[Endogenous opioid peptides and the control of pain in man: fiction or reality?]

After a brief discussion of physiologic bases of pain sensation, particularly with respect to central mechanisms of integration and control of nociceptive impulses, emphasis is centered on the possible existence of endogenous opioid systems functioning effectively to control pain in humans. Inducement of stress and certain techniques for applying stimuli of the electroacupuncture type activate such systems with resulting "hypoalgesia" that can be inhibited by naloxone. Moreover, patients with congenital analgesia show pronounced elevation of nociceptive reflex thresholds which can be reduced to within almost normal levels by dosing with naloxone. In contrast, the beta-endorphin of pituitary origin is not apparently implicated in these pain regulatory mechanisms.