Paradoxical absence of aggression during naloxone-precipitated morphine withdrawal

Abstract
Aggression, which is normally seen during withdrawal from narcotics, could not be produced in morphine-dependent rats by the administration of naloxone at doses which cause other signs of withdrawal. Apomorphine injected instead of naloxone was capable of producing aggression, without other withdrawal signs. Naturally occurring aggression (72-hr withdrawal) was enhanced by apomorphine and unaffected by naloxone.