Naloxone reversal of endogenous opiates: paradoxical effect on humoral endorphin

Y. Sarne, Yehoshua Gothilf, B. Avi Weissman

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Naloxone, a specific opiate antagonist, reverses the in vitro effect of morphine, enkaphalin and β-endorphin in the conventional concentration-dependent manner. However, naloxone affects the opioid activity of humoral endorphin, an endogenous substance present in blood, CSF and brain, in a paradoxical fashion: Low concentrations of naloxone antagonise the effect of humoral endorphin, while high concentrations fail to block, and even potentiate its opiate activity. This agonist-antagonist interaction sheds new light on conflicting results of experiments using naloxone antagonism as a criterion for the opioid nature of physiological mechanisms.

Original languageEnglish
Pages (from-to)17-21
Number of pages5
JournalSpeculations in Science and Technology
Issue number1
StatePublished - 1980


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