Beneficial effects of α-tocopherol against intracellular calcium overload in human sperm

Calcium (Ca(2+)) and reactive oxygen species (ROS) constitute the most influential intracellular signaling molecules participating in the regulation of different sperm functions. Elevating intracellular Ca(2+) and ROS in physiologic range regulate capacitation, motility, acrosome reaction, and sperm-oocyte fusion; whereas cytosolic Ca(2+) overload and ROS overproduction have pathologic effects. Our aim of this study was determination of antioxidant effects of α-tocopherol on sperm motility, viability, and DNA integrity in a condition where cytosolic calcium overload was induced by A23187 (a calcium ionophore). Our results indicated that, α-tocopherol has ability to prevent sperm mortality and save sperm rapid motility after 1 hour incubation. At the same time, A23187 reduced significantly percentage of rapid sperm motility and increased sperm mortality and DNA damage. Results of sperms incubation in the medium contain a combination of A23187 and α-tocopherol showed that α-tocopherol can reduce many of the deleterious effects of A23187. In conclusion, it seems that the harmful effects of A23187 are due to excessive ROS production, and α-tocopherol neutralizes these effects.