title: Sensitization of amphetamine-induced wheel running suppression in rats: dose and context factors.
abstract: BACKGROUND
  This study explored whether repeated injections of amphetamine (AMP), which increase general locomotion, also increase acute wheel running, a highly structured, rewarding, motor behavior not correlated with other locomotor activities.
  
  
  OBJECTIVE
  The experiments determine how 1-5 mg/kg d-AMP affects wheel running and see if, over repeated injections, the AMP effects show context specific sensitization.
  
  
  METHODS
  In experiment 1, 2 mg/kg AMP or saline (SAL) was injected on days 1, 3, 6, 8, and 10 to male Sprague-Dawley rats with either limited or no wheel experience. 20 min after the injection animals were tested in an open field for 5 min and then in a running wheel for 1 h. Rats were injected with SAL or AMP on the days following testing. On days 13 and 15, animals were tested for conditioning (following SAL) and sensitization (following AMP). In experiment 2, the effects on wheel running of repeated 1, 2, or 5 mg/kg AMP were tested.
  
  
  RESULTS
  In experiment 1, AMP (2 mg/kg) elevated open field ambulation but suppressed wheel running. Limited wheel experience potentiated the AMP-induced suppression. At test, the suppression of running was found to be context specific. In experiment 2, 1 mg/kg did not affect running, while 2 and 5 mg/kg resulted in dose-dependent running suppression. Acquisition and test AMP dose both influenced the running suppression at test; context had a marginal influence.
  
  
  CONCLUSIONS
  The degree of running suppression induced by repeated AMP is determined by both psychological (the injection context) and pharmacological (the acquisition dose) factors. This AMP-induced running suppression is consistent with the sensitization of stereotyped behavior.
authors.affiliation: Department of Psychology, Wilfrid Laurier University, Waterloo, Ontario, Canada. reikelbo@wlu.ca
authors.forename: C
authors.initials: C
authors.lastname: Serwatkiewicz
authors.forename: C
authors.initials: C
authors.lastname: Limebeer
authors.forename: R
authors.initials: R
authors.lastname: Eikelboom
mesh_terms: D000661:Amphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004777:Environment; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000697:Central Nervous System Stimulants; D000661:Amphetamine