GABAA receptor subunit interactions important for benzodiazepine and zinc modulation:: a patch-clamp and single cell RT-PCR study

The expression of mRNAs for the GABA(A) receptor subunits alpha (1), alpha (6), beta (2), beta (3), gamma (2) and delta in single mouse cerebellar granule cells and cortical interneurons were analysed by RT-PCR and correlated to their midazolam and zinc modulation of agonist-induced receptor currents. The registration of molecular and electrophysiological data from each cell allowed us to estimate the significance of individual subunits and their two-factor interaction for modulation. The presence of alpha (6) decreased midazolam modulation, but statistical analysis also suggested interactions of alpha (6) with beta (3) and gamma (2) with respect to midazolam modulation. Zinc modulation was decreased by the presence of gamma (2), and analysis points to an beta (3) effect as well as an interaction between gamma (2) and delta in zinc modulation. Thus, our model confirmed, in single native cells, the known effects of alpha (6) in midazolam and gamma (2) in zinc modulation, and additionally pointed to significant subunit interactions that need to be further tested in recombinant receptors. The present study offers a method to identify subunit interactions in heteromeric receptor complexes.