Generation of reactive oxygen species, lipid peroxidation, and human sperm function.

Recent studies have demonstrated that hwnan spermatozoa are capable of generating reactive oxygen species and that this activity is significantly accelerated in cases of defective sperm function. In view of the pivotal role played by lipid peroxidation in mediating free radical dwnage to cells, we have examined the relationships between reactive oxygen species production, lipid peroxidazion, and the functional competence of human spermatozoa. Using malondialdehyde production in the presence of ferrous ion promoter as an index of lipid peroxidation, we have shown that lipid peroxidation is significantly accelerated in populations of defective spennafozoa exhibiting high levels of reactive oxygen species production or in normal cells stimulated to produce oxygen radicals by the ionophore, A23187. The functional consequences of lipid peroxidation included a dose-dependent reduction in the ability of human spermatozoa to exhibit sperm oocyte-fusion, which could be reversed by the inclusion of a chain-breaking antioxidant, cs-tocopherol. Low levels of lipid peroxidation also had a slight enhancing effect on the generation of reactive oxygen species in response to