Role of TRPV1 in consolidation of fear memories depends on the averseness of the conditioning procedure

Despite the fact that TRPV1 receptors are widely expressed in brain structures such as the hippocampus, its functions remain largely unknown. In the present study, we have investigated the possible modulatory role of the hippocampal endovanilloid system upon memory consolidation of two different behavioral tasks in rats. Post-training infusion of the TRPV1 antagonist capsazepine disrupted memory consolidation with a strong training protocol, but not with a weak one in the contextual fear conditioning or in the step-down inhibitory avoidance task. These results provide evidence that the modulation of the hippocampal memory consolidation through TRPV1 receptors takes place only in presence of a strong emotional experience, suggesting that a certain aversiveness level is required in order to recruit endovanilloids to exert this function. A possible synergic role of hippocampal endovanilloid and endocannabinoid system on memory consolidation is discussed.