Reactive Oxygen Species

Reactive Oxygen Species

The excessive generation of reactive oxygen species (ROS) and the presence of high activities of cytoplasmic enzymes, such as creatine phosphokinase, may reflect abnormal spermatozoa with excess residual cytoplasm in the midpiece (Rao et al., 1989; Gomez et al., 1996; Aitken et al., 2004).

Indication of factors causing the formation of Reactive Oxygen Radicals

Reactive oxygen species are metabolites of oxygen and include

  • The superoxide anion,
  • Hydrogen peroxide,
  • Hydroxyl and hydroperoxyl radicals,
  • Nitric oxide

When present in excess, they can initiate pathological changes by induc- ing oxidative damage to cellular lipids, proteins and DNA (Griveau & Le Lannou, 1997; Aitken et al., 2003; Henkel et al., 2004). Most cells are equipped with either enzymatic antioxidant systems (superoxide dismutase, glutathione peroxidase and catalase) or non-enzymatic antioxidant systems (uric acid, ascorbic acid, D-toco- pherol), and when these defences are overwhelmed, sperm function is impaired (Agarwal et al., 2004).

In the human ejaculate, reactive oxygen species are produced by both sperma- tozoa (Aitken & Clarkson, 1987; Alvarez et al., 1987; Iwasaki & Gagnon, 1992) and leukocytes (Aitken & West, 1990). Seminal plasma possesses free radical anti- oxidant scavengers and antioxidant enzymes, which may be deficient in some men (Jones et al., 1979; Smith et al., 1996). Thus the removal of seminal plasma during the preparation of spermatozoa for assisted conception (see Chapter 5) may render these cells vulnerable to oxidative attack. High ROS production may cause peroxidative damage and loss of sperm function, as well as DNA damage in both the nuclear and mitochondrial genomes (Sawyer et al., 2003). Sperm survival assays are frequently used to assess the quality of human spermatozoa. The results of such assays are highly correlated with the lipid peroxidation status of the spermatozoa (Gomez et al., 1998).

A chemiluminescent procedure, employing probes such as luminol or lucigenin, may be used to measure ROS production and the redox activity of human spermatozoa.

*This entire article is taken from the WHO Laboratory Handbook-Examination and processing of human semen, from pages 142 and 143 of the 5th Edition. To the complete of the book and references to the information given

**Images used in this article are taken from web site.