Chronic morphine treatment diminished ethanol mediated responses in the CNS

The purpose of present experiment was to investigate the pharmacological effects of ethanol on morphine tolerant rats. We found that chronic morphine injection diminished the duration of ataxia induced by ethanol in rats. Using enzymatic and spectrophotometric methods, we found that chronic injection of morphine did not affect the metabolism of ethanol. On the other hand, the sensitivity to ethanol was decreased in the cerebellar Purkinje neurons. These suggested that behavior tolerance to ethanol in chronic morphine treated rats may possibly involve the desensitization of ethanol in the CNS.