P-28: The Effect of Hydrostatic Pressure on the In vitro Maturation of Preantral Follicles Derived from Polycystic Ovaries in Mouse Model

Background: Polycystic ovary syndrome (PCOS) is a multifactorial, heterogeneous, complex genetic endocrine and metabolic disorder, diagnostically characterized by chronic anovulation, polycystic ovaries and biochemical and clinical manifestations of hyperandrogenism. In patients with PCOS lower apoptotic rates found in granulosa cells compared to women with regular ovulatory cycles and this leads to the arrest of follicle development. Early apoptosis in the cumulus-oocyte complex (cocs) is beneficial for developmental competence of the developing embryo at post fertilization. It has been reported that a well-defined sublethal high hydrostatic pressure treatment offers a solution to improve the overall quality of gametes and embryos, fertilizing ability, and developmental competence. This study, examined the effect of hydrostatic pressure on maturation of ovarian follicles derived from polycystic ovaries in mouse model. Materials and Methods: To induce polycystic ovary phenotype, female NMRI mice 6-8 weeks-old were injected daily with testosterone enantate 1 mg/100g body weight dissolved in sesame oil (experiment group), while control group were injected only with vehicle for 2 weeks. The isolated preantral follicles of both groups were cultured in α-MEM culture medium supplemented with 5% FBS, 100 mIU/ml rFSH (Gonal-f), 10 ng/ml rEGF, under mineral oil for 12 days. On day 12, the size of follicles and oocytes were assessed. Follicles with diameter ≥ 500 µm and good quality have been induced using 5 IU/ml HCG for in vitro maturation. Then follicles from each groups divided to two treatments (treatments I and II). In treatment I, follicles were transferred to pressure chamber and subjected to 20 mmHg pressure for 30 minutes. Follicles without exposure to pressure were considered as treatment II. Follicles from two groups were cultured for 48 hours and the in vitro maturation of oocytes was assessed. Results: Testosterone enantate significantly increased the percentage of cystic follicles and decreased the percentage of preantral and antral follicles in experiment group in comparison to control group (p<0.05). During the in vitro culture, the diameter of cultured isolated preantral follicles and oocytes was increased in two groups. There was no significant difference in growth rate of follicles and oocytes between the experiment and control groups. After 48 hours of in vitro maturation, the percentage of MII oocytes was %37and %20 in treatments I and II, experiment group and %41 and %30 in control group respectively. There was significant differences between the in vitro maturation rates of hydrostatic pressure treated follicles with those of non treated by hydrostatic pressur (p<0.05). Conclusion: These findings suggest that hydrostatic pressure have a positive effect on the in vitro maturation of oocyte in follicles derived from polycystic ovaries. Hydrostatic pressure may play a role in oocyte maturation by improving in releasing and mediating signals to oocyte.