Stallion Semen Preservation II: Effects of Oxidative and Osmotic Stress on Sperm Storage

摘要

Over the past few years, considerable information has been developed relative to factors responsible for damage to spermatozoa during the process of cryopreservation. Our previous work has suggested that equine sperm undergoing low temperature storageexperience characteristics of premature capacitation, oxidative and osmotic damage, and DNA damage. Cryopreservation-induced sperm cell damage results from two processes: 1) oxidative damage to membrane phospholipids and chromatin and 2) osmotic stressleading to mechanical damage to the plasma membrane and alteration in sperm metabolism. Oxidative stress is a well-defined component of many disease processes. The generation of "reactive oxygen species" may occur as a normal consequence of oxidative metabolism or may result from specific mechanisms within particular cell types, such as leukocytes. Oxidative stress was suggested as an important factor in disruption of sperm function over 50 years ago; however, it is only recently that the importance ofoxidative stress in normal and abnormal sperm function has gained a better understanding. It is now clear that reactive oxygen species (ROS) play an important role in normal sperm function and that an imbalance in either the production or degradation ofROS may have serious adverse effects on sperm. The effects of oxidative stress are particularly important during sperm storage by either cooling or cryopreservation. This review will examine how ROS are generated and scavenged in equine semen, the effects of ROS on sperm function, as well as methods to reduce oxidative stress in stored semen.