A review: Oxidative stress and its role in reproduction

Recently the problem of infertility has become more acute. About 3% - 7% of couples suffer a lasting infertility problem and there is a tendency of constant increasing of this number. Existing data reveal that in many of the infertility cases, the cause of sterility is the disabled sperm as a result of the oxidative stress (OS). There are several sources of reactive oxygen species (ROS) in the sperm. Both enzymatic and nonenzymatic antioxidants act as a counteraction against ROS production in seminal plasma. However due to the limited cytoplasm, the spermatozoa are more susceptible to oxidative damage because of the lack of protective cytoplasmic antioxidant enzymes. Currently, many couples suffering fertility problems resort to assisted reproductive technology (ART). Unfortunately, the success rate of ART is relatively low—about 30%. Sperm processing incl. centrifugation, freezing and thawing is associated with the generation of ROS. A range of strategies for sperm prevention of OS are developed. Many studies concern antioxidants and their impact on sperm function, but there are a lot of contradictions in terms of doses and types of combinations that can be used in ART. Future studies should aim the creation of standard and reliable operating procedures for increasing the successfulness of these techniques. This paper offers an overview of the impact of OS on the reproduction, pointing out the sources of ROS in the sperm, the antioxidant defense systems, and the strategies for prevention and improvement of the sperm reproductive functions, incl. those applied in ART.