Differential effect of NMDA receptor antagonist in the nucleus accumbens on reconsolidation of morphine -related positive and aversive memory in rats.

Dysfunctional reconsolidation processes may help drug memories resist extinction and contribute to high rate of relapse. Reconsolidation of drug memory is mainly affected by the appetitive and aversive emotional experiences associated with an addictive drug. The nucleus accumbens has been shown to mediate the reconsolidation of positive emotional addictive memory, but its role in negative emotional addictive memory remains elusive. In the present study, we used morphine-induced CPP (m-CPP) and morphine-naloxone induced conditioned place aversion (m-CPA) to investigate the role of N-methyl-d-aspartate (NMDA) receptors within the nucleus accumbens on reconsolidation of emotional drug memory. Here we demonstrate that infusion of the NMDA receptor antagonist, d-(-)-2 amino-5-phosphonopentanoic acid ((D)-APV), into the nucleus accumbens before memory reactivation disrupts the reconsolidation of m-CPP, but does not affect m-CPA. The effect on m-CPP reconsolidation depended on memory reactivation: (D)-APV infusion had no effect in the absence of reactivation. The findings show that the glutamatergic NMDA receptor in nucleus accumbens mechanisms involved in reconsolidating aversive and positive morphine-associated memories can be dissociated.