Homologous growth hormone (GH) binding in gilthead sea bream (Sparus aurata). Effect of fasting and refeeding on hepatic GH-binding and plasma somatomedin-like immunoreactivity |
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Authors: | J Pérez-Sánchez H Martí-Palanca P-Y Le Bail† |
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Institution: | Instituto de Acuicultura de Torre de la Sal, CSIC, 12595 Torre de la Sal, Ribera de Cabanes, Castellon, Spain;Laboraloire de Physiologie des Poissons, INRA, Campus de Beaulieu, 35042 Rennes Cedex, France |
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Abstract: | Specific binding of gilthead sea bream growth hormone (sbGH) to liver membrane preparations was a time and temperature dependent process, and was saturable by increasing amounts of membrane proteins. Scatchard analysis evidenced a single class of high-affinity and lowcapacity binding sites. Ovine prolactin, recombinant tilapia prolactin, carp gonadotropin and chinook salmon gonadotropin did not compete for the125I-sbGH binding sites, while recombinant trout GH, bovine GH and human GH displaced iodinated sbGH in a dose dependent-manner. IGF-I-like immunoreactivity was detected after acidification of plasma and removal of IGF-I binding activity. A parallel displacement to the rhIGF-1 standard was observed with extracted plasma samples. Free and total hepatic GH-binding decreased during long-term starvation (3–9 weeks), returning to control values during the refeeding period. Plasma IGF-I-like immunoreactivity showed a similar trend. To our knowledge, this is the first report that indicates a coordinated regulation of GH-binding and plasma somatomedin-like activity in a typical marine fish. |
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Keywords: | growth hormone insulin-like growth factors fasting gilthead sea bream teleost |
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