A. The light/dark box (LDB) exploration test showed that alcohol-preferring (P) rats display innate anxiety-like behaviors in comparison to alcohol-nonpreferring (NP) rats. Acute ethanol treatment (1 g/kg) produced anxiolytic effects in P rats, but not NP rats. Values are represented as the mean ± SEM of the percentage of time spent in each compartment averaged from 13 rats per group. *Significantly different from respective control groups (Two-way ANOVA; group × treatment, F1,48 = 58.6, p<0.001 followed by post hoc analysis by Tukey’s test, p<0.001).
B. The nuclear fraction, but not cytosolic fraction, of the amygdala from P rats displays higher histone deacetylase (HDAC) activity at baseline compared to NP rats. Acute ethanol treatment inhibited the nuclear HDAC activity in the amygdala of P rats, without any effect in NP rats. Values are represented as the mean ± SEM of the optical density (OD) per mg of protein from 6 rats per group. *Significantly different from respective control groups (Nuclear HDAC activity, two-way ANOVA; group × treatment, F1, 20 = 29.6, p<0.001 followed by post hoc analysis by Tukey’s test, p<0.001).