A sensitive bioassay for melanotropic hormones using isolated medaka melanophores.
Melanophore-stimulating hormones (MSHs) from chum salmon cause pigment dispersion in isolated melanophores of medaka, a teleost. The in vitro medaka melanophore bioassay that responded to light with pigment dispersion and to the dark with pigment aggregation was utilized for measuring the activity of melanotropic hormones. alpha-MSH I was the most potent melanophore-dispersing agent tested. The minimal dose for the induction of pigment dispersion was 10(-15) M alpha-MSH I, 10(-13) M N-des-acetyl(Ac)-alpha-MSH, and 10(-11) M beta-MSH I, respectively. The melanosome-dispersing activity of beta-MSH I was enhanced about 40% by salmon N-acetyl-endorphin I (N-Ac-EP). The results suggest that N-Ac-EP may act as an enhancer for the activity of certain MSHs. The present bioassay provides a unique method for determining the biological activity of melanotropic peptides.
Negishi
S
S
Department of Biology, Keio University, Yokohama, Japan.
Kawazoe
I
I
Kawauchi
H
H
D000818:Animals; D001681:Biological Assay; D003532:Cyprinodontiformes / Q000378:metabolism*; D004723:Endorphins / Q000494:pharmacology; D008027:Light; D008543:Melanins / Q000378:metabolism; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology*; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism; D008547:Melanophores / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D009990:Oryzias / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D010902:Pituitary Gland / Q000032:analysis; D011433:Propranolol / Q000494:pharmacology; D012474:Salmon / Q000378:metabolism; D000521:alpha-MSH / Q000031:analogs & derivatives / Q000494:pharmacology
D004723:Endorphins; D008543:Melanins; D010446:Peptide Fragments; D000521:alpha-MSH; D009074:Melanocyte-Stimulating Hormones; D011433:Propranolol