Psychopharmacology

, Volume 143, Issue 2, pp 209–214 | Cite as

Effects of baclofen on maintenance and reinstatement of intravenous cocaine self-administration in rats

  • U. C. Campbell
  • S. T. Lac
  • Marilyn E. Carroll
ORIGINAL INVESTIGATION

Abstract

Rationale: Recent studies suggest that the GABAB receptor agonist, baclofen, may be a useful pharmacotherapy for cocaine abuse. Objectives: To investigate further the effects of baclofen on maintenance and reinstatement of cocaine-reinforced behavior in rats. Methods: Two groups of rats were trained to self-administer IV cocaine (0.2 or 0.4 mg/kg per infusion) during daily 7-h sessions under a fixed-ratio 1 schedule. Rats were pretreated with baclofen (1.25, 2.5 or 5 mg/kg IP) or saline before the session for 5 consecutive days. An additional group of rats was trained to self-administer IV cocaine (0.4 mg/kg per infusion) during the first 2 h of daily 7-h sessions. Cocaine was replaced by saline for the remaining 5 h of the session. Once behavior had stabilized over the 7-h period, priming injections of saline (IV), cocaine (3.2 mg/kg IV) or baclofen (1.25 or 2.5 mg/kg IP) were administered prior to hour 4. Injections of baclofen (1.25 or 2.5 mg/kg IP) or saline were also given before priming injections of cocaine. Results: Pretreatment with the two higher doses of baclofen (2.5 and 5 mg/kg) decreased the number of cocaine infusions in both maintenance groups (0.2 and 0.4 mg/kg) over the 5-day treatment period. Baclofen had a greater suppressant effect on responding maintained by the lower dose of cocaine. Priming injections of baclofen (1.25 and 2.5 mg/kg) or saline did not reinstate responding. However, these same doses of baclofen dose-dependently reduced the reinstatement of responding produced by priming injections of cocaine. Conclusions: 1) The magnitude of the suppressant effects of baclofen on maintenance of cocaine self-administration depends upon the maintenance dose, 2) baclofen may be useful in preventing reinstatement of cocaine-seeking behavior, and 3) compared to maintenance, reinstatement of responding is more sensitive to the suppressant effects of baclofen.

Key words Baclofen Cocaine Extinction Intravenous self-administration Maintenance dose Rat Reinstatement of responding Relapse 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • U. C. Campbell
    • 1
  • S. T. Lac
    • 1
  • Marilyn E. Carroll
    • 1
  1. 1.Department of Psychiatry, University of Minnesota Medical School, UMHC Box 392, Minneapolis, MN 55455-0392, USA, e-mail: savag009@gold.tc.umn.edu, Fax: +1-612-624-8935US

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