Long-term treatment with SR141716A, the CB1 receptor antagonist, influences morphine withdrawal syndrome

The role of the cannabinoid system in morphine withdrawal was examined thro ugh longterm CB1 receptor antagonist administration in morphine pellet impl anted rats. SR141716A chronic treatment (5mg/kg i.p. twice a day for four d ays) did not influence the development of tolerance to the morphine analges ic effect but significantly reduced the intensity of naloxone-induced opiat e withdrawal in tolerant rats: Specifically there was a significant reducti on in the number of digging teeth chattering and penile licking and the inc idence of diarrhoea while other signs such as writhing, head dog shakes and rearing were unaffected. These results suggest that the pharmacological tr eatment with SR141716A could be of some interest in ameliorating opiate wit hdrawal syndrome.