Liver and intestine oxidative status of gilthead sea bream fed vegetable oil and carbohydrate rich diets

This study investigated the effects of dietary lipid source and carbohydrate content on liver and intestine oxidative status of gilthead sea bream juveniles, by assessing antioxidant defences enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX; glutathione reductase, GR; and glucose-6-phosphate clehydrogenase, G6PD); total, reduced, and oxidized glutathione (GSH); and lipid peroxidation (LPO). Fish were fed for 13 weeks with four diets (2 x 2 factorial design) differing in lipid source (Fish oil- FO or a blend of vegetable oil-VO) and carbohydrate level (0 or 20% of digestible starch). Dietary VO reduced liver and intestine LPO, and enhanced liver GSH reclox status (total and reduced GSH), GPX, GR, and G6PD activities, while in the intestine a decrease of G6PD activity and an increase of catalase activity and of reduced GSH (only in the carbohydrate diet) were recorded. Dietary carbohydrate promoted an increase of hepatic SOD and G6PD activities, and a decrease of CAT activity, total, oxidized, and reduced GSH, LPO, and oxidative stress index (OSI) (only in the FO diet). In the intestine, dietary carbohydrate did not induce alterations in LPO or enzymatic antioxidant defences but negatively affected GSH redox status (OSI, reduced and oxidized GSH). Overall, few interactions between dietary lipid source and carbohydrates were recorded. Dietary VO appeared to have a protective role against LPO in both tissues. Dissimilarities in liver and intestine susceptibility to LPO by dietary carbohydrate may reflect differences in glucose and GSH metabolism in the two tissues. Statement of relevance: Plant related macronutrients improve fish oxidative status. (C) 2016 Elsevier B.V. All rights reserved.