Initial acceptance of ethanol: gustatory factors and patterns of alcohol drinking.

Individual differences related to taste, determined by prior two-bottle tests of quinine and saccharin selection against water, were found to be related to the initial selection of 15% ethanol solution during the first week of access by 60 randomly bred male rats. The 36 rats that drank the least alcohol during the first week (mean +/- SE: 0.49 +/- 0.06 g/kg/day), however, greatly increased their intake during the second and third weeks, to the level of the 24 initially high alcohol drinkers (4.07 +/- 0.39 g/kg/day during 1st week), and the influence of gustatory factors was no longer apparent. Subsequently, the initially low rats drank less alcohol when saccharin was the alternative fluid. The results can be interpreted as showing that initially low rats, that only drank rather large amounts of alcohol after prolonged exposure, resemble Cloninger's Type 1 alcoholics not only in this temporal pattern but also in being high in novelty seeking, and low in harm avoidance and reward dependence, and that the initially high rats that spontaneously drank rather large amounts even in the first week show the opposite characteristics and resemble Type 2 alcoholics. Although these rats are not themselves models for alcoholism, the results nevertheless suggest it might be possible to develop two separate animal models for the two types of alcoholism.