Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in reproductive-aged women. Its most typical form is the association of hyperandrogenism with chronic anovulation. Theca cells (TC) of large antral and ovulatory follicles are the main source of ovarian androgens and express P450c17α, encoded by Cyp17a1, which converts progesterone to 17α-hydroxyprogesterone and androstenedione. It is known that Cyp17a1 expression in TC from PCOS women is up-regulated by the hypersecretion of LH. However, the pathophysiology of PCOS still remains unclear.
To investigate the regulation of Cyp17a1 by LH in TC, 3-month-old female C57BL/6J mice were treated with PMSG and hCG, and ovaries were collected at 0, 4, 8, 12, 16, 20, 24 and 48h after hCG. TC isolated from 2125-day-old mice were cultured in the RPMI culture medium with or without LH (1, 10, 100 or 1000 ng/ml) and collected at 0, 4, 8, 12, 24 and 48h. To examine the effects of E2, TC were cultured in RPMI with or without LH (100 ng/ml) plus ethanol or E2 (10−9M) and collected 48h later. Total RNA was isolated from ovaries or TC, and real-time RT-PCR was performed.
In vivo, the expression of Cyp17a1, Hsd17b1, and Cyp19 mRNA was reduced at 8h after hCG compared with 0h and it remained decreased through 48h. In contrast, the expression of Cyp17a1 mRNA in TC was increased at 48h after the addition of LH and a dose-dependent response was not shown in vitro. E2 (10−9M) had no effect on an increase of Cyp17a1 expression. These results suggest that Cyp17a1 may be differently regulated between in vivo and in vitro, and the granulosa cells may contribute to the regulation of Cyp17a1 in vivo.