Contextual drug-associated memories precipitate craving and relapse in cocaine users. Such associative memories can be weakened through interference with memory reconsolidation, a process by which memories are maintained following memory retrieval-induced destabilization. We hypothesized that cocaine-memory reconsolidation requires cannabinoid type 1 receptor (CB1R) signaling based on the fundamental role of the endocannabinoid system in synaptic plasticity and emotional memory processing. Using an instrumental model of cocaine relapse, we evaluated whether systemic CB1R antagonism (AM251; 3 mg/kg, i.p.) during memory reconsolidation altered (1) subsequent drug context-induced cocaine-seeking behavior as well as ( 2) cellular adaptations and (3) excitatory synaptic physiology in the basolateral amygdala (BLA) in male Sprague Dawley rats. Systemic CB1R antagonism, during, but not after, cocaine-memory reconsolidation reduced drug context-induced cocaine-seeking behavior 3 d, but not three weeks, later. CB1R antagonism also inhibited memory retrieval-associated increases in BLA zinc finger 268 (zif268) and activity regulated cytoskeletal-associated protein (Arc) immediate-early gene (IEG) expression and changes in BLA AMPA receptor (AMPAR) and NMDA receptor (NMDAR) subunit phosphorylation that likely contribute to increased receptor membrane trafficking and synaptic plasticity during memory reconsolidation. Furthermore, CB1R antagonism increased memory reconsolidation-associated spontaneous EPSC (sEPSC) frequency in BLA principal neurons during memory reconsolidation. Together, these findings suggest that CB1R signaling modulates cellular and synaptic mechanisms in the BLA that may facilitate cocaine-memory strength by enhancing reconsolidation or synaptic reentry reinforcement, or by inhibiting extinction-memory consolidation. These findings identify the CB1R as a potential therapeutic target for relapse prevention.

30Contextual drug-associated memories precipitate craving and relapse in cocaine users. Such 31 associative memories can be weakened through interference with memory reconsolidation, a 32 process by which memories are maintained following memory retrieval-induced destabilization. 33We hypothesized that cocaine-memory reconsolidation requires cannabinoid type 1 receptor 34 (CB1R) signaling based on the fundamental role of the endocannabinoid system in synaptic 35 plasticity and emotional memory processing. Using an instrumental rat model of cocaine relapse, 36we evaluated whether systemic CB1R antagonism (AM251; 3 mg/kg, I.P.) during memory 37 reconsolidation alters (a) subsequent drug context-induced cocaine-seeking behavior, as well as 38 (b) cellular adaptations and (c) excitatory synaptic physiology in the basolateral amygdala (BLA). 39Systemic CB1R antagonismduring, but not after, cocaine-memory reconsolidationreduced 40 drug context-induced cocaine-seeking behavior three days, but not three weeks, later. CB1R 41 antagonism also inhibited memory retrieval-associated increases in BLA zinc finger 268 (zif268) 42 and activity regulated cytoskeletal-associated protein (Arc) immediate-early gene expression and 43 changes in BLA α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and 44 N-methyl-D-aspartate receptor (NMDAR) subunit phosphorylation that likely contribute to 45 increased receptor membrane trafficking and synaptic plasticity during memory reconsolidation. 46 Furthermore, CB1R antagonism increased memory reconsolidation-associated spontaneous 47 excitatory post-synaptic current frequency in BLA principal neurons during memory 48 reconsolidation. Together, these findings suggest that CB1R signaling modulates cellular and 49 synaptic mechanisms in the BLA during cocaine-memory reconsolidation, thereby facilitating 50 cocaine-memory maintenance. These findings identify the CB1R as a potential therapeutic target 51 for relapse prevention. 52 SIGNIFICANCE STATEMENT 53Drug relapse can be triggered by the retrieval of context-drug memories upon re-exposure to a 54 drug-associated environment. Context-drug associative memories become destabilized upon 55 retrieval and must be reconsolidated into long-term memory stores in order to persist. Hence, 56 targeted interference with memory reconsolidation can weaken maladaptive context-drug 57 memories and reduce the propensity for drug relapse. Our findings indicate that cannabinoid type 58 1 receptor (CB1R) signaling is critical for context-cocaine memory reconsolidation and 59 subsequent drug context-induced reinstatement of cocaine-seeking behavior. Furthermore, 60 cocaine-memory reconsolidation is associated with CB1R-dependent immediate-early gene 61 expression and changes in excitatory synaptic proteins and physiology in the basolateral 62 amygdala. Together, our findings provide initial support for CB1R as a potential therapeutic target 63 for relapse prevention. 64

The dorsal hippocampus (DH) is key to the long-term maintenance of cocaine memories following retrieval-induced memory destabilization; even though, it is not the site of protein synthesis-dependent memory reconsolidation. Here, we took advantage of the temporal and spatial specificity of an optogenetic manipulation to examine the role of the cornu ammonis 3 subregion of the DH (dCA3) in early-stage cocaine-memory reconsolidation. Male Sprague-Dawley rats expressing eNpHR3.0 in the DH were trained to self-administer cocaine in a distinct context and underwent extinction training in a different context. Rats then received a 15-min memory-reactivation session, to destabilize cocaine memories and trigger reconsolidation, or remained in their home cages (no-reactivation controls).Optogenetic inhibition of the dCA3 for 1 h immediately, but not 1 h, after memory reactivation resulted in cocaine-memory impairment as indicated by reduction in drug-seeking behavior selectively in the cocaine-paired context 3 d later, at test, relative to responding in no-inhibition, no-reactivation, and no-eNpHR3.0 controls. Cocaine-memory impairment was associated with reduced c-Fos expression, an index of neuronal activation, in the dCA3 stratum lucidum (SL) and stratum pyramidale (SP) at test.Based on these observations and extant literature, we postulate that recurrent circuits in the SP are activated during early-stage memory reconsolidation to maintain labile cocaine memories prior to protein synthesis-dependent restabilization in another brain region, such as the basolateral amygdala.Furthermore, SL and SP interneurons may enhance memory reconsolidation by limiting synaptic noise in the SP and also contribute to recall as elements of the updated cocaine engram or retrieval links..

The dorsal hippocampus (DH) is key to the long-term maintenance of cocaine memories following retrieval-induced memory destabilization; even though, it is not the site of protein synthesis-dependent memory reconsolidation. Here, we took advantage of the temporal and spatial specificity of an optogenetic manipulation to examine the role of the cornu ammonis 3 subregion of the DH (dCA3) in early-stage cocaine-memory reconsolidation. Male Sprague-Dawley rats expressing eNpHR3.0 in the DH were trained to self-administer cocaine in a distinct context and underwent extinction training in a different context. Rats then received a 15-min memory-reactivation session, to destabilize cocaine memories and trigger reconsolidation, or remained in their home cages (no-reactivation controls). Optogenetic inhibition of the dCA3 for 1 h immediately, but not 1 h, after memory reactivation resulted in cocaine-memory impairment as indicated by reduction in drug-seeking behavior selectively in the cocaine-paired context 3 d later, at test, relative to responding in no-inhibition, no-reactivation, and no-eNpHR3.0 controls. Cocaine-memory impairment was associated with reduced c-Fos expression, an index of neuronal activation, in the dCA3 stratum lucidum (SL) and stratum pyramidale (SP) at test. Based on these observations and extant literature, we postulate that recurrent circuits in the SP are activated during early-stage memory reconsolidation to maintain labile cocaine memories prior to protein synthesis-dependent restabilization in another brain region, such as the basolateral amygdala. Furthermore, SL and SP interneurons may enhance memory reconsolidation by limiting synaptic noise in the SP and also contribute to recall as elements of the updated cocaine engram or retrieval links.