Response specificity of behaviorally augmented tolerance to ethanol supports a learning interpretation.

A modified before-after design was used to assess the influence of behavioral contingencies on the development of tolerance to ethanol, monitored with both a behavioral (moving belt, shock avoidance) task and a physiological (body temperature) response measure. Male Long-Evans rats received ethanol (2.0 g/kg IP) and daily moving belt training under one of four conditions: (1) daily injection of ethanol before moving belt sessions; (2) daily injection of ethanol after belt sessions, with intermittent intoxicated practice; (3) daily injection of ethanol after belt sessions, with no intoxicated practice; (4) daily injections of saline, with intermittent intoxicated practice. After a 28-day tolerance acquisition phase, all groups received a final moving belt test and temperature assessment after injection of ethanol. Development of tolerance to the motor effects of ethanol was seen only in animals receiving daily injections before behavioral training. By contrast, tolerance to the hypothermic effect of ethanol developed equally in all groups. The augmented development of tolerance to the motor effects of ethanol may not, therefore, indicate a generalized state of neuronal adaptation; rather, it appears to reflect a fairly specific response acquired by the organism.