Differential patterns of alcohol consumption and dopamine-2 receptor binding in Wistar-Kyoto and Wistar rats

The Wistar-Kyoto (WKY) rat strain has been described as an animal model of depressive behavior that consumes significantly greater amounts of alcohol compared to the Wistar (WIS) rat strain. Since the mesolimbic dopamine (DA) type-2 (D2) receptors mediate reward-related behaviors, the present study measured the binding of [(125)I]-Iodosulpiride to D2 receptors in the brains of WKY versus WIS rats following 24 days of voluntary alcohol or water consumption. Alcohol consuming WKY rats showed a significant increase in D2 receptor binding in several regions of the mesolimbic and nigrostriatal systems. In contrast, alcohol consuming WIS rats showed a reduction in D2 receptor binding in DA cell body areas. The differential regulation of D2 receptors by voluntary alcohol consumption in the two rat strains suggests that D2 receptor mediated neurotransmission may be playing a role in the increased alcohol drinking behavior reported in WKY rats.