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United States Department of Agriculture

Agricultural Research Service

Research Project: CATFISH GENETICS, BREEDING, AND PHYSIOLOGY Title: Effects of Exogenous Cortisol on the Gh/igf-I/igfbp Network in Channel Catfish

Authors
item Peterson, Brian
item Small, Brian

Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 25, 2005
Publication Date: May 1, 2005
Citation: Peterson, B.C., Small, B.C. 2005. Effects of exogenous cortisol on IGFBPs and mRNA expression levels of IGF-I and GH in channel catfish. Domestic Animal Endocrinology 28:391-404.

Interpretive Summary: Glucocorticoids are known to hinder growth in a number of species. In order to better understand the mechanisms through which they slow growth in channel catfish, we examined the effects of feeding cortisol on the axis that regulates growth (the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF-binding protein (IGFBP) axis). Catfish were fed a cortisol-laden diet or commercial catfish feed. Fish fed diets with cortisol weighed approximately 50% less and ate approximately 30% less than fish that ate the commercial catfish feed. A small IGFBP was increased in the blood of fish fed cortisol while levels of IGF-I were decreased. These data indicate that feeding cortisol reduces weight gain, feed intake, and plasma levels of IGF-I and induces a small IGFBP. One mechanism through which cortisol may impede growth of catfish is through an increase in a low molecular weight IGFBP which may lead to inhibitory effects on the action of IGF-I.

Technical Abstract: Glucocorticoids are known to hinder somatic growth in a number of vertebrate species. In order to better understand the mechanisms through which they may act in channel catfish, we examined the effects of feeding cortisol on the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF-binding protein (IGFBP) network. Fish (30.6 +/- 3.0 g) were fed once daily for four weeks and treatments included: 1) High cortisol (dietary cortisol provided at 400 mg/kg feed), 2) Low cortisol (dietary cortisol provided at 200 mg/kg feed), and 3) Control (commercial catfish feed). Fish fed diets with cortisol weighed approximately 50% less than Controls. Feed intake was reduced by approximately 30% in both treatments of cortisol fed fish compared to Controls. A ~20-kDa IGFBP was observed in plasma from High and Low treated fish while it was not detected in Control fish plasma. High cortisol treatment increased pituitary GH mRNA expression approximately 10-fold while liver IGF-I mRNA expression was not different between cortisol treated fish and Controls. Cortisol treatments decreased plasma levels of IGF-I. These data indicate that feeding cortisol for 4 weeks reduces weight gain, feed intake, and plasma levels of IGF-I and induces a ~20-kDa IGFBP. One mechanism through which cortisol may impede growth of catfish is through an increase in a low molecular weight IGFBP which may lead to inhibitory effects on the action of IGF-I.

Last Modified: 10/24/2014
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