Effects of lifelong ethanol consumption on drinking behavior and motor impairment of alcohol-preferring AA and alcohol-avoiding ANA rats

The effects of drinking ethanol throughout a lifetime on voluntary drinking behavior and ethanol-induced motor impairment were studied in alcohol-pref erring AA (Alko, Alcohol) and alcohol-avoiding ANA (Alko, Non-Alcohol) rats of both sexes. At the age 3 months, the rats were tested for individual vo luntary ethanol (10% [vol./vol.]) intake and ethanol-induced motor impairme nt (2 g/kg, i.p.). The rats were housed in group cages, half of them having 12% (vol./vol.) ethanol as the only source of fluid and the other half hav ing free access to water. Food was always available for all animals. At the age of 23 months, their individual voluntary ethanol intake and ethanol-in duced motor impairment were tested again. During forced drinking, the femal es of both strains consumed more ethanol than did the males. The ethanol co nsumption of the AA and ANA females and the ANA males increased significant ly (P <.001) with age, but a slight decrease was seen in the ethanol consum ption of the AA males. Time x strain interaction showed a significant (P<.0 5) difference in the ethanol consumption of male rats, with the AA males ha ving a slight decrease in ethanol consumption with age, whereas the ANA mal es increased their ethanol consumption. After 19 months of forced ethanol e xposure, AA males significantly decreased their individual voluntary ethano l consumption, and individual voluntary ethanol consumption by ethanol-expo sed AA males was more pronounced (P<.001) than that of the AA rats that had free access to water (P<.05). For the female AA rats, those having fi ee a ccess to water significantly decreased their voluntary ethanol consumption (P<.05), but those having ethanol only did not. No significant changes in v oluntary ethanol consumption with age or with different exposures were seen in the ANA rats. Body weights were higher in the groups having access to w ater than in the ethanol-only groups, but the differences were not signific ant within the AA and ANA strains. The ANA rats were significantly heavier in all groups. These results indicate that the voluntarily nondrinking ANA rats can drink almost as much ethanol as the voluntarily drinking AA rats w hen they are forced to drink ethanol and that lifelong forced ethanol drink ing does not change their inherent drinking habits. When sensitivity to eth anol was measured with the tilting-plane test, the old AA female rats were more sensitive to ethanol than were the young ones. The young ANA females w ere more sensitive than the AA females when tested at 4 months. In males, a ging did not produce any differences in ethanol sensitivity. (C) 2001 Elsev ier Science Inc. All rights reserved.