Pavlovian-conditioned changes in body temperature induced by alcohol and morphine. Drug Dev. Res. 16295-303, 1989.
Several theoretical analyses of drug-taking behavior posit an important mediating role for Pavlovian-conditioned drug responses that develop as a result of stimulus-drug pairings imbedded within the self-administration paradigm. Some of these analyses focus attention on the learning of physiological responses that appear to counteract or compensate for the direct effects of a drug, thereby producing tolerance and encouraging increased drug taking. Others place greater emphasis on the learning of responses that mimic the drug's effect and presumably increase drug taking through a positive incentive mechanism. Our laboratory has been especially interested in the determinants of drug-induced conditioned changes in body temperature and the roles that such responses might play in drug tolerance, sensitization, and self-administration. Our research has involved both alcohol and morphine, drugs that produce a similar conditioned thermal response despite the fact that the direct thermal effects of these drugs are completely different.
In the case of alcohol, our initial studies showed that environmental (cage) cues paired with intraperitoneal (i.p.) injection of the drug acquire the ability to evoke a conditioned hyperthermic response that reduces the hypothermic reaction to ethanol (i.e., tolerance). More recent studies have explored the nature of the events capable of serving as conditioned stimuli (CSs) for such learning. These studies show that interoceptive thermal cues can mediate tolerance to alcohol's thermal effect, but taste cues cannot. The inability of taste cues to mediate tolerance may have special implications for the study of responses that are conditioned during oral self-administration of alcohol, a procedure that offers very salient gustatory cues.