[Rho/ROCK signaling pathway and anti-cryodamage ability of human sperm].

Objective: To investigate the influence of the Rho/ROCK signaling pathway on the anti-cryodamage ability of human sperm and provide some theoretical evidence for the development of high-efficiency semen cryoprotectants.

METHODS: We collected semen samples from 25 healthy males, each divided into a fresh, a normal cryopreservation control and an Rho-inhibition group. Before and after freezing, we detected sperm motility, viability, membrane integrity, morphology, DNA fragmentation index (DFI), acrosomal enzyme activity (AEA) and mitochondrial membrane potential (MMP) and determined the expressions of RhoA and ROCK proteins in the sperm by immunofluorescence staining.

RESULTS: Compared with the normal cryopreservation control, the frozen-thawed sperm of the Rho-inhibition group showed significantly increased sperm motility （ ［51.20 ± 7.70］% vs ［57.50 ± 6.83］%, P = 0.002), survival rate ( ［52.87 ± 5.07］% vs ［60.24 ± 5.53］%, P = 0.001), membrane integrity (［59.78±5.56］% vs ［67.10 ± 4.43］%, P = 0.001), percentage of morphologically normal sperm (［4.83 ± 1.11］% vs ［7.46 ± 1.28］, P = 0.001) and MMP (56.30 ± 4.28 vs 63.11 ± 2.97, P = 0.001), but decreased DFI (［27.64 ± 6.64］% vs ［18.87 ± 4.07］%, P = 0.001). There was no statistically significant difference in the AEA of the frozen-thawed sperm between the control and Rho-inhibition groups (97.65 ± 9.31 vs 98.30 ± 11.33, P > 0.05). Immunofluorescence staining revealed extensive expressions of RhoA and ROCK proteins in the head and neck of the sperm.

CONCLUSIONS: The Rho/ROCK signaling pathway plays a role in the cryodamage to human sperm, and inhibiting the activity of Rho/ROCK can significantly improve the ability of sperm to resist cryodamage.