Cellular signalling of PCH-induced pigment aggregation in the crustacean Macrobrachium potiuna erythrophores.
The cellular system responsible for the transduction of the pigment-concentrating hormone (PCH) signal was investigated in erythrophores of the freshwater shrimp, Macrobrachium potiuna. Dose-response curves to the hormone were determined in the absence and in the presence of several drugs that affect sequential steps of the Ca(2+)-dependent signalling pathway. Additionally, the ability of forskolin to induce pigment dispersion was evaluated. Neomycin sulphate (10(-4) and 10(-3) mol.l-1), trifluoperazine (10(-5) and 10(-4) mol.l-1), 1-(5-isoquinolinesulfonlyl)-2-methylpiperazine (10(-7) and 10(-5) mol.l-1) and okadaic acid (10(-7) mol.l-1) significantly (P < 0.05) decreased the responses to PCH. However, okadaic acid at low concentration (10(-9) mol.l-1) and cyclosporin A (10(-6) and 10(-5) mol.l-1) did not significantly (P > 0.05) affect PCH activity. Forskolin (10(-4) mol.l-1) was able to half-maximally reverse the hormone-induced aggregation. Our results suggest that the pigment-concentrating hormone induces pigment aggregation through a Ca(2+)-dependent pathway with a posteriori phosphatase activation, probably the serine/threonine phosphatase 1.
Nery
L E
LE
Departamento de Ciências Fisiológicas, Fundação Universidade do Rio Grande, Brasil.
da Silva
M A
MA
Josefsson
L
L
Castrucci
A M
AM
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D000818:Animals; D002856:Chromatophores / Q000187:drug effects / Q000502:physiology*; D005576:Colforsin / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D066298:In Vitro Techniques; D007447:Invertebrate Hormones / Q000494:pharmacology; D009355:Neomycin / Q000494:pharmacology; D019319:Okadaic Acid / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D033541:Palaemonidae / Q000502:physiology*; D010860:Pigments, Biological / Q000378:metabolism*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014268:Trifluoperazine / Q000494:pharmacology
D007447:Invertebrate Hormones; D009842:Oligopeptides; D010860:Pigments, Biological; D005576:Colforsin; D019319:Okadaic Acid; D014268:Trifluoperazine; C022059:red pigment-concentrating hormone; D016572:Cyclosporine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D009355:Neomycin; D011761:Pyrrolidonecarboxylic Acid