Tonic GABA current increased after the overexpression of α5β3γ2 GABA
receptors. A, Typical GABA (100 μM) induced currents in HEK293T cells transfected with α5β3γ2 subunits (left panel), which could be largely blocked by α5 subunit-specific inverse agonist L655,708 (100 nM, right panel). B, Summarized data showing GABA-induced α5β3γ2 receptor currents in HEK293T cells significantly inhibited by L655,708 (Control, 437.1 ± 63.1 pA, n = 10; L655,708, 142.8 ± 25.7 pA, n = 10; ***, p < 0.001). C, Typical GABA current traces in cultured hippocampal neurons transfected with mCherry or plus the α5β3γ2 subunits. D, Bar graphs showing no significant difference between the total whole-cell GABA currents in neurons transfected with mCherry or plus the α5β3γ2 subunits. E, Representative tonic GABA currents revealed by rapid application of GABAA-R blocker bicuculline (100 μM) in hippocampal neurons transfected with mCherry or plus the α5β3γ2 subunits. F, Summarized data showing that tonic GABA current in α5β3γ2-transfected neurons (24.5 ± 4.2 pA, n = 8) was significantly increased in comparison with the control neurons (13.1 ± 1.7 pA, n = 8; *, p < 0.05).