Localization of GABAA-receptor gamma 2-subunit mRNA-containing neurons in the rat central nervous system.

The localization of neurons containing mRNA of the gamma 2-subunit of GABAA receptors was examined in the rat central nervous system with in situ hybridization histochemistry using an oligonucleotide probe to the sequence of the gamma 2-subunit. Neurons containing the gamma 2-subunit mRNA were widely but unevenly distributed in the brain. The location of gamma 2-subunit mRNA-containing neurons differed from those containing alpha- or beta-subunits. According to our results brain regions can be divided into three categories: one containing only gamma 2-subunit, one containing mRNA of at least one subunit other than gamma 2 and one containing more than one other subunit but not the gamma 2-subunit. The distribution of strongly labeled nuclei partly coincided with that of glutamate decarboxylase, suggesting that the GABAA receptor gamma 2-subunit would be involved in an autoreceptive mechanism of the GABAergic transmission.