| Anatomy and function of group III metabotropic glutamate receptors in gastric vagal pathways. | |
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MedLine Citation:
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PMID: 18371991 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Metabotropic glutamate receptors (mGluR) are classified into groups I (excitatory), II and III (inhibitory) mGluR. Activation of peripheral group III mGluR (mGluR4, mGluR6, mGluR7, mGluR8), particularly mGluR8, inhibits vagal afferent mechanosensitivity in vitro which translates into reduced triggering of transient lower oesophageal sphincter relaxations and gastroesophageal reflux in vivo. However, the expression and function of group III mGluR in central gastrointestinal vagal reflex pathways is not known. Here we assessed the expression of group III mGluR in identified gastric vagal afferents in the nodose ganglion (NG) and in the dorsal medulla. We also determined the central action of the mGluR8a agonist S-3,4-DCPG (DCPG) on nucleus tractus solitarius (NTS) neurons with gastric mechanosensory input in vivo. Labelling for mGluR4 and mGluR8 was abundant in gastric vagal afferents in the NG, at their termination site in the NTS (subnucleus gelatinosus) and in gastric vagal motorneurons, while labelling for mGluR6 and mGluR7 was weaker in these regions. DCPG (0.1 nmol or 0.001-10 nmol i.c.v.) inhibited or markedly attenuated responses of 8/10 NTS neurons excited by isobaric gastric distension with no effect on blood pressure or respiration; 2 NTS neurons were unaffected. The effects of DCPG were significantly reversed by the group III mGluR antagonist MAP4 (10 nmol, i.c.v.). In contrast, 4/4 NTS neurons inhibited by gastric distension were unaffected by DCPG. We conclude that group III mGluR are expressed in peripheral and central vagal pathways, and that mGluR8 within the NTS selectively reduce excitatory transmission along gastric vagal pathways. |
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Authors:
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Richard L Young; Nicole J Cooper; L Ashley Blackshaw |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2008-02-19 |
Journal Detail:
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Title: Neuropharmacology Volume: 54 ISSN: 0028-3908 ISO Abbreviation: Neuropharmacology Publication Date: 2008 May |
Date Detail:
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Created Date: 2008-04-21 Completed Date: 2008-07-22 Revised Date: 2008-10-05 |
Medline Journal Info:
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Nlm Unique ID: 0236217 Medline TA: Neuropharmacology Country: England |
Other Details:
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Languages: eng Pagination: 965-75 Citation Subset: IM |
Affiliation:
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Nerve Gut Research Laboratory, Department of Gastroenterology and Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, SA 5000, Australia. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Balloon Dilatation Benzoates / pharmacology Data Interpretation, Statistical Dose-Response Relationship, Drug Electrophysiology Excitatory Amino Acid Antagonists / pharmacology Extracellular Space / physiology Ferrets GABA Agonists / pharmacology Gastroesophageal Reflux / drug therapy Glycine / analogs & derivatives, pharmacology Immunohistochemistry Male Microelectrodes Microscopy, Fluorescence Neural Pathways / anatomy & histology*, physiology* Physical Stimulation Receptors, Metabotropic Glutamate / agonists, physiology* Solitary Nucleus / drug effects, physiology Stomach / innervation*, physiology Vagus Nerve / anatomy & histology*, physiology* |
| Chemical | |
Reg. No./Substance:
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0/3,4-dicarboxyphenylglycine; 0/Benzoates; 0/Excitatory Amino Acid Antagonists; 0/GABA Agonists; 0/Receptors, Metabotropic Glutamate; 0/metabotropic glutamate receptor 3; 56-40-6/Glycine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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