The rewarding properties of MDMA are presented in mice lacking μ-opioid receptors

Patricia Robledo, Victoria Mendizabal, Jordi Ortuño, Rafael De La Torre, Brigitte L. Kieffer, Rafael Maldonado

    Research output: Contribution to journalArticleResearchpeer-review

    39 Citations (Scopus)

    Abstract

    The involvement of μ-opioid receptors in the rewarding properties of MDMA was explored in μ-opioid receptor knockout mice using the conditioning place preference paradigm. The associated release of dopamine in the nucleus accumbens was investigated by in vivo microdialysis. A significant rewarding effect of MDMA (10 mg/kg, i.p.) was observed in both wild-type and μ-opioid receptor knockout mice. MDMA (10 mg/kg, i.p.) also induced similar increases in dopamine and decreases in 3,4-dihydroxyphenylacetic acid and homovanillic acid in the nucleus accumbens dialysates of both wild-type and μ-opioid receptor knockout mice. No significant differences in basal levels of dopamine, 3,4-dihydroxyphenylacetic or homovanillic acids between wild-type and μ-opioid receptor knockout mice were observed. In summary, the present results suggest that, in contrast to what has been reported for other drugs of abuse such as opioids, ethanol, nicotine and Δ9- tetrahydrocannabinol, μ-opioid receptors do not play a major role in the rewarding properties of MDMA. These differences could be due to distinct mechanisms controlling dopamine release in the nucleus accumbens and suggest that the effects of MDMA on dopaminergic neurons are independent of μ-opioid receptors.
    Original languageEnglish
    Pages (from-to)853-858
    JournalEuropean Journal of Neuroscience
    Volume20
    Issue number3
    DOIs
    Publication statusPublished - 1 Aug 2004

    Keywords

    • Conditioned place preference
    • Dopamine
    • Ecstasy
    • Microdialysis
    • Nucleus accumbens

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