GLP-1R activation, explaining the observed hyperphagia in this model. Altogether, we elucidated novel physiological mechanisms regarding the gut-brain axis by which intestinal NAPE-PLD regulates appetite rapidly after lipid exposure.

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