Papel de la cadena mitocondrial de transporte de electrones en el desencadenamiento de la senescencia en el espermatozoide equino

Résumé

Mitochondria are cellular organelles with multiple roles in the spermatozoa, like energy supply, maintenance of membranes integrity, production of reactive oxygen species (ROS) and regulation of cell death. Mitochondria have been proposed as the main source of ROS in human somatic cells and spermatozoa. However, there is not any published data on the production of mitochondrial ROS in equine spermatozoa. In this Doctoral Thesis we studied the role of the mitochondria's electron transport chain (ETC) and oxidative stress as origin of senescence in equine sperm. In order to study that relation, a wide range of specific inhibitors and uncouplers of this organelle have been used. The main consequences were the reduction in sperm motility and velocity, the reduction in ATP production, the reduction of the membrane potential, a negative effect on the spermatozoa-oocyte binding ability and an increase or decrease in the production of ROS. We found that the increase could be a good indication of the presence of active spermatozoa. Also, the inhibition of the ATP-synthase produced a collapse of mitochondrial membrane integrity, suggesting for the first time its importance for the maintenance of the equine sperm membranes. Additionally, we inhibited glycolysis to see its role as producer of energy in equine sperm. Our results showed that OXPHOS is the main energy source of equine sperm, and showed for the first time that glycolysis is also necessary for maintaining sperm velocity.