Kainate evokes the release of endogenous glycine from striatal neurons in primary culture.
The actions of 56 mM KCl and excitatory amino acid (EAA) agonists on the release of endogenous glycine (Gly) from striatal neurons in primary culture was examined. During a 3 min period, 2 x 10(6) striatal neurons released 743 +/- 51 pmol of Gly. In the presence of 56 mM KCl, an additional 492 +/- 52 pmol of Gly (+66%) were released, 75% of which was dependent upon the presence of extracellular calcium. When striatal neurons were exposed to 1 mM N-methyl-D-aspartate (NMDA) or quisqualate (QA), endogenous Gly released was increased by 370 +/- 71 (+50%) or 120 +/- 31 (+16%) pmol, respectively. In the presence of 1 mM kainate (KA), however, the release of endogenous Gly increased by 994 +/- 82 pmol (+135%). Interestingly, while KA (1 mM) was twice as effective as KCl (56 mM) in evoking the release of endogenous Gly, KCl was 5 times more effective than KA in evoking the release of endogenous gamma-aminobutyric acid (GABA). KA-induced increases of endogenously released Gly were dose-dependent (EC50, 100 microM), saturable and not significantly reduced in the absence of extracellular calcium. The actions of KA were blocked by coincubation with 6-cyano-2,3-dihydroxy-7-nitro-quinoxaline (CNQX), a competitive antagonist at the KA receptor. These data suggest that the release of endogenous Gly from striatal neurons in primary culture is regulated principally by EAA actions at the KA receptor system.
Weiss
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Department of Pathology, University of Calgary, Faculty of Medicine, Alta, Canada.
Kemp
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Bauce
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D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism*; D007608:Kainic Acid / Q000494:pharmacology*; D016202:N-Methylaspartate; D010069:Oxadiazoles / Q000494:pharmacology; D016318:Quisqualic Acid; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*
D010069:Oxadiazoles; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D001224:Aspartic Acid; D016202:N-Methylaspartate; D016318:Quisqualic Acid; D007608:Kainic Acid; D005998:Glycine