Abstract
The metabotropic glutamate receptor 5 (mGluR5) has been suggested to modulate energy balance. For example, mGluR5 antagonists inhibit food intake in rodents and mGluR5 knockout mice resist diet-induced obesity. However, nonspecific effects can reduce food intake. Thus, to further support the role of mGluR5 in feeding behaviour, we evaluated if the mGluR5 agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG) would induce the opposite effect, i.e. increased food intake in rats. Intracerebroventricularly injected CHPG (0.5-1.5 micromol) induced a dose-dependent stimulation of food intake (349% increase at 2 h with 1.5 micromol). The mGluR5 antagonist 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine (10 mg/kg intraperitoneally) reduced 24 h food intake, without altering CHPG-induced feeding. These findings further support a physiologically relevant role of mGluR5 in appetite regulation.
MeSH terms
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Animals
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Catheterization
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Dose-Response Relationship, Drug
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Eating / drug effects*
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Eating / physiology
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Excitatory Amino Acid Agonists / administration & dosage
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Excitatory Amino Acid Agonists / pharmacology*
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Excitatory Amino Acid Antagonists / pharmacology
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Fasting
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Glycine / administration & dosage
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Glycine / analogs & derivatives*
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Glycine / pharmacology
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Injections, Intraperitoneal
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Male
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Phenylacetates / administration & dosage
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Phenylacetates / pharmacology*
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Pyridines / pharmacology
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Rats
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Rats, Wistar
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Receptor, Metabotropic Glutamate 5
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Receptors, Metabotropic Glutamate / agonists*
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Receptors, Metabotropic Glutamate / antagonists & inhibitors
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Receptors, Metabotropic Glutamate / metabolism
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Thiazoles / pharmacology
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Time Factors
Substances
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2-chloro-5-hydroxyphenylglycine
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3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine
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Excitatory Amino Acid Agonists
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Excitatory Amino Acid Antagonists
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Grm5 protein, mouse
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Grm5 protein, rat
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Phenylacetates
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Pyridines
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Receptor, Metabotropic Glutamate 5
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Receptors, Metabotropic Glutamate
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Thiazoles
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Glycine