Antioxidant systems of brown trout (Salmo trutta f. fario) semen.

The present study characterizes the antioxidant systems of brown trout, Salmo trutta, semen as supplementation of semen dilution media with antioxidants can be beneficial to improve techniques for semen storage and cryopreservation. Antioxidants and oxidant defensive enzymes of spermatozoa and seminal plasma were analyzed. To determine whether antioxidants and oxidant defensive enzymes have an effect on sperm functionality, in vitro experiments were performed. Selected antioxidants and oxidant defensive enzymes were added to sperm motility-inhibiting saline solution and their effects on sperm viability (motility when activated, membrane integrity, and lipid peroxidation) were measured. In seminal plasma and spermatozoa the enzymes catalase, glutathione reductase, methionine sulfoxide reductase, peroxidase, and superoxide dismutase and the metabolites ascorbic acid, glutathione, methionine, tocopherol, and uric acid were detected. Of the enzymes superoxide dismutase had the highest activity, of the metabolites uric acid occurred in highest concentrations. During in vitro incubation uric acid and catalase increased the sperm motility, sperm membrane integrity, and decreased the sperm lipid peroxidation in comparison to the control. However, catalase was effective only at an activity much higher than that occurring in seminal plasma. Reduced methionine increased the sperm motility and sperm membrane integrity and oxidized methionine the motility. However, neither reduced nor oxidized methionine decreased the sperm membrane lipid peroxidation. It is concluded, that uric acid is the main antioxidant of brown trout semen.

The effect of dietary supplementation with blueberry, alpha-tocopherol or astaxanthin on oxidative stability of Arctic char (Salvelinus alpinus) semen.

The objective was to determine the oxidative stability of Arctic char (Salvelinus alpinus) semen following dietary supplementation with lowbush blueberry (Vaccinium angustifolium) product, alpha-tocopherol, alpha-tocopherol+blueberry product, or alpha-tocopherol+astaxanthin. Sperm lipid peroxidation was initiated by challenging with ferrous sulphate/ascorbic acid (Fe(++)/Asc) at level of 0.04/0.2 mmol/L. Addition of blueberry, alpha-tocopherol, or both to char diets inhibited semen lipid peroxidation by: (a) decreasing the rate of sperm lipid peroxidation, an effect which was more pronounced with alpha-tocopherol treatments; and (b) increasing the antioxidant potential of seminal plasma, based on the lipid peroxidation process of sperm and an in vitro chicken brain tissue model. Dietary supplementation with astaxanthin and alpha-tocopherol had the same effect as the supplementation with alpha-tocopherol alone on inhibiting the lipid peroxidation process of sperm and chicken brain. Catalase-like activity increased significantly in sperm of fish fed alpha-tocopherol, blueberry, or both. There was a negative correlation (r= -0.397, P < 0.05) between catalase-like activity in sperm cells and the rate of sperm lipid peroxidation. Seminal plasma alpha-tocopherol levels increased significantly in fish supplemented with alpha-tocopherol alone or in combination with blueberry or astaxanthin. There were negative correlations between seminal plasma alpha-tocopherol levels and lipid peroxidation rates of sperm cells (r= -0.625, P < 0.01) and brain tissue (r= -0.606, P < 0.01). In conclusion, dietary supplementation of blueberry product or alpha-tocopherol inhibited lipid peroxidation in Arctic char semen. Further experiments are needed to test the effect of dietary blueberry and antioxidants on Arctic char semen quality during liquid and cryopreserved storage.