Figure 1.

Okadaic acid (OA) mimics a single ethanol (EtOH) withdrawal-induced decreases in extrasynaptic GABA_AR-mediated tonic current (I_tonic) and I_tonic responsiveness to acute EtOH in cultured hippocampal neurons. Neurons were whole-cell voltage-clamped at −70 mV (holding potential, I_hold). (A) Left: sample traces of individual recordings from neurons during 30-min vehicle (Ctrl) or 60 mM EtOH exposure (EtOH). Right: averaged miniature inhibitory postsynaptic currents (mIPSCs). The I_tonic amplitude is measured as currents at the experimental conditions vs. the mean current following bicuculline (Bic, 10 μM) application (dotted lines indicate I_hold: basal, light-gray line commencing at left margin; Bic application, and light-gray line commencing near far right end). (B–D) Changes in I_tonic amplitude (B), total chargetransfer of mIPSCs (mIPSC area, C) and mIPSC frequency (D) recorded in neurons from Ctrl and EtOH groups as shown in (A). (E) Left: sample traces of individual recordings from neurons at 30 min after withdrawal from Ctrl and EtOH (60 mM for 30 min, E/W) as well as during 30-min OA (100 nM, OA) exposure. Right: averaged mIPSCs. (F–H) Changes in I_tonic amplitude (F), mIPSC area (G) and frequency (H) recorded in neurons from Ctrl, E/W and OA groups as shown in (E). (I) Sample traces of individual recordings from Ctrl-, E/W- and OA-treated neurons. The I_hold after acute EtOH application is indicated by light-gray dotted lines (middle line commencing near far right end). (J) The effects of EtOH on I_tonic amplitude from the same recordings as shown in (I). n = 10–13 per group. ^#p < 0.001 vs. Ctrl group (t test in B and one-way ANOVA with post hoc Dunnett’s test in F); ^†p < 0.001 vs. the pre-EtOH baseline value, *p < 0.001 vs. Ctrl group (two-way ANOVA with post hoc Holm-Sidak test).