Abstract
The effect of peritoneal fluid (PF) on the human sperm acrosome reaction (AR) was tested. Sperm was pre-incubated with PF and the AR was induced by calcium ionophore A23187 and a neoglycoprotein bearing N-acetylglycosamine residues (NGP). The AR induced by calcium ionophore was inhibited 40% by PF from controls (PFc) and 50% by PF from the endometriosis (PFe) group, but not by PF from infertile patients without endometriosis (PFi). No significant differences were found in the spontaneous AR. When the AR was induced by NGP, pre-incubation with PFc reduced (60%) the percentage of AR, while PFe and PFi caused no significant differences. The average rates of acrosome reactions obtained in control. NGP- and ionophore-treated sperm showed that NGP-induced exocytosis differed significantly between the PFc (11%) and PFe/PFi 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 first 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.
Highlights
Mammalian sperm must undergo a specialized exocytotic event, the acrosome reaction (AR), to fertilize the oocyte
The average rates of acrosome reactions obtained in control, NGP- and ionophoretreated sperm showed that NGP-induced exocytosis differed significantly between the PF from controls (PFc) (11%) and PF from the endometriosis (PFe)/PFi groups (17%), and the ionophore-induced AR was higher for PFi (33%) than PFc/PFe (25%)
Human sperm acrosomal exocytosis was induced with NGP and calcium ionophore after pre-incubation with peritoneal fluid from infertile women with (PFe) and without endometriosis (PFi)
Summary
Mammalian sperm must undergo a specialized exocytotic event, the acrosome reaction (AR), to fertilize the oocyte. Sperm-egg binding involves lectinlike proteins on the sperm surface that recognize specific glycans of the zona pellucida [3], and multiple carbohydrates appear to be involved in human sperm-zona pellucida binding [4]. Binding sites for mannose and N-acetylglucosamine have been proposed to play an important role in human fertilization. They are involved in the induction of AR by N-acetylglucosamine- and mannose-containing neoglycoproteins (NGP) [5,6,7] and are related to the fertilizing potential of spermatozoa [8,9,10]. The stimulation of human sperm AR by neoglycoproteins is strongly correlated with the rate of fertilization in vitro [9,10], and may be used to predict fertilization success
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