Research reportCB1 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 24 h 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.

► Pre-training anandamide infusion into the nucleus accumbens core (NAcC) impairs contextual fear conditioning. ► Pre-training anandamide infusion into the NAcC does not have an effect on cued fear conditioning. ► The behavioral effect of anandamide is reversed by co-infusion of AM251. ► Pre-training anandamide infusion into the nucleus accumbens shell does not have an effect on contextual fear conditioning. ► Post-training anandamide infusions into the NAcC does not impair contextual fear conditioning.