The dopamine release inhibitor CGS 10746B blocks conditioned physical signs of morphine withdrawal.

Abstract

Environment previously paired with morphine withdrawal leads to conditioned physical signs of withdrawal, this effect being modulated by additional exposition to morphine administration. In this study, the putative role of dopamine in conditioned withdrawal signs is evaluated by administering the dopamine release inhibitor CGS 10746B prior to suffering two naloxone-induced withdrawals in a distinctive environment associated or not with morphine administration. The results show that dopamine seems to be necessary for the development of conditioned somatic signs of morphine withdrawal, as animals which received CGS 10746B do not present paw tremor or body shakes when they are placed in the environment paired with two previously induced withdrawals. On the other hand, the conditioned decrease in aggression is not affected by the dopamine release inhibitor. Taken together, our results confirm a critical role for dopamine in the processes of conditioning to the aversive physical signs of withdrawal.