Pre-exposure of rats to amphetamine sensitizes self-administration of this drug under a progressive ratio schedule.
Two groups of male rats were tested to determine whether pre-exposure to d-amphetamine would enhance the motivation to self-administer the drug under a progressive ratio schedule of reinforcement. In the first phase of the experiment, one group of rats received d-amphetamine (2 mg/kg IP), while a second group received saline on alternate days for a total of ten injections. Following a 21-day drug withdrawal period, behavioral sensitization was confirmed by a significant increase in amphetamine-induced stereotypy in the d-amphetamine-pretreated group, relative to the saline-pretreated group. In the second phase of the study, all rats were implanted with chronic jugular catheters and trained to self-administer d-amphetamine (0.2 mg/kg per infusion) under a fixed-ratio schedule of reinforcement. The progressive ratio paradigm was then imposed for 7 consecutive days; d-amphetamine-pretreated rats attained significantly higher break points than saline-pretreated animals. These data suggest that pre-exposure to d-amphetamine may enhance the motivation to self-administer this drug.
Mendrek
A
A
University of British Columbia, Department of Psychology, Vancouver, Canada.
Blaha
C D
CD
Phillips
A G
AG
D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D003913:Dextroamphetamine / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D012055:Reinforcement Schedule; D012646:Self Administration; D013239:Stereotyped Behavior / Q000187:drug effects
D000697:Central Nervous System Stimulants; D003913:Dextroamphetamine