REINSTATEMENT OF HEROIN-REINFORCED BEHAVIOR FOLLOWING LONG-TERM EXTINCTION - IMPLICATIONS FOR THE TREATMENT OF RELAPSE TO DRUG TAKING

The effect of non contingent priming injections of heroin on drug-rein forced behavior following long-term extinction was examined. Male rats were trained to lever press for 100 mu g/kg/infusion of intravenous h eroin during four 6 h sessions per day. The drug-reinforced behavior w as extinguished by daily reductions in dose followed by at least 12 se ssions of saline self-administration. A single non-contingent priming injection of heroin (100 mu g/kg, i.v.) resulted in the reinstatement of the drug-reinforced behavior, even though extinction conditions rem ained. The results indicate that the drug-induced reinstatement of pre viously extinguished drug-reinforced behavior is possible even after l ong periods of extinction. The implications of the present findings fo r the treatment of relapse to drug abuse in humans are discussed.