ETHANOL ATTENUATION OF MORPHINE-DEPENDENCE - COMPARISON TO DIZOCILPINE

Recent studies indicate that morphine dependence, assessed as the seve rity of naloxone-precipitated opiate withdrawal in rats, is attenuated by dizocilpine, a non-competitive, excitatory amino acid antagonist. Because ethanol is a putative excitatory amino acid antagonist, the pr esent study compared the effects of co-administration of ethanol to th at of dizocilpine on morphine dependence. Rats were administered morph ine (10 mg/kg) twice daily for 9 days. One group received ethanol (1 g /kg) co-administration, another received dizocilpine (0.05 mg/kg) co-a dministration, and a third served as vehicle controls. On day 10, all rats received naloxone (4 mg/kg) injections and ratings of several cla ssic signs of opiate withdrawal were made. Both ethanol-and dizocilpin e-treated rats showed significantly less severe precipitated opiate wi thdrawal overall, with the ethanol group showing reduced ratings of so me specific signs. These results demonstrate that ethanol, like dizoci lpine. attenuates the development of morphine dependence. The results are consistent with the action of ethanol at glutamate receptors.