An endogenous morphine-like factor in mammalian brain

Gavril W. Pasternak, Robert Goodman, Solomon H. Snyder

Research output: Contribution to journalArticlepeer-review

273 Scopus citations


An endogenous morphine-like substance (MLF) found in rat and calf brains has a regional distribution correlating with that of opiate receptors, with the highest levels in the caudate and negligible amounts in the cerebellum. In binding assays MLF behaves like an opiate agonist. Sodium ion and enzyme and reagent treatment of membranes decrease its potency and manganese ion enhances it. MLF is localized in synaptosomal fractions, stored in an osmotically labile compartment, and can be degraded by carboxypeptidase A and leucine amino peptidase, implying a peptide structure. Its molecular weight is about 1000 as determined by gel chromatography.

Original languageEnglish (US)
Pages (from-to)1765-1769
Number of pages5
JournalLife Sciences
Issue number12
StatePublished - Jun 15 1975

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)


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