OXIDATIVE STRESS AND REPRODUCTIVE FUNCTION: Oxidative stress and the long-term storage of horse spermatozoa

The growing understanding of the mechanisms regulating redox homeostasis in the stallion spermatozoa, together with its interactions with energetic metabolism, is providing new clues applicable to the improvement of sperm conservation in horses. Based on this knowledge, new extenders, adapted to the biology of the stallion spermatozoa, are expected to be developed in the near future.

The preservation of semen either by refrigeration or cryopreservation is a principal component of most animal breeding industries. Although this procedure has been successful in many species, in others, substantial limitations persist. In the last decade, mechanistic studies have shed light on the molecular changes behind the damage that spermatozoa experience during preservation. Most of this damage is oxidative, and thus in this review, we aim to provide an updated overview of recent discoveries about how stallion spermatozoa maintain redox homeostasis, and how the current procedures of sperm preservation disrupt redox regulation and cause sperm damage which affects viability, functionality, fertility and potentially the health of the offspring. We are optimistic that this review will promote new ideas for further research to improve sperm preservation technologies, promoting translational research with a wide scope for applicability not only in horses but also in other animal species and humans.