Distribution of GABAA-receptor alpha 1 subunit gene expression in the rat forebrain.

The localization of neurons containing mRNA of the alpha 1 subunit of the gamma-aminobutyric acid-A (GABAA) receptor was examined in the rat forebrain by in situ hybridization histochemistry using an oligonucleotide probe for the alpha 1 subunit. Moderately to strongly labeled neurons were numerous in the mitral cell layer of the olfactory bulb, the anterior olfactory nucleus, the diagonal band of Broca, the globus pallidus, the tenia tecta, the hippocampal formation, the thalamic and subthalamic nuclei, the zona incerta, and the amygdaloid complex. A few positive neurons were found in the caudate-putamen, the lateral and medial septal areas, the nucleus accumbens, the bed nucleus of the stria terminalis, the ventral pallidum, and the hypothalamus. The distribution of neurons containing alpha 1 subunit mRNA in the forebrain was very similar to that of neurons expressing beta 2 subunit mRNA, suggesting that these two subunits frequently coexist in the same neurons in the forebrain.