Blockade of synaptic transmission from hair cells to auditory afferent nerves by 6-cyano-2,3-dihydroxy-7-nitroquinoxaline, a selective non-NMDA receptor antagonist.
6-Cyano-2,3-dihydroxy-7-nitroquinoxaline (CNQX) is a new, potent and selective competitive antagonist for the non-N-methyl-D-aspartate (non-NMDA) type of excitatory amino acids receptors. We studied the effect of CNQX on the compound auditory nerve action potential (CAP), cochlear microphonics (CM), summating potential (SP) and endocochlear potential (EP). CNQX in doses of 10-20 microM reduced the CAP magnitude and increased the N1 latency without affecting the CM, SP, or EP. Parallel shifts of CAP amplitude- and latency-intensity functions were observed. The CAP suppressed by 10 microM CNQX was completely reversed by a 10-min washout with artificial perilymph. As 10 microM and 20 microM CNQX seem to exert a selective antagonism for non-NMDA receptors, results indicate that non-NMDA receptors play a major role in synaptic transmission from hair cells to auditory afferent nerves.
Doi
K
K
Department of Otolaryngology, Osaka University Medical School, Japan.
Mori
N
N
Matsunaga
T
T
Tsumoto
T
T
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000161:Acoustic Stimulation; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003055:Cochlear Microphonic Potentials / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects*; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects*; D011810:Quinoxalines / Q000008:administration & dosage / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects; D013569:Synapses / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*; D000159:Vestibulocochlear Nerve / Q000187:drug effects*
D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione