Naloxone pain perception

It was found that the effects of these opiate-like substances could be rapidly reversed by administration of the morphine antagonist naloxone and this and other findings led to the conclusion that the enkephalins and endorphins bind to the same receptors in the central nervous system, of which there appear to be at least three types, as morphine itself. Evidence was also obtained that the natural opiates may play a part in normal emotional responses as well as in the control of pain perception. The natural opiates differ fi om morphine and its derivatives in that they do not accumulate and lead to the tolerance which occurs with morphine. It has been suggested that the effects of acupuncture may result from the release of natural opiates. 

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