Melanin concentrating hormone exhibits both MSH and MCH activities on individual melanophores.
Asp-Thr-Met-Arg-Cys-Met-Val-Gly-Arg-Val-Tyr-Arg-Pro-Cys-Trp-Glu-Val (melanin concentrating hormone, MCH) and several fragment analogs (MCH1-14, MCH5-17, MCH5-14) were synthesized and their biological activities determined in a very sensitive fish skin bioassay. The potency ranking and minimum effective doses of the peptides were determined to be: MCH1-17 (10(-12)M) greater than less than MCH5-17 (10(-12)M) greater than MCH1-14 (10(-11)M) greater than MCH5-14 (2 X 10(-10)M). The melanosome aggregating activity of MCH could be completely reversed by a 100-fold higher concentration of pounds-MSH. MCH was self-antagonized in a dose-related manner by higher concentrations of the peptide as was the activity of the MCH1-14 fragment analog. The MCH activities of the MCH5-17 and MCH5-14 analogs were not compromised by even the highest concentrations of the peptides employed. The MSH-like activity of MCH appears to relate to the N-terminus of the peptide whereas MCH activity is more a function of the C-terminus of the hormone. Self-antagonism of MCH at high concentrations appears to relate to the N-terminal tetrapeptide, which is responsible for the intrinsic MSH-like activity of the hormone.
D000818:Animals; D004524:Eels; D005260:Female; D007028:Hypothalamic Hormones; D066298:In Vitro Techniques; D008297:Male; D008543:Melanins / Q000494:pharmacology*; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology; D008547:Melanophores / Q000187:drug effects*; D010446:Peptide Fragments / Q000494:pharmacology; D010907:Pituitary Hormones / Q000494:pharmacology*
D007028:Hypothalamic Hormones; D008543:Melanins; D010446:Peptide Fragments; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone; D009074:Melanocyte-Stimulating Hormones