Cannabinoid CB 2 receptor agonist activity in the hindpaw incision : model of postoperative pain

Abstract

The identification of peripherally expressed CB 2 receptors and reports that the selective activation of cannabinoid CB 2 receptors produces antinociception without traditional cannabinergic side effects suggests that selective cannabinoid CB 2 receptor agonists might be useful in the management of pain. In a rat hindpaw incision model, we examined the antiallodynic activity of the selective cannabinoid CB 2 receptor agonists AM1241 (3–30 mg/kg i.p.), GW405833 (3–30 mg/kg i.p.), and HU-308 (0.3–30 mg/kg i.p.). The rank order for efficacy in the hindpaw incision model following a dose of 10 mg/kg, i.p. was AM1241 > GW405833 = HU-308, and the selective cannabinoid CB 2 receptor antagonist, SR144528, reversed the antiallodynic effect of HU-308. Together, these data suggest that selective cannabinoid CB 2 receptor agonists might represent a new class of postoperative analgesics.