003. OXIDATIVE STRESS, OSMOTIC STRESS AND APOPTOTIC CHANGES: EFFECTS ON EQUINE SPERMATOZOA

Although considerable progress has been made over the past few years in liquid or frozen storage of equine spermatozoa, there remains a large inter-individual difference in the success of semen preservation for the stallion. Equine spermatozoa undergoing low-temperature storage undergo oxidative damage to membrane phospholipids, proteins and chromatin. Osmotic stress also leads to damage to the plasma membrane and alteration in sperm metabolism. Furthermore, evidence from a number of species suggests that ejaculated spermatozoa undergo apoptotic-like changes as a consequence of cryopreservation. It appears likely that these three processes are interlinked and may impact various compartments in the sperm cell via similar pathways. Therefore, an understanding of these processes and their common metabolic pathways may be important in attempts to obviate adverse affects on equine spermatozoa during storage. Further research should evaluate the molecular pathways which may represent convergence of these stresses on the sperm cell with an aim to reducing their net detrimental effect on sperm during preservation. Supported by the John P. Hughes Endowment, the UC Davis Center for Equine Health, and the National Center for Research Resources, National Institutes of Health.