Metabolic, antioxidant, and immune response of broodstock males of Penaeus brasiliensis Latreille, 1817 fed diets supplemented by vitamin C

Abstract Controlling oxidative stress in shrimps under culture conditions is of vital importance to ensure that males have an optimal physiological status. The use of diets supplemented with vitamins are widely used for this purpose. We evaluated the effects of vitamin C on the metabolic, antioxidant, and immune responses of Penaeus brasiliensisLatreille, 1817 broodstock males under culture conditions. A formulated diet was used as a control (16 mg kg–1 of total ascorbic acid (vitamin C) content) and three diets were prepared with three vitamin C levels: 322 mg kg–1 (Diet A), 628 mg kg–1 (Diet B), and 934 mg kg–1 (Diet C). Triglycerides, cholesterol, glucose, and prophenoloxidase, total proteins, and quantity and type of hemocytes in the hemolymph were determined. We also quantified the antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx) and lipid peroxidation in the reproductive tract. Differentially expressed genes of the immune system, namely those of α-2 macroglobulin (α2M), peneidin (Pen), hemocyanin, prophenoloxidase, and the genes encoding the antioxidant enzymes SOD, CAT, and Gpx were quantified in the tract. Sperm quantity and quality were recorded. In males fed Diet C, the lowest cholesterol values and triglycerides obtained in the hemolymph were not significantly different from those fed the control diet (P < 0.05); those fed Diet C showed the highest amount of hyaline hemocytes, the lowest CAT enzyme activity, and the highest Gpx activity. The immune system genes only showed differences between α2M and Pen; sperm quantity and quality were not affected by diet. The results indicated that Diet C (13.9 g kg–1 vitamin C) was effective for the maintenance of P. brasiliensis broodstock males because it controlled cholesterol and triglyceride levels; there was less CAT activity and less activation of the immune system mediated by hemocytes.