 These SPMs also dampen pain perception arising from various inflammation-based causes in animal models.The mechanism behind their pain-dampening effects involves the inhibition of TRPV1, probably (in at least certain cases) by an indirect effect wherein they activate other receptors located on the neurons or nearby microglia or astrocytes.CMKLR1, GPR32, FPR2, and NMDA receptors have been proposed to be the receptors through which these SPMs operate to down-regulate TRPV1 and thereby pain perception.