GRPR (gastrin-releasing peptide receptor), COMT, dopamine receptors D1A, and D2 were not altered in adolescence immediately following binge treatment (P38), but after treatment, during young adulthood, mRNA expressions were about half as much as their age matched controls (Table 1, P88 Ethanol). Binge ethanol treatment of adolescent rats has been found to reduce D1 and D2 protein levels in frontal cortex and other brain regions (Pascual et al., 2009) and human alcoholics have fewer brain D2 receptors that are suggested to be a predisposing factor due to persistently low levels in both early and late withdrawal (Volkow et al., 2002). Decreases in dopamine receptors could be associated with decreased motivation (Ernst et al., 2009). GRPR expression, a receptor for gastrin releasing peptide and bombesin, was stable across the ages studied, but adolescent binge treatment reduced adult expression 45% without altering adolescent expression. GRPR is enriched in amygdala and GRPR deficient mice show enhanced fear conditioning with normal spatial learning and no anxiety-like behavior in the water maze and elevated plus maze, respectively (Shumyatsky et al., 2002). Environmental enrichment during adolescence
