Wheel running decreases the positive reinforcing effects of heroin

BackgroundThe purpose of this study was to examine the effects of voluntary wheel running on the positive reinforcing effects of heroin in rats with an established history of drug self-administration.MethodsRats were assigned to sedentary (no wheel) and exercise (wheel) conditions and trained to self-administer cocaine under positive reinforcement contingencies. Rats acquiring cocaine self-administration were then tested with various doses of heroin during daily test sessions.ResultsSedentary rats self-administered more heroin than exercising rats, and this effect was greatest at low and moderate doses of heroin.ConclusionThese data suggest that voluntary wheel running decreases the positive reinforcing effects of heroin.