Pre-exposure of rats to amphetamine sensitizes self-administration of this drug under a progressive ratio schedule |
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Authors: | Adrianna Mendrek Charles D Blaha A G Phillips |
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Institution: | (1) University of British Columbia, Department of Psychology, 2136 West Mall, Vancouver BC, Canada V6T 1Z4, CA |
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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.
Received: 16 July 1997 / Final version: 22 October 1997 |
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Keywords: | Sensitization d-Amphetamine Drug self-administration Progressive ratio Incentive motivation |
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