Free-choice ethanol intake and ethanol metabolism in the hamster and rat.

Hamsters, as previously reported, demonstrated greater ethanol intake and preference than rats. However, as ethanol was gradually added to a sweet solution, hamster ethanol intakes did not consistently exceed ethanol metabolic capacity for prolonged periods. In ethanol-naive hamsters and rats, alcohol dehydrogenase activities and ethanol metabolic rates of isolated hepatocytes in vitro and blood ethanol elimination rates in vivo show consistent large interspecific differences corresponding to the species' differences in ethanol intake and preference. The data suggest a limiting role of ethanol metabolism in the regulation of maximized free-selection ethanol intake by rodents, and provide an explanation for the absence of continuously elevated blood ethanol levels and alcohol withdrawal syndrome in hamsters during periods of comparatively high daily ethanol intake.