Induction of physical dependence on and tolerance to ethanol in rats fed a new nutritionally complete and balanced liquid diet.

Rats offered a nutritionally balanced and complete liquid diet containing 35% of energy as ethanol, 12% as fat, 21% as protein, and the balance as carbohydrate consumed greater than 9 g/kg ethanol after 10 days. Rats displayed signs of physical dependence and tolerance while showing a net gain in weight. Physical dependence was indicated by severe intensity of the following signs during withdrawal from ethanol: Muscle rigidity; tail tremors; caudal tremors; and general tremors. Severity of these signs reached a maximum intensity by 19 h after withdrawal of ethanol. Tolerance was exhibited by chronically treated rats as measured by significantly reduced time off the belt after 7 days. Concentrations of ethanol in blood were documented on selected mornings and were observed to increase. These data suggest that physical dependence and tolerance can be induced through voluntary consumption of ethanol by rats and without nutritional compromises or weight loss.