title: Wheel running decreases the positive reinforcing effects of heroin.
abstract: BACKGROUND
  The 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.
  
  
  METHODS
  Rats 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.
  
  
  RESULTS
  Sedentary rats self-administered more heroin than exercising rats, and this effect was greatest at low and moderate doses of heroin.
  
  
  CONCLUSIONS
  These data suggest that voluntary wheel running decreases the positive reinforcing effects of heroin.
authors.affiliation: Department of Psychology, Davidson College, Davidson, NC 28035, USA. masmith@davidson.edu
authors.forename: Mark A
authors.initials: MA
authors.lastname: Smith
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Pitts
mesh_terms: D000818:Animals; D003042:Cocaine / Q000008:administration & dosage; D003932:Heroin / Q000008:administration & dosage*; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D012055:Reinforcement Schedule; D012420:Running / Q000502:physiology*; D012646:Self Administration / Q000379:methods
chemical_list: D003932:Heroin; D003042:Cocaine