title: Direct actions of cortisol, thyroxine and growth hormone on IGF-I mRNA expression in sea bream hepatocytes.
abstract: The present study aims to investigate potential regulatory effect of different growth-related hormones including growth hormone (GH), human insulin-like growth factor-I (hIGF-I), thyroxine (T(4)), triiodothyronine (T(3)) and cortisol, on insulin-like growth factor-I (IGF-I) mRNA expression of hepatocytes isolated from silver sea bream. By using real-time PCR, IGF-I mRNA expression profiles of hepatocytes in response to individual hormones were determined in vitro. Hepatocytes incubated with GH at concentrations of 10-1000 ng/mL showed significantly higher IGF-I expression, but the elevation was attenuated at high concentration of GH (1000 ng/mL). IGF-I expression remained unchanged in hepatocytes after incubation with hIGF-I. Hepatocytes incubated with T(4) at concentration of 1000 ng/mL exhibited a significant elevation in IGF-I expression, whereas no difference in IGF-I expression was demonstrated in hepatocytes after incubation with T(3). Upon incubation with cortisol (1-1000 ng/mL), IGF-I expression was significantly decreased in hepatocytes in a dose-dependent manner. Our study demonstrated that GH, T(4), and cortisol had direct modulatory effects on IGF-I expression in fish hepatocytes in vitro.
authors.affiliation: Department of Biology, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong SAR, China.
authors.forename: L Y
authors.initials: LY
authors.lastname: Leung
authors.forename: Anna K Y
authors.initials: AK
authors.lastname: Kwong
authors.forename: Angel K Y
authors.initials: AK
authors.lastname: Man
authors.forename: Norman Y S
authors.initials: NY
authors.lastname: Woo
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics; D013006:Growth Hormone / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D021541:Sea Bream / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D013974:Thyroxine / Q000494:pharmacology*; D014284:Triiodothyronine / Q000494:pharmacology
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014284:Triiodothyronine; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D005954:Glucosephosphate Dehydrogenase; D013974:Thyroxine; D006854:Hydrocortisone