Background: Study of the long-term effects of chronic alcohol consumption in human populations is confounded by genetic and environmental factors.
Methods: The study was intended to investigate the effects on morbidity and survival of lifetime forced ethanol consumption in male and female AA (Alko, Alcohol) and ANA (Alko, Non-Alcohol) rats. The ethanol-exposed rats had 12% ethanol as the only available fluid from 3 to 24 months of age. The control groups had water. Rats that died during the experiment and those that were killed at 24 months of age were all autopsied, and the pathologic findings were recorded.
Results: Lifelong ethanol consumption did not change the survival rate of the rats, and had no significant effect on the rates of any of the pathologic measures in either the AA or ANA line of rats, suggesting that this may not be a good animal model for studying the detrimental effects of chronic alcohol. An unexpected, highly significant finding was observed: the AA rats, bred for high voluntary ethanol drinking, lived much longer than the ANA rats, bred for ethanol avoidance. The death rate by 24 months in the AA line was less than one-third of that in the ANA line. This difference was found regardless of whether the animals were maintained on alcohol or water, and in both genders. The AA rats had significantly lower rates of kidney disease, benign tumors, and cardiovascular disease than the ANA animals.
Conclusions: Lifelong ethanol consumption increased neither the mortality nor the morbidity of AA and ANA line of rats. Genes selected in the development of the high drinking AA line have additional effects producing rats that are healthier and living longer than the ANA rats possessing genes resulting in alcohol avoidance.