CB receptor-dependent desensitisation of TRPV1 channels contributes to the analgesic effect of dipyrone in sensitised primary sensory neurons.

Background And Purpose: While dipyrone is a widely used analgesic, its mechanism of action is not completely understood. Recently, we have reported that the dipyrone metabolite 4-aminoantipyrine (4-AA) reduces PGE -induced pain-related behaviour through cannabinoid CB receptors. Here, we ascertained, in naive and PGE -induced "inflamed" conditions, both in vivo and in vitro, the molecular mechanisms involved in the 4-AA-induced analgesic effects.