[Effect of oxidative stress and apoptosis in granulosa cells on the outcome of IVF-ET]

OBJECTIVE: To examine the association among malondialdehyde (MDA), superoxide dismutase (SOD) and incidence of apoptosis of granulosa cells in follicular fluid with the outcome of in vitro fertilization-embryo transfer (IVF-ET). METHODS: We recruited 51 women undergoing an IVF-ET programme for tubal factor infertility. The women with endometriosis or endocrine diseases and those with male factor infertility were excluded. All the 51 patients underwent a long gonadotropin-releasing hormone (GnRH) agonist protocol for pituitary downregulation followed by controlled ovarian hyperstimulation with rFSH. Granulosa cells were isolated from all aspirated follicular fluid using gradient centrifugation at oocyte retrieval. The level of MDA and the activity of the SOD were measured by the thiobarbituric acid(TBA)and the chemiluminescence method, respectively. The apoptosis was studied by flow cytometry using propidium iodide. RESULTS: Twenty-six out of the 51 patients (51.0%) were pregnant after IVF-ET. Non-pregnant patients showed significantly higher MDA level [(1.7±0.72) nmol/(g × prot) vs. (1.1±0.56) nmol/(g × prot), P<0.05)], higher incidence of apoptosis (24.8%±6.57% vs.19.0%±5.59%, P<0.05) and lower SOD level [(3.5±1.08)×10(3)NU/(g × prot) vs. (4.4±0.99)×10(3)NU/(g × prot), P<0.05)] in the granulose cells and lower good-embryo rate (54.9±20.22% vs. 65.9±16.16%, P<0.05) compared with the pregnant patients. No correlation was detected among SOD and the number of retrieved oocytes, oocyte maturity, embryo quality, fertilization, or cleavage. A significant negative correlation was detected between MDA and fertilization rate (r=-0.425, P=0.002). No significant correlation was detected between MDA and age, the number of retrieved oocytes, oocyte maturity, cleavage, or good-embryo rate. A significant negative correlation was detected between the incidence of apoptosis and the number of retrieved oocytes (r=-0.286, P=0.042), mature oocytes (r=-0.330, P=0.020) and good-embryo rate (r=-0.311, P=0.026). There was significant negative correlation between MDA and SOD levels (r=-0.471, P<0.001); and significant positive correlation between MDA level and incidence of apoptosis (r=0.475, P<0.001). CONCLUSION: Oxidative stress may induce apoptosis in granulose cells and subsequently lower oocyte quality and lead to poor outcome of IVF-ET.