Plasminogen activator inhibitor 1 and Antipain preserve acrosome integrity of bovine spermatozoa during cryopreservation

ABSTRACT Seminal plasma contains serine proteases and serine protease inhibitor, which are involved in mammalian fertilization, and the inhibitors can be applied to prevent cold-induced sperm capacitation. The effects of different concentrations of two serine protease inhibitors were analyzed, Plasminogen activator inhibitor 1 - PAI-1 (70ƞg, 140ƞg and 210 ƞg) and Antipain (10µg, 50µg and 100µg) as supplementation to bovine semen cryopreservation extender. The effects of the inhibitors on the sperm parameters (sperm kinetics - CASA, acrosome integrity, plasma membrane integrity, mitochondrial membrane potential, sperm defects and acrosome reaction rate) were evaluated in the post-thaw semen. Cryopreservation of sperm with Antipain decreased post-thaw kinetic parameters of MP, VSL, LIN, SRT and the percentage of hyper-activated sperm while PAI-1 (210 ƞg) decreased VSL and LIN. Antipain and PAI-1 had no effect on the integrity parameters of the plasma membrane, mitochondrial membrane potential and sperm defects. Sperm cryopreserved in the presence of Antipain and PAI-1 (70 and 140 ƞg) preserved acrosome integrity, as they were able to complete the in vitro acrosome reaction. In conclusion, the serine protease inhibitors, Antipain and PAI-1 (70 and 140ƞg) are able to preserve the acrosome integrity of cryopreserved bovine sperm.