Figure 3.

Several pyrazoloquinolinones/ pyrazolopyridinones are null modulators at the α1+β3− binding site. (A) The positive modulatory effect of 300 nM compound 11 (243 ± 11%) on GABA EC3 current (100%) in α1β3 receptors is significantly inhibited (***P < 0.001) by the co-application of 60 μM compound 15, compound 25, compound 23, compound 33, or compound 27. Data are expressed as means ± SEM (n = 4–7). (B) Concentration–response curves for ROD188 at α1β3 receptors (□) and ROD188 with co-applied 60 μM compound 25 (▴), 60 μM compound 23 (▾), 60 μM compound 33 (•) and 60 μM compound 27 (♦), indicating that the α1+β3− null modulators had no influence on the GABA enhancing effect of ROD188 in α1β3 receptors. (C) Compound 15 dose dependently inhibits the effects of 300 nM compound 11 on GABA EC3 in α1β3 receptors; IC₅₀ values for compound 15 and those of the other four null modulators (compounds 25, 23, 33, 27), are mean values obtained from similar inhibition studies (curves not shown, n = 4–6), and are displayed in the Table 1. IC₅₀ values were calculated using GraphPad Prism and a non-linear regression – one site competition curve. (D) Concentration–response curves for diazepam (▪), and diazepam together with 60 μM compound 25 (□), compound 23 (○), compound 33 (▴) and compound 27 (▾) at α1β3γ2 receptors. The positive modulatory effect of diazepam on the GABA EC3 current was completely abolished by compound 25 and compound 23 (P < 0.01 at 100 μM-10 μM). Compound 33 decreased only partially the positive modulation of diazepam, whereas this effect remained almost unchanged in the presence of 60 μM compound 27. All experiments were performed four to seven times in oocytes of different batches. Data represent means ± SEM.