CB1 receptor activation in the nucleus accumbens core impairs contextual fear learning

Contextual fear conditioning is a behavioral model in which a subject learns that a specific context is predictive of danger occurrence. There is evidence suggesting an important role for both the nucleus accumbens (NAc) and the endocannabinoid system in contextual fear conditioning formation. The purpose of this study was to assess whether endocannabinoids within the NAc modulate fear memory formation. Pre-training anandamide (AEA) infusions into the NAc core (NAcC) of male Wistar rats decreased freezing behavior in the contextual fear-conditioning paradigm, as evaluated 24h after training. However, AEA did not induce any effect on the cued fear-conditioning paradigm. Likewise, AEA infusions into the NAc shell did not interfere with the contextual fear learning. AEA's effect was blocked when co-infused with AM251 (CB1R inverse agonist). Post-training AEA infusions failed to exert an effect on contextual conditioning. These results suggest a cannabinergic regulation in the NAcC of the acquisition of contextual fear conditioning.