Damage to ram spermatozoa by peroxidation of endogenous phospholipids

Abstract

The damaging effects on spermatozoa of endogenous phospholipid peroxidation brought about by aerobic incubation at 37.degree. C in the presence of 0.5 mM-ascorbic acid and 0.5 mM-FeSO4 were examined. As well as becoming immotile, such peroxidized spermatozoa also lost, through leakage, certain intracellular enzymes into the surrounding medium, on a scale resembling that produced by cold shocking non-peroxidized spermatozoa. Morphological observations revealed that peroxidation damaged the plasma membrane, particularly in the region of the acrosome. Further experiments showed that lipid peroxidation irreversibly abolished the fructolytic and respiratory activity of spermatozoa. The susceptibility of spermatozoa to peroxidation was greater when the cells were damaged before incubation with ascorbic acid and FeSO4. To some extent, peroxidation could be prevented, but not reversed, by the addition to sperm suspensions of dialyzed egg yolk or dialyzed bull seminal plasma. Dialyzed seminal plasma from ram, stallion or man had no protective effect.