The endocannabinoid and endovanilloid systems interact in the rat prelimbic medial prefrontal cortex to control...

Cannabinoid receptor 1 (CB(1)) agonists usually induce dose-dependent biphasic effects on anxiety-related responses. Low doses induce anxiolytic-like effects, whereas high doses are ineffective or anxiogenic, probably due to activation of Transient Receptor Potential Vanilloid Type 1 (TRPV(1)) channels. In this study we have investigated this hypothesis by verifying the effects of the CB(1)/TRPV(1) agonist ACEA injected into the prelimbic medial prefrontal cortex (PL) and the participation of endocannabinoids in the anxiolytic-like responses induced by TRPV(1) antagonism, using the elevated plus-maze (EPM) and the Vogel conflict test (VCT). Moreover, we verified the expression of these receptors in the PL by double labeling immunofluorescence. ACEA induced anxiolytic-like effect in the intermediate dose, which was attenuated by previous injection of AM251, a CB(1) receptor antagonist. The higher and ineffective ACEA dose caused anxiogenic- and anxiolytic-like effects, when injected after AM251 or the TRPV(1) antagonist 6-iodonordihydrocapsaicin (6-I-CPS), respectively. Higher dose of 6-I-CPS induced anxiolytic-like effects both in the EPM and the VCT, which were prevented by previous administration of AM251. In addition, immunofluorescence showed that CB(1) and TRPV(1) receptors are closely located in the PL. These results indicate that the endocannabinoid and endovanilloid systems interact in the PL to control anxiety-like behavior.