Bahareh Ebrahimi - Department of Physiology, School of Medicine, Shiraz University of Medical Sciences
Sara Keshtgar - Department of Physiology, School of Medicine, Shiraz University of Medical Sciences

Background: Sperm cryopreservation leads to various structural and functional damage which is named cryoinjury. Cryoinjury decreases the viable and motile sperm, increases reactive oxygen species (ROS) production and also damages the mitochondrial membrane. We investigated the effect of Trolox as a well-known antioxidant onmitochondrial membrane potential (MMP) and ROS production after human sperm cryopreservation. Methods: Forty normal human semen samples were randomly divided into fresh and cryopreserved groups. Each group was allocated to control, solvent (DMSO) and Trolox subgroups. Origio Cryosperm was used for cryopreservation of samples in liquid nitrogen at least for one month. Trolox and DMSO were added 30 minutes before assessment in fresh subgroups and just before freezing in cryopreserved subgroups. ROS production and MMP were assessed by chemiluminescence and flowcytometric method using luminol and JC-1. Statistical analysis was performed by SPSS 16 software, using ANOVA and t-test. & nbsp; Results: ROS production in live cryopreservedthawed cells was increased compared to fresh group. This increment is effectively reduced byTrolox. Furthermore, MMP of live cells decreased significantly after cryopreservation. Trolox increased MMP and kept more cells on depolarized state in both fresh and cryopreservedthawed sperm. Conclusion: High levels of ROS can induce more ROS production, which in turn causes more damages to mitochondria. Trolox as a potent cellpermeable antioxidant can relatively protect cryopreserved sperm from cryoinjury and mitochondrial damage. The effects of Trolox on cryopreserved sperm was more potent than fresh sperm, because ROS generation in fresh sperm is significantly lower than freeze-thawed sperm.

Human Sperm, Cryopreservation, Trolox, Mitochondrial Membrane Potential