Regulation of the somatotropic axis by dietary factors in rainbow trout (Oncorhynchus mykiss)

Type Article
Date 2005-09
Language English
Author(s) Gomez Requeni P2, Calduch Giner J2, de Celis S2, Medale Francoise1, 3, Kaushik Sadasivam1, 3, Perez Sanchez Jaume3
Affiliation(s) 1 : IFREMER, Unite Mixte INRA, Lab Nutr Poissons, F-64310 St Pee Sur Nivelle, France.
2 : CSIC, Inst Acuicultura Torre Sal, Castellon, Spain.
Source British Journal of Nutrition (0007-1145) (Cambridge University Press), 2005-09 , Vol. 94 , N. 3 , P. 353-361
DOI 10.1079/BJN20051521
WOS© Times Cited 45
Keyword(s) Insulin like growth factor, Growth hormone receptor, Growth hormone, Plant proteins, Rainbow trout
Abstract The activity of the somatotropic axis was analysed in juvenile rainbow trout (Oncorhynchus mykiss) fed either a fishmeal-based diet (FM) or graded levels of plant proteins to replace 50 % (PP50 diet), 75 % (PP75 diet) or 100 % (PP100 diet) of the fishmeal protein. For this purpose, partial cloning and sequencing of the gene encoding rainbow trout growth hormone receptor (GHR) was first accomplished by RT-PCR, using degenerate primers based on the sequences of non-salmonid fish GHR. Growth rates and energy retention were lowered by the PP75 and PP100 diets and a concurrent and progressive increase in plasma levels of growth hormone (GH) was found. However, no changes in hepatic GH binding and total plasma insulin-like growth factor (IGF)-I levels were observed among the four experimental groups. This fact agrees with the lack of changes in hepatic measurements of GHR and IGF-I transcripts. No consistent changes in IGF transcripts were found in peri-visceral adipose tissue and skeletal muscle, but GHR mRNA was up-regulated in the peri-visceral adipose tissue of fish fed the PP75 and PP100 diets, which would favour the lipolytic action of GH. Two specific bands (47 and 33 kDa) of IGF-binding proteins were found in the plasma of all analysed fish, but the sum of the two integrated areas increased progressively with plant protein supply, which might reflect a reduced free IGF availability. Therefore, in our experimental model, the growth impairment could be due, at least in part, to a lowered availability of biologically active IGF (free IGF fraction) rather than to liver GH desensitization or defect in IGF synthesis and release at the systemic and/or paracrine-autocrine level.
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Gomez Requeni P, Calduch Giner J, de Celis S, Medale Francoise, Kaushik Sadasivam, Perez Sanchez Jaume (2005). Regulation of the somatotropic axis by dietary factors in rainbow trout (Oncorhynchus mykiss). British Journal of Nutrition, 94(3), 353-361. Publisher's official version : , Open Access version :