EXPRESSION PATTERNS OF THE GABA(A) RECEPTOR ALPHA-1-SUBUNIT, BETA-2-SUBUNIT, GAMMA-2-SUBUNIT AND GAMMA-4-SUBUNIT GENES IN CHICK RETINA

We have investigated the locations of the GABA(A) receptor alpha 1-, b eta 2-, gamma 2- and gamma 4-subunit mRNAs, in chick retina, by in sit u hybridization. The alpha 1-, beta 2- and gamma 2-subunit genes were chosen for study because they are co-expressed throughout the mammalia n and avian brain. The gamma 4-polypeptide gene was selected because i t is highly expressed, in the chick brain, in those regions that are i nvolved in the processing of visual information. We find that the alph a 1-, beta 2- and gamma 2-subunit mRNAs are present m both the inner n uclear layer (INL) and the ganglion cell layer (GCL>; however, the dis tributions of the three transcripts in these two layers show significa nt differences. In contrast, the gamma 4-polypeptide mRNA is only dete cted in the inner portion of the INL. These results strongly suggest t he existence of multiple GABA(A) receptor subtypes in chick retina.