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

Abstract

It is now widely accepted that the higher levels of reactive oxygen species (ROS) produced by damaged or deficient spermatozoa are associated with a loss of motility and a decreased capacity for sperm-oocyte fusion. Furthermore, earlier studies show, under physiological conditions, that some ROS may be involved in capacitation and hyperactivation of human spermatozoa. We measured ROS levels, acrosome reaction (AR) and acrosin activity (AA) in semen samples from suspected subfertile men to reveal the influence of ROS on AR and AA of human spermatozoa. Semen samples were obtained from 60 patients. Samples with > or = 1 x 10(6) leukocytes/mL were excluded from the study. ROS production was determined using a chemiluminescence technique. AR was determined using a triple stain technique. The percentage of acrosome-reacted spermatozoa after low temperature induction of the AR (test value), and the inducibility of AR (= the difference between the test value and the control), were calculated. The AA was analysed by determining the proteolytic potential of spermatozoa on gelatin plates. The mean halo diameter and percentage of halo formation in each sample were measured as AA parameters. Scatter plots of ROS levels and AR parameters showed that the percentage of acrosome reacted spermatozoa and AR inducibility were better in samples with low rather than high ROS levels. On the other hand, there were no apparent similarities between ROS and the AA parameters. Therefore, 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 semen may have a role in AR but excessive ROS may exert a negative influence on AR, while ROS in semen has no relationship to AA.

Unraveling the sperm proteome and post-genomic pathways associated with sperm nuclear DNA fragmentation

“…Oxidative stress has been suggested as one of the major cellular mechanisms involved in male infertility [105]. Oxidative stress affects the sperm membrane through lipid peroxidation [106], leading to loss of membrane stability and selective permeability, which, in turn, can cause mitochondrial dysfunctions [81], defective acrosome reaction [107], and sperm DNA fragmentation [108]. Hence, our results clearly show that viable sperm from an ejaculate of lower quality possesses protective mechanisms against the effects of the surrounding oxidative stress.…”

Contemporary evidence on the physiological role of reactive oxygen species in human sperm function

“…Ichikawa et al [83] compared the effect of small amounts of free radicals in stimulating the exocytosis and activation of acrosin. Samples were collected from normozoospermic and oligozoospermic patients.…”

The protective effects of α-ketoacids against oxidative stress on rat spermatozoa in vitro

“…Superoxide anion (O 2 -·) and hydrogen peroxide (H 2 O 2 ) are the common forms of ROS. Some studies suggested that relatively low concentrations of ROS are beneficial for the normal functions of sperm capacitation [4], but excessively high concentrations of ROS are associated with lower acrosin activity [5], sperm DNA fragmentation, impaired sperm motility [6,7], decrease in sperm acrosome reaction and fusiogenic ability [8]. Clinical studies showed that oral antioxidant treatment appeared to improve sperm DNA integrity and outcomes of in vitro fertilization with intracytoplasmic sperm injection among patients with sperm DNA damage or other male infertility [9,10].…”