REACTIVE OXYGEN SPECIES IN SEMEN OF INFERTILE PATIENTS - LEVELS OF SUPEROXIDE DISMUTASE-LIKE AND CATALASE-LIKE ACTIVITIES IN SEMINAL PLASMAAND SPERMATOZOA

Reactive oxygen species (ROS) can be detected in the semen of 40% of i nfertile men, whereas none is detected in semen from normal men. The R OS detected in semen are a reflection of the imbalance between ROS pro duction and degradation. The aim of the present study was to determine whether a lowered scavenging capacity or an increased production of R OS was responsible for the ROS detected in semen samples from infertil e men. Two activities were investigated: (1) catalase-like activity, w hich is responsible for the degradation of H2O2, and (2) superoxide di smutase-like (SOD-like) activity which is responsible for the degradat ion of .O2-. Catalase-like and SOD-like activities were found in whole seminal plasma, in dialyzed seminal plasma (> 12 kD), in an ultrafilt rate of seminal plasma (< 5 kD) and in spermatozoa. There was no signi ficant difference in the SOD-like activities measured in spermatozoa, or in seminal plasma (whole or fractionated) from samples that did or did not produce ROS. SOD-like activity originated mostly from the high molecular weight components of seminal plasma. However, the catalase- like activity of whole seminal plasma and of spermatozoa was significa ntly greater (P = 0.01) in those samples that produced ROS as compared to those that did not. The catalase-like activity in dialyzed seminal plasma, and an ultrafiltrate of seminal plasma from semen samples tha t did or did not produce ROS were not statistically different. The cat alase-like activity of the seminal plasma originated equally from high and low molecular weight components. In conclusion, the data suggest that the ROS detected in the semen of infertile patients are likely du e to increased ROS production rather than to decreased ROS scavenging capacity.