Abstract
Exosomes as bilayer membranous vesicles are abundant in seminal plasma and mediate intercellular communication by transferring active biomolecules. Numerous studies have revealed the involvement of exosomes in regulating various biological properties of spermatozoa. However, the beneficial roles of seminal plasma exosomes in maintaining spermatozoon motility and mitochondrial function during liquid storage have not yet been unexplored in goat. In this study, the reduction of ATP content in goat spermatozoa was detected along with the decrease in spermatozoon motility under liquid storage, and the level of oxidative phosphorylation was also decreased. The interaction of exosomes and spermatozoon mitochondria was observed using high pressure freezing/freeze-substitution in combination with transmission electron microscope. Seminal plasma exosomes of goat were isolated and used to incubate with spermatozoa, and the binding and fusing of exosomes with spermatozoa was further validated. Furthermore, the addition of seminal plasma exosomes exhibited an increase in motility and oxidative phosphorylation in liquid-stored spermatozoa. Several mitochondrial functional parameters, including mitochondrial membrane potential, the levels of mitochondrial ROS and intracellular Ca2+, and the copy number and integrity of mitochondrial DNA, were also improved in spermatozoa after incubating with exosomes. Notably, the level of TFAM protein was increased in exosome-treated spermatozoa, indicating that the enhanced proteins may be delivered by exosomes to spermatozoa. These results suggest that seminal plasma exosomes could improve spermatozoon motility and mitochondrial function by regulating oxidative phosphorylation, which would provide insights into the understanding of protective roles of exosomes in goat spermatozoa during liquid storage.