Rewarding effects of ethanol and cocaine in μ opioid receptor-deficient mice

Axel Becker, Gisela Grecksch, Jürgen Kraus, Horace H. Loh, Helmut Schroeder, Volker Höllt

Research output: Contribution to journalArticlepeer-review

101 Scopus citations

Abstract

To investigate the role of μ opioid receptors in the reinforcing effects of psychotropic drugs, the voluntary ethanol intake and ethanol- and cocaine-induced conditioned place preference in μ opioid receptor-deficient mice and their wild-type counterpartners was tested. Moreover, dopamine D1 and D2 receptor binding was measured. It was found that ethanol intake was significantly lower in deficient mice. Conditioned place preference in wild-type animals was induced with 5.0 mg/kg cocaine and this dose was ineffective in the knockouts. In this group conditioned place preference occurred after injection of 10.0 mg/kg cocaine. Cocaine induced a similar increase in locomotor activity in both groups of mice. There was no difference in dopamine D1 receptor binding, whereas dopamine D2 receptor binding was significantly lower in the hippocampus of deficient animals. This suggests that interaction between opioid systems and dopaminergic systems may account for the differences in responding to the drugs.

Original languageEnglish (US)
Pages (from-to)296-302
Number of pages7
JournalNaunyn-Schmiedeberg's Archives of Pharmacology
Volume365
Issue number4
DOIs
StatePublished - 2002

Keywords

  • Cocaine
  • Conditioned place preference
  • Dopamine binding
  • Ethanol
  • Self-administration
  • Transgenic mice
  • μ opioid receptor

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