Motivational control of heroin seeking by conditioned stimuli associated with withdrawal and heroin taking by rats.

The authors investigated the impact of conditioned withdrawal on drug seeking by training rats to work for a heroin infusion on a seeking-taking schedule, which required responding on a seeking lever in order to gain the opportunity to self-administer the drug by a single response on a taking lever. Following the establishment of opiate dependence, a conditioned stimulus (CS) that had been previously paired with naloxone-precipitated withdrawal suppressed heroin seeking in extinction. However, when the rats had prior experience of heroin taking in the presence of the withdrawal CS, drug seeking was elevated in the presence of this stimulus. The authors conclude that the conditioned motivation of drug seeking in withdrawal depends on previous association of the CS with drug taking.