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Behav Brain Res. 2014 Nov 1;274:158-63. doi: 10.1016/j.bbr.2014.08.012. Epub 2014 Aug 12.

The effects of amphetamine, butorphanol, and their combination on cocaine self-administration.

Author information

1
Department of Psychology and Program in Neuroscience, Davidson College, Box 7037, Davidson, NC 28035-7037, United States. Electronic address: masmith@davidson.edu.
2
Department of Psychology and Program in Neuroscience, Davidson College, Box 7037, Davidson, NC 28035-7037, United States.

Abstract

There have been recent calls to examine the efficacy of drug-combination therapies in the treatment of substance use disorders. The purpose of the present study was to examine the ability of a novel stimulant-opioid combination to reduce cocaine self-administration, and to compare these effects to those of each drug administered alone. To this end, male Long-Evans rats were implanted with intravenous catheters and trained to self-administer cocaine under positive reinforcement contingencies. Once self-administration was acquired, rats were divided into four different groups and treated chronically for 20 days with (1) saline, (2) the psychomotor stimulant and monoamine releaser amphetamine, (3) the mu/kappa opioid agonist butorphanol, or (4) a combination of amphetamine and butorphanol. During chronic treatment, cocaine self-administration was examined on both fixed ratio (FR) and progressive ratio (PR) schedules of reinforcement. On the FR schedule, butorphanol significantly decreased cocaine self-administration, but this effect was not enhanced by amphetamine. On the PR schedule, amphetamine and butorphanol non-significantly decreased cocaine self-administration when administered alone but significantly decreased cocaine self-administration when administered in combination. These data suggest that under some conditions (e.g., when the response requirement of cocaine is high), a dual stimulant-opioid pharmacotherapy may be more effective than a single-drug monotherapy.

KEYWORDS:

Amphetamine; Butorphanol; Cocaine; Fixed ratio; Progressive ratio; Self-administration

PMID:
25127681
PMCID:
PMC4179971
DOI:
10.1016/j.bbr.2014.08.012
[Indexed for MEDLINE]
Free PMC Article
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