262 SPERM CHROMATIN STRUCTURE, OXIDATIVE STRESS AND BASIC SEMEN PARAMETERS OF MEN FROM SUBFERTILE COUPLES

Abstract

It is known that the mammalian sperm chromatin structure plays an important role in male fertility. In opposition to many other areas of biological research, the human sperm chromatin can be considered as a model for animal fertility investigations. This is due to the great number of males with high levels of chromatin abnormalities and the ease of tracking their fertility potential. The aim of the study was to find a relationship between sperm chromatin structure, level of reactive oxygen species (ROS) and the basic semen parameters: sperm concentration and motility. The semen from a total of 391 men from subfertile couples 22–51 years old was used. The sperm chromatin abnormalities were examined flow cytometrically according to the SCSA method (sperm chromatin structure assay; Evenson D.P. Methods In Cell Biology, vol. 33, 1990) and ROS level was examined by luminometry (Kolletis et al. 1999 Fertil. Steril.). Sperm concentration and motility were checked microscopically. Sperm concentration of the examined ejaculates ranged from 0.05 × 10⁶/mL to 627.5 × 10⁶/mL and progressive motility ranged from 0% to 70%. More than 30% of spermatozoa with abnormal chromatin (level considered as the infertility threshold) was found in 70 (17.9%) patients; 15–30% of spermatozoa with abnormal chromatin (level of decreased fertility potential) was found in 154 (39.4%) patients; and in 167 (42.7%) patients the number of abnormal spermatozoa did not exceed 15% (level of normal fertility potential; Evenson et al. 1999 Hum. Reprod.; Zini et al. 2001 Fertil. Steril.). High significant correlations were found between chromatin abnormality and: patients' age (0.1008, P = 0.017), sperm concentration (−0.2735, P < 0.001), progressive motility (−0.4365, P < 0.001), and ROS level (0.2709, P < 0.001). However in patients with normal sperm concentration (>20 × 10⁶/mL, according to the World Health Organization), as many as 11.5% had a high level of chromatin abnormality (>30% of abnormal chromatin) and 29.7% of moderate chromatin abnormality (15–30% abnormal chromatin). Similarly, in patients with normal progressive sperm motility (>50%, according to the World Health Organization) 1.7% had a high level of chromatin abnormality (>30% of abnormal chromatin), and 33.9% had a moderate level of chromatin abnormality (15–30% abnormal chromatin). Contrary to the findings of many earlier investigations, a strong relationship between sperm chromatin damages and basic semen parameters was observed in this work. The sperm chromatin structure assay should be included in standard semen examination to avoid expensive and time consuming in vitro procedures for spermatozoa with damaged DNA.