Effects of learned safety and tolerance on alcohol consumption by the rat.

Evidence is presented that learned safety increases the rat's willingness to drink ethanol: induction of tolerance to ethanol following learned safety training produces a further increase. Rats with chronically implanted intragastric fistulae consumed substantially more (30%) alcohol when aversive post-ingestional effects were minimized by draining stomach contents during drinking than did rats allowed to retain stomach contents. Half the rats from each group were then made tolerant by prolonged forced alcohol intubation. Later testing showed an increase in alcohol consumption by rats receiving learned safety training or rendered tolerant, with the two factors being additive.