Objective: To study the damage of mitochondrial function of sperm induced by reactive oxygen species (ROS), and the protection of melatonin (MLT) against the damage.
Methods: Spermatozoa of normal physiological function selected from semen samples by Percoll gradient centrifugation technique were used as normal sperm models in the present study. Reactive oxygen species were generated by hypoxanthine xanthine oxidase system, and in the presence (or absence) of MLT (6 mmol/L), incubated with normal sperm models for 30 and 60 minutes. After incubation, the activity of succinate dehydrogenase (SDH) in mitochondria of spermatozoa was assessed by histochemical method, and spermatozoa were labeled with specific fluorescent probe of Rhodamine 123 to measure mitochondrial membrane potential (MMP) by flow cytometry.
Results: After normal spermatozoa were incubated with ROS, MMP of spermatozoa significantly decreased, and the activity of SDH almost decreased to zero. However, MLT had effect on reducing the damage of the mitochondrial function of sperm induced by ROS.
Conclusion: ROS can damage the mitochondrial function of sperm by affecting MMP of spermatozoa and the activity of SDH. MLT can protect sperm mitochondria from the damage induced by ROS through its effective antioxidative potential.