The effect of platelet activating factor on the motility andacrosome reaction of ram spermatozoa

Platelet activating factor (PAF) is a novel signaling phospholipids that in addition to platelet activationhas many biological properties. The acrosome reaction, as an essential step in mammalian fertilization, can occur in response to several agents such as PAF. Therefore, the present study aimed to assess the effect of PAF on the motility and acrosome reaction of ram spermatozoa. Semen was collected from 18 fertile rams and incubated with four levels of PAF (10-7, 10-8, 10-9 and 10-10 mol) at 37°C for 15, 30, 60 or 120 min. Sperm motility and acrosome reaction were analyzed at varying levels of PAF with different incubation periods. With increasing PAF concentration, acrosome reaction was enhanced, while sperm motility was reduced (P 0.001). As the period of incubation increased, there was a gradual decrease in sperm motility and increase in acrosome reaction percentages. There were high correlation between PAF concentrations and incubation times on induction of acrosome reaction (R2 = 0.86) and reduction in sperm motility (R2 = 0.82). In addition, it was found that a PAF level of 10-9 and incubation time for 30 min is the best optimum for inducing acrosome reaction in ram spermatozoa without drastically decreases in sperm motility. The present study optimized for the first time the concentration and incubation time of PAF for induction of acrosome reaction in fresh ram spermatozoa.