Melanin concentrating hormone analogues: Contraction of the cyclic structure. II. Antagonist activity

Michal Lebi, Victor J. Hruby, Ana M. Ana, Mac E. Hadley

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Asp-Thr-Met-Arg-Cys-Met-Val-Gly-Arg-Val-Tyr-Arg-Pro-Cys-Trp-Glu-Val, melanin concentrating hormone (MCH), is a cyclic hormone possessing both MCH-like (melanin granule aggregating effect) and melanocyte stimulating hormone (MSH)-like (melanin granule dispersing effect) activities. Nine ring-contracted analogues were synthesized and characterized for their melanotropic activity on the fish (Synbranchus marmoratus) and frog (Rana pipiens) bioassays. In most cases, these analogues were totally devoid of MCH-like agonist activity, demonstrating the essential role of the disulfide bridge between residues 5 and 14 of the hormone. [Ala5, Cys10]MCH, for example, was totally devoid of MCH-like activity. This analogue, like α-MSH, however, antagonized the melanosome aggregating actions of MCH on fish melanocytes. The antagonistic activity of the analogue, like that of α-MSH, was Ca2+-dependent. Evidence suggested that this antagonism of MCH activity was related to the intrinsic MSH-like activity of the analogue. These results suggest that MCH and α-MSH may be structurally and, therefore, evolutionarily related.

Original languageEnglish (US)
Pages (from-to)451-457
Number of pages7
JournalLife Sciences
Volume44
Issue number7
DOIs
StatePublished - 1989

ASJC Scopus subject areas

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

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