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Background: Women with anovulatory polycystic ovary syndrome (PCOS) are generally insulin-resistant and as a consequence are often treated with the biguanide metformin. Results with metformin have, however, been variable with some studies demonstrating induction of regular cycles and an increase in ovulation, whereas others do not. Hence more understanding is needed regarding the mechanism of metformin's actions in ovarian granulosa cells especially in light of previous demonstrations of direct actions., Objective: The aim of this study was to investigate metformin's interaction with the FSH/cAMP/protein kinase A pathway, which is the primary signaling pathway controlling CYP19A1 (aromatase) expression in the ovary., Methods: The effect of metformin on FSH and forskolin-stimulated aromatase expression in human granulosa cells was measured by quantitative real-time PCR. Activity was assessed after transfection with a promoter II-luciferase construct, and by an RIA measuring conversion of androgen to estrogens. The effect on FSH receptor (FSHR) mRNA was assessed by quantitative PCR. Levels of phosphorylated cAMP response element binding protein (CREB) and CREB-regulated transcription coactivator 2 (CRTC2) were measured by Western blotting and cAMP by a bioluminescent assay., Results: Metformin markedly reduced FSH but not forskolin-stimulated aromatase expression and activity. This effect was exerted by inhibition of basal and ligand-induced up-regulation of FSHR expression. Metformin also reduced FSH-induced phosphorylation of CREB and hence CRE activity, which could potentially disrupt the CREB-CREB-binding protein-CRTC2 coactivator complex that binds to CRE in promoter II of the aromatase gene. This is mediated in an AMP-activated protein kinase-independent manner, and does not involve alteration of cAMP levels., Conclusion: These finding have implications for the use of metformin in the treatment of anovulation in women with PCOS.

Objective: To determine that anti-Müllerian hormone (AMH) has been shown to inhibits E(2) production in rodents and in luteinized granulosa cells (GC). We determined whether this occurs in human cells most highly expressing AMH (i.e., from small antral follicles) and whether this is an effect on aromatase promoter activity. We also investigated the effects of AMH on other factors determining FSH sensitivity., Design: Granulosa cells were exposed to AMH with and without gonadotropins for 48 hours., Setting: University laboratory., Patient(s): Not applicable., Intervention(s): None., Main Outcome Measure(s): Aromatase and FSH receptor messenger RNA expression measured using real time quantitative polymerase chain reaction (PCR). Aromatase promoter II activity measured using a luciferase assay. Estradiol, inhibin A and B, and vascular endothelial growth factor production were measured in the conditioned medium., Result(s): The AMH decreased gonadotropin-stimulated aromatase expression and decreased forskolin-stimulated aromatase in KGN cells and this effect was through a dose-dependent inhibition of promoter II. Surprisingly, AMH also reduced FSH receptor mRNA expression. High AMH doses had no effect on inhibin B, whereas a low dose stimulated production. There was no effect on inhibin A or vascular endothelial growth factor., Conclusion(s): The AMH inhibits factors affecting FSH sensitivity. As AMH levels decrease with follicle growth, this inhibition would be removed. The AMH overproduction in anovulatory polycystic ovaries (PCO) may therefore restrict folliculogenesis by an inhibitory effect on FSH sensitivity, thereby contributing to anovulation., (Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.)

Several studies have now documented the existence of IGFBPs in follicular fluid and their correlation with the health of the follicle. In particular, increased levels of IGFBP-4 have been reported in androgen-dominant atretic follicles and those from polycystic ovaries. The aim of this study was to elucidate the role of IGFBP-4 in ovarian steroidogenesis. Granulosa cells and theca tissue were incubated with or without LH or FSH in the presence or absence of IGFBP-4 (0.5-50 ng/ml). Inhibition by IGFBP-4 of estradiol production in the presence of testosterone alone was seen in three of four experiments. IGFBP-4 completely inhibited FSH-stimulated estradiol production in three experiments and caused 67% inhibition in a fourth. Similar results were obtained for theca, in which concurrent incubation with IGFBP-4 completely negated the stimulatory effects of LH on androstenedione production. The mechanism by which IGFBP-4 exerts these potent effects and the possibility that this may by IGF-independent are currently being investigated.

The underlying cause of anovulation in polycystic ovary syndrome is unknown. Circulating levels of immuno- and bioactive FSH are within the normal range, and the follicles contain measurable levels of bioactive FSH. The aim of this study was to compare estradiol (E2) production in response to FSH by granulosa cells from normal ovaries with those from polycystic ovaries derived from both anovulatory (anovPCO) and ovulatory subjects (ovPCO). Intrafollicular levels of immunoactive FSH, E2, and androstenedione in follicles of less than 12 mm were also measured. Follicular fluid steroid concentrations were obtained from 41 pairs of normal ovaries and 23 pairs of polycystic ovaries (8 anovPCO and 15 ovPCO). In size-matched follicles from each group there were no significant differences in follicular fluid FSH or E2 concentrations, but androstenedione levels were significantly higher in 5- to 11-mm follicles from ovPCO than in corresponding follicles from normal ovaries. Dose responses to FSH were determined in granulosa cells derived from 9 pairs of normal ovaries, 7 anovPCO, and 8 ovPCO. Cells from anovPCO produced 6- to 10-fold more E2 in response to FSH than normal cells, although there was no significant difference in the ED50 values. The response in cells from ovPCO was reduced compared to normal, but this difference did not reach significance. In summary, as judged by their FSH and E2 contents, polycystic ovaries do not have a higher proportion of atretic follicles than normal. Indeed, cells from anovPCO are hyperesponsive to FSH in vitro. This could be explained by stimulation of aromatase in vivo by either paracrine or, more probably, by endocrine factors, of which insulin is an arguable candidate.

The effects of recombinant human follicle stimulating hormone (rFSH; Org 32489) have been examined in human granulosa cells from ovaries obtained from women with spontaneous menses. In the first series of experiments the actions of rFSH on production of oestradiol and progesterone were compared with those of urinary-derived gonadotrophins. Recombinant FSH induced dose-dependent increases in production of both oestradiol and progesterone which were similar to the effects of 'pure' FSH (Metrodin) and the International Standard IS 71/223. In further studies, the actions of rFSH on oestradiol production by individual preovulatory follicles were investigated; rFSH increased oestradiol accumulation from cells obtained from follicles before the luteinizing hormone (LH) surge. In contrast, rFSH inhibited oestradiol production by granulosa cells derived from a follicle after the onset of the LH surge, whereas the gonadotrophic action of growth hormone was maintained. Following preliminary reports of the in-vivo effects of rFSH in women, these findings provide further validation of the efficacy of rFSH in the human ovary. The results of studies of the preovulatory follicle illustrate the experimental importance of the availability of recombinant preparations of pure gonadotrophins, produced by recombinant technology, in the understanding of human ovarian function.

The mechanism of the ovarian dysfunction in polycystic ovary syndrome, the most common cause of anovulatory infertility, remains obscure. Clinical data suggest that follicle stimulating hormone (FSH) action may be inhibited at the ovarian level by paracrine factors derived, presumably, from interstitial cells. The greater responsiveness to FSH of granulosa cells isolated from polycystic ovaries (PCO) compared with that seen in cells derived from normal ovaries, provides some support for this hypothesis and we present data which suggests that epidermal growth factor, or more likely transforming growth factor alpha, could be a candidate for this inhibitor. It should be emphasized, however, that the cardinal biochemical feature of the PCO is hypersecretion of androgens by interstitial cells. Stromal tissue from the PCO will secrete significant quantities of androstenedione in response to LH, whereas there is a negligible response in stroma from normal ovaries. It remains to be determined whether androgens have a direct inhibitory effect on FSH-induced oestradiol production in the human follicle, or whether they might exert an indirect effect by activating inhibitory polypeptide growth factors.

Ten women with clomiphene-resistant chronic anovulation associated with polycystic ovary syndrome were treated with purified urinary FSH (urofollitrophin). The gonadotrophin was given s.c. by pulsatile infusion pump starting at a low dose (1 ampoule or 75 U/d) and increasing by 37.5 U/d at weekly stages in an attempt to induce ovulation of a single follicle. Seventy percent of the 33 cycles were ovulatory and in 18 of these (78%) a single dominant follicle developed and ovulated. Each of the 10 women ovulated when the optimum dose was reached and five of these women became pregnant. The maximum dose of FSH in uni-ovulatory cycles was 150 U/d or less. Endogenous LH concentrations which were raised at the onset of treatment were suppressed in the late follicular phase. The rate of follicular growth and gonadal steroid concentrations were consistent with those observed in spontaneous ovulatory cycles. This study demonstrates that by using low-dose gonadotrophin therapy it is possible to find the 'threshold' dose of FSH to promote maturation of a single dominant follicle. The high rate of ovulation and pregnancy suggest that this approach is of practical importance in treatment of infertile patients with polycystic ovaries.