[Role of reactive oxygen species (ROS) on human spermatozoa and male infertility]

Pro- and antioxidant are balanced in the sperm environment. Reactive Oxygen Species (ROS) are essential to the acquisition of fertilizing ability and contribute to chromatin condensation, membrane remodeling and activation of intracellular signaling pathways, during epididymal maturation, capacitation, and acrosome reaction. However, endogenous and exogenous factors can upset that balance by stimulating ROS production and/or decreasing antioxidant defenses, a situation called oxidative stress. Oxidative stress is described as a major cause of male infertility. It induces membranes and nucleus alterations, resulting in loss of mobility and decline in sperm fertilizing ability. Those are risk factors for low fertility, abnormalities of preimplantation development, and miscarriages. Various methods exist for measuring the pro- and antioxidants status of sperm, yet are little used in routine for diagnostic purposes. Meanwhile, many studies have shown the beneficial effects of oral antioxidants supplementation, or addition to semen freezing medium, to prevent in vivo and limit in vitro the deleterious effects of ROS, respectively.