Antioxidant defense system is altered by dietary oxidized lipid in first-feeding rainbow trout (Oncorhynchus mykiss) Stéphanie Fontagné-Dicharry ⁎, Emilie Lataillade, Anne Surget, Laurence Larroquet, Marianne Cluzeaud, Sadasivam Kaushik INRA, UR 1067 Nutrition, Métabolisme et Aquaculture, F-64310 Saint Pée-sur-Nivelle, France abstract article info Article history: Received 19 October 2013 Received in revised form 9 January 2014 Accepted 13 January 2014 Available online 23 January 2014 Keywords: Antioxidant enzymes Lipid peroxidation Oxidized lipids Phospholipids Larval development Rainbow trout High concentrations of n-3 polyunsaturated fatty acids (PUFA) that are readily susceptible to lipid peroxidative damage are found in fish feeds and in the tissues of fish, especially in early developmental stages. A dietary phos- pholipid (PL) supply has been shown to be beneficial during these critical stages. The objective of the study was to characterize the response of the antioxidant defense system under dietary prooxidant conditions in presence or absence of dietary PL during early development of rainbow trout. Rainbow trout (Oncorhynchus mykiss) at the first-feeding fry stage (mean weight: 66 ± 2 mg) or at the fingerling stage (mean weight: 1.5 ± 0.4 g) were fed 4 semi-purified diets supplemented with 12% fresh fish oil or 12% oxidized fish oil and 6% soybean lecithin or 6% soybean oil for 4 weeks at 17 °C. At fry stages, rainbow trout fry fed the PL-supplemented diets had a sig- nificantly higher final body weight than fry fed the PL-free diets (0.37 ± 0.07 vs. 0.27 ± 0.03 g, respectively). Di- etary inclusion of oxidized lipid reduced growth (0.19 ± 0.02 vs. 0.45 ± 0.07 and 2.5 ± 0.6 vs. 4.8 ± 0.6 g, respectively) and increased the mRNA expression of antioxidant enzymes such as glutathione reductase and glu- tathione S-transferase at both developmental stages. However, dietary control of antioxidant enzyme activities and vitamins was low in rainbow trout fry whereas increased activities of antioxidant enzymes and decreased tocopherol contents were noticed in rainbow trout fingerlings fed oxidized lipid compared to rainbow trout fry fed fresh oil. This resulted in higher content of lipid peroxidation products in rainbow trout fry fed oxidized lipid compared to fish fed fresh lipid whereas this difference was reduced at the fingerling stage. The present study demonstrates that rainbow trout fry are more susceptible to oxidative stress induced by dietary oxidized lipid than rainbow trout fingerlings, possibly due to delayed response or lack of complete development of endog- enous antioxidant defense system. © 2014 Elsevier B.V. All rights reserved. 1. Introduction High concentrations of n -3 polyunsaturated fatty acids (PUFA), in particular docosahexaenoic acid (DHA, 22:6n -3) and eicosapentaenoic acid (EPA, 20:5n -3), that have potential benefits for human health (Ruxton et al., 2005) are found in the tissues of fish, right from early on- togeny (Tocher, 2010). In the absence of suitable antioxidant protection, due to the high degree of unsaturation, the long-chain n -3 PUFA are prone to in vivo lipid peroxidation within the fish tissues leading to pathologies, including muscular dystrophy (Boglione et al., 2013). In the feeds also, these fatty acids are readily susceptible to autoxidation when exposed to atmospheric oxygen and if adequate care is not taken in the preparation and storage of feeds, the positive nutritional value of long- chain n -3 PUFA derived from fish oils and meals can become a negative factor for fish (Hsieh and Kinsella, 1989). To limit lipid peroxidation, all aerobic organisms possess two types of antioxidant defense system: free radical scavengers, generally of low molecular weight, and antioxidant enzymes (Halliwell and Gutteridge, 2007). These antioxidant enzymes have been shown to be active all through the development of rainbow trout and to be modulated by feed- ing moderate levels of oxidized lipid (Fontagné et al., 2008). Early devel- opmental stages of fish appear to be particularly sensitive to oxidative stress due to the overpowering effects of prooxidants on antioxidant defenses of cells that can cause alteration in development (Boglione et al., 2013; Fontagné et al., 2006; Hata and Kaneda, 1980; Lewis- McCrea and Lall, 2007, 2010). At a molecular level, some of the genes cod- ing for antioxidant enzymes, such as superoxide dismutase (SOD), cata- lase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione S-transferase (GST), contain binding sites for oxidative stress-sensitive transcription factors, such as the nuclear factor erythroid-2 related factor 2 (Nrf2) and the nuclear factor kappa-light- chain-enhancer of activated B cells (NF-κB), in their regulatory region (Thimmulappa et al., 2002; Zhou et al., 2001). Early life stages of fish also need a dietary phospholipid (PL) supply for good development (Boglione et al., 2013; Cahu et al., 2009; Tocher et al., 2008). Dietary PL Aquaculture 424–425 (2014) 220–227 ⁎ Corresponding author. Tel.: +33 559 515 951; fax: +33 559 545 152. E-mail address: fontagne@st-pee.inra.fr (S. Fontagné-Dicharry). 0044-8486/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aquaculture.2014.01.009 Contents lists available at ScienceDirect Aquaculture journal homepage: www.elsevier.com/locate/aqua-online