title: Role of the GH-IGF-1 system in Atlantic salmon and rainbow trout postsmolts at elevated water temperature.
abstract: A comparative experiment with Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) postsmolts was conducted over 35 days to provide insight into how growth, respiration, energy metabolism and the growth hormone (GH) and insulin-like growth factor 1 (IGF-1) system are regulated at elevated sea temperatures. Rainbow trout grew better than Atlantic salmon, and did not show reduced growth at 19 °C. Rainbow trout kept at 19 °C had increased blood hemoglobin concentration compared to rainbow trout kept at 13 °C, while salmon did not show the same hemoglobin response due to increased temperature. Both species showed reduced length growth and decreased muscle glycogen stores at 19 °C. Circulating IGF-1 concentration was higher in rainbow trout than in Atlantic salmon, but was not affected by temperature in either species. Plasma IGF-binding protein 1b (IGFBP-1b) concentration was reduced in Atlantic salmon reared at 19 °C after 15 days but increased in rainbow trout at 19 °C after 35 days. The igfbp1b mRNA level in liver showed a positive correlation to plasma concentrations of glucose and IGFBP-1b, suggesting involvement of this binding protein in carbohydrate metabolism at 19 °C. At this temperature muscle igfbp1a mRNA was down-regulated in both species. The muscle expression of this binding protein correlated negatively with muscle igf1 and length growth. The plasma IGFBP-1b concentration and igfbp1b and igfbp1a expression suggests reduced muscle igf1 signaling at elevated temperature leading to glucose allostasis, and that time course is species specific due to higher thermal tolerance in rainbow trout.
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), PO Box 2029, Nordnes, N-5817 Bergen, Norway. Electronic address: ernst.hevroy@ewos.com.
authors.forename: Ernst M
authors.initials: EM
authors.lastname: Hevrøy
authors.affiliation: University of Arkansas, Department of Biological Science, SCEN 601, Fayetteville, AR 72701 USA.
authors.forename: Christian K
authors.initials: CK
authors.lastname: Tipsmark
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), PO Box 2029, Nordnes, N-5817 Bergen, Norway.
authors.forename: Sofie C
authors.initials: SC
authors.lastname: Remø
authors.affiliation: Institute of Marine Research, Matre Research Station, N-5984 Matredal Norway.
authors.forename: Tom
authors.initials: T
authors.lastname: Hansen
authors.affiliation: Hokkaido University, Faculty of Fisheries Sciences, 3-1-1 Minato, Hakodate, Hokkaido 041-8611 Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: Institute of Marine Research, Matre Research Station, N-5984 Matredal Norway.
authors.forename: Thomas
authors.initials: T
authors.lastname: Torgersen
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), PO Box 2029, Nordnes, N-5817 Bergen, Norway; University of Bergen, Department of Biology, Bergen Norway; Skretting Aquaculture Research Center, PO Box 48, N-4001 Stavanger Norway.
authors.forename: Vibeke
authors.initials: V
authors.lastname: Vikeså
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), PO Box 2029, Nordnes, N-5817 Bergen, Norway.
authors.forename: Pål A
authors.initials: PA
authors.lastname: Olsvik
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), PO Box 2029, Nordnes, N-5817 Bergen, Norway.
authors.forename: Rune
authors.initials: R
authors.lastname: Waagbø
authors.affiliation: Hokkaido University, Faculty of Fisheries Sciences, 3-1-1 Minato, Hakodate, Hokkaido 041-8611 Japan.
authors.forename: Munetaka
authors.initials: M
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D029941:Fish Proteins / Q000097:blood / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D013006:Growth Hormone / Q000502:physiology*; D007118:Immunoassay; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood / Q000145:classification / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017686:Oncorhynchus mykiss / Q000097:blood / Q000235:genetics / Q000254:growth & development*; D010802:Phylogeny; D011986:Receptors, Somatotropin / Q000097:blood / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020317:Salmo salar / Q000097:blood / Q000235:genetics / Q000254:growth & development*; D013696:Temperature; D013997:Time Factors; D014867:Water
chemical_list: D029941:Fish Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D011986:Receptors, Somatotropin; D014867:Water; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone
keywords: Climate; GH-IGF system; Hemoglobin; IGFBP-1; Oxygen consumption; Salmonids