In vitro mercury exposure on spermatozoa from normospermic individuals

Epidemiological evidence suggests that exposure to industrial metal aerosols is detrimental to the male reproductive system. Oxidative stress has been identified as a crucial factor leading to male factor infertility largely due to peroxidative damage to the sperm cell membrane. The objectives of the present study were to test the effect of mercury in the concentration range from 50 to 800 micromol(-1), in vitro, on the sperm membrane and DNA integrity, motility and acrosomal status of human spermatozoa. We found a significant increase in the Lipo Per Oxidation (LPO) indicating the deleterious effect of mercury on the sperm membrane integrity. This effect was prominent at the concentration of 800 microM mercury. There was also a strong negative correlation between LPO rate and percentage of viable spermatozoa (r = -0.941, p<0.001). Data obtained from SCGE assay technique revealed that mercury is capable of inducing DNA breaks in the sperm nuclei. Almost, 88% of DNA breaks were of double-stranded. The correlation between LPO rate and percentage of DNA breaks was found to be 0.918 (p<0.001). Performing the gelatin digestion test indicates that mercury was able to alter the integrity of acrosomal membranes showing an abnormal acrosome reaction. In this regard, a strong correlation was found between LPO rate and percentage of halos (r = -0.893, p<0.001). Taken together, mercury induced membrane impairments, lowered sperm viability, DNA breaks and a decreased rate in the acrosome reaction of human spermatozoa leading to sperm dysfunction. Entering mercury in the male gonads and seminal plasma may exert deleterious effects on the human spermatozoa. Hence, considering the wide spread use of mercury and its compounds, these metals should regarded with more concern.