Follicle-stimulating hormone suppressed excessive production of antimullerian hormone caused by abnormally enhanced promoter activity in polycystic ovary syndrome granulosa cells

AOP key event relationship report: Linking decreased androgen receptor activation with decreased granulosa cell proliferation of gonadotropin-independent follicles

We recently proposed to formally recognize Key Event Relationships (KERs) as building blocks of Adverse Outcome Pathways (AOPs) that can be independently developed and peer-reviewed. Here, we follow this approach and provide an independent KER from AOP345, which describes androgen receptor (AR) antagonism leading to decreased female fertility. This KER connects AR antagonism to reduced granulosa cell proliferation of gonadotropin-independent follicles (KER2273). We have developed both the KER and the two adjacent Key Events (KEs). A systematic approach was used to ensure that all relevant supporting evidence for KER2273 was retrieved. Supporting evidence for the KER highlights the importance of AR action during the early stages of follicular development. Both biological plausibility and empirical evidence are presented, with the latter also assessed for quality. We believe that tackling isolated KERs instead of whole AOPs will accelerate the AOP development. Faster AOP development will lead to the development of simple test methods that will aid screening of chemicals, endocrine disruptor identification, risk assessment, and subsequent regulation.

Serum testosterone levels are positively associated with serum anti-mullerian hormone levels in infertile women

Anti-Mullerian hormone (AMH) and testosterone (T) both play distinct roles in the early stages of folliculogenesis. However, the relationship between serum T and AMH levels is poorly understood. This study aimed to investigate the association between serum T and AMH levels in infertile women. A total of 1935 infertile women aged 20-46 years were included in the cross-sectional study and divided into four quartile groups (Q1 to Q4) based on serum T levels. Compared to the subjects in the highest T quartile (Q4), those in the lowest T quartile (Q1) showed significantly lower AMH levels. After adjustment for age, body weight, body mass index and FSH, increasing T quartile categories were associated with higher AMH levels. Binary logistic regression analyses revealed that the odds for the risk of diminished ovarian reserve (DOR) were 11.44-fold higher in Q1 than in Q4 and the odds for the risk of excess ovarian reserve (EOR) were 10.41-fold higher in Q4 than in Q1. Our data show that serum T levels are positively associated with serum AMH levels and suggest that androgen insufficiency may be a potential risk factor for DOR; androgen excess may lead to EOR in infertile women.

Promoter Identification and Transcriptional Regulation of the Goose AMH Gene

Simple Summary

Anti-Müllerian hormone (AMH) plays a vital role in the development of follicles. We found that the cloning nucleotide sequence of AMH was high homology in geese with other species. Several regulatory elements were identified and transcriptional factors were predicted in the AMH promoter sequence. Through a double-luciferase reporter assay, potential regulatory relationship spanning from −637 to −87 bp were identified. In addition, the mRNA expression of AMH gradually decreased during the development of follicles in geese. In the Chinese hamster ovary (CHO) cell line, the luciferase activity significantly increased by co-expression of AMH and GATA-4. However, when the binding sites of GATA-4 to the promoter of AMH were mutated, the luciferase activity significantly decreased. These results indicated that the transcription of AMH was activated by GATA-4 to inhibit the development of follicles in geese.

Abstract

Anti-Müllerian hormone (AMH) is recognized as a reliable marker of ovarian reserve. However, the regulatory mechanism of goose AMH gene remains poorly understood. In the present study, both the full-length coding sequence (CDS) and promoter sequence of goose AMH have been cloned. Its CDS consisted of 2013 nucleotides encoding 670 amino acids and the amino acid sequence contained two structural domain: AMH-N and transforming growth factor beta (TGF-β) domain. The obtained promoter sequence spanned from the −2386 bp to its transcription start site (ATG). Core promoter regions and regulatory elements were identified as well as transcription factors were predicted in its promoter sequence. The luciferase activity was the highest spanning from the −331 to −1 bp by constructing deletion promoter reporter vectors. In CHO cells, the luciferase activity significantly increased by co-expression of AMH and GATA binding protein 4 (GATA-4), while that significantly decreased by mutating the binding sites of GATA-4 located in the −778 and −1477 bp. Results from quantitative real-time polymerase chain reaction (qPCR) indicated that levels of AMH mRNA in geese granulosa layers decreased gradually with the increasing follicular diameter. Taken together, it could be concluded that the transcriptional activity of AMH was activated by GATA-4 to inhibit the development of small follicles in goose.

Interactions between androgens, FSH, anti-Müllerian hormone and estradiol during folliculogenesis in the human normal and polycystic ovary

BACKGROUND

Androgens, FSH, anti-Müllerian hormone (AMH) and estradiol (E2) are essential in human ovarian folliculogenesis. However, the interactions between these four players is not fully understood.

OBJECTIVES AND RATIONALE

The purpose of this review is to highlight the chronological sequence of the appearance and function of androgens, FSH, AMH and E2 and to discuss controversies in the relationship between FSH and AMH. A better understanding of this interaction could supplement our current knowledge about the pathophysiology of the polycystic ovary syndrome (PCOS).

SEARCH METHODS

A literature review was performed using the following search terms: androgens, FSH, FSH receptor, anti-Mullerian hormone, AMHRII, estradiol, follicle, ovary, PCOS, aromatase, granulosa cell, oocyte. The time period searched was 1980-2015 and the databases interrogated were PubMed and Web of Science.

OUTCOMES

During the pre-antral ('gonadotropin-independent') follicle growth, FSH is already active and promotes follicle growth in synergy with theca cell-derived androgens. Conversely, AMH is inhibitory by counteracting FSH. We challenge the hypothesis that AMH is regulated by androgens and propose rather an indirect effect through an androgen-dependent amplification of FSH action on granulosa cells (GCs) from small growing follicles. This hypothesis implies that FSH stimulates AMH expression. During the antral ('gonadotropin-dependent') follicle growth, E2 production results from FSH-dependent activation of aromatase. Conversely, AMH is inhibitory but the decline of its expression, amplified by E2, allows full expression of aromatase, characteristic of the large antral follicles. We propose a theoretical scheme made up of two triangles that follow each other chronologically. In PCOS, pre-antral follicle growth is excessive (triangle 1) because of intrinsic androgen excess that renders GCs hypersensitive to FSH, with consequently excessive AMH expression. Antral follicle growth and differentiation are disturbed (triangle 2) because of the abnormally persisting inhibition of FSH effects by AMH that blocks aromatase. Beside anovulation, this scenario may also serve to explain the higher receptiveness to gonadotropin therapy and the increased risk of ovarian hyperstimulation syndrome (OHSS) in patients with PCOS.

WIDER IMPLICATIONS

Within GCs, the balance between FSH and AMH effects is pivotal in the shift from androgen- to oestrogen-driven follicles. Our two triangles hypothesis, based on updated data from the literature, offers a pedagogic template for the understanding of folliculogenesis in the normal and polycystic ovary. It opens new avenues for the treatment of anovulation due to PCOS.

Is the suppressive effect of cyproterone acetate on serum anti-Müllerian-hormone levels in women with polycystic ovary syndrome stronger than under oral contraceptive pill?

OBJECTIVE

To compare the suppressive effect of anti-androgen therapy by cyproterone acetate (CPA) and by oral contraceptive pill (OCP) on anti-müllerian hormone (AMH) levels in women with polycystic ovary syndrome (PCOS) in order to detect a putative direct anti-androgen effect on AMH excess.

METHODS

This is a prospective longitudinal study including 58 women with PCOS between January 2010 and April 2014 at the Lille University Hospital. A total of 47 women with clinical hyperandrogenism were treated by CPA (50 mg/d was administered 20 days out of 28) and 11 women with PCOS but without clinical hyperandrogenism received OCP.

RESULT(S)

Serum AHM levels at baseline were similar in CPA and OCP groups (median [5-95th percentiles]: 60.4 pmol/l [25.1-200.2] versus 58 pmol/l [27.6-100], respectively, p = 0.39). After 3 months of treatment, serum AMH levels decreased significantly by 28% ± 20% and by 22% ± 27% in CPA and OCP groups, respectively. The decrease under both treatments was similar (p = 0.48).

CONCLUSION(S)

That any anti-androgen effect could be observed on AMH in our CPA group in addition to the gonadotropin-suppressing effect suggests that either androgens are not involved in AMH regulation or that they act by interfering with gonadotropin effects on granulosa cells.

Lack of Serum anti-Mullerian hormone responses after recombinant human chorionic gonadotropin stimulation in women with polycystic ovary syndrome

CONTEXT

Polycystic ovary syndrome (PCOS) is an anovulatory disorder characterized by excess androgen production and increased LH secretion. Serum anti-Mullerian hormone (AMH) is also elevated in this disorder. Women with PCOS exhibit a positive correlation between AMH and LH levels and recent in vitro data demonstrate that LH can directly stimulate AMH production by granulosa cells from women with PCOS.

OBJECTIVE

The objective of the study was to directly test whether LH increases AMH production in women with PCOS in vivo by assessing responses after recombinant human chorionic gonadotropin (r-hCG) stimulation.

DESIGN

This was a prospective study.

SETTING

The study was conducted at a research center at an academic medical center.

PARTICIPANTS

Women with PCOS (n = 28) and normal controls (n = 29) participated in the study.

INTERVENTIONS

Blood samples were obtained before and 24 hours after iv administration of 25 μg r-hCG.

MAIN OUTCOME MEASURES

Basal and stimulated serum AMH, androstenedione, T, and 17-hydroxyprogesterone levels were measured.

RESULTS

Baseline AMH levels in women with PCOS were greater than in normal controls and correlated with levels of LH as well as androstenedione, T, and 17-hydroxyprogesterone. A rise of serum AMH levels was not observed after r-hCG administration in women with PCOS or normal ovaries.

CONCLUSION

These findings are in contrast to in vitro evidence demonstrating that AMH secretion by granulosa cells of PCOS women in response to LH stimulation and suggest AMH regulation in vivo is complex and that the elevated serum AMH in women with PCOS is not a direct effect of the excess LH production characteristic of PCOS.

Relationship between 17-hydroxyprogesterone responses to human chorionic gonadotropin and markers of ovarian follicle morphology in women with polycystic ovary syndrome

CONTEXT

Women with polycystic ovary syndrome (PCOS) have increased 17-hydroxyprogesterone (17-OHP) responses to gonadotropin stimulation although individual variability is substantial, as reflected by exaggerated as well as normal responses. The relationship between 17-OHP responses to gonadotropin stimulation and markers of ovarian function has not been assessed.

OBJECTIVE

To determine whether 17-OHP responses are associated with antral follicle count (AFC), anti-Mullerian hormone (AMH), or inhibin B (Inh B) levels in PCOS and normal women.

DESIGN

Prospective study.

SETTING

Research center at an academic medical center.

PARTICIPANTS

Women with PCOS (n = 18) and normal controls (n = 18).

INTERVENTIONS

Blood samples were obtained before and 24 hours after administration of 25 μg recombinant-human chorionic gonadotropin. Ovarian imaging was conducted with three-dimensional pelvic ultrasound.

MAIN OUTCOME MEASURES

Basal and stimulated levels of 17-OHP, androgens, estrogen, AMH, Inh B, and AFC.

RESULTS

In women with PCOS, 17-OHP responses were heterogeneous and inversely correlated with AMH and Inh B levels, but not AFC. In a subgroup of PCOS women with exaggerated 17-OHP responses, AMH levels were equivalent to that of normal women. In PCOS women with normal 17-OHP responses, AMH levels were markedly elevated.

CONCLUSION

Based on heterogeneous 17-OHP responses to human chorionic gonadotropin in women with PCOS, AMH levels are inversely linked to ovarian androgen production while positively correlated with AFC. These findings suggest that in PCOS, AMH production may reflect redistribution of the follicle population or regulation by intraovarian mechanisms.

[What's new in 2014 about anti-Müllerian hormone?]

The existence of the anti-Müllerian hormone (AMH) has been postulated by Professor Alfred Jost to explain the regression of the Müllerian ducts during male sexual differentiation. Since then, AMH has been purified, its gene and specific receptor, AMHR-II have been cloned. Further, the signaling pathways were identified and it has been observed that AMH was produced by the granulosa cells of growing follicles. From the 2000s, unexpected roles of AMH have been highlighted, reactivating international research on this hormone. It is now well established that AMH plays a key role in the follicular recruitment and development. Over the past years, serum AMH measurements have been proposed as a marker of the follicular ovarian status, and a predictor of assisted reproductive cycles. AMH is also useful to assess the effectiveness of treatment of some gynecological tumors. This article is a review of the past five years advances on the regulation of the expression of AMH and its specific receptor AMHR-II in female.

Association between serum anti-Müllerian hormone level and ovarian response to mild stimulation in normoovulatory women and anovulatory women with polycystic ovary syndrome

OBJECTIVE

To evaluate the correlation between serum levels of anti-Müllerian hormone (AMH) and ovarian response to mild stimulation in normoovulatory women and anovulatory women with polycystic ovary syndrome (PCOS).

METHODS

Seventy-four cycles of mild stimulation (clomiphene citrate+gonadotropin followed by timed intercourse or intrauterine insemination) performed in normoovulatory women (57 cycles) and anovulatory women with PCOS (17 cycles). Ovarian sensitivity was defined by the number of mature follicles (≥14 mm) on triggering day per 100 IU of gonadotropin. A correlation between ovarian sensitivity and the baseline serum AMH level (absolute or multiples of the median [MoM] value for each corresponding age) was calculated. Correlation between ovarian response and serum AMH level was evaluated.

RESULTS

Ovarian sensitivity to mild stimulation was positively correlated with absolute serum AMH (r=0.535, p<0.001) or AMH-MoM value (r=0.390, p=0.003) in normoovulatory women, but this correlation was not observed in anovulatory women with PCOS (r=0.105, p>0.05, r=-0.265, p>0.05, respectively).

CONCLUSION

Ovarian response to mild stimulation is possibly predicted by the serum AMH level in normoovulatory women, but not in anovulatory women with PCOS.

Polycystic ovary syndrome (PCOS)-like phenotypes in the d-galactose-induced aging mouse model

The D-galactose (D-gal)-induced animal model, which is established by consecutive subcutaneous d-gal injections for approximately 6weeks, has been frequently used for aging research. This animal model has been shown to accelerate aging of the brain, kidneys, liver, and blood cells. However, aging of the female reproductive organs in this animal model has not been reported. The aim of this study was to investigate changes in the ovary in the d-gal-induced aging mouse model. First, we evaluated anti-Müllerian hormone (AMH) as a marker of ovarian aging in blood plasma. We speculated there would be lower AMH levels in d-gal-treated mice because ovarian aging would be induced by d-gal, as reported for other tissues. However, the results showed that AMH levels in d-gal-treated mice were approximately four-fold higher than control mice. Abnormally high AMH levels are detected in ovarian cancer and polycystic ovary syndrome (PCOS) patients. Therefore, we examined PCOS-related markers in this mouse model. Total testosterone levels were high and abnormal estrous cycles were induced in d-gal-treated mice. These changes, including AMH levels, in d-gal-treated mice were inhibited by aminoguanidine treatment, an advanced glycation end product reducer. In addition, ovarian cysts were observed in some d-gal-treated mice. These results indicate that with respect to female reproduction, d-gal-treated mice are suitable for PCOS studies, rather than aging studies.

Different diagnostic power of anti-Mullerian hormone in evaluating women with polycystic ovaries with and without hyperandrogenism

PURPOSE

The aim of this study is to compare the secretory profiles and diagnostic power of anti-Mullerian hormone (AMH) for the PCOS patient with and without hyperandrogenism.

METHODS

One hundred and thirty-one PCOS patients with oligomenorrhea or amenorrhea were recruited into the study. Sixty-two and sixty-nine patients had and did not have hyperandrogenism (HA+) hyperandrogenism (HA-), respectively. Sera were collected for determining the levels of AMH, basal sexual hormones, glucose and lipid metabolic indicators.

RESULTS

The AMH serum levels of PCOS patients were significantly higher than the control group, with the highest AMH serum level in the HA+ group. The cut-off value for predicting PCOS patients of all types was 3.92 ng/mL, with a sensitivity of 65 %, and specificity of 62 %. The cut-off value for predicting PCOS patients in the HA+ group was 4.23 ng/mL, with a sensitivity of 82 %, and specificity of 64 %. The cut-off value for predicting PCOS patients in the HA- group was 3.76 ng/mL, with a sensitivity of 64 %, and specificity of 62 %. In the HA+ group, AMH was negatively associated with FSH and positively associated with LH. In the HA- group, AMH was negatively associated with HDL and positively associated with BMI, fasting glucose and LDL.

CONCLUSIONS

AMH is only suitable for predicting the PCOS patients with hyperandrogenism. The diagnostic power of AMH is limited when used to predict patients without hyperandrogenism. It reflects the differences in pathophysiology and severity of disrupted folliculogenesis between the two subtypes.