Involvement of amygdaloid protein synthesis in early- and late-phase reconsolidation of emotion-related memories

This study was undertaken to test whether de novo protein synthesis in the basolateral (BLA) and central (CeA) nucleus of amygdala was required for reconsolidation of emotion-related memories. Mice were trained to sequentially acquire both cocaine-induced conditioned place preference (CPP) and step-through passive avoidance (PA) memories. Immediately following PA retrieval, intra-BLA anisomycin infusion was found to decrease subsequent PA performance in retests. Immediately following PA retrieval, intra-CeA anisomycin infusion did not acutely affect PA performance but decreased such a PA memory 5 days later. Given PA retrieval procedure was omitted, intra-BLA and intra-CeA anisomycin infusion did not affect PA memory. Likewise, intra-BLA anisomycin infusion immediately following cocaine-induced CPP retrieval was found to decrease cocaine-induced CPP magnitude in early and late retests. Immediately after cocaine-induced CPP retrieval, intra-CeA anisomycin infusion did not acutely affect cocaine-induced CPP but decreased this memory 5 days later. Given the cocaine-induced CPP retrieval procedure was omitted, intra-BLA and intra-CeA anisomycin infusion did not affect cocaine-induced CPP in subsequent retests. These results, taken together, imply that de novo protein synthesis in amygdala plays an important role in modulating reconsolidation of emotion-related memory. More importantly, de novo protein synthesis in the BLA is essential for early phase reconsolidation of retrieved emotion-related memories. Protein synthesis in the CeA is required for late phase reconsolidation of retrieved emotion-related memories.