title: Effects of chronic cysteamine treatment on growth enhancement and insulin-like growth factor I and II mRNA levels in common carp tissues.
abstract: Insulin-like growth factors (IGF) belong to a family of growth factors with structural homology to proinsulin. In our previous studies, we found that both IGF-I and IGF-II gene expression showed growth hormone (GH) dependence in the brain and liver of juvenile common carp when treated in vivo with GH for a short time. This present work aimed to study the effects of both the short-term and long-term GH induction of IGF gene expression using cysteamine (CSH) and fasting/re-feeding. CSH is an agent that can deplete somatostatin to increase circulating GH level. IGF mRNA levels in the flesh (muscle) and liver of common carp were determined using real-time PCR. The chronic treatment of common carp with CSH was carried out for 63 d, with growth enhancement of the treated fish noted. Hepatic IGF-I and IGF-II mRNA levels increased in a dose-dependent manner with short-term CSH treatment, whereas IGF-I decreased and IGF-II increased in the liver after chronic CSH treatment. IGF-I and IGF-II mRNA levels in muscle were found to be elevated with the high-dose, long-term CSH treatment. Under the experimentally induced catabolic states of fasting, both hepatic IGF-I and IGF-II gene expression were significantly reduced, whereas they showed no change in muscle. After re-feeding, the hepatic expression of IGF-I in liver and muscle rebounded significantly. The hepatic IGF-II expression level showed no rebound after re-feeding, but the IGF-II level in muscle rebounded to the level of the fed group after re-feeding.
authors.affiliation: Department of Biochemistry, The Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong SAR, China.
authors.forename: Margaret C L
authors.initials: MC
authors.lastname: Tse
authors.forename: Christopher H K
authors.initials: CH
authors.lastname: Cheng
authors.forename: King Ming
authors.initials: KM
authors.lastname: Chan
mesh_terms: D000818:Animals; D001699:Biometry; D001835:Body Weight / Q000187:drug effects; D002347:Carps / Q000254:growth & development* / Q000378:metabolism; D003543:Cysteamine / Q000008:administration & dosage / Q000494:pharmacology*; D004334:Drug Administration Schedule; D005786:Gene Expression Regulation / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis* / Q000235:genetics; D007335:Insulin-Like Growth Factor II / Q000096:biosynthesis* / Q000235:genetics; D008099:Liver / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D003543:Cysteamine; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II