Excitatory amino acid pharmacology of the auditory nerve and nucleus magnocellularis of the chicken.

Experiments were performed on the nucleus magnocellularis and auditory nerve in tissue slices of 19-20-day-old chick embryos. Bath-applied kainate, quisqualate and N-methyl-D-aspartate induced dose-dependent alterations in the antidromic responses of nucleus magnocellularis neurons. The sensitivity of these agonist-induced responses to 2,3-cis-piperidine dicarboxylate, glutamate diethylester and D-alpha-aminoadipate were tested, as was the sensitivity of auditory nerve transmission. The data suggest that receptors for all three agonists are present on nucleus magnocellularis neurons and that the postsynaptic receptor of the nucleus magnocellularis-auditory nerve synapse is of the kainate type. The effects of bath-applied baclofen were also studied. Baclofen blocked orthodromic responses suggesting that an excitatory amino acid is released from the presynaptic terminal.