Free thiols in human spermatozoa: Correlation with sperm DNA integrity

Objectives. To examine the levels of sperm protamine free sulfhydryl or thi ol (SH) groups and DNA denaturation (DD) in semen from fertile and infertil e men. Methods. Semen samples were obtained from consecutive nonazoospermic men pr esenting for infertility evaluation (n = 66) and fertile men presenting for vasectomy (n = 10). The standard semen parameters (sperm concentration, mo tility, and morphology), sperm DD, and SH content were monitored. Sperm DNA integrity was evaluated by flow cytometry analysis of acridine orange-trea ted spermatozoa and expressed as the percentage of spermatozoa demonstratin g denatured DNA. Results. The mean (+/- SE) levels of sperm SH groups and the percentage of spermatozoa with DD were significantly higher in the infertile men than in the fertile men (SH groups 1083 +/- 97 and 570 +/- 101 nmol/10(6) spermatoz oa, respectively; and DD 21%+/-1.7% and 8.9%+/-1.9%, respectively). The lev els of sperm SH groups and DD correlated positively (r = 0.53). Also, the l evels of sperm SH groups and DD correlated negatively with the standard sem en parameters. Conclusions. Our data demonstrate that sperm SH content correlates positive ly with sperm DD and that significantly higher levels of sperm DD and SH co ntent are found in infertile men than are found in fertile men. These data suggest that the enhanced susceptibility of sperm DNA to denaturation in in fertile compared with fertile men may be associated with incomplete oxidati on of the sperm SH groups. UROLOGY 58: 80-84, 2001. (C) 2001, Elsevier Scie nce Inc.