Different receptor mechanisms underlying phytocannabinoid- versus synthetic cannabinoid-induced tetrad effects: Opposite roles of CB1 /CB2 versus GPR55 receptors.

These findings suggest that in addition to CB1 , both CB2 and GPR55 receptors are also involved in some pharmacological effects produced by cannabinoids. CB1 /CB2 , in contrast to GPR55, receptors appears to play opposite roles in cannabinoid action.