Endorphins: naloxone fails to alter experimental pain or mood in humans

Science  10 Mar 1978:
Vol. 199, Issue 4333, pp. 1093-1095
DOI: 10.1126/science.343250


In 30 human subjects, experimental pain was produced by either ischemia or cold-water immersion. In a double-blind procedure, intravenous doses of up to 10 milligrams of naloxone hydrochloride in saline were indistinguishable from similarly administered saline alone. There were no effects on subjective pain ratings, finger plethysmograph recordings, or responses to mood-state questionnaires. These laboratory procedures do not activate any functionally significant pain-attenuating or mood-altering effect of endorphins.