Dietary taurine supplementation affects lipid metabolism and improves the oxidative status of European seabass (Dicentrarchus labrax) juveniles

Abstract

The aim of this study was to assess the effect of dietary taurine (Tau) in intermediary metabolism, oxidative status, and Tau biosynthesis capacity in European seabass juveniles. For that purpose, four diets (45% protein and 18% lipid) were formulated with increasing levels of Tau (0.2, 0.5, 0.7, and 1.2% of DM) and fed to triplicate groups of fish (IBW 55g) until apparent visual satiety for 10 weeks.Total bile acid content in the liver increased as dietary Tau supplementation increase, while the opposite occurred in the plasma. Plasma glucose, total cholesterol, HDL, and LDL cholesterol decreased, while total and indirect bilirubin increased with the increase of dietary Tau level.The activity of the key intermediary enzymes measured decreased with the increase of dietary Tau up to 0.7%. Regarding the antioxidant-related enzymes, dietary Tau supplementation decreased hepatic catalase, glutathione peroxidase, glutathione reductase, and superoxide dismutase activities with the maximum effects being observed as dietary Tau increased from 0.2 to 0.5%. Overall, there was a decreasing trend of hepatic lipid peroxidation with the increase of dietary Tau.This study is the first to demonstrate that in European seabass juveniles the capacity of expressing cysteine dioxygenase, an enzyme involved in the cysteine sulfinate pathway for Tau synthesis, although its expression was not affected by Tau levels in the diet.This study indicates that dietary Tau levels affect intermediary metabolism, namely carbohydrates and lipidic metabolism, and improve the antioxidant status of European seabass juveniles. Furthermore, although CDO expression was detected, European seabass seems unable to regulate its activity, these results supporting the essentiality of Tau for this species.