Andrology: Effects of platelet activating factor on human sperm function in vitro

The direct effects of platelet activating factor (PAF) and thespecific PAF receptor antagonist, CV-3988, on the fertilizingability of human spermatozoa were investigated. PAF (10^–7–10^–11M) increased the human sperm penetration rates in a sperm penetrationassay at all doses >10^–11 M. In contrast, treatmentof the spermatozoa with 10^–5 CV-3988 caused a significantdecrease in human sperm penetration of zona-free hamster oocytesand adversely affected sperm motility after 24 h of incubation.This suppression was reversed by the addition of PAF. The acrosomereaction was also enhanced by PAF treatment of spermatozoa butthis effect was not observed in calcium-free medium. While 10^–5M CV-3988 decreased the acrosome reaction, the inhibition wasalso reversed by the addition of PAF. These results suggestthat PAF may have a direct role in the fertilizing capacityof human spermatozoa. These findings also suggest that PAF mayhave a clinical application in an in-vitro fertilization programme.