Polycystic ovary syndrome: anomalies in progesterone production

The underlying cause of anovulation and miscarriage in polycystic ovary syndrome (PCOS) is unknown. Progesterone may play an important role in oocyte fertilization and embryo implantation. Therefore, in this study we analyse the endocrine function of luteinizing granulosa cells to synthesize progesterone in vivo and in vitro in PCOS and normal patients participating in an in-vitro fertilization programme. Human luteinizing granulosa cells were obtained from 10 patients with normal ovaries (controls) and 10 patients with PCOS by follicular aspiration of individual follicles of each patient and pooled in an attempt to obtain three groups: cells from follicle sizes < or =10,>10< or =15 and > or =16. Serum concentrations of oestradiol and progesterone on the day of human chorionic gonadotrophin (HCG) injection were significantly higher (P < 0.01 and P < 0.05) in PCOS patients than in controls. After HCG stimulation, in-vitro progesterone production was enhanced in granulosa cells of the control group and concentrations increased with follicular size as expected. However, the concentration of progesterone of PCOS patients did not increase with follicular size and there was a significant difference between normal and PCOS groups in follicles >10< or =15 mm (P < 0.05) and > or =16 mm (P < 0.01). Oestradiol production was increased in follicles > or =16 mm in both groups, although this did not reach significance. In summary, it seems that PCOS granulosa cells demonstrate an abnormal capacity to synthesize progesterone in vivo and in vitro. The understanding of granulosa cell function in PCOS may explain the anovulation and miscarriage that occurs in these patients.