The mechanism of sperm
- N Inoue, M Ikawa, M. Okabe
- Kanani et al Crescent Journal of Medical and…
Introduction Today, infertility is one of the main problems of human societies that affects about 10%-15% of young couples. According to the definition of the World Health Organization (WHO), infertility means failure to pregnancy within a year among couples who are sexually active and do not use any contraception method (1,2). About 30%-50% of infertility is related to males’ factors that may be due to azoospermia, oligospermia, abnormal sperms in terms of morphology and motility and fertility (3,4). One of the factors that could affect fertility is oxidative stress (5). Oxidative stress is clearly associated with male factor infertility by inducing lipid peroxidation, DNA damage and problem related spermoocyte interaction (2,6). Assisted reproductive technology (ART) is the most common treatment for infertility. In vitro fertilization (IVF) is one of the common methods in ART (2). The membrane fusion of spermatozoon and oocyte cells is the central event of fertilization. Fertilization occurs only in the case of interaction between protein receptors located on the surface of sperm and oocyte that recognizes and binds sperm and oocyte (7,8). The new science of molecular and biology by comparing fertile and infertile men’s surface sperm proteins have identified potential markers of fertility involved in male infertility (9). Several protein receptors involve in the fertilization process. But, clearly 2 proteins have been proven in in-vivo fertility, including IZUMO1 in sperm and Cd9 in the oocyte. Izumo1 is expressed at the plasma membrane of acrosome-reacted sperm (7,9,10). During the acrosomal reaction that is carried out in 3 stages, the protein is moved from the anterior of the sperm head to the site where fusion will take place(9). Men with inadequate IZUMO1 are infertile and even sperms without IZUMO1 are not able to bind to the oocyte (7,11). In fact, infertility of oocytes extracted from the in-vivo after fertilization with sperms without IZUMO1 showed that sperms passed through the zona pellucida (ZP), but accumulated in the perivitelline setting and could not combine and pierce the oocyte membrane (9). These results were shown in an in vitro environment through an IZUMO monoclonal antibody by preventing the sperm-oocyte fussing and were approved. Furthermore, intracytoplasmic sperm injection (ICSI) without IZUMO1 into the normal oocyte was associated with fertility of female mice. These results provide evidence that IZUMO1 is an important factor for fertility (7,12,13). Recently Juno has been identified as IZUMO1 receptor that is known as membrane-tethered folate receptor also known as Folr4. Female mice with Abstract Objective: IZUMO 1 is one of the most important and the most recent known proteins of sperm-oocyte fusion function. The present study aims to investigate the expression of IZUMO1 gene with melatonin injection in in-vitro conditions. Moreover, the sperm-oocyte fusion rate in in vitro fertilization (IVF) condition was examined. Materials and Methods: In this study, 30 female and 45 male mice were divided into control and experimental groups. To investigate Izomo1 gene expression and sperm motility, 10 μM melatonin was added to the culture medium in the experimental group for 1 hour and to examine the fertilization rate 10 μM melatonin was added to culture medium in the experimental group for 1 hour. Then, sperms of the control and experimental groups were added to the oocyte collected and the fertilization was examined on embryo formation. Results: Examinations showed a significant increase in IZUMO1 gene expression and sperm motility in the experimental group (receiving melatonin) compared to the control group. Counting formed embryos showed that 83% of the oocytes have evolved to the fetus. Conclusion: We conclude that melatonin may be a good alternative for rising oocyte fertilization success by sperm in IVF.