Opiate antagonists reduce cocaine but not nicotine self-administration (original) (raw)

Abstract

Rats were trained to self-administer cocaine in 1-h sessions on a fixed ratio 5 (FR5) schedule of reinforcement. Acquisition was carried out at a unit dose of 0.3 mg/kg and responding was then stabilized at cocaine doses of 0.1, 0.3, and 1.0 mg/kg/infusion. Pretreatments with naltrexone (0.1–10 mg/kg, SC) 20 min prior to the start of self-administration sessions resulted in decreases in cocaine self-administration at doses of 0.1 and 0.3 mg/kg/infusion, but not at 1.0 mg/kg/infusion. Decreases depended on the dose of naltrexone used, with greater decreases in self-administration occurring at higher antagonist doses. In addition, treatment with the opiate antagonist naloxone also reduced cocaine self-administration at a unit dose of 0.3 mg/kg. A group of rats trained to self-administer nicotine at a dose of 0.03 mg/kg/infusion on the same schedule of reinforcement was unaffected by naltrexone treatment. These results may indicate that an endogenous opiate system plays a role in cocaine reinforcement.

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Authors and Affiliations

  1. Addiction Research Foundation, 33 Russell Street, M5S 2S1, Toronto, Ontario, Canada
    William A. Corrigall & Kathleen M. Coen
  2. Department of Physiology, Faculty of Medicine, University of Toronto, M5S 2S1, Toronto, Ontario, Canada
    William A. Corrigall

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  1. William A. Corrigall
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  2. Kathleen M. Coen
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The views expressed in this manuscript are those of the authors and do not necessarily reflect those of the Addiction Research Foundation.

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Corrigall, W.A., Coen, K.M. Opiate antagonists reduce cocaine but not nicotine self-administration.Psychopharmacology 104, 167–170 (1991). https://doi.org/10.1007/BF02244173

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