The Effect of Differential Rearing Conditions on the Consumption of and Operant Responding for Ethanol in the Indiana University Selectively Bred Alcohol-preferring (p) and -non- Preferring (np) Rat Lines

Exposing rats to differential rearing conditions, during early post-weaning development, has been shown to produce changes in a number of behaviors displayed during adulthood. The purpose of the current study was to investigate whether rearing alcohol-preferring (P) and non-preferring (NP) rats in an environmental enrichment condition (EC), a social condition (SC), or an impoverished condition (IC) would differentially affect the consumption of and operant responding for 10% ethanol. In Experiment 1 rats were tested for both limited access and free access (two bottle choice between water and ethanol) consumption of 10% ethanol. For, Experiment 2 rats were trained to respond in an operant chamber for ethanol and then provided concurrent access to 10% ethanol (right lever) and water (left lever). After concurrent access, rats were required to respond over a gradually increasing fixed-ratio schedule for 10% ethanol and finally a progressive ratio schedule for 10% ethanol, 15% ethanol, and 10% sucrose. For Experiment 3 rats were trained to respond for 10% sucrose and then assessed for the maintenance of operant responding for 10% sucrose. The data from this series of experiments shows that EC P rats consumed, responded for, and preferred 10% ethanol significantly less than their IC P counterparts. Also, EC P rats did not significantly differ from NP rats during any aspect of testing for all experiments. Experiment 3 failed to reveal a significant effect of rearing although there was a line effect that has been previously observed in the literature. Thus, it would appear from these results that rearing in an EC condition acts to protect alcohol-preferring rats from increased levels of consumption of, preference for, and responding for ethanol compared to rearing in an impoverished environment. THE EFFECT OF DIFFERENTIAL REARING CONDITIONS ON THE CONSUMPTION OF AND OPERANT RESPONDING FOR ETHANOL IN THE INDIANA UNIVERSITY SELECTIVELY BRED ALCOHOL-PREFERRING (P) AND -NONPREFERRING (NP) RAT LINES