Metabolic hormones modulate the effect of growth hormone (GH) on insulin-like growth factor-I (IGF-I) mRNA level in primary culture of salmon hepatocytes

Pierce, Andrew L.; Fukada, Haruhisa; Dickhoff, Walton W.

doi:10.1677/joe.1.05892

Cited by 63 publications

(60 citation statements)

References 42 publications

(56 reference statements)

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“…Meanwhile, cortisol inhibited igf1 expression in the liver both with and without exogenous Gh induction. This effect is in full agreement with in vitro observations on primary culture of salmon hepatocytes, where dexamethasone blocks Gh-induced igf1 expression possibly due to decreased ghr expression (Pierce et al 2005). In the gill, cortisol had either no effect (in vivo, FW) or a stimulatory effect (in vitro, FW) on igf1 expression, which agreed well with the elevated ghr1 levels induced by the steroid.…”

Section: Endocrine and Paracrine Mechanisms Of Actionsupporting

confidence: 89%

Distinct hormonal regulation of Na+,K+-atpase genes in the gill of Atlantic salmon (Salmo salar L.)

Tipsmark

Madsen²

2009

Journal of Endocrinology

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It has recently become evident that maintenance of ionic homoeostasis in euryhaline salmonids involves a reciprocal shift in expression of two isoforms of the gill Na+,K+-atpase α-subunit when the surrounding salinity changes. The present study investigated the regulation of this shift between the α1a (freshwater (FW) isoform) and the α1b (seawater (SW) isoform) by cortisol, Gh, prolactin (Prl) and Igf 1. Injection with cortisol into FW salmon increased α1a expression, while Gh had no effect. Conversely, both cortisol and Gh stimulated α1b expression, and a significant synergy was observed. igf1 expression was increased by Gh in both gill and liver, and inhibited by cortisol in the liver. Gill igf1 and gh receptor expression increased in response to cortisol. Injection with Prl into SW salmon compromised their hypo-osmoregulatory performance, selectively reduced the expression of the α1b isoform and decreased enzymatic Na+,K+-atpase activity in the gill. Cortisol and Prl reduced gill and liver igf1 expression, and both hormones stimulated gill igf1 receptor expression. In a short-term experiment with incubation of FW gill cell suspensions, cortisol stimulated α1a and α1b expression, while Igf1 stimulated only α1b. The data elaborate our understanding of Prl and Gh as being antagonists in the control of gill ion regulation, and support a dual role for Gh involving endocrine and paracrine Igf1 action. Gh and Prl may be the decisive stimuli that direct cortisol-aided mitochondrion-rich cell development into either secretory or absorptive types.

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Section: Endocrine and Paracrine Mechanisms Of Actionsupporting

confidence: 89%

Distinct hormonal regulation of Na+,K+-atpase genes in the gill of Atlantic salmon (Salmo salar L.)

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Madsen²

2009

Journal of Endocrinology

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“…No significant correlation was found between cellular IGFBP-1 mRNA level and medium IGFBP-1 protein immunoreactivity in the insulin concentration-response study. As expected, insulin significantly reduced mRNA levels of the salmon GHR in these cells (Pierce et al 2005a), showing that cells were able to respond to insulin (Fig. 4B).…”

Section: Gh (5!10supporting

confidence: 81%

“…The effect on GH-stimulated IGFBP-1 mRNA levels may be due to insulin induction of GH resistance. Insulin reduced mRNA levels of the GH receptor and reduced the stimulatory effect of GH on IGF-I mRNA levels in salmon hepatocytes (Pierce et al 2005a, Fig. 4).…”

Section: Discussionmentioning

confidence: 91%

“…The lack of repression of IGFBP-1 mRNA levels by insulin cannot be attributed to an anomalous culture, since it was found in five independent cell preparations, or to unresponsive cells, since insulin was effective at reducing GHR mRNA levels and inhibiting the IGF-I response to GH in these cultures (Fig. 4, Pierce et al 2005a). Bovine and salmon insulin had similar effects, suggesting that the lack of repression of IGFBP-1 by insulin was not due to the use of heterologous insulin.…”

Section: Discussionmentioning

confidence: 95%

“…The full range of regulation occurred from 10 K10 to 10 K8 M, similar to the range of cortisol from basal to stressed levels respectively (Barton & Iwama 1991). However, in a previous study using the same culture conditions and hormones, dexamethasone substantially reduced GH-stimulated IGF-I mRNA levels at 10 K12 M, and maximal inhibition of the IGF-I response to GH occurred at 10 K8 M dexamethasone and above (Pierce et al 2005a). Recently, two functional glucocorticoid receptors with different sensitivities of transactivational activity in response to cortisol and dexamethasone were characterized in rainbow trout (Bury et al 2003).…”

Section: Discussionmentioning

confidence: 98%

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Metabolic hormones regulate insulin-like growth factor binding protein-1 mRNA levels in primary cultured salmon hepatocytes; lack of inhibition by insulin

Pierce¹,

Shimizu²,

Felli³

et al. 2006

Journal of Endocrinology

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IGF-binding proteins (IGFBPs) modulate the effects of the IGFs, major stimulators of vertebrate growth and development. In mammals, IGFBP-1 inhibits the actions of IGF-I. Rapid increases in circulating IGFBP-1 occur during catabolic states. Insulin and glucocorticoids are the primary regulators of circulating IGFBP-1 in mammals. Insulin inhibits and glucocorticoids stimulate hepatocyte IGFBP-1 gene expression and production. A 22 kDa IGFBP in salmon blood also increases during catabolic states and has recently been identified as an IGFBP-1 homolog. We examined the hormonal regulation of salmon IGFBP-1 mRNA levels and protein secretion in primary cultured salmon hepatocytes. The glucocorticoid agonist dexamethasone progressively increased hepatocyte IGFBP-1 mRNA levels (eightfold) and medium IGFBP-1 immunoreactivity over concentrations comparable with stressed circulating cortisol levels (10 K9-10 K6 M). Triiodothyronine had no effect on hepatocyte IGFBP-1 mRNA, whereas glucagon increased IGFBP-1 mRNA (2 . 2-fold) at supraphysiological concentrations (10 K6 M). This study suggests that the major inhibitory role of insulin in the regulation of liver IGFBP-1 production in mammals is not found in salmon. However, regulation of salmon liver IGFBP-1 production by other metabolic hormones is similar to what is found in mammals.

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The Genetic Basis of Smoltification: Functional Genomics Tools Facilitate the Search for the Needle in the Haystack

Giger

Amstutz

Excoffier

et al. 2007

Sea Trout: Biology, Conservation and Management

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Metabolic hormones modulate the effect of growth hormone (GH) on insulin-like growth factor-I (IGF-I) mRNA level in primary culture of salmon hepatocytes

Cited by 63 publications

References 42 publications

Distinct hormonal regulation of Na+,K+-atpase genes in the gill of Atlantic salmon (Salmo salar L.)

Distinct hormonal regulation of Na+,K+-atpase genes in the gill of Atlantic salmon (Salmo salar L.)

Metabolic hormones regulate insulin-like growth factor binding protein-1 mRNA levels in primary cultured salmon hepatocytes; lack of inhibition by insulin

The Genetic Basis of Smoltification: Functional Genomics Tools Facilitate the Search for the Needle in the Haystack

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