Alcohol Preference in the Rat: Its Relationship to Total Fluid Consumption

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Abstract
Four experimental groups of 6 Wlstar rats were subjected to forced consumption of 2%, 4%, 8% and 16% solutions of alcohol for 6 mo. Two control groups drank tap water only. A stock diet was provided ad libitum. Daily measurements were taken of the volumes of fluid consumed. On 4 occasions, at monthly intervals individual animals from the 4 experimental groups were presented with a choice of water or the appropriate alcohol solutions for 24 hrs. On 2 other occasions, they were deprived of all fluid for 24 hr. before being presented with the choice of fluids. At the start of the experiment the animals were aged 125 days and weighed 250 [plus or minus] 12 g. Consumption of fluid, and thus of alcohol, was increased in all groups during the second 3 mo. of the study, but significant increases were found only in the 8% and 16% alcohol groups. The 8% group increased its fluid consumption from 131 to 140 ml per 24 hr. (p. <001) and the 16% group from 106 to 115 ml (p <.01). The control groups showed no change in consumption. All the rats increased in weight during the 6 mo. but with no significant intergroup differences. The dally fluid consumption of the rats receiving the 8% and 16% alcohol solutions was less than that of the other 2 groups. Evidently above an alcohol concentration of 5.5% the rats decrease their consumption. When presented with a choice of water or alcohol-water solution, the 2%, 4% and 8% groups drank the same quantities of absolute alcohol as in the no choice situation, but the 16% group decreased its consumption. After being deprived of fluid for 24 hr. the rats drank more alcohol at all concentrations than ,in the nondeprlved condition; the 16% group drank less alcohol but more water than the other groups. Under no-choice conditions the alcohol metabolism rate increased as the concentration of alcohol increased: 2% group, 52 mg per kg per hr; 16% group, 287. Under the choice condition, the 8%-group rate was greater than that of the 16%: non-deprived, 180 vs 172 mg per kg per hr; deprived, 281 vs 193. The results demonstrate that after forced alcohol consumption rats will drink some alcohol-water solutions in preference to water. When presented with water and alcohol-water solutions of different strengths they drank enough of the alcohol solutions to consume on the average 5.5% alcohol. The volume of absolute alcohol consumed is to some extent determined by the quantity of water with which they can dilute it and the caloric value of the alcohol.

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