Journal of Nippon Medical School
Online ISSN : 1347-3409
Print ISSN : 1345-4676
ISSN-L : 1345-4676
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Rewarding Effects of Ethanol Combined with Low Doses of Morphine through Dopamine D1 Receptors
Yuya IseTomohisa MoriShirou KatayamaHiroshi NagaseTsutomu Suzuki
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JOURNAL FREE ACCESS

2013 Volume 80 Issue 1 Pages 34-41

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Abstract

This study investigated whether ethanol combined with low doses of morphine produces rewarding effects in rats. Ethanol (0.075-1.2 g/kg, intraperitoneal [i.p.]) alone did not induce place preference. A moderate dose (1 mg/kg, s.c.), but not a low dose (0.1 mg/kg), of morphine induced a significant place preference. The combination of ethanol (0.075-0.6 g/kg, i.p.) and 0.1 mg/kg of morphine, as well as low doses of morphine (0.03-0.1 mg/kg, subcutaneous [s.c.]) combined with ethanol (0.3 g/kg, i.p.), induced a significant place preference. The combined effect of ethanol and morphine was significantly attenuated by naloxone (0.3 mg/kg, s.c.), naltrindole (1.0 mg/kg, s.c.), or long-term administration of the dopamine D1 receptor antagonist SCH23390 (1.0 mg/kg/day, s.c.). These results suggest that the rewarding effect induced by ethanol and a low dose of morphine is mediated by activation of the central opioidergic and dopaminergic systems through dopamine D1 receptors.

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© 2013 by the Medical Association of Nippon Medical School
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