title: Elevations of somatolactin in plasma and pituitaries and increased alpha-MSH cell activity in red drum exposed to black background and decreased illumination.
abstract: The effects of different backgrounds and illumination levels on somatolactin (SL) concentrations in juvenile red drum (Sciaenops ocellatus) plasma and pituitaries were investigated using a homologous radioimmunoassay. Both plasma and pituitary SL concentrations were significantly higher in red drum exposed for 1 week to black backgrounds than in fish exposed to light backgrounds. Plasma SL levels decreased from 5.39 +/- 1.18 ng/ml in red drum adapted to a dark-blue background to 0.73 +/- 0.05 ng/ml within 1 hr of transfer to light-background tanks. Plasma SL concentrations were significantly elevated in fish 3 hr after transfer from light-background tanks (0.41-0.99 ng/ml) to black-background tanks (5.38 +/- 1.60 ng/ml) or black-background tanks without illumination (3.54 +/- 1.34 ng/ml). Maximum circulating SL levels (9.47 +/- 0.78 ng/ml) were observed 1 day after transfer of red drum to a black-background tank without illumination. Fish exposed to black backgrounds had the darkest body coloration, the greatest dispersion of melanin in their melanophore cells, and the most numerous and active alpha-melanophore-stimulating hormone (alpha-MSH) cells. These results provide evidence that SL may be involved in adaptation of red drum to different backgrounds and illuminations. However, the relative importance of SL and alpha-MSH in the regulation of this process remains to be elucidated.
authors.affiliation: University of Texas at Austin, Marine Science Institute, Port Aransas 78373, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu
authors.forename: P
authors.initials: P
authors.lastname: Thomas
mesh_terms: D000818:Animals; D029941:Fish Proteins; D005399:Fishes / Q000502:physiology*; D006023:Glycoproteins / Q000097:blood / Q000378:metabolism*; D007150:Immunohistochemistry; D008027:Light; D008547:Melanophores / Q000378:metabolism; D010858:Pigmentation / Q000502:physiology; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D010907:Pituitary Hormones / Q000097:blood / Q000378:metabolism*; D013997:Time Factors; D000521:alpha-MSH / Q000502:physiology*
chemical_list: D029941:Fish Proteins; D006023:Glycoproteins; D010907:Pituitary Hormones; C064448:somatolactin protein, fish; D000521:alpha-MSH