dose-dependent effects of celecoxib on cb-1 agonist-induced antinociception in the mice

objective: endocannabinoid produce analgesia that is comparable which of opioids. the mechanism of antinociceptive effects of (∆) - 9 tetrahydrocannabinol (thc) is suggested to be through cyclooxygenase (cox) pathway. in the present work, the effect of two extreme dose ranges of celecoxib (mg/kg and ng/kg), a cyclooxygenase-2 (cox-2) antagonist, on arachidonylcyclopropylamide (acpa, a selective cb1 agonist) induced antinociception in mice was examined. methods: we have investigated the interaction between celecoxib, at the doses of mg/kg (50, 100, 200 and 400 i.p.) and ultra low dose (uld) (25 and 50 ng/kg, i.p.), on the antinociceptive effect of intracerebroventricular (i.c.v.) administration of acpa (0.004, 0.0625 and 1 μg/mice), using formalin test in mice. results: i.c.v. administration of acpa induced antinociception. intraperitoneal administration of celecoxib (mg/kg) and its uld (ng/kg) attenuated and potentiated, acpa antinociceptive effects, respectively. conclusion: it is concluded that the mg/kg doses of cox-2 antagonist showed opposite effects compare to the ultra-low dose of the drug.