Abstract
ObjectivesIt has been suggested that inhibin secretion is altered in women with the polycystic ovary syndrome (PCOS). However, the contribution of a preceding luteal phase has not been taken into account. The aim of the present study was to investigate whether progesterone in the context of a simulated luteal phase affects basal and FSH-induced inhibin secretion in women with PCOS and elevated LH.MethodsTen women with PCOS and 8 normally cycling women participated in an experimental procedure (Exp) involving the administration of a single injection of recombinant FSH (450 IU sc). In the women with PCOS, the procedure was performed before (Exp 1) and after a 20-day treatment with progesterone (Exp 2), while in the normal women on day 2 of the cycle (Exp 3). Inhibin A and B levels were measured in blood samples taken before and 24 hours after the FSH injection.ResultsBasal LH levels were significantly higher and inhibin A levels were significantly lower in the PCOS group compared to the control group, while inhibin B levels were comparable in the two groups. In the PCOS group, after treatment with progesterone inhibin A and LH but not inhibin B levels decreased significantly (p < 0.05). After the FSH injection, inhibin A and B levels increased significantly in the women with PCOS (Exp 1 and Exp 2) but not in the control women (Exp 3).ConclusionsIn women with PCOS, as compared to control women, the dissimilar pattern of inhibin A and inhibin B secretion in response to FSH appears to be independent of a preceding simulated luteal phase. It is possible that compared to normal ovaries, the PCOS ovaries are less sensitive to endogenous LH regarding inhibin A secretion and more sensitive to exogenous FSH stimulation in terms of inhibin A and inhibin B secretion.
Highlights
Data regarding inhibin levels in the circulation of women with polycystic ovary syndrome (PCOS) are conflicting
Previous experiments investigating the dynamic response of inhibin to a single dose of FSH were performed in PCOS women at a random day or after exclusion of recent ovulation, i.e. at a time far beyond the luteal phase, while in normally cycling women in the early to mid follicular phase [9,12]
It has been shown that exogenous progesterone reduces elevated circulating LH levels in women with PCOS [13], while LH may affect inhibin A secretion in normally cycling women [11]
Summary
Data regarding inhibin levels in the circulation of women with polycystic ovary syndrome (PCOS) are conflicting. Previous experiments investigating the dynamic response of inhibin to a single dose of FSH were performed in PCOS women at a random day or after exclusion of recent ovulation, i.e. at a time far beyond the luteal phase, while in normally cycling women in the early to mid follicular phase [9,12]. It is not known if the above differences in inhibin secretion are related to the lack of progesterone in PCOS due to chronic anovulation. It has been shown that exogenous progesterone reduces elevated circulating LH levels in women with PCOS [13], while LH may affect inhibin A secretion in normally cycling women [11]
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