Fig. 2.

Effect of δ subunit expression on neurosteroid-induced modulation of GABA-gated currents in cells transfected with α1, β1, β3, and γ2 subunit cDNAs.A, HEK cells were transfected with α1β3γ2 and α1β3δ subunits, and currents were elicited by GABA in the absence or presence of THDOC. GABA or GABA + THDOC were applied by a Y-tubing system for the duration indicated by the bars. GABA-induced currents were recorded from isolated HEK 293 cells voltage-clamped at −50 mV. B, Potentiation was calculated by comparing current levels induced by coapplications of GABA + THDOC to GABA alone. GABA concentrations used were as follows: α1β3γ2, 0.5 μm; α1β3, 0.1 μm; α1β3γ2δ, 0.5 μm; α1β3δ, 0.8 μm; and α1β1δ, 1 μm. Each point represents the mean ± SEM of the percent potentiation observed at each concentration in at least 12 cells. Asteriskindicates statistical significance (p < 0.01) when compared with the α1β3δ subunit cotransfection.C, Potentiation of GABA-activated currents induced by 1 μm THDOC for individual cells transfected with α1β3γ2, α1β1δ, α1β3, α1β3γ2δ, or α1β3δ. Bars represent the mean values.