Melanin concentrating hormone. I. Influence of nerves and hormones on the control of trout melanophores.
When melanophores on trout scales are cultured in vitro they show a transitory melanin concentration, which can be prevented by addition to the medium of the alpha adrenergic blocker, phentolamine. This indicates the release of endogenous nor-epinephrine from local nerve terminals. This initial phase of melanin aggregation is followed by redispersion and then by a second, more gradual melanin concentration over several days, which is not antagonized by phentolamine. A final melanophore index of between 2-2.5 is attained which may be the resting state of trout melanophores. Using short-term cultured melanophores which have passed the phase of endogenous nor-epinephrine release, it is shown that exogenous nor-epinephrine will interact synergistically with the melanin-concentrating hormone to achieve full melanin concentration. Evidence is discussed for believing that in the trout, such synergy is necessary to achieve maximum pallor in vivo.
Green
J A
JA
School of Biological Sciences, Bath University, England.
Baker
B I
BI
D000818:Animals; D002347:Carps / Q000502:physiology*; D002478:Cells, Cultured; D003530:Cyprinidae / Q000502:physiology*; D004357:Drug Synergism; D007028:Hypothalamic Hormones; D007700:Kinetics; D008543:Melanins / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology*; D008547:Melanophores / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology / Q000502:physiology*; D010646:Phentolamine / Q000494:pharmacology; D010907:Pituitary Hormones / Q000494:pharmacology; D012487:Salmonidae / Q000502:physiology*; D014337:Trout / Q000502:physiology*; D000521:alpha-MSH / Q000494:pharmacology
D007028:Hypothalamic Hormones; D008543:Melanins; D010907:Pituitary Hormones; D000521:alpha-MSH; C019463:melanin-concentrating hormone; D009638:Norepinephrine; D010646:Phentolamine