Influence of sperm cryopreservation on sperm motility and proAKAP4 concentration in mice

Background: The protein proAKAP4 is crucial for sperm motility and has been suggested as an indicator of male fertility. We determined the relationship between proAKAP4 concentration and sperm motility parameters in mice, and investigated the effects of cryopreservation on these variables. Methods: Computer-assisted sperm analysis and ELISA were applied to determine sperm motility and proAKAP4 concentration in fresh and frozen-thawed epididymal sperm of SWISS, B6D2F1, C57BL/6N, and BALB/c mice. Results: ProAKAP4 levels ranged between 12 and 89 ng/ml and did not differ between fresh and frozen-thawed samples, or between strains. We found a negative relationship between proAKAP4 levels and some sperm motility parameters. Sperm traits differed between strains, and cryopreservation negatively affected sperm velocity but not sperm direction parameters. Conclusion: ProAKAP4 levels in epididymal mouse spermatozoa were unaffected by cryopreservation, highlighting the robustness of this parameter as a potentially time-independent marker for sperm motility and fertility. The high individual variation in proAKAP4 levels supports the potential role of proAKAP4 as a marker for sperm quality, though we found no positive, and even negative relationships between proAKAP4 levels and some sperm motility parameters. Future studies have to investigate the significance of proAKAP4 as an indicator for fertility in mice.