Effects of environmental enrichment on voluntary ethanol intake in rats.

The effects of exposure to four environmental rearing conditions on subsequent voluntary ethanol intake were examined. Male weanling rats were were reared in either an enriched environment or individually for 90 days. After the 90-day environmental exposure period, the initial groups (Enriched and Isolated) were randomly subdivided into four groups (Enriched, Enriched/Isolated, Isolated, and Isolated/Enriched) and exposed to increasing concentrations of ethanol (3% to 9% v/v) in a free choice with water. Therefore, half the animals raised in the enriched environment were permanently placed into individual cages (Enriched/Isolated) for the remainder of the study. Likewise, half of the animals previously reared individually were exposed daily (0900-1700) to the enriched environment (Isolated/Enriched). Results indicated that the enriched animals consumed greater amounts of ethanol as compared to all other groups. In contrast, rats placed in isolation following 90 days of enrichment demonstrated significant reductions in voluntary ethanol intake. The data suggest that rearing in an enriched environment for 90 days and continued exposure following 111 days of age, are necessary to enhance voluntary ethanol consumption.