Dissociation of ethanol and saccharin preference in sP and sNP rats

Background: It has been proposed that ethanol intake and consumption of swe et tasting solutions are positively correlated in rodents. Experiment 1 of the present study investigated whether selectively bred ethanol-preferring (sP) and -nonpreferring (sNP) rats differed, consistently with the above hy pothesis, as to saccharin intake and preference. Experiment 2 evaluated whe ther saccharin addition to the ethanol solution, likely resulting in a high ly palatable fluid, would result in an increase in voluntary ethanol intake in sP rats. Methods: The saccharin solution was offered, in free choice with water, at a fixed concentration of 1 g/liter for 6 consecutive days in Experiment 1A or at ascending concentrations (0.002 to 16.4 g/liter, doubling the concent ration every day) in Experiment 1B. In Experiment 2, 1 g/liter saccharin wa s added to the standard 10% ethanol solution and offered to sP rats in free choice with water for 7 consecutive days. Results: In both Experiments 1A and 1B, sP and sNP rats showed avidity for the saccharin solution with marginal line difference in saccharin intake an d preference. In Experiment 2, daily ethanol intake remained stable at base line levels (6-7 g/kg), irrespective of the saccharin addition to the ethan ol solution. Conclusions: The results of Experiments 1A and 1B suggest that saccharin dr inking behavior in sNP rats deviates from the hypothesis that saccharin and ethanol intakes may co-vary; thus, at least in sNP rats, saccharin and eth anol intakes do not appear to be influenced by the same genetic factors. Th e results of Experiment 2 provide further support to the existence of a cen tral set-point mechanism that regulates daily ethanol intake in sP rats, li kely based on the pharmacological effects of ethanol.