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

摘要: Specific binding of gilthead sea bream growth hormone (sbGH) to liver membrane preparations was a time and temperature dependent process, saturable by increasing amounts proteins. Scatchard analysis evidenced single class high-affinity lowcapacity sites. Ovine prolactin, recombinant tilapia carp gonadotropin chinook salmon did not compete for the125I-sbGH sites, while trout GH, bovine GH human displaced iodinated sbGH in dose dependent-manner. IGF-I-like immunoreactivity detected after acidification plasma removal IGF-I activity. A parallel displacement the rhIGF-1 standard observed with extracted samples. Free total hepatic GH-binding decreased during long-term starvation (3–9 weeks), returning control values refeeding period. Plasma showed similar trend. To our knowledge, this is first report that indicates coordinated regulation somatomedin-like activity typical marine fish.