Effects of ethanol on cocaine discrimination in rats

Michael B. Gatch, Bradley D. Youngblood, Michael J. Forster

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Ethanol and cocaine are frequently abused in combination, but little is known about how the subjective effects of the two drugs interact. The ability of ethanol and other GABAA-active compounds to alter the discriminative stimulus effects of cocaine was tested. Male Sprague-Dawley rats were trained to discriminate cocaine (10 mg/kg ip) from saline using either single- or cumulative-dosing methods. In single-dose testing, ethanol (0.1-0.5 g/kg) dose-dependently decreased cocaine-appropriate responding following the training dose of cocaine. Ethanol (0.5 g/kg) produced a rightward shift in the cocaine cumulative dose-effect curve. Ethanol (0.1-1.0 g/kg) failed to substitute for the discriminative stimulus effects of cocaine and the higher doses (1-2 g/kg) completely suppressed responding. Indirect GABAA agonists diazepam (benzodiazepine site) and pentobarbital (barbiturate site) did not block the discriminative stimulus effects of cumulative doses of cocaine. The GABAA antagonist pentylenetetrazol (PTZ) (10-40 mg/kg) did not substitute for cocaine. These findings suggest that ethanol can modulate the discriminative stimulus effects of cocaine, and that these effects may not be mediated by the actions of ethanol at the GABAA receptor.

Original languageEnglish
Pages (from-to)837-844
Number of pages8
JournalPharmacology Biochemistry and Behavior
Issue number4
StatePublished - Jul 2003


  • Cocaine
  • Drug discrimination
  • Ethanol
  • GABA receptor
  • Rat


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