Effects of enkephalin analogues on prolactin release in the rat

H. Y. Meltzer*, R. J. Miller, R. G. Fessler, M. Simonovic, V. S. Fang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


The effects of nineteen enkephalin analogues on the circulating levels of prolactin in the male rat following intraventricular injection of the peptides were determined and compared with that of Met- and Leu-enkephalin. Eleven of the 19 analogues stimulated prolactin secretion. It was found, in general, that the structure activity relationship for enkephalin stimulation of prolactin secretion was similar to that for opiate receptor activity. Analogues which contained a [DAla2] substitution were generally effective in stimulating prolonged prolactin release. Some, but not all analogues containing [DTrp2] or [DLeu5] were active. Analogues containing the [DTrp1], [DPhe4] or [DMet5] substitutions were ineffective. The prolactin releasing effect of intravenous Tyr-DAla-Gly-Phe-DLeu was reversed by naloxone. Naloxone had no effect on the haloperidol- and alpha-methylparatyrosine induced increases in plasma prolactin levels. The results of these studies are discussed in the light of the suggestion that the enkephalins may function as neuroendocrine modulators.

Original languageEnglish (US)
Pages (from-to)1931-1937
Number of pages7
JournalLife Sciences
Issue number21
StatePublished - Jun 5 1978

ASJC Scopus subject areas

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

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