Naltrexone reduces ethanol- and sucrose-reinforced responding in rhesus monkeys

Keith L. Williams, Gail Winger, Eric D. Pakarinen, James H. Woods

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47 Scopus citations

Abstract

These experiments evaluated the ability of naltrexone (NTX) to reduce selectively oral and IV ethanol-reinforced responding, and examined the ethanol-NTX interaction in terms of the competitive opioid antagonist property of NTX. Five rhesus monkeys self-administered ethanol or sucrose and concurrently available water. Ethanol concentration was varied from 0.25% to 8% (w/v). Naltrexone (0.032-0.32 mg/kg) or saline was given IM 38 min prior to some drinking sessions. NTX (0.32 mg/kg) reduced ethanol-reinforced responding at the concentration that maintained the most responding (1% or 2%). NTX (0.1 mg/kg) reduced ethanol-reinforced responding, both at a low ethanol concentration (0.25%) that produced little ethanol intake (g/kg), and at a higher concentration (4%) with an appreciable intake. Thus, NTX (0.1 mg/kg) shifted the ethanol concentration-consumption curve down, in an insurmountable manner. NTX (0.1 and 0.32 mg/kg) also reduced reinforced responding for sucrose 100 g/l. In another experiment, three rhesus monkeys were given opportunities to self-administer ethanol IV. NTX (0.1 mg/kg) reduced the number of ethanol injections obtained by the monkeys at all ethanol doses tested (0.01, 0.032, and 0.1 g/kg per injection). The dose-effect curve was also shifted down. These results showed that NTX reduced behavior maintained by either ethanol or sucrose non-selectively. Furthermore, the ability of NTX to suppress ethanol-reinforced responding did not depend on the route of ethanol administration and was not overcome by increasing the concentration or dose per injection of ethanol.

Original languageEnglish (US)
Pages (from-to)53-61
Number of pages9
JournalPsychopharmacology
Volume139
Issue number1-2
DOIs
StatePublished - 1998
Externally publishedYes

Keywords

  • Alcohol
  • Intravenous self-administration
  • Operant behavior
  • Opioid antagonists
  • Oral self-administration

ASJC Scopus subject areas

  • Pharmacology

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