NMDA and non-NMDA receptor-mediated release of [3H]GABA from granule cell dendrites of rat olfactory bulb.
We have studied the effect of glutamate and the glutamatergic agonists N-methyl-D-aspartate (NMDA), kainate, and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) on [3H]GABA release from the external plexiform layer of the olfactory bulb. The GABA uptake blocker nipecotic acid significantly increased the basal [3H]GABA release and the release evoked by a high K+ concentration, glutamate, and kainate. The glutamate uptake blocker pyrrolidine-2,4-dicarboxylate (2,4-PDC) inhibited by 50% the glutamate-induced [3H]GABA release with no change in the basal GABA release. The glutamatergic agonists NMDA, kainate, and AMPA also induced a significant [3H]GABA release. The presence of glycine and the absence of Mg2+ have no potentiating effect on NMDA-stimulated release; however, when the tissue was previously depolarized with a high K+ concentration, a significant increase in the NMDA response was observed that was potentiated by glycine and inhibited by the NMDA receptor antagonist 2-amino-5-phosphonoheptanoic acid (AP-7). The kainate and AMPA effects were antagonized by the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) but not by AP-7. The glutamate effect was also inhibited by CNQX but not by the NMDA antagonist 2-amino-5-phosphonopentanoic acid (AP-5); nevertheless, in the presence of glycine, [3H]GABA release evoked by glutamate was potentiated, and this response was significantly antagonized by AP-5. Tetrodotoxin inhibited glutamate- and kainate-stimulated [3H]GABA release but not the NMDA-stimulated release.(ABSTRACT TRUNCATED AT 250 WORDS)
García
Y
Y
Laboratorio Neuroquimica, Centro Biofisca y Bioquimica, Instituto Venezolano de Investigaciones Cientificas, Caracas.
Ibarra
C
C
Jaffé
E H
EH
D000818:Animals; D003712:Dendrites / Q000378:metabolism*; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D005998:Glycine / Q000494:pharmacology; D006098:Granulocytes / Q000378:metabolism*; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D009830:Olfactory Bulb / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017459:Receptors, Amino Acid / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D005971:Glutamates; D017459:Receptors, Amino Acid; D016194:Receptors, N-Methyl-D-Aspartate; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D007608:Kainic Acid; D005998:Glycine