Differences in the consumption of ethanol and flavored solutions in three strains of rats

Several studies have shown a correlation between ethanol consumption and the intake of flavored solutions in rats, particularly sweet solutions. This observation, however, has not been shown in all strains of rats. The present study examined whether the intake of ethanol and that of flavored solutions would be related in Lewis (LEW), Wistar (WIS), and Wistar Kyoto (WKY) rats. During phase I, all rats were presented with water and a flavored solution following a continuous access paradigm as developed by Overstreet et al.: quinine (0.25% wt/vol), saccharin (0.1% wt/vol), ethanol (ETOH) (10% vol/vol), and saccharin-quinine (SQ) solutions (0.4% wt/vol-0.04% wt/vol). During phase II, fluid presentations were reduced to a 10-min limited access schedule and were presented in the same order. Results showed strain differences in intake and preference for ETOH and SQ during both phases, but not in quinine or saccharin intake. ETOH and saccharin intake were only correlated in the LEW strain during limited access drinking, while ETOH and SQ intake were correlated in the LEW strain as well as when all strains were collapsed during continuous drinking. These findings suggested that any association between ETOH and sweet intake may not be generalizable to all rat strains. The animals used in this study may have differed in taste sensitivity, as low ETOH-consuming LEW rats were sensitive to the bitter taste of quinine alone, as well as when mixed with saccharin. Sensitivity to bitter tastes may be an important predictor of low ETOH consumption and/or preference. These data provide further evidence for the role of taste factors in the mediation of voluntary ETOH consumption in rats.