The status of naloxone in the identification of pain control mechanisms operated by endogenous opioids. 
Since the discovery of endogenous opioids within the central nervous system much research has been directed towards the demonstration of a physiological control of pain operated by these substances.  One way of studying this problem is to challenge the process suspected of being opioid-operated with a specific opiate antagonist, and prior experiments coupled with clinical experience suggested that naloxone was a suitable substance of this type.  This short review examines the status of naloxone as an antagonist of endogenous pain control mechanisms and their neuronal correlates, but is not comprehensive.  The reader is referred to refs.  4, 29 and 36 for additional detail which space does not allow to be included here.