Figure 3.

Ethanol enhances granule cell tonic GABA current, and the enhancement is larger in Gabra6^100Q/100Q rats. (a,b) Tonic GABA currents in granule cells recorded from Gabra6^100R/100R (a) or Gabra6^100Q/100Q (b) slices in the presence of indicated concentrations of ethanol or in a saturating concentration (10μM) of the GABAR antagonist SR95531. To the right are histograms of all points in each segment. Gaussian functions have been fit to each condition and are superimposed. The dashed lines indicate the mean current from these fits. (c) Summary of the mean ± s.e.m. percentage change in tonic current amplitude caused by 30 or 100 mM ethanol in the two genotypes (wild type, n = 5; mutant, n = 7 granule cells). Ethanol caused a significantly larger enhancement of mutant versus wild-type currents. Mean tonic GABA current under control conditions was −9.7 ± 1.7 pA and did not differ significantly between the two genotypes (P > 0.4). (d) Ethanol-induced increases in sIPSC frequency are significantly larger in mutant granule cells (Gabra6^100R/100R, n = 5; Gabra6^100Q/100Q, n = 7 granule cells). No significant changes were observed in either the amplitude (Gabra6^100R/100R, 112.43 ± 12.57% of control, P > 0.49, n = 5; Gabra6^100Q/100Q, 101.55 ± 2.42% of control, P > 0.7, n = 7) or the decay of sIPSCs (Gabra6^100R/100R, 90 ± 12% of control, P > 0.42, n = 4; Gabra6^100Q/100Q, 96 ± 18% of control, P > 0.77, n = 6) in ethanol (data not shown).