Quercetin in the diet of silver catfish: Effects on antioxidant status, blood parameters and pituitary hormone expression

We analysed the effects of quercetin-containing diet on blood parameters, antioxidant status and pituitary hormone expression in silver catfish. Diets containing three concentrations of quercetin (0, 0.15 and 0.30%) were provided to fish once a day. The results indicated that quercetin did not promote any significant change on the haematological and biochemical parameters measured. Fish that received the diet with quercetin presented decreased lipid peroxidation (LPO) (measured by lipid hydroperoxides and thiobarbituric acid reactive substances) in all tissues evaluated. On the other hand, the activity of antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase and glutathione S-transferase were higher in tissues of fish fed with diets containing quercetin. Additionally, the content of non-protein thiols, total reactive antioxidant potential and ascorbic acid were also higher in tissues of quercetin fed fish. Finally, there was no changes regarding cortisol levels and the expression of growth hormone, prolactin and somatolactin in fish fed with quercetin when compared with the control. Our results suggests that supplementation of silver catfish diet with quercetin is beneficial since it reduced the LPO and increased antioxidant capacity in vital tissues of fish without having any impact on haematological and biochemical parameters, and on pituitary hormone gene expression. Statement of relevance: We propose quercetin as supplement in fish diets. (C) 2016 Elsevier B.V. All rights reserved.