Platelet activating factor enhances the acrosome reaction, fertilization in vitro by subzonal sperm injection and resulting embryonic development in the rabbit

This study was conducted to investigate the effect of plateletactivating factor (PAF) on the acrosome reaction and fertilizingcapacity of spermatozoa, and development of the resulting embryosin the rabbit. Rabbit spermatozoa were exposed to PAF, Iyso-PAF,or high ionic strength medium (HIS) prior to subzonal sperminjection (SUZI) into 326 mature oocytes, or morphological assessmentof the acrosome reaction. The rates of fertilization and blastocystformation were compared among the three treatment groups. Acrosomereaction was assessed by fluorescein isothiocyanate-conjugatedPisum sativum agglutinin (FITC–PSA) staining and electronmicroscopy. PAF-treated spermatozoa fertilized the oocytes ata significantly higher rate (56.1%) than did lyso-PAF-(36.8%,P< 0.01) or HIS- (38.2%, P < 0.05) treated spermatozoa.The embryos produced by PAF-treated spermatozoa showed significantlyhigher blastocyst formation rates (34.0%) than lyso-PAF- (8.6%,P < 0.050) or HIS-(8.8%, P< 0.05) treated spermatozoa.FITC-PSA staining demonstrated a significantly higher incidenceof acrosome reaction in PAF-treated spermatozoa (45.8%) thanin Iyso-PAF- (28.0%, P < 0.01) or HIS- (34.9%, P < 0.01)treated spermatozoa. Acrosome reaction of PAF-treated spermatozoawas also confirmed by electron microscopy. PAF treatment ofspermatozoa enhances fertilizing capacity for SUZI possiblyby augmenting the acrosome reaction. Enhanced embryonic developmentwas also found in the oocytes fertilized by SUZI of PAF-treatedspermatozoa.