Osmoregulatory actions of insulin-like growth factor-I in rainbow trout (Oncorhynchus mykiss)

1991 ◽  
Vol 130 (1) ◽  
pp. 87-92 ◽  
Author(s):  
S. D. McCormick ◽  
T. Sakamoto ◽  
S. Hasegawa ◽  
T. Hirano
Keyword(s):  
Rainbow Trout ◽  
Growth Factor ◽  
Oncorhynchus Mykiss ◽  
Bovine Insulin ◽  
Insulin Like Growth Factor ◽  
Plasma Osmolarity ◽  
Seawater Adaptation ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

ABSTRACT The ability of insulin-like growth factor-I (IGF-I), insulin and GH to promote hypoosmoregulatory ability was examined in juvenile rainbow trout (Oncorhynchus mykiss). Following adaptation to 12 parts per thousand (p.p.t.) seawater for 5 days, fish were given a single injection of hormone or vehicle, then exposed to 29 p.p.t. for 24 h and examined for changes in plasma osmolarity, ions and glucose. Ovine GH (oGH; 0·2 μg/g) significantly improved the ability of rainbow trout to maintain plasma osmolarity and sodium levels following transfer to 29 p.p.t. seawater. Recombinant bovine IGF-I (0·01, 0·05 and 0·2 μg/g) also improved the hypoosmoregulatory ability of trout; the effect being dose-dependent and greater than that of oGH. Bovine insulin (0·01, 0·05 and 0·2 μg/g) had no statistically significant effect on plasma ions. The results indicate that IGF-I is a potential mediator of the action of GH in seawater adaptation of salmonids. Journal of Endocrinology (1991) 130, 87–92

Effects of insulin-like growth factor-I, insulin, and leucine on protein turnover and ubiquitin ligase expression in rainbow trout primary myocytes

2010 ◽  
Vol 298 (2) ◽  
pp. R341-R350 ◽  
Author(s):  
Beth M. Cleveland ◽  
Gregory M. Weber
Keyword(s):  
Protein Synthesis ◽  
Rainbow Trout ◽  
Growth Factor ◽  
Protein Degradation ◽  
Ubiquitin Ligase ◽  
Protein Turnover ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

The effects of insulin-like growth factor-I (IGF-I), insulin, and leucine on protein turnover and pathways that regulate proteolytic gene expression and protein polyubiquitination were investigated in primary cultures of 4-day-old rainbow trout myocytes. Supplementing media with 100 nM IGF-I increased protein synthesis by 13% ( P < 0.05) and decreased protein degradation by 14% ( P < 0.05). Treatment with 1 μM insulin increased protein synthesis by 13% ( P < 0.05) and decreased protein degradation by 17% ( P < 0.05). Supplementing media containing 0.6 mM leucine with an additional 2.5 mM leucine did not increase protein synthesis rates but reduced rates of protein degradation by 8% ( P < 0.05). IGF-I (1 nM–100 nM) and insulin (1 nM-1 μM) independently reduced the abundance of ubiquitin ligase mRNA in a dose-dependent manner, with maximal reductions of ∼70% for muscle atrophy F-box (Fbx) 32, 40% for Fbx25, and 25% for muscle RING finger-1 (MuRF1, P < 0.05). IGF-I and insulin stimulated phosphorylation of FOXO1 and FOXO4 ( P < 0.05), which was inhibited by the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor wortmannin, and decreased the abundance of polyubiquitinated proteins by 10–20% ( P < 0.05). Supplementing media with leucine reduced Fbx32 expression by 25% ( P < 0.05) but did not affect Fbx25 nor MuRF1 transcript abundance. Serum deprivation decreased rates of protein synthesis by 60% ( P < 0.05), increased protein degradation by 40% ( P < 0.05), and increased expression of all ubiquitin ligases. These data suggest that, similar to mammals, the inhibitory effects of IGF-I and insulin on proteolysis occur via P I3-kinase/protein kinase B signaling and are partially responsible for the ability of these compounds to promote protein accretion.

Effects of insulin-like growth factor-I and insulin on the in-vitro uptake of sulphate by eel branchial cartilage: evidence for the presence of independent hepatic and pancreatic sulphation factors

1992 ◽  
Vol 133 (2) ◽  
pp. 211-219 ◽  
Author(s):  
C. Duan ◽  
T. Hirano
Keyword(s):  
Growth Factor ◽  
Coho Salmon ◽  
Bovine Insulin ◽  
Dependent Manner ◽  
Insulin Like Growth Factor ◽  
Cartilage Growth ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

ABSTRACT The possible roles of insulin-like growth factor-I (IGF-I) and insulin in regulating cartilage growth were studied in the teleost Anguilla japonica. Significant sulphation activity was found in the extracts of pancreas, liver and muscle, but not in those of kidney, intestine or spleen. The hepatic sulphation activity was significantly decreased by hypophysectomy or by fasting for 14 days, suggesting that this activity is regulated by pituitary function and nutritional status. Northern blot analysis revealed that the hepatic IGF-I mRNA in the eel consists of a major 4·0 kb band. This mRNA was GH-dependent and was significantly decreased by fasting for 14 days. On the other hand, fasting for 14 days had no significant effect on pancreatic sulphation activity. Pancreatic extracts from both intact and hypophysectomized eels exhibited equally significant stimulating activity. Addition of bovine or human insulin (1–250 ng/ml) to the culture medium significantly stimulated sulphate uptake in a dose-dependent manner. Teleost (coho salmon) insulin was as effective as bovine insulin. Bovine insulin was more effective than IGF-I at lower concentrations (1–4 ng/ml) but less effective at higher concentrations (10–250 ng/ml). These results indicate that not only IGF-I but also insulin are likely to be involved in the regulation of cartilage growth in the eel. Journal of Endocrinology (1992) 133, 211–219

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