Reactive oxygen species influence the acrosome reaction but not acrosin activity in human spermatozoa

It is now widely accepted that the higher levels of reactive oxygen species (ROS) produced by damaged or deficient spermatozoa are associated with a l oss of motility and a decreased capacity for sperm-oocyte fusion. Furthermo re, earlier studies show, under physiological conditions, that some ROS may be involved in capacitation and hyperactivation of human spermatozoa. We m easured ROS levels, acrosome reaction (AR) and acrosin activity (AA) in sem en samples from suspected subfertile men to reveal the influence of ROS on AR and AA of human spermatozoa. Semen samples were obtained from 60 patient s. Samples with greater than or equal to 1 x 10(6) leukocytes/ml were exclu ded from the study. ROS production was determined using a chemiluminescence technique. AR was determined using a triple stain technique. The percentag e of acrosome-reacted spermatozoa after low temperature induction of the AR (test value), and the inducibility of AR ( = the difference between the te st value and the control), were calculated. The AA was analysed by determin ing the proteolytic potential of spermatozoa on gelatin plates. The mean ha lo diameter and percentage of halo formation in each sample were measured a s AA parameters. Scatter plots of ROS levels and AR parameters showed that the percentage of acrosome reacted spermatozoa and AR inducibility were bet ter in samples with low rather than high ROS levels. On the other hand, the re were no apparent similarities between ROS and the AA parameters. Therefo re, the percentage of acrosome-reacted spermatozoa and AR inducibility were significantly higher in the low than in the high ROS group (p = 0.028, p = 0.0001, respectively). In addition, there was no significant difference in AA parameters between groups. These findings suggest that lower ROS in sem en may have a role in AR but excessive ROS may exert a negative influence o n AR, while ROS in semen has no relationship to AA.