Cadmium as an etiology of sperm dysfunction in Holstein bulls

Oxidative stress has been identified as a crucial factor leading to male infertility largely due to peroxi-dative damage to the sperm cell membrane. Cadmium (Cd) is a widespread environmental pollutant and one of the well-known reproductive toxicants. Because of its long biological half-life (10-30 years), Cd accumulates in the biological systems. The present study was designed to assess the concentration-dependent in vitro effect of 20 to 700 uM of Cd on the membrane integrity, motility, and acrosomal status of Holstein bull spermatozoa. We recorded a significant elevation in the malondialdehyde (MDA) level, increased lipid peroxidation (LPO) rate and a drastic decrease in the spermatocrit values, especially at the 700 uM concentration of Cd, indicating deleterious effects of Cd on the intactness of the sperm membrane. There was also a negative correlation between the LPO rate and both the percentage of motile spermatozoa (r ^ -0.89) and sperm viability (r = -0.86). Performing the gelatin test indicated that Cd altered the integrity of acrosomal membranes and showed an abnormal acrosome reaction. In this regard, a reverse correlation was found between the LPO rate and the percentage of halos (r = -0.96). In conclusion, Cd was proved to be a potential toxicant in the category of environmental factors that induced membrane impairments, lowered motility and viability, and decreased rate of acrosome reactions leading to bull sperm dysfunction.