Premium
Content and In Vitro Release of Endogenous Amino Acids in the Area of the Nucleus of the Solitary Tract of the Rat
Author(s) -
Meeley Mary P.,
Underwood Mark D.,
Talman William T.,
Reis Donald J.
Publication year - 1989
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1989.tb09247.x
Subject(s) - taurine , solitary tract , gamma aminobutyric acid , glutamic acid , amino acid , nucleus , calcium , glutamatergic , glutamate receptor , medicine , nodose ganglion , neurotransmitter , chemistry , biochemistry , endocrinology , aminobutyric acid , biology , stimulation , receptor , neuroscience , vagus nerve
We sought to identify amino acid neurotransmitter candidates within the nucleus of the solitary tract in rats. Twenty endogenous amino acids were quantified by reverse‐phase HPLC with fluorescence detection (30‐fmol limit). Mi‐cropunches (1 mm) of the intermediate area of the solitary nucleus were prepared, and the amino acid content determined. Of all the components measured, the putative transmitters Glu, Gly, γ‐aminobutyric acid, taurine, Asp, and Ala appeared in greatest concentrations. Bilateral micropunches superfused in vitro with buffered medium containing 56 m M potassium released Glu, γ‐aminobutyric acid, and Gly in a significant manner (p < 0.05) compared with basal levels. With Glu, 78% was calcium‐dependent and, therefore, presumably from nerve endings; 99% of γ‐aminobutyric acid and 42% of Gly were dependent on calcium. After removal of the nodose ganglion, a bilateral decrease in the calcium‐dependent release of Glu and γ‐aminobutyric acid, but not Gly, was observed; decreases were significant ipsilateral to the site of ablation. We conclude that (a) Glu is a transmitter of primary afferents in the nucleus of the solitary tract; (b) glutamatergic afferents may interact with γ‐aminobutyric acid system(s) in this region; (c) Gly also may participate in the mediation and/or modulation of cardiovascular or other visceral reflexes; and (d) amino acid neurotransmission may play an integral role in the neurogenic control of arterial pressure