Differential ethanol intake in high and low responders to novelty.

The aim of the study was to determine whether high responders (HR) and low responders (LR) to novelty, selected from an outbred Wistar rat population, show differences in ethanol consumption. HR and LR differ in catecholaminergic activity in the nucleus accumbens as well as in brain sensitivity to corticosteroids, biological features believed to play a role in ethanol consumption. Due to these differences it was predicted that HR would consume less ethanol and show less preference than would LR. Animals were maintained on a schedule of alternative day presentation of ethanol. Starting with an ethanol presentation of 2% in a free choice with water, ethanol solutions were presented and increased by increments of 1% every second day. HR showed a preference for water over ethanol, whereas LR showed no preference for water over ethanol. In order to determine intake and preference stability, animals were switched to daily presentations of ethanol and maintained on a 10% ethanol solution for 18 days. Individual-specific differences remained stable throughout the entire period. Given the available knowledge about biological differences between HR and LR, the present data indicate that these animals are good models for the study of the mechanisms underlying individual-specific differences in the behavioral responses to ethanol.