ANALYSIS OF GAMMA-AMINOBUTYRIC ACID(A) RECEPTOR SUBUNITS IN THE MOUSECOCHLEA BY MEANS OF THE POLYMERASE CHAIN-REACTION

Thirteen GABA(A) receptor subunits were examined in the cochlea of the CBA(J) mouse by PCR analysis. Total RNA was extracted from the audito ry organs of 14-18-day-old animals, and mRNA was isolated using oligo- dT cellulose. After reverse transcription, resulting cDNA was amplifie d by PCR with primers specific for nucleotide sequences representing G ABA(A) subunits. PCR products corresponding to subunits alpha1-alpha6, beta1-beta3, and gamma2 were amplified, whereas those representing ga mma, gamma3, and delta were not amplified above background. These resu lts provide the most direct evidence to date that GABA(A) receptors co mposed of the detected subunits are expressed in the mammalian cochlea , lending new support to previous studies implicating GABA as a cochle ar transmitter. The pronounced expression Of alpha2 and alpha6 subunit s suggests type II and ''cerebellar-type'' benzodiazepine pharmacology in the cochlea.