Could oxidative stress be responsible for poor oocyte competence in women with polycystic ovary syndrome?

Abstract

OBJECTIVE: Circulating reactive oxygen species (ROS) have been reported to induce insulin resistance and hyperandrogenism in women with polycystic ovary syndrome (PCOS). Animal experiments have shown that oxidative stress (OS), induced in vitro, disturbs spindle organization during oocyte meiosis. This study aims to evaluate the effects of follicular fluid (FF) OS on meiotic spindle (MS) formation in oocytes and outcome of in vitro fertilization in PCOS women.DESIGN: Prospective randomized-controlled study at Institute of Reproductive Medicine.MATERIALS AND METHODS: 301 oocytes retrieved from 28 PCOS (Group-A) women and 218 oocytes from 32 age-matched non-PCOS (Group-B) women were analyzed. Long-protocol ovarian stimulation was undertaken and urinary human chorionic gonadotrophin (10,000IU) was used for final oocyte maturation. FF was collected from all follicles above 14mm. 217 FF samples of both groups containing mature oocytes were analyzed for ROS by chemiluminescence (luminometer). All mature oocytes were denuded and observed under Polscope to visualize MS. FF samples of Gr-A were classified as Gr-A1 (oocyte with MS) and Gr-A2 (oocyte without MS). Intracytoplasmic Sperm Injection was performed in all oocytes. After 16-17 hours of injection, pronuclei were scored by revised Z-scoring system. Embryo grading, 48 hours following oocyte retrieval, was done by Veeck's classification. A maximum of 3 embryos were transferred on D2. Gestational sac demonstrated on transvaginal sonography was considered as clinical pregnancy. Statistical comparisons were performed by Student's t-test and Chi Square Test. P<0.05 was considered as statistically significant.RESULTS: The average number of oocytes recovered were significantly (p<0.001) higher in Gr-A (12.08±2.15) compared to Gr-B (6.81±2.16). Oocytes without MS were significantly higher (p<0.001) in Gr-A (3.5±1) than Gr-B (1.62±1.14). In Gr-A, ROS (101.70±19.09) were observed to be significantly (P≤0.001) higher than Gr-B (88.91±25.34). Interestingly, ROS levels were also significantly (p<0.001) less in Gr-A1 (62.37±20.18) compared to Gr-A2 (120.14±17.28). An average of 3.5±0.9 and 3.06±1.06 zygotes (Z1/Z2) were observed in PCO and normal women respectively. However, the number of high-grade embryos was not significantly different (2.9±1.08 and 2.56±1.03). The clinical pregnancy rates were significantly higher (p=0.02) in Gr-B (37.5%) than Gr-A (8.3%).CONCLUSIONS: Higher oxidative stress in FF of PCOS women appears to inhibit MS formation and hence affect embryo quality and pregnancy rates. OBJECTIVE: Circulating reactive oxygen species (ROS) have been reported to induce insulin resistance and hyperandrogenism in women with polycystic ovary syndrome (PCOS). Animal experiments have shown that oxidative stress (OS), induced in vitro, disturbs spindle organization during oocyte meiosis. This study aims to evaluate the effects of follicular fluid (FF) OS on meiotic spindle (MS) formation in oocytes and outcome of in vitro fertilization in PCOS women. DESIGN: Prospective randomized-controlled study at Institute of Reproductive Medicine. MATERIALS AND METHODS: 301 oocytes retrieved from 28 PCOS (Group-A) women and 218 oocytes from 32 age-matched non-PCOS (Group-B) women were analyzed. Long-protocol ovarian stimulation was undertaken and urinary human chorionic gonadotrophin (10,000IU) was used for final oocyte maturation. FF was collected from all follicles above 14mm. 217 FF samples of both groups containing mature oocytes were analyzed for ROS by chemiluminescence (luminometer). All mature oocytes were denuded and observed under Polscope to visualize MS. FF samples of Gr-A were classified as Gr-A1 (oocyte with MS) and Gr-A2 (oocyte without MS). Intracytoplasmic Sperm Injection was performed in all oocytes. After 16-17 hours of injection, pronuclei were scored by revised Z-scoring system. Embryo grading, 48 hours following oocyte retrieval, was done by Veeck's classification. A maximum of 3 embryos were transferred on D2. Gestational sac demonstrated on transvaginal sonography was considered as clinical pregnancy. Statistical comparisons were performed by Student's t-test and Chi Square Test. P<0.05 was considered as statistically significant. RESULTS: The average number of oocytes recovered were significantly (p<0.001) higher in Gr-A (12.08±2.15) compared to Gr-B (6.81±2.16). Oocytes without MS were significantly higher (p<0.001) in Gr-A (3.5±1) than Gr-B (1.62±1.14). In Gr-A, ROS (101.70±19.09) were observed to be significantly (P≤0.001) higher than Gr-B (88.91±25.34). Interestingly, ROS levels were also significantly (p<0.001) less in Gr-A1 (62.37±20.18) compared to Gr-A2 (120.14±17.28). An average of 3.5±0.9 and 3.06±1.06 zygotes (Z1/Z2) were observed in PCO and normal women respectively. However, the number of high-grade embryos was not significantly different (2.9±1.08 and 2.56±1.03). The clinical pregnancy rates were significantly higher (p=0.02) in Gr-B (37.5%) than Gr-A (8.3%). CONCLUSIONS: Higher oxidative stress in FF of PCOS women appears to inhibit MS formation and hence affect embryo quality and pregnancy rates.