Shogo Tokuyama, Fumihiro Nakamura, Kaoru Nakao, Masakatsu Takahashi and Hiroshi Kaneto
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852, Japan
Abstract: Reinforcing effects of dihydroetorphine (DHE) and morphine were evaluated by the conditioned place preference paradigm. Both DHE and morphine produced an antinociceptive effect in a dose-dependent manner. On the other hand, DHE (0.1, 1, 3 and 10 microg/kg, i.p.) failed to induce the conditioned preference, while morphine (0.1, 1, 3 and 10 mg/kg, i.p.) caused a dose-dependent preference for the drug-paired place. Thus, these characteristic properties of DHE make it attractive for development as a novel potent analgesic compound that has less dependence liability.
Dihydroetorphine, Morphine, Conditioned place preference
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