Influence of the forms and levels of dietary selenium on antioxidant status and oxidative stress-related parameters in rainbow trout (Oncorhynchus mykiss) fry

Abstract

Se is an essential micronutrient required for normal growth, development and antioxidant defence. The objective of the present study was to assess the impact of dietary Se sources and levels on the antioxidant status of rainbow trout (Oncorhynchus mykiss) fry. First-feeding fry (initial body weight: 91 mg) were fed either a plant-or fishmeal-based diet containing 0·5 or 1·2 mg Se/kg diet supplemented or not with 0·3 mg Se/kg diet supplied as Se-enriched yeast or sodium selenite for 12 weeks at 178C. Growth and survival of rainbow trout fry were not significantly affected by dietary Se sources and levels. Whole-body Se was raised by both Se sources and to a greater extent by Se-yeast. The reduced:oxidised glutathione ratio was raised by Se-yeast, whereas other lipid peroxidation markers were not affected by dietary Se. Whole-body Se-dependent glutathione peroxidase (GPX) activity was enhanced in fish fed Se-yeast compared to fish fed sodium selenite or non-supplemented diets. Activity and gene expression of this enzyme as well as gene expression of selenoprotein P (SelP) were reduced in fish fed the non-supplemented plant-based diet. Catalase, glutamate -cysteine ligase and nuclear factor-erythroid 2-related factor 2 (Nrf2) gene expressions were reduced by Se-yeast. These results suggest the necessity to supplement plant-based diets with Se for rainbow trout fry, and highlight the superiority of organic form of Se to fulfil the dietary Se requirement and sustain the antioxidant status of fish. GPX and SelP expression proved to be good markers of Se status in fish.Key words: Selenium: Oxidative stress: Glutathione peroxidase: Rainbow trout fry Se is an essential micronutrient for animals and humans required for normal growth and development (1,2) . This role is attributed to low molecular weight Se compounds, as well as to the presence of Se within proteins and enzymes, named selenoproteins, in the form of the amino acid selenocysteine. Mammals have at least twenty-five selenoproteins, and fish probably more than thirty-two, although the functions of many selenoproteins are not yet elucidated (3,4) . Selenoproteins are involved in diverse physiological functions such as antioxidant defence, reduction of inflammation, thyroid hormone production, DNA synthesis, fertility and reproduction (1) . As a component of glutathione peroxidases (GPX), thioredoxin reductases (TR), and methionine sulphoxide reductases (MSR), Se plays, in particular, a pivotal role against oxidative cellular injury and lipid peroxidation. GPX can reduce H 2 O 2 and organic hydroperoxides to the corresponding alcohols with oxidation of glutathione to glutathione disulphide (5) . Seven GPX have been described in mammals, five of which are selenoproteins (2) . The GPX selenoproteins include the ubiquitously expressed cytosolic GPX1, a gastrointestinal-specific enzyme GPX2, a secreted protein found in plasma GPX3, a ubiquitously expressed enzyme that acts on oxidised lipids named * Corresponding author: S. Fontagné-Dicharry, fax þ33 55954515...

Evaluating dietary supply of microminerals as a premix in a complete plant ingredient-based diet to juvenile rainbow trout (Oncorhynchus mykiss)

“…Fontagné‐Dicharry et al. () also reported similar results in whole body Se content of rainbow trout fry fed similar V‐based diets and also on GPx activity. Therefore, higher inclusion of Se in plant ingredient‐based diets is recommended to maintain normal Se balance and GPx levels in the body.…”

Growth, enzymatic glutathione peroxidase activity and biochemical status of juvenile barramundi (Lates calcarifer) fed dietary fermented lupin meal supplemented with organic selenium

“…Previously, PP‐based diets deficient in Se were acceptable for growth although supplemental Se was required to maintain optimal GPx activity in rainbow trout O . mykiss (Fontagne‐Dicharry et al., ). In addition, in a FM‐based study, supplemental Se was not required to enhance growth although it seemed to be necessary for GPx activity maintenance in common carp Cyprinus carpio (Elia, Prearo, Pacini, Dörr & Abete, ).…”

Dietary taurine supplementation to a plant protein source‐based diet improved the growth and intestinal immune function of young grass carp (Ctenopharyngodon idella)

“…At the end of the challenge trial, the fishes were collected from each cage and euthanasia was performed with benzocaine bath as described by Díaz et al (). Then, the intestines of fish were quickly removed, segmented (PI, MI and DI), frozen in liquid nitrogen and stored at −80°C for later analysis according to previous studies (Fontagnédicharry et al, ; Jiang, Deng et al, ; Jiang, Hu et al, ). In this study, we used six samples to analyse enzyme activities and gene expressions, and three samples to analyse Western blot, respectively (Song et al, ).…”