Direct actions of cortisol, thyroxine and growth hormone on IGF-I mRNA expression in sea bream hepatocytes

Leung, Ling Yan; Kwong, Anna Ka-Yee; Man, Angel K.Y.; Woo, Norman Y.S.

doi:10.1016/j.cbpa.2008.08.023

Cited by 45 publications

(23 citation statements)

References 58 publications

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“…Both igf1 and igf2 mRNA levels were stimulated by GH in tilapia primary hepatocytes, as has been found in previous in vitro studies in teleost fishes and elasmobranches (Shamblott et al 1995, Schmid et al 2000, Pierce et al 2004, Leung et al 2008, Moriyama et al 2008a. Recent in vivo studies have shown that GH treatment increases liver igf2 mRNA levels in a wide variety of fish species (see Introduction for citations), which is consistent with our results.…”

Section: Discussionsupporting

confidence: 93%

“…Cortisol injection reduced liver igf1 gene expression and circulating Igf1 in vivo in tilapia . In sea bream hepatocytes, cortisol reduced basal igf1 mRNA levels at physiological concentrations (Leung et al 2008), and in coho salmon hepatocytes, the glucocorticoid receptor agonist dexamethasone strongly inhibited GH-stimulated igf1 mRNA levels (Pierce et al 2005). Thus, glucocorticoid suppression of igf1 expression, either directly or via GH resistance, appears to be conserved in teleost fishes.…”

Section: Discussionmentioning

confidence: 95%

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Differential regulation of Igf1 and Igf2 mRNA levels in tilapia hepatocytes: effects of insulin and cortisol on GH sensitivity

Pierce

Breves²,

Moriyama³

et al. 2011

Journal of Endocrinology

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Igf1 and Igf2 stimulate growth and development of vertebrates. In mammals, liver-derived endocrine Igf1 mediates the growth promoting effects of GH during postnatal life, whereas Igf2 stimulates placental and fetal growth and is not regulated by GH. Insulin enhances Igf1 production by the mammalian liver directly, and by increasing hepatocyte sensitivity to GH. We examined the regulation of igf1 and igf2 mRNA levels by GH, insulin, and cortisol, and the effects of insulin and cortisol on GH sensitivity in primary cultured hepatocytes of tilapia, a cichlid teleost. GH increased mRNA levels of both igf1 and igf2 in a concentration-related and biphasic manner over the physiological range, with a greater effect on igf2 mRNA level. Insulin increased basal igf2 mRNA level, and strongly increased GH-stimulated igf2 mRNA level, but slightly reduced basal igf1 mRNA level and did not affect GH-stimulated igf1 mRNA level. Cortisol inhibited GH stimulation of igf1, but increased GH stimulation of igf2 mRNA level. The synergistic effect of insulin and GH on igf2 mRNA level was confirmed in vivo. These results indicate that insulin and cortisol differentially modulate the response of igf1 and igf2 mRNA to GH in tilapia hepatocytes, and suggest that the regulation of liver Igf2 production differs between fish and mammals. Regulation of liver Igf2 production in fish appears to be similar to regulation of liver Igf1 production in mammals.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 95%

Differential regulation of Igf1 and Igf2 mRNA levels in tilapia hepatocytes: effects of insulin and cortisol on GH sensitivity

Pierce

Breves²,

Moriyama³

et al. 2011

Journal of Endocrinology

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“…The procedures used for standard preparation and realtime PCR analyses were as previously described (Leung et al 2008). Standards for real-time PCR analysis of G6PDH, GK, G6Pase, GP, GS, IGF-I and GH mRNA and 18S rRNA were prepared by RT-PCR amplification of cDNA fragment; the amplicon was purified and quantified by electrophoresis along with DNA molecular size marker (TaKaRa, Shiga, Japan).…”

Section: Standard Preparation and Real-time Pcrmentioning

confidence: 99%

Influence of dietary carbohydrate level on endocrine status and hepatic carbohydrate metabolism in the marine fish Sparus sarba

Leung

Woo

2011

Fish Physiol Biochem

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Silver sea bream, Sparus sarba, were fed two diets of different carbohydrate levels (2 and 20% dextrin) for 4 weeks, and the effects on organ indices, liver composition, serum metabolite and hormone levels and gene expression profile of key enzymes of carbohydrate metabolism in the liver were investigated. By using real-time PCR, mRNA expression levels of carbohydrate metabolic enzymes including glucokinase (GK, glycolysis), glucose-6-phosphatase (G6Pase, gluconeogenesis), glycogen synthase (GS, glycogenesis), glycogen phosphorylase (GP, glycogenolysis) and glucose-6-phosphate dehydrogenase (G6PDH, pentose phosphate pathway) in liver of sea bream have been examined, and it was found that high dietary carbohydrate level increased mRNA level of GK but decreased mRNA levels of G6Pase and GP. However, mRNA levels of GS and G6PDH were not significantly influenced by dietary carbohydrate. Silver sea bream fed high dietary carbohydrate had higher hepatosomatic index (HSI), liver glycogen and protein, but there were no significant changes in gonadosomatic index (GSI), serum glucose and protein level, as well as liver lipid and moisture level. Pituitary growth hormone (GH) and hepatic insulin-like growth factor I (IGF-I) transcript abundance were assayed by real-time PCR, and it was found that both parameters remained unchanged in fish fed different dietary carbohydrate levels. Serum triiodothyronine (T(3)) and thyroxine (T(4)) were not significantly affected by dietary carbohydrate levels, but lower serum cortisol level was found in fish fed high dietary carbohydrate level. These results suggest that silver sea bream is able to adapt to a diet with high carbohydrate content (up to 20% dextrin), the consumption of which would lead to fundamental re-organization of carbohydrate metabolism resulting in hepatic glycogen deposition.

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“…!48 h). Overall, on an acute time scale, cortisol injections or stressors in fish either have no effect or decrease plasma GH levels, reduce liver igf1 gene expression and plasma IGF1 levels, counteract GH stimulation of liver igf1 transcription, and increase the hepatic expression and plasma levels of low molecular weight IGF binding proteins (IGFBPs) (Kelley et al 2001, Kajimura et al 2003, Pierce et al 2005, Wilkinson et al 2006, Leung et al 2008, Saera-Vila et al 2009, Breves et al 2010, Shepherd et al 2011, Nakano et al 2013. In channel catfish (Ictalurus punctatus), chronic dietary cortisol had no effect on liver igf1 mRNA levels, reduced plasma IGF1, and increased the plasma levels of low molecular weight IGFBPs (Peterson & Small 2005).…”

Section: Introductionmentioning

confidence: 99%

Chronic cortisol and the regulation of food intake and the endocrine growth axis in rainbow trout

Madison

Tavakoli

Krämer

et al. 2015

Journal of Endocrinology

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To gain a better understanding of the mechanisms by which cortisol suppresses growth during chronic stress in fish, we characterized the effects of chronic cortisol on food intake, mass gain, the expression of appetite-regulating factors, and the activity of the GH/IGF axis. Fish given osmotic pumps that maintained plasma cortisol levels at w70 or 116 ng/ml for 34 days were sampled 14, 28 and 42 days post-implantation. Relative to shams, the cortisol treatments reduced food intake by 40-60% and elicited marked increases in liver leptin (lep-a1) and brain preoptic area (POA) corticotropin-releasing factor (crf) mRNA levels. The cortisol treatments also elicited 40-80% reductions in mass gain associated with increases in pituitary gh, liver gh receptor (ghr), liver igfI and igf binding protein (igfbp)-1 and -2 mRNA levels, reduced plasma GH and no change in plasma IGF1. During recovery, while plasma GH and pituitary gh, liver ghr and igfI gene expression did not differ between treatments, the high cortisol-treated fish had lower plasma IGF1 and elevated liver igfbp1 mRNA levels. Finally, the cortisol-treated fish had higher plasma glucose levels, reduced liver glycogen and lipid reserves, and muscle lipid content. Thus, our findings suggest that the growth-suppressing effects of chronic cortisol in rainbow trout result from reduced food intake mediated at least in part by increases in liver lep-a1 and POA crf mRNA, from sustained increases in hepatic igfbp1 expression that reduce the growth-promoting actions of the GH/IGF axis, and from a mobilization of energy reserves.

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Direct actions of cortisol, thyroxine and growth hormone on IGF-I mRNA expression in sea bream hepatocytes

Cited by 45 publications

References 58 publications

Differential regulation of Igf1 and Igf2 mRNA levels in tilapia hepatocytes: effects of insulin and cortisol on GH sensitivity

Differential regulation of Igf1 and Igf2 mRNA levels in tilapia hepatocytes: effects of insulin and cortisol on GH sensitivity

Influence of dietary carbohydrate level on endocrine status and hepatic carbohydrate metabolism in the marine fish Sparus sarba

Chronic cortisol and the regulation of food intake and the endocrine growth axis in rainbow trout

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