Differential expression of GABA(A) receptor subunits in the distinct nuclei of the rat amygdala.

Detailed knowledge of the anatomical distribution of different GABA(A) receptor subunits is crucial for understanding the physiological actions of GABA in individual brain areas and for developing drugs acting through the individual GABA receptor subtypes. Since the amygdala is a key brain structure in the processing of emotional information with distinct functions in each nucleus, GABA(A) receptors in the amygdala are an important target of treatment for emotional disorders. In this study, we analyzed by quantitative RT-PCR the expression levels of all GABA(A) receptor subunits in distinct nuclei of the amygdala, the central (Ce) and the lateral/basolateral (LA/BLA) amygdala. We found the strongest expression of the gamma(2) subunit mRNA in both the Ce and LA/BLA, modest expressions of alpha(1), alpha(2) and alpha(3) mRNAs in the LA/BLA and alpha(2) and gamma(1) mRNAs in the Ce, and weak expressions of alpha(6), rho(2) and rho(3) mRNAs in both regions. We further revealed the significantly different expressions of alpha(1), alpha(3), alpha(5), gamma(1), gamma(2), delta, epsilon and theta subunit mRNAs in the Ce and LA/BLA. Differences in the expression levels of GABA(A) receptor subunits suggest different sensitivity to a variety of drugs including benzodiazepines and anesthetics in amygdala nuclei with distinct functions.