Lipid peroxidation in human spermatozoa

Abstract

Oxidation of lipids can be a blessing or a curse as far as spermatozoa are concerned. Beatitudes are conferred via the oxidative generation of oxysterols, which then drive sperm capacitation by promoting the removal of cholesterol from the sperm plasma membrane. Conversely, the anathema involves peroxidation of polyunsaturated fatty acids (PUFA) to generate lipid peroxides that have a detrimental effect on spermatozoa, disrupting DNA integrity and limiting their competence for fertilization. Spermatozoa actively detoxify and remove toxic lipid peroxides from the sperm plasma membrane, but once these defense mechanisms have been overwhelmed, lipid peroxidation spreads rapidly through the cell leading to membrane damage, leakage of ATP, and a rapid loss of sperm motility and viability. The excessive presence of unesterified PUFA may be instrumental in the genesis of oxidative stress through the ability of these amphiphiles to interfere with the mitochondrial electron transport chain and promote cellular generation of superoxide anion.