Effect of alpha-tocopherol and tocopherol succinate on lipid peroxidation in equine spermatozoa.

The objective of this study was to compare the effect of alpha-tocopherol and its ester, alpha tocopherol succinate, on lipid peroxidation and motility of equine spermatozoa. In experiment one, spermatozoa were incubated with dl-alpha-tocopherol (5, 25, 100 or 500 microM), DL-alpha tocopherol succinate (5, 25, 100 or 500 microM) or vehicle (0.5% ethanol) at 38 degrees C, and sperm motility was determined at 30, 60 and 120 min. In experiment two, spermatozoa loaded with the lipophilic probe, C11BODIPY(581/591), were incubated with dl-alpha-tocopherol (50 and 100 microM), DL-alpha-tocopherol succinate (50 and 100 microM) or ethanol (0.5%) and with the promoters cumene hydroperoxide, Fe2SO4, and ascorbate at 38 degrees C in 5% CO2. Lipid peroxidation was determined by changes in fluorescence of C11BODIPY(581/591), and motility was determined by CASA at 0, 15, 30 and 60 min. In experiment three, spermatozoa loaded with C11BODIPY(581/591) were incubated with dl-alpha-tocopherol (5, 25, 100 or 500 microM), DL-alpha-tocopherol succinate (5, 25, 100 or 500 microM) or ethanol (0.5%) at 38 degrees C and then submitted to a 4-hour incubation at room temperature. Motility and lipid peroxidation were determined at 1 and 4 h. In experiment four, the effect of DL alpha tocopherol (5, 25 or 500 microM), DL-alpha-tocopherol succinate (5, 25 or 500 microM) or ethanol (0.5%) on lipid peroxidation and motility were evaluated during storage at 5 degrees C in a skim-milk based extender. Although dl-alpha-tocopherol succinate appeared more effective than DL-alpha-tocopherol in preventing lipid peroxidation during short-term incubations, the succinate ester suppressed sperm motility compared to dl-alpha-tocopherol alone.