Interference with the interaction between sperm arylsulfatase A and sulfated carbohydrate chain residues of the zona pellucida effectively suppresses polyspermy during in vitro fertilization of porcine oocytes

The present study investigated the effects of treatments with sulfatase to desulfate the sulfated carbohydrate chain residues of the zona pellucida (ZP) and arylsulfatase A-blocking peptide (ARSA-BP) for the specific masking of sperm ARSA on the interaction of sperm ARSA with ZP, which plays an important role in the in vitro fertilization (IVF) of porcine oocytes. The pretreatment of oocytes with sulfatase for 10 min before the onset of insemination or the addition of 5 ng/mL ARSA-BP to IVF medium significantly reduced the incidence of polyspermy; however, these treatments did not affect sperm penetrability or male pronucleus formation. Combined treatments with sulfatase plus ARSA-BP significantly reduced the incidence of polyspermy to the range of 23-26 % under conditions maintaining a high sperm penetration rate from that of untreated oocytes (56 %). Although the treatments with sulfatase or ARSA-BP alone and sulfatase plus ARSA-BP during IVF did not affect the number of sperm that bound to the ZP or ZP solubility, the incidence of sperm with the acrosome reaction that bound to the ZP was efficiently reduced by the treatment. In oocytes treated with ARSA-BP but not sulfatase, developmental potency to the blastocyst stage was enhanced by decreasing the number of apoptotic blastomeres. Therefore, the present results clearly indicate that interference with the interaction between sperm ARSA and sulfated ZP glycoprotein residues reduced the induction of the acrosome reaction in sperm that bound to the ZP, effectively suppressing polyspermy during porcine IVF.