Evidence for an excitatory amino acid as the transmitter of the auditory nerve in the in vitro mouse cochlear nucleus.
Microionophoretically applied excitatory amino acids induced firing of extracellularly recorded single units in a tissue slice preparation of the mouse cochlear nucleus, and the similarly applied antagonist 2-amino-5-phosphonovalerate (2APV) was demonstrated to be a selective N-methyl-D-aspartate (NMDA) receptor antagonist. In addition, the effect of various bath-applied excitatory amino acid receptor antagonists on auditory nerve evoked field potentials was studied. Antagonists which block NMDA type receptors, blocked auditory nerve evoked potentials in a dose-dependent manner. The 50% effective concentration (EC50) for three of the antagonists used was: D-alpha-aminoadipate, 7.8 mM; 2APV, 4.2 mM; and 2,3-cis-piperidine dicarboxylate, 1.1 mM. Glutamate diethylester (5 mM) had no effect. The results suggest that NMDA, kainate and quisqualate receptors are present in the cochlear nucleus and that auditory nerve transmission in the mouse is mediated by an NMDA type receptor. This is consistent with the concept that the auditory nerve postsynaptic receptor in mammals is of the NMDA type.
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D015763:2-Amino-5-phosphonovalerate; D015074:2-Aminoadipic Acid / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000596:Amino Acids / Q000502:physiology*; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D003056:Cochlear Nerve / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D016202:N-Methylaspartate; D018377:Neurotransmitter Agents / Q000502:physiology*; D010069:Oxadiazoles / Q000494:pharmacology; D010875:Pipecolic Acids / Q000494:pharmacology; D016318:Quisqualic Acid; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology; D000159:Vestibulocochlear Nerve / Q000502:physiology*
D000596:Amino Acids; D018377:Neurotransmitter Agents; D010069:Oxadiazoles; D010875:Pipecolic Acids; D017981:Receptors, Neurotransmitter; D015074:2-Aminoadipic Acid; D001224:Aspartic Acid; C029262:2,3-piperidinedicarboxylic acid; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D016318:Quisqualic Acid; D014633:Valine; D007608:Kainic Acid