Effect of platelet-activating factor on motility and acrosome reaction of human spermatozoa

The effect of platelet-activating factor (PAF) on motility parametersand induction of the acrosome reaction in human spermatozoawas investigated in 36 unselected men with different degreesof initial sperm motility. The characteristics of sperm movementwere assessed by computer-assisted sperm analysis (Hamilton-ThornMotility Analyser) and the percentage of acrosome-reacted spermatozoawas evaluated after 1 h incubation with PAF (10 nM) and stainingwith fluorescent peanut lectin. We found that short-term (4h max) incubation with PAF significantly enhanced total andprogressive sperm motility as well as acrosome reaction. Anincrease of sperm motility in response to PAF was present in16 out of the 25 subjects studied (defined as responders) andwas inversely correlated with basal motility. In the 11 samples(six responders and five non-responders) where the incubationwith PAF was prolonged overnight, an increase of sperm motilitywas present in all the subjects studied. Similarly, an increasein numbers of acrosome reactions in response to 10 nM PAF waspresent in 20 out of the 26 subjects examined, and was inhibitedby the PAF receptor antagonist L659 989. Our results indicatea possible physiological role for PAF in fertilization and suggesta potential use of PAF in in-vitro fertilization techniquesin cases of reduced sperm motility.