ETHANOL-INDUCED TASTE-AVERSION IN ETHANOL-DEPENDENT AND NORMAL RATS

It has previously been shown that the intragastric and parenteral administration of an acutely intoxicating dose of ethanol to naive rats paired with the oral intake of a flavored solution induces a conditioned taste aversion to the solution. Experiments have been designed to examine possible differences in the ethanol-induced aversion between naive rats and rats rendered ethanol dependent by chronic forced administration of alcohol. The classical conditioned taste aversion paradigm was used. Control rats and rats previously fed on an ethanol-containing liquid diet for 15 days were offered a saccharin solution for a 30-min period, 2 hr after the removal of either the control or the intoxicating liquid diet. In four groups of animals, the free intake of the flavored solution was immediately followed by either no injection or an ip administration of 1.5, 3.0 or 4.5 g/kg 20% ethanol solution. Three days later, the acquired aversion was tested with a second 30-min presentation of the saccharin solution. It was shown that in dependent rats, compared to controls, a single association between the oral intake and the withdrawal illness establishes a strong aversion to the flavored solution. In controls, aversion was induced by the three postingestive doses of ethanol. In intoxicated rats, 1.5 g/kg resulted in a maintained or slightly enhanced saccharin intake, whereas higher doses again induced the aversion. Nevertheless, the aversion obtained with the 3 g/kg was significantly lower than in controls. The findings of a withdrawal illness-induced aversion and of a maintained intake of this same solution, induced by the postingestional effect of a small dose of ethanol in dependent rats, are discussed in relation to the problem of the experimental establishment of behavioral ethanol dependence in rats. © 1979 Academic Press, Inc.