The effects of ethanol and pentobarbital on the naloxone precipitated escape response in morphine dependent mice.

Morphine dependence in mice is produced in a two day test. The effects of (1) ethanol, (2) pyrazole, (3) ethanol with pyrazole, and (4) pentobarbital are observed and recorded on the naloxone precipitated escape response in morphine dependent mice. Ethanol suppresses the escape response in doses of 2.0 and 3.0 g/kg which produce mean blood ethanol concentrations of 1.88 and 3.28 mg/ml, respectively. When a pyrazole regimen is employed with morphine dependent mice, ethanol reduces or abolishes the naloxone precipitated escape response at doses of 1.0, 2.0 and 3.0 mg/kg. The corresponding mean blood ethanol concentrations are 1.14, 2,82 and 3.74 mg/ml, respectively. When pentobarbital (20 and 30 mg/kg) is given to morphine dependent mice, jumping bevarior is prevented following naloxone injection. Since narcotic antagonists such as naloxone may be employed in studying the phenomenon of physical dependence on ethanol based on the hypothesis of a relationship between endogenous opiates and ethanol dependence, it is essential to verify that blood ethanol concentrations are low enough so that ethanol will not interfere with the effects of naloxone in ethanol dependent animals.