CONTINUOUS TREATMENT WITH MORPHINE INCREASES DIAZEPAM-BINDING INHIBITOR MESSENGER-RNA IN MOUSE-BRAIN

Effects of acute and chronic morphine treatment on the expression of d iazepam binding inhibitor (DBI) mRNA in the mouse brain were examined. Cerebral DBI mRNA expression significantly increased in morphine-depe ndent mice, and this increase is more remarkable in morphine-withdrawn mice, whereas a single administration of morphine (50 mg/kg) produced no changes in the expression. Simultaneous administration of naloxone (3 mg/kg) with morphine completely abolished the increase in cerebral DBI mRNA expression observed in morphine-dependent and -withdrawn mic e. These results indicate that a chronic functional interaction betwee n morphine and opioid receptors has a critical role in increases in DB I mRNA expression.