Lipid profile of the plasma membrane and morphofunctional changes of resistant and sensitive stallion spermatozoa to cryopreservation of semen

Abstract

The freezing process of equine semen enables storing the genetic material from stallions for an unlimited time. However, the semen of some stallions, especially from the breed Mangalarga Marchador has low quality after thawing. Some authors have described that the composition and the proportion of the lipids, that composes the sperm plasma membrane, interfere on the resistance of the sperm cell and damage resulting from cryopreservation. Thus, this study aims to analyze the lipid profile of the sperm plasma membrane from stallions and to ascertain their relationship with their resistance to freezing sperm. Furthermore, it was still aimed to verify the morphofunctional differences in resistant and susceptible sperm to injuries resulting from cryopreservation of stallions. For that, 80 stallions will be used, 40 animals (20 Quarter Horse and 20 Mangalarga Marchador) resistant and 40 stallions (20 Quarter Horse and 20 Mangalarga Marchador) susceptible to sperm plasma membrane damage due to freezing process. The semen will be collected in an artificial vagina and the analysis of sperm kinetic parameters and plasma membrane integrity will be performed before and after freezing. It will be performed computerized analysis of sperm kinetic parameters of fresh and of semen after thawing. After thawing will be evaluated the sperm morphofunctional changes using differential phase microscopy (DIC) and assessment of plasma membrane and acrosomal integrity, DNA fragmentation index, mitochondrial potential, lipid peroxidation, free radical formation, translocation of membrane phospholipids, activated caspase and apoptosis rate by flow cytometry. The lipid profile of the sperm plasma membrane will be performed at different times during the freezing process of semen by mass spectrometry MALTI-TOF and fluoremeter. (AU)