[Apoptosis of sperm induced by murine cytomegalovirus infection and its mechanism regulated by sperm mitochondria: experiment with mice].

Objective: To study the effects of murine cytomegalovirus (MCMV) infection on mature sperm apoptosis in mice, and to explore the mechanism of MCMV-induced apoptosis regulated by mitochondria.

Methods: MCMV was inoculated into the testes of 15 BALB/c mice to establish acute MCMV infection models and 15 mice were used as controls. 1, 2, 4, 6, and 9 days after the infection 3 mice from each group were killed. Flow cytometry was used to observe the apoptosis of sperms. Laser scanning confocal microscopy was performed to examine the mitochondrial membrane potential (delta psi psi m) of sperm. The mitochondria ultrastructure of sperm was observed under electron microscope.

Results: The sperm apoptotic ratebeganto increase from day 2 after inoculation (D2 PI), peaked to the level of (39.3 +/- 1.0)% compared with that of the control group on D4 PI, and then fell-off (F = 362.822, P < 0.05). The delta psi m of sperm began to increase on D1 PI at the level of (74.0 +/- 1.4), began to decrease on D2 PI [( 63.0 +/- 2.2)], dropped to the minimum on D4 PI [(40.2 +/- 2.3)], then ascended slowly again (F = 32.257, P < 0.05). The mitochondria ultrastructure of sperm showed damage after MCMV infection that was especially severe from D2 PI to D6 PI.

Conclusion: MCMV acute infection in reproductive organ induces apoptosis of mature sperm in the cauda epididymidis. Sperm mitochondria participate in and regulate initiatively the apoptosis of sperm.