Ethanol reinforcement and its relationship to saccharin preference in Wistar rats

Forty rats were given a choice between 0.1% sodium saccharin and water. Based on their intakes, three groups of six rats representing high, intermediate, and low saccharin preferences were selected. These rats were reduced to 80% of their free-feeding weights. Ethanol was established as a reinforcer by use of a food-induced drinking procedure. Between-group differences were assessed based on response rates across acquisition sessions (0, 1, 2, 4, 5.7, 8%, w/v), a fixed-ratio series (1, 2, 4, 8, 1), and a concentration series (8, 5.7, 4, 2, 2, 4, 5.7, 8, 11.3, 16, 22.6, 32, 8%, w/v). In 29 of 32 conditions which were analyzed, the mean number of responses for ethanol was higher for the high saccharin preference group than for the low, and in 25 of 32 conditions, the intermediate group fell between the high and the low. However, there was considerable variability within groups across all conditions, such that mean between-group differences were not significant. This variability may be reduced by considering diet preferences in addition to saccharin preference. Nonetheless, these results offer limited support for the increasing body of evidence indicating a relationship between the factors mediating ethanol self-administration and those involving ingestion of palatable foods and fluids.