Peritoneal fluid modulates the sperm acrosomal exocytosis induced by N-acetylglucosaminyl neoglycoprotein

The effect of peritoneal fluid (PF) on the human sperm acrosome reaction (A R) was tested. Sperm was pre-incubated with PF and the AR was induced by ca lcium ionophore A23187 and a neoglycoprotein bearing N-acetylglycosamine re sidues (NCP). The AR induced by calcium ionophore was inhibited 40% by PF f rom controls (PFc) and 50% by PF from the endometriosis (PFe) group, but no t by PF from infertile patients without endometriosis (PFi). No significant differences were found in the spontaneous AR. When the AR was induced by N GP, pre-incubation with PFc reduced (60%) the percentage of AR, while PFe a nd PFi caused no significant differences. The average rates of acrosome rea ctions obtained in control, NGP- and ionophore-treated sperm showed that NG P-induced exocytosis differed significantly between the PFc (11%) and PFe/P Fi groups (17%), and the ionophore-induced AR was higher for PFi (33%) than PFc/PFe (25%). The incidence of the NGP-induced AR was reduced in the firs t hour of pre-incubation with PFc and remained nearly constant throughout 4 h of incubation. The present data indicate that PF possesses a protective factor which prevents premature AR.