Influence of circulating GH levels on GH-binding capacity measurements in the hepatic membrane of rainbow trout (Oncorhynchus mykiss): importance of normalization of results

Yao, Kouassi Benjamin; Gabillard, Jean-Charles; Bail, Pierre‐Yves Le

doi:10.1007/s10695-006-0004-7

Cited by 3 publications

(2 citation statements)

References 35 publications

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“…A similar qRTPCR normalization scheme was utilized in gene expression analyses of spermatogenesis in rainbow trout where testes size varies considerably with reproductive state (Kusakabe et al 2006). Hepatic Ghr-binding assays in fed and fasted rainbow trout were also argued to be more biologically relevant when expressed as total liver binding, as opposed to Ghr binding per unit of liver weight (Yao et al 2006). We suggest that this normalization procedure be considered for all endocrine organs whose size changes significantly with physiological state.…”

Section: Discussionmentioning

confidence: 99%

Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysops×Morone saxatilis)

Picha

Turano

Tipsmark

et al. 2008

Journal of Endocrinology

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Compensatory growth (CG) is a period of growth acceleration that exceeds normal rates after animals are alleviated of certain growth-stunting conditions. In hybrid striped bass (HSB, Morone chrysops!Morone saxatilis), 3 weeks of complete feed restriction results in a catabolic state that, when relieved, renders a subsequent phase of CG. The catabolic state was characterized by depressed levels of hepatic Type I and II GH receptor (ghr1, ghr2) and igf1 mRNA, along with considerable decreases in plasma Igf1. The state of catabolism also resulted in significant declines in hepatic igf2 mRNA and in circulating 40 kDa Igfbinding protein (Igfbp). Skeletal muscle expression of ghr2 mRNA was significantly increased. Upon realimentation, specific growth rates (SGRs) were significantly higher than sized-matched controls, indicating a period of CG. Hepatic ghr1, ghr2, igf1 and igf2 mRNA levels along with plasma Igf1 and 40 kDa Igfbp increased rapidly during realimentation. Plasma Igf1 and total hepatic igf2 mRNAwere significantly correlated to SGR throughout the study. Skeletal muscle igf1 mRNA also increased tenfold during CG. These data suggest that endocrine and paracrine/autocrine components of the GH-Igf axis, namely igf1, igf2, and ghr1 and ghr2, may be involved in CG responses in HSB, with several of the gene expression variables exceeding normal levels during CG. We also demonstrate that normalization of hepatic mRNA as a function of total liver production, rather than as a fraction of total RNA, may be a more biologically appropriate method of quantifying hepatic gene expression when using real-time PCR.

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Section: Discussionmentioning

confidence: 99%

Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysops×Morone saxatilis)

Picha

Turano

Tipsmark

et al. 2008

Journal of Endocrinology

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“…In this context, in a contrasting situation in which GH levels were increased, such as during fasting or feeding a high-plantprotein diet, a reduction in GHRs in the liver was also found in gilthead sea bream (37, 78) and hybrid striped bass (72), whereas fasted rainbow trout exhibited enhanced gene expression of GHR-I (32). Moreover, it should be noted that hepatic GH binding and signaling are also influenced by GH plasma levels, independently of GHR expression (98).…”

Section: Effects Of Sustained Exercise On Hepatic Gh-igfs Expressionmentioning

confidence: 99%

Effects of sustained exercise on GH-IGFs axis in gilthead sea bream (Sparus aurata)

Vélez

Azizi

Millán-Cubillo

et al. 2016

American Journal of Physiology-Regulatory, Integrative and Comp

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The endocrine system regulates growth mainly through the growth hormone (GH)/insulin-like growth factors (IGFs) axis and, although exercise promotes growth, little is known about its modulation of these factors. The aim of this work was to characterize the effects of 5 wk of moderate sustained swimming on the GH-IGFs axis in gilthead sea bream fingerlings. Plasma IGF-I/GH ratio and tissue gene expression of total IGF-I and three splice variants, IGF-II, three IGF binding proteins, two GH receptors, two IGF-I receptors, and the downstream molecules were analyzed. Fish under exercise (EX) grew more than control fish (CT), had a higher plasma IGF-I/GH ratio, and showed increased hepatic IGF-I expression (mainly IGF-Ia). Total IGF-I expression levels were similar in the anterior and caudal muscles; however, IGF-Ic expression increased with exercise, suggesting that this splice variant may be the most sensitive to mechanical action. Moreover, IGFBP-5b and IGF-II increased in the anterior and caudal muscles, respectively, supporting enhanced muscle growth. Furthermore, in EX fish, hepatic IGF-IRb was reduced together with both GHRs; GHR-II was also reduced in anterior muscle, while GHR-I showed higher expression in the two muscle regions, indicating tissue-dependent differences and responses to exercise. Exercise also increased gene and protein expression of target of rapamycin (TOR), suggesting enhanced muscle protein synthesis. Altogether, these data demonstrate that moderate sustained activity may be used to increase the plasma IGF-I/GH ratio and to potentiate growth in farmed gilthead sea bream, modulating the gene expression of different members of the GH-IGFs axis (i.e., IGF-Ic, IGF-II, IGFBP-5b, GHR-I, and TOR).

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Coordinated regulation of the GH/IGF system genes during refeeding in rainbow trout (Oncorhynchus mykiss)

Gabillard¹,

Kamangar²,

Montserrat³

2006

Journal of Endocrinology

182

122

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The GH/IGF system is a complex regulation network strongly dependent on nutrient availability. While the effect of starvation on the GH/IGF system has been extensively studied, the time course of events leading to the restoration of GH/IGF system activity after starvation is largely unknown. We, therefore, measured the plasma levels of GH, IGF-I and IGF-II and the expression of the GH/IGF system in liver and muscle. Starvation increased the plasma GH level and 1 day of refeeding completely restored it (1$10G0$27 vs 1$12G0$28 ng/ml). Thereafter, plasma GH continued to decrease until day 7 and returned to control values from day 15. Starvation decreased plasma IGF-I and IGF-II and refeeding raised plasma IGF-I only from day 4. In contrast, the plasma IGF-II level doubled after 1 day's refeeding (26$5G1$9 vs 44$0G3$4 ng/ml; P!0$01). Starved fish exhibited higher GH receptor (GHR)1 mRNA abundance in liver and muscle than in controls, whereas GHR2 mRNA abundance was increased only in muscle. In liver, 1 day of refeeding, decreased GHR1 (twofold), but increased GHR2 mRNA abundance (twofold). Thereafter, a progressive return to normal values was observed. Liver IGFBP-4 mRNA abundance was lowered in starved fish followed by a progressive restoration during refeeding. Starvation had no effect on liver IGFBP-2 and IGFBP-6 mRNA abundance, whereas refeeding provoked a peak of IGFBP-2 and IGFBP-6 expression at day 7. In muscle, starvation led to a decrease of the IGFBP-2 mRNA level, which was restored only from day 7. IGFBP-4 mRNA abundance in starved fish was lower than in the controls and refeeding led to a transient upregulation (sevenfold) of IGFBP-4 gene at day 1. IGF-I, IGFBP-5, and IGFBP-related protein 1 (rP1) expression profiles were similar, showing a decrease of expression after starvation, a first peak of expression at day 2, a second peak at day 7, and a return to normal value from day 15. Moreover, IGF-I, IGFBP-5, and IGFBP-rP1 mRNA abundance were positively correlated (rZ0$6-0$8; P!0$0001). In conclusion, plasma IGF-I was restored later than plasma GH level, which suggests that plasma IGF-I levels cannot account for plasma GH changes. The coordinated regulation of IGF-I, IGFBP-5, and IGFBP-rP1 expression would be a signature for the resumption of myogenic activity.

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Influence of circulating GH levels on GH-binding capacity measurements in the hepatic membrane of rainbow trout (Oncorhynchus mykiss): importance of normalization of results

Cited by 3 publications

References 35 publications

Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysops×Morone saxatilis)

Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysops×Morone saxatilis)

Effects of sustained exercise on GH-IGFs axis in gilthead sea bream (Sparus aurata)

Coordinated regulation of the GH/IGF system genes during refeeding in rainbow trout (Oncorhynchus mykiss)

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