Different receptor mechanisms underlying phytocannabinoid‐ versus synthetic cannabinoid‐induced tetrad effects: Opposite roles of CB ₁ /CB ₂ versus GPR55 receptors

Background and Purpose Cannabis or cannabinoids produce characteristic tetrad effects—analgesia, hypothermia, catalepsy and suppressed locomotion, which are believed to be mediated by the activation of cannabinoid CB 1 receptors. Given recent findings of CB 2 and GPR55 receptors in the brain, we examined whether these receptors are also involved in cannabinoid action. Experimental Approach We compared Δ 9 ‐tetrahydrocannabinol (Δ 9 ‐THC)‐,...