Distinct GABAA receptor alpha subunit mRNAs show differential patterns of expression in bovine brain

Specific oligonucleotide probes have been used to visualize the regional and cellular distribution of the mRNAs encoding three structurally distinct GABAA receptor alpha subunits in bovine brain. In situ hybridization analysis showed that these transcripts differ in distribution and in relative abundance. In frontal cortex the alpha 1 and alpha 2 transcripts are most abundant in layers II-IV, whereas the alpha 3 mRNA is most abundant in layers V and VI. In the hippocampal complex, the alpha transcripts are differentially distributed in the entorhinal cortex and subiculum. The alpha 2 transcript is enriched in the dentate gyrus and CA4/CA3 regions of the hippocampus. In the cerebellum, essentially only the alpha 1 transcript is detectable in granule cells, Purkinje cells, and stellate/basket cells. These results suggest that the different alpha subunits represent components of distinct GABAA receptor subtypes.