Abstract
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.
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Received: 16 July 1997 / Final version: 22 October 1997
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Mendrek, A., Blaha, C. & Phillips, A. Pre-exposure of rats to amphetamine sensitizes self-administration of this drug under a progressive ratio schedule. Psychopharmacology 135, 416–422 (1998). https://doi.org/10.1007/s002130050530
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DOI: https://doi.org/10.1007/s002130050530