The Enzymatic Antioxidant System of Human Spermatozoa

Abstract

The ejaculated spermatozoon, as an aerobic cell, must fight against toxic levels of reactive oxygen species (ROS) generated by its own metabolism but also by other sources such as abnormal spermatozoa, chemicals and toxicants, or the presence of leukocytes in semen. Mammalian spermatozoa are extremely sensitive to oxidative stress, a condition occurring when there is a net increase in ROS levels within the cell. Opportunely, this specialized cell has a battery of antioxidant enzymes (superoxide dismutase, peroxiredoxins, thioredoxins, thioredoxins reductases, and glutathione s-transferases) working in concert to assure normal sperm function. Any impairment of the antioxidant enzymatic activities will promote severe oxidative damage which is observed as plasma membrane lipid peroxidation, oxidation of structural proteins and enzymes, and oxidation of DNA bases that lead to abnormal sperm function. Altogether, these damages occurring in spermatozoa are associated with male infertility. The present review contains a description of the enzymatic antioxidant system of the human spermatozoon and a reevaluation of the role of its different components and highlights the necessity of sufficient supply of reducing agents (NADPH and reduced glutathione) to guarantee normal sperm function.

Diagnostic application of oxidation-reduction potential assay for measurement of oxidative stress: clinical utility in male factor infertility

“…glutathione and cysteine) and protein-based buffers (e.g. thioredoxin) that help them regulate ambient redox potentials in the various intracellular compartments, influence the status of redox-sensitive macromolecules and protect against OS (O'Flaherty, 2014a(O'Flaherty, , 2014b. Pluschkell and Flickinger (1996) demonstrated that the redox potential of the culture medium is directly proportional to the number of viable cells (Pluschkell and Flickinger, 1996).…”

The Effect of L-Carnitine, Hypotaurine, and Taurine Supplementation on the Quality of Cryopreserved Chicken Semen

“…Moreover, the specific characteristics of spermatozoa such as low cytoplasm content, a large number of mitochondria, and low level of antioxidants in sperm cytoplasm make them susceptible to damage from free radicals [5, 6]. Damage of a sperm plasma membrane in the fresh semen is partially limited by the presence of antioxidant system in both spermatozoa and seminal plasma [7–9].…”

Histone retention, protein carbonylation, and lipid peroxidation in spermatozoa: Possible role in recurrent pregnancy loss

“…Besides, the retention of histone is not random and is known to have epigenetic significance making it one of the important parameters to be studied in sperm of RPL [Brunner et al 2014;Castillo et al 2014]. Moreover, it is well-known that spermatozoa themselves contain negligible levels of antioxidants, and thus render the cells particularly reliant to their immediate seminal plasma for protection [O'Flaherty 2014]. As a result, if the scavenging capacity of seminal plasma is impaired, the oxidative damage to sperm is increased manifold irrespective of production amount of ROS.…”