Fig. 6. Gabapentin (GBP) and vigabatrin (VIG) did not alter the expression of α1, α2, or α5subunits in hippocampal neurons. ( A ) Western blots were probed separately with antibodies against the various subunits. Molecular mass (in kilodaltons) is indicated to the left , and subunit antibody is indicated to the right . ( B ) Quantitative densitometry showed that neither GBP nor VIG altered the expression of the α1, α2, and α5subunits, as summarized in the bar chart (n = 3 for each condition). The results after drug treatment were normalized to placebo control. ( C ) The concentration–response plot for γ-aminobutyric acid (GABA)–evoked current recorded from GBP-treated (▪) and vehicle control (CONT)–treated (□) neurons. The amplitude of the current (I) was normalized to the maximal response (IMAX). The GABA EC50values for GBP-treated and CONT neurons, estimated from the fitted curves, were 12.5 ± 0.9 μm, n = 6 versus 11.7 ± 1.0 μm, n = 6, respectively ( P > 0.05).