Seminal superoxide dismutase activity and its relationship with semen quality and SOD gene polymorphism

Superoxide dismutase (SOD) is an important component of antioxidative defense systems and plays an important role in protecting spermatozoa from oxidative damage. In this study, we assessed seminal SOD activity, its association with semen parameters, and also genetic and non-genetic factors contributing to the determination of SOD activity in infertile men. Semen samples were obtained from 435 male infertility patients. Sperm DNA damage levels were detected with the Tdt-mediated dUTP nick end labelling (TUNEL) assay. Four single nucleotide polymorphisms (SNPs) in SOD2 and SOD3 genes were genotyped using OpenArray platform. We found that seminal SOD activity was positively associated with sperm concentration and overall motility, whereas inversely with sperm DNA fragmentation. In addition, infertile men with SOD2 rs4880 CC variants showed a low level of SOD activity when compared with TT carriers (Mean +/- SD: 268.3 +/- 102.3 and 342.8 +/- 98.2, respectively, P = 0.005). Those who consumed vitamin C/E (a parts per thousand yen3 times per week) had a significantly higher SOD activity level than those who did not (mean +/- SD: 379.8 +/- 93.3 and 332.2 +/- 94.9, respectively, P = 0.001). Seminal SOD activity and other factors influencing SOD activity play a role in determining sperm fertilization potential and male infertility.