Basolateral amygdala CB1 receptors modulate HPA axis activation and context-cocaine memory strength during reconsolidation

Re-exposure to a cocaine-associated context triggers craving and relapse through the retrieval of salient context-drug memories. Upon retrieval, context-drug memories become labile and temporarily sensitive to modification before they are reconsolidated into long-term memory stores. Cannabinoid type 1 receptor (CB1R) signaling is necessary for cocaine-memory reconsolidation and associated glutamatergic plasticity in the basolateral amygdala (BLA); however, it remains unclear whether CB1Rs in the BLA mediate this phenomenon. To investigate this question, we examined whether CB1R antagonist or agonist administration into the BLA immediately after cocaine-memory retrieval (i.e., during memory reconsolidation) alters cocaine-memory strength and subsequent drug context-induced cocaine-seeking behavior in an instrumental rodent model of cocaine relapse. Intra-BLA administration of the CB1R antagonist, AM251 (0.3 {micro}g/hemisphere) - during, but not after, memory reconsolidation - increased drug context-induced cocaine-seeking behavior three days later, while the CB1R agonist, WIN55,212-2 (0.5 {micro}g/hemisphere) failed to alter this behavior. Furthermore, AM251 administration into the posterior caudate putamen (anatomical control region) during memory reconsolidation did not alter subsequent context-induced cocaine-seeking behavior. In a follow-up experiment, cocaine-memory retrieval elicited robust hypothalamic-pituitary-adrenal axis activation, as indicated by an increase in blood serum corticosterone concentration, and this response was selectively extended by intra-BLA AM251 administration during the putative time of memory reconsolidation relative to all control conditions. Together, these findings suggest that CB1R populations in the BLA gate memory strength or interfere with memory maintenance, possibly by diminishing the impact of cue-induced arousal on the integrity of the reconsolidating memory trace or on the efficiency of the memory reconsolidation process.