Expression of NMDA-receptor mRNA in the rat cochlea.

While there is considerable evidence that an excitatory amino acid and excitatory amino acid receptors are involved in the synapse between inner hair cells and the auditory nerve, evidence for the specific involvement of the N-methyl-D-aspartate (NMDA) receptor is more ambiguous. With the cloning of the NMDA receptor, probes are now available that can determine in which neurons the receptor is being expressed. In situ hybridization histochemical techniques were therefore utilized to examine the expression of NMDA receptor messenger ribonucleic acid (mRNA) in the rat cochlea. Expression of NMDA receptor mRNA was seen in spiral ganglion cells. These results suggest that NMDA receptor is a component of excitatory amino acid synapses in the cochlea.