Reduction in channel catfish hepatic growth hormone receptor expression in response to food deprivation and exogenous cortisol

Small, Brian C.; Murdock, Christopher A.; Waldbieser, Geoffrey C.; Peterson, Brian

doi:10.1016/j.domaniend.2005.12.003

Cited by 63 publications

(27 citation statements)

References 39 publications

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“…Similarly to GHR1, variability in GHR2 expression in liver exists among species and experiments. The mRNA level of liver GHR2 is unaffected in mozambique tilapia after starvation (Pierce et al 2007), and decrease in catfish and gilthead sea bream (SaeraVila et al 2005;Small et al 2006). Rainbow trout has two receptors in the GHR2 clade.…”

Section: Discussionmentioning

confidence: 96%

Identification and expression analysis of two growth hormone receptors in zanzibar tilapia (Oreochromis hornorum)

Gao

et al. 2010

Fish Physiol Biochem

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Growth hormone plays important roles in various physiological processes such as growth, metabolism, and reproduction. In this study, two cDNAs encoding growth hormone receptor (GHR) were isolated from the liver of zanzibar tilapia (Oreochromis hornornum). The two cDNAs were 2,831 and 2,044 bp in length and named GHR1 and GHR2, respectively. GHR1 and GHR2 shared 57.4% similarity in nucleotide sequences and 33.5% similarity in deduced amino acid sequences. Consequently, it was presumed that they were two different genes. Conserved regions of GHR1 and GHR2 in zanzibar tilapia were different from those of other vertebrates. For example, conserved box2 regions of GHR1 and GHR2 in zanzibar tilapia were, respectively, WVELM and WVEFT, while it was WVEFI for GHRs in other vertebrates. Similar to other fish species, GHR1 and GHR2 were expressed in brain, gill, liver, muscle, spleen, gonad, stomach, kidney, and pituitary in zanzibar tilapia. The expression levels were the highest in liver. Unlike fathead minnow (Pimephales promelas) and mossambique tilapia (O. mossambicus), the expression levels of GHR1 in most female fish tissues were higher than those in male fish. No significant difference in GHR2 expression was found in all the tissues in male and female of zanzibar tilapia. Under fasting condition, the expressions of GHRs and IGF-II were significantly up-regulated (P < 0.05) in liver, while the expression of IGF-I remained stable. This observation would contribute to understanding the evolution of the GHR family in further investigation of growth regulation of zanzibar tilapia.

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Section: Discussionmentioning

confidence: 96%

Identification and expression analysis of two growth hormone receptors in zanzibar tilapia (Oreochromis hornorum)

Gao

et al. 2010

Fish Physiol Biochem

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“…By its turn, augmented IGF-I production could be directly attributed to increased GH tissue sensitivity as a consequence of higher GHR levels, especially in liver and muscle. Recently, Small et al (2006) stated the relation between GHR and IGF-I in channel catfish, I. punctatus. According to these authors, stress and fasting may induce an increase in hepatic growth hormone resistance through a diminished GHR synthesis, with a consequent lower level of IGF-I production.…”

Section: Discussionmentioning

confidence: 99%

Increased growth hormone (GH), growth hormone receptor (GHR), and insulin-like growth factor I (IGF-I) gene transcription after hyperosmotic stress in the Brazilian flounder Paralichthys orbignyanus

Meier

Figueiredo

Kamimura

et al. 2008

Fish Physiol Biochem

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Growth hormone (GH) action is the result of an intracellular cascade initiated just after its interaction with the growth hormone receptor (GHR) located on the surface of target cells. This cascade culminates with the transcription of target genes, such as the insulin-like growth factors (IGFs), which are responsible for most GH biological effects. In addition to its central role in growth, fish GH is also involved with osmoregulatory control. Within this context, the objective of the present work was to isolate GH, GHR, and IGF-I cDNAs from the Brazilian flounder Paralichthys orbignyanus and evaluate whether these genes are induced by hyperosmotic stress. The obtained results indicated that GH mRNA had a significant peak only 24 h after hyperosmotic stress. In gills, GHR mRNA was significantly increased after 7 days. In liver, GHR and IGF-I mRNAs were significantly increased in 72 h and both reached even higher levels after 7 days. These results indicate that hyperosmotic stress can increase GH sensitivity in the gills and liver of P. orbignyanus and, consequently, improve IGF-I production. The management of this parameter could be useful in achieving better growth performance for this and other commercially important species in which GH has a direct correlation with osmoregulatory mechanisms.

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“…Since over-expression of low molecular weight IGFBPs can inhibit growth in mammals and fish (reviewed by Duan et al 2010), we suggest that the cortisol-induced increases in hepatic igfbp1 and igfbp2 expression reduced the role of IGF1 as a growth-promoting agent and contributed to the discordant relationship between plasma IGF1 levels and SGR in the Cort-II treatment. In contrast, channel catfish fed cortisol diets that raised plasma cortisol levels to w180 ng/ml daily for 4 weeks were characterized by reduced hepatic ghr expression, no change in liver igfI mRNA levels, a marked increase in the circulating levels of a low molecular weight IGFBP and depressed plasma IGF1 levels (Peterson & Small 2005, Small et al 2006). While differences in dosage, modes of application, and speciesspecific transcriptional regulation of the GH/IGF system may explain the variable effects of chronic cortisol on liver ghr and igf1 gene expression between studies, our results suggest that an increase in the circulating levels of low molecular weight IGFBPs is a conserved mechanism by which chronic stress inhibits growth in fish.…”

Section: Discussionmentioning

confidence: 99%

“…The fact that Cort-II inhibited mass gained, fork length and CF to a greater extent than Cort-I despite having similar effects on food intake suggests that the relative contribution of reduced food intake to the growthsuppressing effects of cortisol is superseded by factors that reduce feed conversion efficiency when plasma cortisol levels increase above w70 ng/ml in rainbow trout. In fish chronically treated with cortisol, lower feed conversion efficiencies may result from a reduction in nutrient absorption in the gut, an increase in metabolic rate, a mobilization of fuel reserves and an inhibition of the growth-promoting effects of the GH/IGF axis (Davis et al 1985, Barton et al 1987, Gregory & Wood 1999, Mommsen et al 1999, De Boeck et al 2001, Small et al 2006.…”

Section: Discussionmentioning

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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Reduction in channel catfish hepatic growth hormone receptor expression in response to food deprivation and exogenous cortisol

Cited by 63 publications

References 39 publications

Identification and expression analysis of two growth hormone receptors in zanzibar tilapia (Oreochromis hornorum)

Identification and expression analysis of two growth hormone receptors in zanzibar tilapia (Oreochromis hornorum)

Increased growth hormone (GH), growth hormone receptor (GHR), and insulin-like growth factor I (IGF-I) gene transcription after hyperosmotic stress in the Brazilian flounder Paralichthys orbignyanus

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

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