Antihyaluronidase Action of Ellagic Acid Effectively Prevents Polyspermy As a Result of Suppression of the Acrosome Reaction Induced by Sperm-Zona Interaction During In Vitro Fertilization of Porcine Oocytes

Faculty of Agriculture, University of the Ryukyus, Nishihara, Okinawa, Japan.
Journal of Reproduction and Development (Impact Factor: 1.52). 08/2007; 53(4):755-64. DOI: 10.1262/jrd.18173
Source: PubMed


The present study was conducted to examine the effects of three tannin relatives (tannic acid, TA; gallic acid, GA; and ellagic acid, EA) on antihyaluronidase and reactive oxygen species (ROS) scavenging activity, in vitro fertilization (IVF) parameters, and the acrosome reaction (AR) induced by sperm-zona interaction. Among the three tannin relatives, TA and EA showed the strongest potency for blocking the hyaluronidase activity of boar sperm, with concentration-dependent inhibition over the range of 2-10 microg/ml. In contrast, ROSs were effectively scavenged by TA and GA, but not EA. When cumulus-free oocytes were inseminated in IVF medium containing 5 microg/ml of the tannin relatives, polyspermy was significantly reduced by TA and EA (32 and 29%, respectively) compared with oocytes treated with or without GA (51 and 69%, respectively) under conditions that maintained a high sperm penetration rate (P<0.05). Interestingly, induction of the AR by treatment of preincubated sperm with progesterone was blocked by TA and GA as a result of their higher levels of ROS scavenging activity, while EA, which possessed weak ROS scavenging activity, did not disturb induction of the AR with progesterone. However, the incidence of AR induced by sperm-zona interaction was significantly decreased by the strong antihyaluronidase actions of TA and EA compared with that in the absence of these compounds. Treatment with the compounds caused neither a protective proteolytic modification of the zona pellucida matrix before fertilization nor a reduction in acrosomal proteolytic activity or the number of zona-bound sperm. These findings suggest that the antihyaluronidase action of EA effectively prevents polyspermy by suppression of AR functionality induced by sperm-zona interaction and that hyaluronidase intervention is therefore required during porcine IVF.

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    • "It has been suggested that as only sufficiently motile sperm will move towards oocytes at the fertilization site in vivo, mimicking the physical conditions of fertilization in vivo will result in the inhibition of simultaneous penetration. Recently, some anti-hyaluronidase factors prevented polyspermy by repression of the zona pellucida-induced acrosome reaction and regulating the hyaluronidase activity (Tatemoto et al., 2005; Tokeshi et al., 2007). However, difficulties have still been encountered in significantly reducing the risk of polyspermy in porcine IVF conditions, and the development potential of polyspermic zygotes has not yet been fully elucidated. "
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    ABSTRACT: The general method of porcine in vitro fertilization (IVF), involving the co-culture of both gametes in a medium drop, is thought to be the main reason for the high incidence of polyspermy. The aim of this study was to reduce the polyspermic fertilization of porcine embryos during IVF by the modified swim-up method, based on general sperm swim-up technique. Within this design, a 70 microm pore sized cell strainer was used to separate the sperm pellet placed at the bottom of a tube from the mature oocytes placed within the upper region. The separation of gametes using this permeable barrier was to ensure that only motile sperm gained access to the oocytes. It was found that the rate of polyspermy was significantly lowered for the sperm preparations from three boar breeds in modified swim-up method when compared with that of the general microdrop method (p<0.05). However, the penetration rates were found to be similar in both methods for two boar breeds. The average occurrence of blastocysts with more total cell number was higher in the modified swim-up method, while no significant difference in blastocyst rates between the two IVF methods was observed. The frequency of normal diploid embryos was also significantly higher in the modified swim-up method and polyploidy was more frequently observed in microdrop method (p<0.05). Our results demonstrated that the modified swim-up IVF method could reduce polyspermic penetration, and consequently produce better quality and karyotypically normal embryos in porcine IVF.
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    ABSTRACT: Our interest in development of hyaluronidase inhibitors as male antifertility agents led to identification of Terminalia chebula (T. chebula) plant with hyaluronidase (HAase) inhibitory activity of human spermatozoa ( approximately 93% inhibition) and rat caudal epididymal spermatozoa ( approximately 86% inhibition) in vitro at 30 mg/ml. We further demonstrated inhibition of hyaluronidase activity of testis and epididymal spermatozoa in vivo coincident with antispermatogenic activity and contraceptive efficacy of TC extract administered at 50 and 100mg/kg/day orally for 60 days in male albino rats. The significant decrease in motility, count and increase in morphological abnormalities of epididymal spermatozoa and severe reduction in fertility (-100%) of male rats treated with T. chebula fruit extract at 100mg/kg dose could be attributed to either direct effect on testis or direct or indirect interference with sperm maturation in epididymis, and/or inhibition of testicular and epididymal sperm hyaluronidase enzyme in vivo probably caused by flavonoids like tannins present in T. chebula.
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