N-methyl-D-aspartate depresses GABAA receptor-mediated currents in neurons of bullfrog dorsal root ganglia.
The effect of N-methyl-D-aspartate (NMDA) on the function of GABAA receptors was examined in acutely dissociated neurons of bullfrog dorsal root ganglia (DRG) by using whole-cell patch clamp methods. The application of NMDA (100 microM) to DRG neurons suppressed the inward currents produced by GABA (100 microM) and muscimol (100 microM). DL-2-Amino-5-phosphonovaleric acid (APV; 100 microM) antagonized the NMDA-induced depression of the GABA current in a competitive manner. Kainic acid (100 microM) did not depress the GABA current. NMDA induced no depression of the GABA current in a nominally Ca(2+)-free solution containing 5 mM Mg2+. These data indicate that the activation of the NMDA receptor inhibits the GABAA receptor-mediated current via a Ca(2+)-dependent process.
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Department of Physiology, Kurume University School of Medicine, Japan.
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D000818:Animals; D002118:Calcium / Q000378:metabolism; D004594:Electrophysiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D058785:GABA-A Receptor Agonists; D058787:GABA-A Receptor Antagonists; D005727:Ganglia, Spinal / Q000166:cytology*; D015640:Ion Channel Gating / Q000502:physiology; D016202:N-Methylaspartate / Q000494:pharmacology*; D009475:Neurons, Afferent / Q000737:chemistry / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism; D011892:Rana catesbeiana; D017661:Receptors, Presynaptic / Q000819:agonists / Q000037:antagonists & inhibitors; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D058785:GABA-A Receptor Agonists; D058787:GABA-A Receptor Antagonists; D018377:Neurotransmitter Agents; D017661:Receptors, Presynaptic; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D002118:Calcium