Physical dependence of opiate-like peptides

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Science  24 Sep 1976:
Vol. 193, Issue 4259, pp. 1262-1263
DOI: 10.1126/science.986687


Methionine-enkephalin and beta-endorphin, endogenous peptides with activities similar to those of opiates, were infused for 70 hours into the periaqueductal gray-fourth ventricular space of the rat brain. When challenged with a naloxone, a specific opiate antagonist, these animals manifested a typical morphine-like withdrawal syndrome. These results show that such peptides can cause physical dependence.