Animal research suggests that selective breeding for alcohol preference might affect the heavily dopaminergic mesocorticolimbic reward system. For example, rodents selectively bred to prefer alcohol have reduced dopamine in the striatum (see Murphy et al., 2002; Strother et al., 2005) and medial prefrontal cortex (Engleman et al., 2006), but greater striatal dopaminergic responses to alcohol itself (Bustamante et al., 2008; also see Smith & Weiss, 1999; Weiss et al., 1993). In at least one case, alcohol-preferring rats (compared to Wistar rats) showed a greater dopaminergic response in the ventral striatum during alcohol anticipation (Katner, Kerr, & Weiss, 1996). In non-abusive drinkers without a family history of alcoholism there is greater striatal dopamine receptor availability (Volkow et al., 2006), suggesting a potential protective factor.
