Effect of naltrexone on oral consumption of concurrently available ethanol and cocaine in the rat

Stromberg, Michael F.; Sengpiel, Till; Mackler, Scott A.; Volpicelli, Joseph R.; O'Brien, Charles P.; Vogel, Wolfgang H.

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Volume 28, Issue 3 , Pages 169-179, November 2002

Effect of naltrexone on oral consumption of concurrently available ethanol and cocaine in the rat☆

Michael F. Stromberg
- Corresponding author. Tel.: +1-215-823-4325; fax: +1-215-823-5171.
- Center For Studies of Addiction, Department of Psychiatry, University of Pennsylvania, 3900 Chestnut Street, Philadelphia, PA 19104, USA
- Philadelphia VAMC, Philadelphia, PA 19104, USA
Till Sengpiel
- Philipps-University of Marberg, Marberg 35043, Germany
Scott A. Mackler
- Department of Medicine and Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Philadelphia VAMC, Philadelphia, PA 19104, USA
Joseph R. Volpicelli
- Center For Studies of Addiction, Department of Psychiatry, University of Pennsylvania, 3900 Chestnut Street, Philadelphia, PA 19104, USA
- Philadelphia VAMC, Philadelphia, PA 19104, USA
Charles P. O'Brien
- Center For Studies of Addiction, Department of Psychiatry, University of Pennsylvania, 3900 Chestnut Street, Philadelphia, PA 19104, USA
- Philadelphia VAMC, Philadelphia, PA 19104, USA
Wolfgang H. Vogel
- Thomas Jefferson University, Philadelphia, PA 19104, USA

Received 11 January 2002; received in revised form 22 July 2002; accepted 29 July 2002.

Abstract

Comorbid abuse of and dependency on multiple drugs is a common occurrence clinically. We have developed an animal model that provides rats with the opportunity to choose, through oral consumption, between concurrently available ethanol and cocaine with water also available. This provides the ability to screen for the effectiveness of potential pharmacotherapeutic agents on the baseline consumption of both drugs. We used this animal model to evaluate the effects of naltrexone, at doses of 0, 1.0, 3.0, and 10.0 mg/kg, on concurrent oral consumption of ethanol and cocaine solutions. Naltrexone at all doses significantly reduced both consumption of and preference for ethanol. Consumption of both cocaine and water was unaffected by naltrexone, supporting the suggestion that the effects of naltrexone were selective for ethanol. These findings support the suggestion that ethanol and cocaine act on different central reward pathways. The implications of these findings for the clinical use of naltrexone in populations with comorbid ethanol and cocaine abuse are discussed.

Keywords: Ethanol, Cocaine, Naltrexone, Rats