Oxidative Stress Measurement in Semen and Seminal Plasma

Excessive generation of seminal reactive oxygen species (ROS) by immature spermatozoa and white blood cells, especially granulocytes, in the ejaculate is detrimental to spermatozoa. The cellular antioxidant defense mitigates the impact of elevated ROS production. The imbalance between ROS and available antioxidants results in oxidative stress (OS), leads to lipids peroxidation, alters proteins expression, and results in DNA fragmentation and male infertility. Accurate assessment of ROS is important as it provides information about oxidative stress as an underlying cause of male infertility. Different direct and indirect methods and instruments are available for the laboratory measurement of oxidative stress in seminal plasma and spermatozoa. The measurement of ROS by the chemiluminescence assay is a direct method that can measure both extracellular and intracellular (global) ROS in real-time using luminol as probe. This assay provides reference values that can help differentiate infertile men from fertile men. Total antioxidant capacity measurement in seminal plasma is indicative of the antioxidant reserves. DNA fragmentation is determined by several assays, including the TUNEL assay. The TUNEL assay measures single- and double-strand damage in spermatozoa as a result of oxidative stress. Measurement of oxidation reduction potential (ORP) in semen and seminal plasma is a measure of the redox potential or the oxidative stress status in a given sample. These tests can be included as advanced andrology screening diagnostic approaches that can complement routine semen analysis and can help explain the underlying cause of idiopathic or unexplained male infertility. This chapter outlines the importance of oxidative stress and its measurement in semen and seminal plasma.