Efeito da dieta enriquecida com rutina sobre os parâmetros sanguíneos e biomarcadores oxidativos em jundiás (Rhamdia quelen)

Abstract

Silver catfish, Rhamdia quelen, is one of the most cultivated fish species in southern Brazil. Products destined for improving rearing and production of this species are required due to its importance for aquaculture. Oxidative stress (OS) is one of the main challenges in fish culture, so the use of compounds with antioxidant capacity may be valuable. The flavonoid rutin has several beneficial effects and represents an important alternative to reduce the physiological changes that arise from rearing-related stress. This study evaluated the influence of three diets containing rutin (0, 0.15 and 0.30 % rutin) on blood parameters and the antioxidant response of silver catfish. After a 21-day feeding period, blood was withdrawn for biochemical analysis and determination of plasma cortisol levels. The fish were then euthanized for sampling of the brain, gills, liver, kidney and muscle. Biomarkers of OS, thiobarbituric reactive substances (TBARS), lipid hydroperoxides (LOOH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), content of non-protein thiol groups (NPSH), content of ascorbic acid (AA) and total antioxidant capacity (TRAP) were determined. Fish fed the diet having 0.15 % rutin had lower cortisol levels compared to control. Nonetheless, the diet with rutin did not affect the hematological parameters. The levels of lipid peroxidation measured by determination of TBARS and LOOH in the brain, gills, liver and muscle decreased in the fish fed the diet containing rutin; in the kidney, however, only the levels of LOOH were reduced in these fish. When compared to control, the rutin-enriched diet increased the activity of SOD, CAT, NPSH content, AA and TRAP in the brain, GST and TRAP in the gills, SOD, CAT, GST, NPSH content, AA and TRAP in the liver, CAT, GST and TRAP in the kidney, and GPx, NPSH content, AA and TRAP in the muscle. In conclusion, these results suggest that rutin supplementation in silver catfish diet is recommended because it increases the tissue antioxidant response, thus preventing oxidative damage.