Bell et al. (2006) examined the effects of chronic alcohol drinking by alcohol-preferring (P) rats on protein levels in the Acb and amygdala, and reported a small number of changes in each region following chronic alcohol drinking. Rodd et al. (2008) examined the effects of operant ethanol self-administration on changes in gene expression in the Acb and amygdala of inbred P rats 24 hours after the last 1-hour drinking session. In the Acb, approximately 200 genes differed significantly between the ethanol and water-control groups, whereas in the amygdala, few significant differences were observed. In another study (Bell et al., 2009), gene expression changes were detected in the Acb of P rats following 2 different alcohol-drinking conditions, i.e., continuous 24-hour access and multiple 1-hour daily scheduled access periods. Significant differences in expression of genes involved in intracellular signaling pathways and transcription factors were found between the continuous-access and water-control groups, whereas no significant differences were observed in the Acb between the multiple scheduled-access and the water-control groups, when measured the day after the last drinking episode. McBride et al. (2010) reported
