Document Detail

Luminal amino acid sensing in the rat gastric mucosa.
MedLine Citation:
PMID:  16809638     Owner:  NLM     Status:  MEDLINE    
Recent advancements in molecular biology in the field of taste perception in the oral cavity have raised the possibility for ingested nutrients to be "tasted" in the upper gastrointestinal tract. The purpose of this study was to identify the existence of a nutrient-sensing system by the vagus in the rat stomach. Afferent fibers of the gastric branch increased their firing rate solely with the intragastric application of the amino acid glutamate. Other amino acids failed to have the same effect. This response to glutamate was blocked by the depletion of serotonin (5-HT) and inhibition of serotonin receptor(3) (5-HT(3)) or nitric oxide (NO) synthase enzyme. Luminal perfusion with the local anesthesia lidocaine abolished the glutamate-evoked afferent activation. The afferent response was also mimicked by luminal perfusion with a NO donor, sodium nitroprusside. In addition, the NO donor-induced afferent activation was abolished by 5-HT(3) blockade as well. Altogether, these results strongly suggest the existence of a sensing system for glutamate in the rat gastric mucosa. Thus luminal glutamate would enhance the electrophysiological firing rate of afferent fibers from the vagus nerve of the stomach through the production of mucosal bioactive substances such as NO and 5-HT. Assuming there is a universal coexistence of free glutamate with dietary protein, a glutamate-sensing system in the stomach could contribute to the gastric phase of protein digestion.
Hisayuki Uneyama; Akira Niijima; Ana San Gabriel; Kunio Torii
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Publication Detail:
Type:  Journal Article     Date:  2006-06-29
Journal Detail:
Title:  American journal of physiology. Gastrointestinal and liver physiology     Volume:  291     ISSN:  0193-1857     ISO Abbreviation:  Am. J. Physiol. Gastrointest. Liver Physiol.     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-11-08     Completed Date:  2006-12-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901227     Medline TA:  Am J Physiol Gastrointest Liver Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  G1163-70     Citation Subset:  IM    
Physiology and Nutrition Group, Institute of Life Sciences, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki 210-8681, Japan.
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MeSH Terms
Afferent Pathways / drug effects,  physiology*
Dose-Response Relationship, Drug
Gastric Mucosa / drug effects,  innervation*,  physiology*
Glutamic Acid / administration & dosage*
Nitric Oxide / metabolism*
Rats, Sprague-Dawley
Serotonin / metabolism*
Signal Transduction / drug effects,  physiology
Vagus Nerve / drug effects,  physiology*
Reg. No./Substance:
10102-43-9/Nitric Oxide; 50-67-9/Serotonin; 56-86-0/Glutamic Acid

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