Endogenous opioid abstinence syndrome.

Starting from the observation that an increase of stress analgesia is followed by a hyperalgesia period, with a series of symptoms characteristic of the exogenous opioid abstinence syndrome (EXOAS), the authors supposed also the possibility of the existence of an endogenous abstinence syndrome (ENOAS). In order to demonstrate the existence of this syndrome, they investigated at first the possibility of the appearance of an acute tolerance to opioids. Then they followed-up the course of behaviour during and after informational stress in untreated animals, in animals treated with naloxone, which--being an antagonist of opioids--can induce EXOAS in toxicomaniacs, and in animals treated with clonidine and propranolol, that are used in the treatment of EXOAS. Experimental researches have demonstrated the possibility of ENOAS occurrence, its aggravation by naloxone and its improvement with clonidine and propranolol.