Effects of cholinergic agonists and antagonists on morphine-withdrawal syndrome.

The effects of pilocarpine, atropine and dexetimide were studied on the occurrence and intensity of morphine-withdrawal signs observed after cessation of chronic morphine injections. Pilocarpine was effective in reducing both 'wet-dog' like body shakes and aggression but it increased diarrhea and weight loss. Pretreatment with atropine blocked all of the effects of pilocarpine on withdrawal signs. Methylscopolamine pretreatment blocked only diarrhea. The administration of atropine or dexetimide produced no significant effect on any of the withdrawal signs. These results indicate a role for central cholinergic mechanism in narcotic withdrawal.