Protection of sperm DNA against oxidative stress in vivo by accessory sex gland secretions in male hamsters

Reactive oxygen species scavengers present in male accessory sex gland secretions might afford antioxidant protection to sperm DNA. This study was conducted to determine whether accessory sex gland secretions protect the genome and function of spermatozoa against oxidative damage in the uterus. Male golden hamsters were divided into four experimental groups: (i) all accessory sex glands removed; (ii) ampullary glands removed; (iii) ventral prostate gland removed and (iv) sham-operated controls. Ejaculated spermatozoa recovered from uteri 15-30 min after mating with experimental males and caput and cauda epididymal spermatozoa obtained from intact males were incubated in 0-20 mmol NADPH l(-1) for 2 h. These spermatozoa and untreated uterine spermatozoa were processed for two types of comet assay (single cell gel electrophoresis): alkaline comet assay (pH > 13) which revealed single-strand DNA breakage and neutral comet assay (pH 9) which revealed double-strand DNA breakage. In comparison with the sham-operated controls, spermatozoa that had not been exposed to accessory sex gland secretions had a higher incidence and more extensive single-strand DNA damage with increasing concentrations of NADPH. Spermatozoa from hamsters without ampullary glands and from hamsters without the ventral prostate glands were similar to those of the control group. After incubation with NADPH, the capacity of spermatozoa from hamsters without accessory glands and from sham-operated controls to fuse with oocytes in vitro was reduced. However, only hamsters without accessory glands showed a negative correlation between single-strand DNA damage and sperm-oocyte fusion. Cauda epididymal spermatozoa were less susceptible to NADPH treatment compared with caput epididymal spermatozoa. The results of the present study showed that male accessory sex gland secretions can preserve the integrity of the sperm genome.