Anti-Müllerian hormone attenuates the effects of FSH on follicle development in the mouse ovary

An endocrinological perspective on polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a complex endocrinological disorder that involves dysfunctions across multiple endocrine axes, including the hypothalamic-pituitary-gonadal (HPG), hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-thyroid (HPT) axes. Our review focuses on understanding the pathophysiology of PCOS through an endocrinological perspective, emphasizing the complex interactions between multiple endocrine axes. We have discussed the roles of the HPG, HPA, and HPT axes in PCOS. Dysregulation of the HPG axis, particularly the altered gonadotropin-releasing hormone pulse frequency resulting in elevated ratio of luteinizing hormone to follicle stimulating hormone, is central to the hyperandrogenism and anovulation, observed in PCOS. We have further highlighted the contributions of the HPA and HPT axes, where elevated adrenal androgen levels and hypothyroidism intensifies the phenotypes of PCOS. Additionally, insulin resistance and hyperinsulinemia, commonly associated with PCOS, aggravates hormonal disturbances and heighten the risk of metabolic complications such as type 2 diabetes and cardiovascular diseases. Elevated levels of anti-Müllerian hormone have also been emphasized as a key factor in inhibiting follicular growth, leading to impaired ovarian function and hyperandrogenism. This review further supports that PCOS is a multifactorial condition involving complex feedback mechanisms between the endocrine, metabolic, and reproductive systems. Furthermore, there remains a huge scope for deciphering the precise molecular interactions between the HPG, HPA, and HPT axes in PCOS, which could pave the way for targeted therapies for better management of both the endocrine and metabolic aspects of this disorder. This review will benefit researchers to get an endocrine perspective on PCOS.

Anti-mullerian hormone in felids: A systematic review

Anti-Müllerian hormone (AMH) is a dimeric glycoprotein that belongs to the transforming growth factor-β (TGF-β) superfamily. This hormone that is produced by gonadal Sertoli cells in males and granulosa cells in females has been extensively studied in humans, rodents, and livestock species. Research on AMH in felids began in 2011 and given the increasing number of studies over recent years, an updated literature review is necessary to clarify and organize future research directions. The objective of this article was to conduct a systematic review of AMH in domestic and wild felids. From a literature search of international publications, 23 were selected for inclusion. AMH determinations were performed using commercial enzyme-linked immunosorbent assays (ELISA) and electrochemiluminescence immunoassays (EQLIA). In female felids, AMH concentrations decrease with age, along with follicular reserve diminution. AMH can also be used to diagnose granulosa cell ovarian tumors and cryptorchidism in females and males, respectively. This hormone serves as a marker for reproductive status and can reflect gonadal function in both genders. Furthermore, AMH may prove to be a valuable predictive tool for reproductive biotechnologies in both domestic and wild felids. Several aspects of this hormone still remain to be elucidated, including its variations throughout the estrous cycle and the effect of photoperiod. Finally, standardization of assays and the establishment of reference ranges for both domestic and wild animals are necessary for widespread clinical application and future research development.

A blocking antibody against anti-Müllerian hormone restores ovulation and normal androgen levels in a spontaneous rat model of polycystic ovary syndrome

BACKGROUND

Polycystic Ovary Syndrome (PCOS), the leading cause of infertility worldwide, is characterised by oligo-anovulation, hyperandrogenism, polycystic ovarian morphology and high Anti-Müllerian hormone (AMH) levels, associated with severe metabolic disturbances. However, the role of AMH in the physiopathology of this syndrome remains poorly understood and strategies to block its effects have never been investigated in animal models of PCOS.

METHODS

We used Western-blotting, ELISA and gene reporter approaches to evaluate the blocking efficacy, interspecificity and mechanism of action of an antibody against human AMH, Mab22A2. Then, we investigated the ability of a rat version of Mab22A2, rMab22A2, to alleviate reproductive dysfunction in Goto-Kakizaki (GK) rats, which spontaneously exhibit all the features of women with PCOS.

FINDINGS

We showed that Mab22A2 was interspecific, did not prevent AMH from binding to its receptor and was able to block the effects of AMH in gonadal cell lines. In addition, treatment of anovulatory GK rats with rMab22A2 reduced their bioavailable serum AMH levels and normalised their androgen concentrations. Finally, this treatment also induced ovulation in 84% of the rats and resulted in 66% of pregnancies.

INTERPRETATION

Our results show that AMH is a major driver of reproductive and hormonal dysfunction in PCOS and provide proof of concept that a blocking antibody against AMH can reverse the major reproductive dysfunction observed in PCOS, opening up promising avenues for the treatment of patients with PCOS.

FUNDING

Inserm, Sorbonne University, Inserm Transfert, the French Endocrine Society and the Medical Research Foundation (grant agreement n°EQU201903007868).

Anti-Mullerian hormone (AMH) protects ovarian follicle loss by downregulating granulosa cell function in in vitro and in vivo models

PURPOSE

AMH inhibits hormone production in luteinized granulosa cells (GCs) and stalls ovarian follicle development in vitro and in vivo. We sought to confirm AMH's mechanism of action through SMAD activation and investigate AMH inhibition of follicle development and function, in vitro and in vivo.

METHODS

A primary culture of GCs isolated from follicular fluid was used, and cells were treated with recombinant AMH (rAMH) or placebo for 24 h. For the mouse model, 18-weeks old C57BL female mice were either euthanized at the beginning or treated with rAMH or normal saline for 3 weeks. Primordial (PDF), primary follicle (PRF), secondary (SEF), and tertiary follicles (TEF) were calculated. Real-time RT-PCR and ELISA were performed to quantify GC gene expression and protein translation of human SMAD 1, 5, and 8, FSH-R and mouse FSH-R, inhibin B, caspase 3, Ki67, BMP15, GDF9, and the epigenetic regulators miRNAa and b.

RESULTS

In vitro, rAMH-treated GC showed activation of the SMAD 1, 5 and downregulation of SMAD 8, with greater magnitude at increasing rAMH doses (p < 0.04) and consequential control of downstream regulators. In vivo, the rAMH-treated mice showed increased SEFs and decreased PRFs while PDFs, TEFs, were unchanged compared with baseline. Compared with Placebo, the rAMH group showed increased PDFs, while PRFs, and TEFs were significantly decreased, and SEFs were unchanged.

CONCLUSIONS

AMH caused SMAD activation in a dose-dependent manner, with downstream downregulation of cell function and replication, also through activation of miRNAs. These mechanisms were confirmed by the in vivo findings with ultimate downregulation of follicular development and preservation of the ovarian follicle number. Counteracting follicular depletion, AMH could be used to protect the ovarian follicle reservoir.

Impact of female age on concentrations of reproductive hormones and oocyte-specific growth factors in follicular fluid from human small antral follicles

STUDY QUESTION

Does maternal age impact hormonal secretions from granulosa cells, theca cells, and the oocyte in human small antral follicles?

SUMMARY ANSWER

Major hormones secreted by granulosa and theca cells, as well as the oocyte-specific TGF-β members-GDF9, BMP15, and the GDF9/BMP15 heterodimer cumulin-maintain a consistent concentration within the follicular fluid of human small antral follicles, regardless of maternal age.

WHAT IS KNOWN ALREADY

It is well established that female fertility declines with increasing age. However, it is not known whether this decline is exclusively due to a reduction in oocyte quality and quantity or also involves a decline in the hormone-secreting capabilities of granulosa cells, theca cells, and the oocyte itself.

STUDY DESIGN, SIZE, DURATION

This is a retrospective study of follicular fluid obtained from human small antral follicles collected in connection with cryopreservation of ovarian tissue at the Laboratory of Reproductive Biology, University Hospital Copenhagen, Rigshospitalet, Denmark, between 2010 and 2020 as part of the hospital's fertility preservation program.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Follicular fluid samples from human small antral follicles measuring 3-13 mm in diameter from macroscopically normal ovaries of 381 patients aged 5-43 years were included in the study, provided that at least one of the following parameters was measured: AMH, Inhibin A, Inhibin B, oestradiol (E2), progesterone (P4), androstenedione, testosterone, and/or the oocyte-specific TGF-β members GDF9, BMP15, or cumulin.

MAIN RESULTS AND THE ROLE OF CHANCE

In a linear regression analysis adjusted for follicular volume, female age did not predict the follicular fluid concentrations of AMH, Inhibin B, Inhibin A, E2, androstenedione, testosterone, GDF9, BMP15, or cumulin. Although a significant association was observed between female age and follicular fluid P4 levels, the predictive value of age was poor, accounting for at most 5% of the variation in P4.

LIMITATIONS, REASONS FOR CAUTION

Hormonal levels may vary with the degree of atresia in each follicle; however, the health status of the small antral follicles in this study was not characterized. Additionally, we cannot exclude possible age-related differences in human follicles larger than 10 mm, as very few of these were included. Furthermore, we did not include women above the age of 43, despite the potential for more pronounced age-related effects in these patients.

WIDER IMPLICATIONS OF THE FINDINGS

Our results support the idea that the age-related decline in female fertility is primarily due to a reduction in oocyte quality and quantity, but further research is needed to confirm this.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was obtained, and the authors have no conflicts of interest to declare in relation to this work.

TRIAL REGISTRATION NUMBER

N/A.

Ovarian stimulation by promoting basal follicular growth

BACKGROUND

Most methods of ovarian stimulation rely on gonadotropin modulation. However, abnormal anti-Müllerian hormone concentrations are frequent in infertility, suggesting that defects in the gonadotropin-independent period of folliculogenesis preceding cyclic recruitment (i.e., basal follicular growth) may often occur. We need to better understand basal follicular growth and determine how to improve it.

METHODS

Section I summarizes a literature search concerning preantral and early antral folliculogenesis, cyclic recruitment, and selection. Section II presents current knowledge about interventions involving early antral folliculogenesis and cyclic recruitment.

RESULTS

While folliculogenesis following cyclic recruitment is gonadotropin-dependent, basal follicular growth is not. Basal follicular growth is regulated by follicle-stimulating hormone and local communication between the oocyte and its granulosa and thecal cells involving gap junctions and many autocrine/paracrine factors. This local communication sustains growth synergistically with follicle-stimulating hormone, but also suppresses this hormone to induce granulosa cell differentiation. As a follicle develops, its responsiveness to gonadotropin progressively increases. Section II describes 4 interventions affecting early antral folliculogenesis, including granulocyte colony-stimulating factor priming, bromocriptine rebound, carbohydrate metabolism intervention, and danazol priming, which have improved embryo development and live birth rate in patients with previous failures.

CONCLUSION

Basal follicular growth modulation can increase live birth rates.

Physiopathology of polycystic ovary syndrome in endocrinology, metabolism and inflammation

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder characterized by elevated androgen levels, ovarian cysts, and impaired ovulation in females. This condition is closely linked with various reproductive health issues and has significant impacts on endocrine and metabolic pathways. Patients with PCOS commonly exhibit hyperandrogenaemia and insulin resistance, leading to complications such as acne, hirsutism, weight fluctuations, and metabolic disturbances, as well as an increased risk for type 2 diabetes, cardiovascular disease, and endometrial cancer. Although extensive research has identified several mechanistic aspects of PCOS, a thorough understanding of its pathophysiology remains incomplete. This review aims to provide a detailed analysis of the physiological and pathological aspects of PCOS, covering endocrine, metabolic, and inflammatory dimensions, to better elucidate its etiological framework.

Gene therapy with feline anti-Müllerian hormone analogs disrupts folliculogenesis and induces pregnancy loss in female domestic cats

For female domestic cats, ovariohysterectomy is the only method of inducing permanent infertility. However, hundreds-of-millions of free-roaming cats globally highlight the necessity for alternative contraceptive approaches. One strategy involves a single injection of vector delivering a fertility-inhibiting protein for lifetime contraception. Recent studies in mice and cats have identified anti-Müllerian hormone as an excellent candidate for this type of contraception. Here, we leverage our recent characterization of the molecular mechanisms underlying human anti-Müllerian hormone synthesis and activity, to generate potent feline anti-Müllerian hormone analogs. Single intramuscular delivery of these analogs to female cats using an adeno-associated viral vector leads to a greater than 1000-fold increase in feline anti-Müllerian hormone levels, which are sustained for 9 months. High serum anti-Müllerian hormone is associated with abnormal estrus cyclicity, non-follicular ovarian cyst formation, and a progressive decline in antral follicle numbers, however, the few surviving large follicles continue to ovulate. Unlike previous studies, supraphysiologic levels of anti-Müllerian hormone do not block conception, although they are incompatible with the maintenance of pregnancy. Our findings highlight the complexity of the effects of anti-Müllerian hormone on ovarian physiology but confirm that this growth factor is a candidate for fertility control in free-roaming cats.

Developmental programming: preconceptional and gestational exposure of sheep to biosolids on offspring ovarian dynamics†

Developmental exposure to environmental chemicals perturbs establishment and maintenance of the ovarian reserve across the reproductive lifetime, leading to premature follicle depletion and ovarian aging. Considering humans are exposed to a complex mixture of environmental chemicals, real-life models assessing their cumulative impact on the ovarian reserve are needed. Biosolids are a source of a real-life mixture of environmental chemicals. While earlier studies demonstrated that grazing pregnant sheep on biosolids-treated pastures did not influence establishment of the ovarian reserve in fetal life, its impact on subsequent depletion of ovarian reserve during reproductive life of offspring is unknown. We hypothesized that developmental exposure to biosolids accelerates depletion of ovarian reserve. Ovaries were collected from F1 juveniles (9.5 weeks) and adults (2.5 years) born to F0 ewes grazed on control inorganic fertilizer pastures or biosolids-treated pastures from before conception and throughout gestation. The impact on follicular density, activation rate, and anti-Müllerian hormone (mediator of activation) expression by immunohistochemistry was determined. Activation rate was increased in F1 biosolids-treated pastures juveniles with a corresponding reduction in primordial follicle density. In contrast, activation rate and ovarian reserve were similar between control and F1 biosolids-treated pastures adults. The density of anti-Müllerian hormone-positive antral follicles was lower in biosolids-treated pastures juveniles, whereas anti-Müllerian hormone expression tended to be higher in antral follicles of biosolids-treated pastures adults, consistent with the changes in the ovarian reserve. These findings of detrimental effects of developmental exposure to biosolids during juvenile life that normalizes in adults is supportive of a shift in activation rate likely related to peripubertal hormonal changes.

A Bird's-Eye Overview of Leptin and Female Reproduction -with Mammalian Comparisons

Leptin, a key regulator of reproductive physiology, influences various processes in vertebrates, including oocyte proliferation, embryogenesis, the onset of puberty, ovarian function, and follicle development. In mammals, leptin affects steroidogenesis, folliculogenesis, and hormonal regulation through the hypothalamic-pituitary-gonadal axis. Instead, in avian species, leptin-controlled mechanisms are poorly understood, because birds do not produce leptin in adipocytes. In birds, leptin is expressed in the brain, pituitary glands, and gonads, where it enhances ovarian function and egg-laying performance, particularly during feed deprivation. In this review, we discuss and summarize the recently discovered role of leptin in regulating ovarian function during different life stages in birds and compare it with its function in mammals.

Unraveling the Clinical FSH Conundrum: Insights From the Small Ovarian Reserve Heifer Model

High doses of follicle stimulating hormone (FSH) are used during ovarian stimulation to maximize the number of oocytes recovered for in vitro fertilization (IVF) during assisted reproductive technology (ART) in women. Whether high FSH doses are detrimental to embryo viability remains controversial. Evidence from many clinical studies revealed that FSH dose is inversely correlated with live birth rate in women. The mechanistic basis for this effect has been elusive. This review summarizes over 20 years of work using a unique biomedical model, the small ovarian reserve heifer (SORH). Those studies revealed that excessive FSH doses can disrupt gene expression via multiple cell-signaling pathways in ovarian cells, resulting in follicular hyperstimulation dysgenesis (FHD). This compromises the capacity of ovulatory-size follicles to respond to gonadotropins, produce estradiol and ovulate, causes premature cumulus expansion and oocyte maturation, and impairs the fertilizability of oocytes. The SORH model has thus provided new insights into the nature and mechanisms of the deleterious effects of excessive FSH doses during ovarian stimulation. The SORH model has been and remains valuable for basic research and for the discovery of ways to optimize FSH dosing clinically to improve IVF success and ART outcomes.

Identification of a functional vitamin D response element in the promoter of goose anti-Müllerian hormone gene

Anti-Müllerian hormone (AMH) plays an important role in avian ovarian follicle development. The high mRNA expression of AMH in avian ovarian prehierarchical follicles helps prevent premature granulosa cell differentiation. Vitamin D3 was reported to downregulate AMH mRNA expression in granulosa cells of prehierarchical follicles in hens; however, the underlying molecular mechanism remains unknown. In this study, AMH mRNA expression was investigated in granulosa cells of prehierarchical follicles in geese under vitamin D3 induction. A potential vitamin D response element (VDRE) present in the goose AMH promoter was identified using luciferase activity, electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation (ChIP) assays. The results showed that AMH mRNA expressions were downregulated by vitamin D3 in granulosa cells of prehierarchical follicles in geese. A classical VDRE-like sequence was identified in the goose AMH promoter by in silico analyses. Luciferase activity assays revealed that the putative VDRE is a negative regulatory element. Vitamin D receptor (VDR) and retinoic X receptor (RXR) are necessary to decrease the AMH promoter activity induced by vitamin D3. The EMSA and ChIP assays demonstrated that the VDR/RXR complex directly binds to the putative VDRE. These results suggest that vitamin D3 downregulates AMH mRNA expression via a functional VDRE that binds the VDR/RXR heterodimer in goose ovarian prehierarchical follicles. These results provide new insights into the regulatory mechanisms of vitamin D3 in avian ovarian follicular development.

High anti-Müllerian hormone level as a predictor of poor pregnancy outcomes in women with polycystic ovary syndrome undergoing in vitro fertilization/intracytoplasmic sperm injection: a retrospective cohort study

OBJECTIVE

To study the correlation between anti-Müllerian hormone levels and pregnancy outcomes after in vitro fertilization/intracytoplasmic sperm injection in women with polycystic ovary syndrome, which remains controversial.

METHODS

This retrospective cohort study recruited 4,719 women with infertility and polycystic ovary syndrome aged 20-40 years who underwent treatment at the Reproductive Center of Peking University Third Hospital between February 2017 and June 2023. We divided the participants into three groups according to the 25th and 75th percentile cutoffs of serum anti-Müllerian hormone: low (≤ 4.98 ng/mL, n = 1,198), average (4.98 - 10.65 ng/mL, n = 2,346), and high (≥ 10.65 ng/mL, n = 1,175). Pregnancy outcomes included live birth rate, miscarriage rate, clinical pregnancy rate, and cumulative live birth rate.

RESULTS

The live birth rate for fresh embryo transfer was 39.8%, 35.9%, and 30.4% in the low, average, and high anti-Müllerian hormone groups, respectively. The miscarriage rate was 11.3%, 17.1%, and 21.8% in the low, average, and high anti-Müllerian hormone groups, respectively. Significant intergroup differences were observed in the live birth rate (P = 0.017) and miscarriage rate (P = 0.018). No significant intergroup difference was observed in the clinical pregnancy rate (P = 0.204) or cumulative live birth rate (P = 0.423). After adjusting the confounders by multivariable logistic regression analysis, anti-Müllerian hormone was associated with decreased live birth rate in the high anti-Müllerian hormone group compared with that in the low anti-Müllerian hormone group (odds ratio: 0.629, 95% confidence interval: 0.460-0.860). Anti-Müllerian hormone was associated with increased miscarriage rate in the average and high anti-Müllerian hormone groups compared with that in the low anti-Müllerian hormone group (average vs. low: odds ratio: 1.592, 95% confidence interval: 1.017-2.490); high vs. low: odds ratio: 2.045, 95% confidence interval: 1.152-3.633).

CONCLUSION

High anti-Müllerian hormone is a prognostic factor for reduced live birth rate after fresh embryo transfer in women with polycystic ovary syndrome aged 20-40 years undergoing in vitro fertilization/intracytoplasmic sperm injection, and is associated with increased miscarriage rate in these patients.

Gene expression levels in cumulus cells are correlated with developmental competence of bovine oocytes

The generation of mammalian embryos by in vitro culture is hampered by the failure of many of the embryos to develop to the blastocyst stage. This problem occurs even when cumulus-oocyte complexes (COCs) with good morphology are visually selected and used for culture. Because cumulus cells are important for oocyte maturation and subsequent embryo development, here we compared gene expression patterns in cumulus cells of COCs that developed in vitro to the blastocyst stage with those of COCs that failed to develop. Cumulus cells were aspirated from bovine COCs selected for in vitro culture. Oocyte developmental competence was evaluated by screening for cleavage and development to the blastocyst stage. The collected cumulus cells were used to quantify mRNA levels of FSH receptor (FSHR), insulin-like growth factor-1 receptor (IGF-1R), anti-Müllerian hormone (AMH), AMH receptor II (AMHRII), epidermal growth factor receptor (EGFR), estrogen receptor β (ERβ), B cell lymphoma/leukemia-2 associated X (Bax), and cysteine-aspartic acid protease-3 (Caspase-3). We found that the expression levels of FSHR, IGF-1R, AMH, and EGFR were higher in cumulus cells from COCs that developed to blastocysts as compared with those that failed to develop, whereas expression levels of Bax and Caspase-3 were lower in cumulus cells of COCs that matured to the blastocyst stage. Positive correlations were found between FSHR and IGF-1R expression (r = 0.59) and between ERβ and EGFR expression (r = 0.43) in cumulus cells from COCs that developed to the blastocyst stage. Our findings indicate that gene expression levels in cumulus cells are correlated with the developmental competence of bovine oocytes. Measurement of gene expression in cumulus cells therefore offers a non-invasive means of predicting oocyte developmental competence.

Comparative Analysis of Controlled Ovarian Hyperstimulation and Modified Natural Cycle Protocols on Gene Expression and Quality of Oocytes, Zygotes, and Embryos in Assisted Reproductive Technology (ART)

This study investigated the influence of two in vitro fertilization (IVF) protocols-controlled ovarian hyperstimulation (COH) and a modified natural cycle protocol-on gene expression levels (Anti-Müllerian Hormone (AMH), Anti-Müllerian Hormone Receptor Type 2 (AMHAMHR2), Follicle-Stimulating Hormone Receptor (FSHR), and Androgen Receptor (AR)) and the subsequent reproductive outcomes of assisted reproductive technology (ART). Gene expression, as well as oocyte, zygote, and embryo morphological parameters, were analyzed to evaluate the differences between the protocols. Our findings show that AMH expression was significantly associated with successful fertilization, while AMHAMHR2 expression correlated with improved embryo transfer outcomes. The modified natural cycle protocol demonstrated a higher association with the favorable gene expression profiles, particularly for AMH and AMHAMHR2, linked to successful fertilization and embryo transfer, suggesting potential advantages of minimal intervention. However, the overall quality scores for the oocytes, zygotes, and embryos were comparable between the protocols. The trend of a higher transfer success for the natural cycle, though not statistically significant, indicated potential protocol effects on the uterine environment. This study highlights the complexity of ART outcomes and suggests that incorporating gene expression markers with protocol adjustments may optimize individual ART strategies.

Anti-Müllerian hormone signaling in the ovary involves stromal fibroblasts: a study in humans and mice provides novel insights into the role of ovarian stroma

STUDY QUESTION

What is the involvement of ovarian stroma in the anti-Müllerian hormone (AMH) signaling pathway and which stromal cells are involved?

SUMMARY ANSWER

Mouse and human ovaries show high expression of AMH receptor II (AMHR2) in the stromal fibroblasts surrounding the follicles and activation of the post-AMHR2 pathway by recombinant AMH was evidenced by increased phosphorylation of SMAD1,5 and 9, increased expression AMHR2 and upregulation of αSMA, suggesting fibroblast activation to initiate myofibroblast differentiation.

WHAT IS KNOWN ALREADY

AMH secreted by small growing follicles, regulates ovarian activity. It suppresses initial primordial follicle (PMF) recruitment and FSH-dependent growth. AMH signal transduction is mediated by AMHR2, activating intracellular SMAD proteins and other signaling cascades to induce target-gene expression. Although AMHR2 expression has been reported within the follicle unit, there is evidence suggesting it may be identified in the stroma as well.

STUDY DESIGN, SIZE, DURATION

Fresh murine ovaries were extracted from BALB/c mice (6 weeks old; n = 12 and 21 days old; n = 56). Frozen-thawed ovarian fragments were obtained from 10 women, aged 18-35, who had undergone ovarian tissue cryopreservation and donated frozen ovarian tissue for research.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Murine (6 weeks old) and human donor ovaries were immunostained for AMHR2 and Collagen 1α/αSMA/VCAM1, with additional vimentin staining in mice. Murine (21 days old) and human donor ovaries were used for fibroblast isolation and subsequent 7-day cultures. Prior to assessing AMH effects on isolated fibroblast culture, purity validation tests were implemented to ensure the absence of epithelial, immune, endothel, granulosa, and theca ovarian cell populations. The fibroblast culture's homogeneity was validated by RT-qPCR and western-blot assays, confirming negativity for E-cadherin, CD31, aromatase, CYP17A1, and positivity for αSMA and vimentin. Fibroblasts were then subjected to rAMH treatment in vitro (200 ng/ml) for 0-72 h, with an additional time point of 96 h for human samples, followed by RT-qPCR, western blot, and immunocytochemistry (ICC) for AMHR2 expression. AMHR2 post-receptor signaling was examined by pSMAD1,5,9 levels via western blot. Activated fibroblast marker, αSMA, was assessed via western blot and ICC.

MAIN RESULTS AND THE ROLE OF CHANCE

Immunostaining of mouse and human ovarian tissue showed that stromal cells around follicles at all developmental stages exhibit high AMHR2 expression, while granulosa cells of growing follicles show considerably lower levels. The majority of these AMHR2-positive stromal cells were identified as fibroblasts (Collagen1α in mice and human; vimentin in mice). RT-qPCR, western blot, and immunostaining were performed on cultured mouse and human fibroblasts, confirming that they consisted of a pure fibroblast population (αSMA/vimentin positive and negative for other cell-type markers). A total of 99.81% (average 28.94 ± 1.34 cells/field in mice) and 100% (average 19.20 ± 1.39 cells/field in human samples) of these fibroblasts expressed AMHR2 (ICC). rAMH treated cultured fibroblasts showed increased pSMAD1,5 and 9 levels, demonstrating the effects of AMH on its downstream signaling pathway. pSMAD1,5 and 9 expression increased, as detected by western blot: 1.92-fold in mice (48 h, P = 0.026) and 2.37-fold in human samples (48 h, P = 0.0002). In addition, rAMH treatment increased AMHR2 protein expression, as observed in ICC (human): a 2.57-fold upregulation of AMHR2 Mean Fluorescence Intensity (MFI) (96 h, P = 0.00036), and western blot, showing a 4.2-fold time-dependent increase (48 h, P = 0.026) in mice and 2.4-fold change (48 h, P = 0.0003) in human donors. Exposure to rAMH affected AMHR2 transcription upregulation, with a 6.48-fold change (72 h, P = 0.0137) in mice and a 7.87-fold change (72 h, P < 0.0001) in humans. rAMH treatment induced fibroblast activation (αSMA positive), demonstrating the dynamic effects of AMH on fibroblast behavior. αSMA expression elevation was detected in ICC with a 2.28-fold MFI increase in humans (96 h, P = 0.000067), and in western blot with a 5.12-fold increase in mice (48 h, P = 0.0345) and a 2.69-fold increase in humans (48 h, P ≤ 0.0001). Activated AMHR2-positive stained fibroblast fractions were solely located around growing follicles, in both human and mice. In addition, a small population of AMHR2-positive stained theca cells (VCAM1 positive) was observed.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Ex vivo, fibroblast gene expression might be changed by adhesion to the tissue-culture plate. Nevertheless, cultured fibroblasts (with and without rAMH) are subjected to the same conditions. Observations or significant differences can therefore be considered reliable. In addition, the presented effect of rAMH on fibroblasts is not directly linked to the known inhibitory effect of AMH on follicle activation.

WIDER IMPLICATIONS OF THE FINDINGS

Clarifying the populations of AMH-responsive cells in the ovary provides a foundation for further investigation of the complex AMH signaling across the ovary. The composition of AMH-releasing and -responsive cells can shed light on the communication network between follicles and their environment, which may elucidate the mechanisms behind the AMH inhibitory effect on PMF activation.

STUDY FUNDING/COMPETING INTEREST(S)

This work was financially supported by grants from the Kahn Foundation. There are no competing interests in this study.

TRIAL REGISTRATION NUMBER

N/A.

Role of the AMP-Activated Protein Kinase in the Pathogenesis of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex disorder characterized by elevated androgen levels, menstrual irregularities, and polycystic morphology of the ovaries. Affecting 6-10% of women in childbearing age, PCOS is a leading cause of infertility worldwide. In recent years, there has been a growing acknowledgment of the involvement of adenosine monophosphate-activated protein kinase (AMPK) in the development of polycystic ovary syndrome (PCOS). The expression of AMPK is diminished in polycystic ovaries, and when AMPK is silenced in human granulosa cells, there is a rise in the expression of steroidogenic enzymes, resulting in increased production of estradiol and progesterone. Additionally, in mouse models, the inhibiting AMPK intensifies the polycystic appearance of ovaries and impairs the process of ovulation. Moreover, it has been shown that AMPK activators like metformin and resveratrol ameliorate PCOS associated signs and symptoms in experimental and clinical studies. These findings, collectively, indicate the key role of AMPK in the pathogenesis of PCOS. Understanding the role of AMPK in PCOS will offer rewarding information on details of PCOS pathogenesis and will provide novel more specific therapeutic approaches. The present review summarizes the latest findings regarding the role of AMPK in PCOS obtained in experimental and clinical studies.

Expression and localization of anti-Müllerian hormone and its receptors in bovine corpus luteum

Although anti-Müllerian hormone (AMH) is involved in the regulation of granulosa cell function in female animals, its role in tissues other than ovarian follicles remains poorly understood. It has also been suggested that cows with high circulating AMH concentrations have increased fertility; however, the mechanism has not been elucidated. This study was conducted to identify the presence of the AMH-signaling system and its target cells in the bovine corpus luteum formed from an ovulated follicle. Immunoblotting revealed that the proteolytically cleaved C-terminal region in AMH (AMHC), a biologically active peptide, was present in trace amounts in the early corpus luteum and significantly increased during the mid to regressed stages. AMHC and cleaved N-terminal region (AMHN) in AMH generate a noncovalent isoform that improves the activity of AMH signaling. An immunohistochemical analysis revealed that AMHC, AMHN, and type II AMH receptor (AMHR2) were localized to luteal cells during the entire estrous cycle. AMH in the corpus luteum seemed to be newly synthesized since AMH expression was detected. These findings suggest that AMH signaling is involved in the regulation of luteal cell function through an autocrine and post-translational processing mechanism. The level of AMHR2 and mRNA expression of AMHR2 and type I AMH receptors (activin-like kinase 2, 3, and 6) were highest in the mid stage. Thus, AMH signaling in the corpus luteum may also be regulated by changes in the receptor levels. Since the transforming growth factor-beta superfamily, to which AMH belongs, is a multifunctional polypeptide growth factor, further studies are needed to evaluate whether AMH signaling has a role in facilitating or inhibiting luteal cell functions.

Implications of obstructive sleep apnea on reproductive health: a study on anti-Mullerian hormone levels

PURPOSE

This study aimed to explore the association between anti-mullerian hormone (AMH) levels and obstructive sleep apnea (OSA) severity.

METHODS

A cross-sectional design was employed to evaluate AMH levels in 68 premenopausal women diagnosed with OSA at Van Yüzüncü Yıl University Faculty of Medicine. OSA severity was scored according to the 2018 AASM guidelines using a 16-channel Embla device. AMH levels were measured from blood samples using a commercially available kit.

RESULTS

The study found that AMH levels in OSA patients were significantly lower than those in the healthy control group. A statistically significant negative correlation between AMH and AHI levels was observed. When stratified by OSA severity, the lowest AMH levels were found in the severe OSA group.

CONCLUSION

OSA may have potential endocrine implications, especially concerning reproductive health. Decreased AMH levels in OSA patients could indicate future risks of infertility or early menopause.

Increased Vasoactive Intestinal Peptide (VIP) in polycystic ovary syndrome patients undergoing IVF

Introduction

Polycystic ovary syndrome (PCOS) is a common multifactorial and polygenic disorder of the endocrine system, affecting up to 20% of women in reproductive age with a still unknown etiology. Follicular fluid (FF) represents an environment for the normal development of follicles rich in metabolites, hormones and neurotransmitters, but in some instances of PCOS the composition can be different. Vasoactive intestinal peptide (VIP) is an endogenous autonomic neuropeptide involved in follicular atresia, granulosa cell physiology and steroidogenesis.

Methods

ELISA assays were performed to measure VIP and estradiol levels in human follicular fluids, while AMH, FSH, LH, estradiol and progesterone in the plasma were quantified by chemiluminescence. UHPLC/QTOF was used to perform the untargeted metabolomic analysis.

Results

Our ELISA and metabolomic results show: i) an increased concentration of VIP in follicular fluid of PCOS patients (n=9) of about 30% with respect to control group (n=10) (132 ± 28 pg/ml versus 103 ± 26 pg/ml, p=0,03) in women undergoing in vitro fertilization (IVF), ii) a linear positive correlation (p=0.05, r=0.45) between VIP concentration and serum Anti-Müllerian Hormone (AMH) concentration and iii) a linear negative correlation between VIP and noradrenaline metabolism. No correlation between VIP and estradiol (E2) concentration in follicular fluid was found. A negative correlation was found between VIP and noradrenaline metabolite 3,4-dihydroxyphenylglycolaldehyde (DOPGAL) in follicular fluids.

Conclusion

VIP concentration in follicular fluids was increased in PCOS patients and a correlation was found with noradrenaline metabolism indicating a possible dysregulation of the sympathetic reflex in the ovarian follicles. The functional role of VIP as noradrenergic modulator in ovarian physiology and PCOS pathophysiology was discussed.

NR5A1 and NR5A2 regulate follicle development in chicken (Gallus gallus) by altering proliferation, apoptosis, and steroid hormone synthesis of granulosa cells

Chicken ovarian follicle development is regulated by complex and dynamic gene expression. Nuclear receptor 5A1 and 5A2 (NR5A1 and NR5A2, respectively) are key genes that regulate steroid hormone production and gonadal development in mammals; however, studies on follicular development in the chicken ovary are scarce. In this study, we investigated the functions of NR5A1 and NR5A2 on follicle development in chickens. The results showed that the expression of NR5A1 and NR5A2 was significantly higher in small yellow follicles and F5. Furthermore, the expression of NR5A1 and NR5A2 was significantly higher in follicular tissues of peak-laying hens (30 wk) than in follicular tissues of late-laying hens (60 wk), with high expression abundance in granulosa cells (GC). The overexpression of NR5A1 and NR5A2 significantly promoted proliferation and inhibited apoptosis of cultured GC; upregulated STAR, CYP11A1, and CYP19A1 expression and estradiol (E2) and progesterone (P4) synthesis in GC from preovulatory follicles (po-GC); and increased STAR, CYP11A1, and CYP19A1 promoter activities. In addition, follicle-stimulating hormone treatment significantly upregulated NR5A1 and NR5A2 expression in po-GC and significantly promoted FSHR, CYP11A1, and HSD3B1 expression in GC from pre-hierarchical follicles and po-GC. The core promoter region of NR5A1 was identified at the -1,095- to -483-bp and -2,054- to -1,536-bp regions from the translation start site (+1), and the core promoter region of NR5A2 was at -998 to -489 bp. Two single nucleotide polymorphisms (SNP) were identified in the core promoter region of the NR5A1 gene, which differed between high- and low-yielding chicken groups. Our study suggested that NR5A1 and NR5A2 promoted chicken follicle development by promoting GC proliferation and E2 and P4 hormone synthesis and inhibiting apoptosis. Moreover, we identified the promoter core region or functional site that regulates NR5A1 and NR5A2 expression.

Synchronously sexual maturity in hermaphrodite fish as revealed by transcriptome analysis in Plectropomus leopardus

Leopard coral grouper (Plectropomus leopardus) is a type of hermaphrodite fish, but the mechanisms of gonadal development and gametogenesis remain unclear. In the present study, we performed histological observation and transcriptomic analysis during the process of sexual differentiation in P. leopardus. According to the histological results, sexual differentiation was completed at 15 months old, developed synchronously in male and female individuals at 2 years old, and matured synchronously at 3 years old. Comparative transcriptomic analyses showed that the gonadal had differentiated by 15 months old, with enrichment of pathways associated with cell proliferation, transcriptional metabolism, and germline stem cell differentiation. Furthermore, cilium movement and fatty acid anabolism, which are associated with spermatogenesis and oocyte growth, were significantly enriched at 3 years old. In addition, key genes associated with male and female sex differentiation, such as amh, dmrt1, dmrt2a, zp4, sox3, gdf9, and gsdf, were identified by weighted gene co-expression network analysis (WGCNA). Finally, the localization and expression of the key genes amh and sox3 were observed in different cell types within the testes and ovaries, reflecting the development of the testes and ovaries, respectively. All the evidence indicates that P. leopardus is a hermaphrodite and synchronously sexually mature fish. Our study complements the gonadal development patterns of hermaphroditic fish by providing new insights into the molecular mechanisms underlying sexual differentiation and sex change in hermaphroditic groupers.

Investigations of the function of AMH in granulosa cells in hens

Anti-mullerian hormone (AMH) plays a crucial role in follicle regulation in mammals by preventing premature primordial follicle activation and restricting follicle development through reduction of FSH sensitivity and inhibition of FSH-induced increase of steroidogenic enzymes. AMH is produced by granulosa cells from growing follicles and expression declines at the time of selection in both mammalian and avian species. The role of AMH in chicken granulosa cells remains unclear, as research is complicated because mammalian AMH is not bioactive in chickens and there is a lack of commercially available chicken AMH. In the current experiments, we used RNA interference to study the role of AMH on markers of follicle development in the presence and absence of FSH. Cultured chicken granulosa cells from 3-5 mm follicles and 6-8 mm follicles, the growing pool from which follicle selection is thought to occur, were used. Transfection with an AMH-specific siRNA significantly reduced AMH mRNA expression in granulosa cells from 3-5 mm and 6-8 mm follicles. Genes of interest were only measured in granulosa cells of 3-5 mm follicles due to low expression of AMH mRNA at the 6-8 mm follicle stage. Knockdown of AMH mRNA did not affect markers of follicle development (follicle stimulating hormone receptor, FSHR; steroidogenic acute regulatory protein, STAR; cytochrome P450 family 11 subfamily A member 1, CYP11A1; bone morphogenetic protein receptor type 2, BMPR2) or FSH responsiveness in granulosa cells from 3-5 mm follicles, indicating that AMH does not regulate follicle development directly by affecting markers of steroidogenesis, FSHR or BMPR2 at this follicle stage in chickens.

Unveiling the Ovarian Cell Characteristics and Molecular Mechanism of Prolificacy in Goats via Single-Nucleus Transcriptomics Data Analysis

Increases in litter size, which are influenced by ovulation, are responsible for between 74% and 96% of the economic value of genetic progress, which influences selection. For the selection and breeding of highly prolific goats, genetic mechanisms underlying variations in litter size should be elucidated. Here, we used single-nucleus RNA sequencing to analyze 44,605 single nuclei from the ovaries of polytocous and monotocous goats during the follicular phase. Utilizing known reference marker genes, we identified 10 ovarian cell types characterized by distinct gene expression profiles, transcription factor networks, and reciprocal interaction signatures. An in-depth analysis of the granulosa cells revealed three subtypes exhibiting distinct gene expression patterns and dynamic regulatory mechanisms. Further investigation of cell-type-specific prolificacy-associated transcriptional changes elucidated that "downregulation of apoptosis", "increased anabolism", and "upstream responsiveness to hormonal stimulation" are associated with prolificacy. This study provides a comprehensive understanding of the cell-type-specific mechanisms and regulatory networks in the goat ovary, providing insights into the molecular mechanisms underlying goat prolificacy. These findings establish a vital foundation for furthering understanding of the molecular mechanisms governing folliculogenesis and for improving the litter size in goats via molecular design breeding.

The Role of Anti-Müllerian Hormone in Ovarian Function

Anti-Müllerian hormone (AMH) is a member of the transforming growth factor β (TGFβ) superfamily, whose actions are restricted to the endocrine-reproductive system. Initially known for its role in male sex differentiation, AMH plays a role in the ovary, acting as a gatekeeper in folliculogenesis by regulating the rate of recruitment and growth of follicles. In the ovary, AMH is predominantly expressed by granulosa cells of preantral and antral follicles (i.e., post primordial follicle recruitment and prior to follicle-stimulating hormone (FSH) selection). AMH signals through a BMP-like signaling pathway in a manner distinct from other TGFβ family members. In this review, the latest insights in AMH processing, signaling, its regulation of spatial and temporal expression pattern, and functioning in folliculogenesis are summarized. In addition, effects of AMH variants on ovarian function are reviewed.

Anti-Müllerian Hormone: A Molecular Key to Unlocking Polycystic Ovary Syndrome?

Anti-Müllerian hormone (AMH) is an important component within androgen receptor (AR)-regulated pathways governing the hyperandrogenic origin of polycystic ovary syndrome (PCOS). In women with PCOS, granulosa cell AMH overexpression in developing ovarian follicles contributes to elevated circulating AMH levels beginning at birth and continuing in adolescent daughters of PCOS women. A 6 to 7% incidence among PCOS women of gene variants coding for AMH or its receptor, AMHR2, suggests genetic contributions to AMH-related pathogenesis. Discrete gestational AMH administration to pregnant mice induces hypergonadotropic hyperandrogenic, PCOS-like female offspring with high circulating AMH levels that persist over three generations, suggesting epigenetic contributions to PCOS through developmental programming. Moreover, adult-onset, selective hyperactivation of hypothalamic neurons expressing gonadotropin-releasing hormone (GnRH) induces hypergonadotropic hyperandrogenism and PCOS-like traits in female mice. Both gestational and adult AMH inductions of PCOS-like traits are prevented by GnRH antagonist coadministration, implicating luteinizing hormone-dependent ovarian theca cell testosterone (T) action, mediated through the AR in AMH-induced pathogenesis. Interestingly, gestational or peripubertal exogenous T or dihydrotestosterone induction of PCOS-like traits in female mice, rats, sheep, and monkeys fails to elicit ovarian AMH hypersecretion; thus, AMH excess per se may lead to a distinct pathogenic contribution to hyperandrogenic PCOS origins.

Impact of In Ovo Leptin Injection and Dietary Protein Levels on Ovarian Growth Markers and Early Folliculogenesis in Post-Hatch Chicks (Gallus gallus domesticus)

Genetically bred for rapid growth, broiler breeder hens develop obesity and ovarian dysfunction when fed ad libitum, resembling a condition that resembles human polycystic ovary syndrome (PCOS). Nutritional control applies to post-hatched chicks from one week onward to prevent the development of a PCOS-like phenotype in adult broilers. This study investigated the impact of a growth marker, leptin, and post-hatch nutritional intake on early-life ovarian function. Fertile broiler eggs were injected in ovo with physiological saline solution or 5 µg of leptin and then incubated. After hatching, female chicks were fed ad libitum a diet containing low protein (17% low crude protein (LP)) or standard protein (22% standard crude protein (SP)). Tissues were collected from 7- and 28-day-old chicks for RT-qPCR and histological analysis. In contrast to the LP diet, the SP diet suppressed the mRNA expression of ovarian growth markers essential for folliculogenesis in post-hatched chicks. Leptin injection did not influence ovarian growth markers but increased pituitary gonadotropin transcripts in 7-day-old chicks fed with LP diet. No treatment effects on follicle activation were noted on day 7, but by day 28, in ovo leptin-treated LP-fed chicks exhibited a higher percentage of primary follicles. These changes may have resulted from the early upregulation of genes by leptin during the first week, including pituitary gonadotropins and ovarian leptin receptors. The decline in ovarian growth markers with the SP diet highlights the importance of precise post-hatch protein calculation, which may influence future ovarian function in animals. These findings may contribute to future dietary strategies to enhance broiler reproduction.

Anti-Müllerian hormone for screening, diagnosis, evaluation, and prediction: A systematic review and expert opinions

AIM

To present evidence-based recommendations for anti-Müllerian hormone (AMH) measurement as an ovarian reserve test.

METHODS

A systematic literature search for the clinical utility of AMH was conducted in PubMed from its inception to August 2022 to identify studies, including meta-analyses, reviews, randomized controlled trials, and clinical trials, followed by an additional systematic search using keywords. Based on this evidence, an expert panel developed clinical questions (CQs).

RESULTS

A total of 1895 studies were identified and 95 articles were included to establish expert opinions subdivided into general population, infertility treatment, primary ovarian insufficiency, polycystic ovary syndrome, surgery, and oncofertility. We developed 13 CQs and 1 future research question with levels of evidence and recommendations.

CONCLUSION

The findings of the current systematic review covered the clinical utility of AMH including its screening, diagnosis, evaluation, and prediction. Although some clinical implications of AMH remain debatable, these expert opinions may help promote a better understanding of AMH and establish its clinical significance.

Comparative analyses of laying performance and follicular development characteristics between fat and lean broiler lines

The deposition of high levels of fat in broiler breeder hens can have a profound impact on follicular development and laying performance. This study was formulated with the goal of comparing egg production and follicular development characteristics at different laying stages in the Northeast Agricultural University broiler lines divergently selected for abdominal fat content (NEAUHLF). The egg production was analyzed using the birds from the 19th to 24th generations of NEAUHLF; the follicular development characteristics were analyzed by hematoxylin-eosin staining and quantitative real-time polymerase chain reaction using the birds from the 24th generation of NEAUHLF. The results showed that the age at first egg of lean hens was significantly earlier than that of fat hens in this study. While no significant differences in total egg output from the first egg to 50 wk of age were noted when comparing these 2 chicken lines, lean hens laid more eggs from the first egg to 35 wk of age relative to fat hens, whereas fat hens laid more eggs from wk 36 to 42 and 43 to 50 relative to their lean counterparts. No differences in ovarian morphology and small yellow follicle (SYF) histological characteristics were noted when comparing these 2 chicken lines at 27 wk of age. At 35 and 52 wk of age, however, lean hens exhibited significantly lower ovarian weight, ovarian proportion values, numbers of hierarchical follicles, hierarchical follicle weight, and SYF granulosa layer thickness as compared to fat hens, together with a significant increase in the number of prehierarchical follicles relative to those in fat hens. Gene expression analyses suggested that follicle selection was impaired in the fat hens in the early laying stage, whereas both follicle selection and maturation were impaired in the lean hens in the middle and late laying stages. Overall, these data highlight that fat deposition in broiler hens can have a range of effects on follicular development and egg production that are laying stage-dependent.

Characterization of the molecular mechanisms that govern anti-Müllerian hormone synthesis and activity

The roles of anti-Müllerian hormone (AMH) continue to expand, from its discovery as a critical factor in sex determination, through its identification as a regulator of ovarian folliculogenesis, its use in fertility clinics as a measure of ovarian reserve, and its emerging role in hypothalamic-pituitary function. In light of these actions, AMH is considered an attractive therapeutic target to address diverse reproductive needs, including fertility preservation. Here, we set out to characterize the molecular mechanisms that govern AMH synthesis and activity. First, we enhanced the processing of the AMH precursor to >90% by introducing more efficient proprotein convertase cleavage sites (RKKR or ISSRKKRSVSS [SCUT]). Importantly, enhanced processing corresponded with a dramatic increase in secreted AMH activity. Next, based on species differences across the AMH type II receptor-binding interface, we generated a series of human AMH variants and assessed bioactivity. AMHSCUT potency (EC50 4 ng/mL) was increased 5- or 10-fold by incorporating Gln484 Met/Leu535 Thr (EC50 0.8 ng/mL) or Gln484 Met/Gly533 Ser (EC50 0.4 ng/mL) mutations, respectively. Furthermore, the Gln484 Met/Leu535 Thr double mutant displayed enhanced efficacy, relative to AMHSCUT . Finally, we identified residues within the wrist pre-helix of AMH (Trp494 , Gln496 , Ser497 , and Asp498 ) that likely mediate type I receptor binding. Mutagenesis of these residues generated gain- (Trp494 Phe or Gln496 Leu) or loss- (Ser497 Ala) of function AMH variants. Surprisingly, combining activating type I and type II receptor mutations only led to modest additive increases in AMH potency/efficacy. Our study is the first to characterize AMH residues involved in type I receptor binding and suggests a step-wise receptor-complex assembly mechanism, in which enhancement in the affinity of the ligand for either receptor can increase AMH activity beyond the natural level.

Mechanisms of DHEA-induced AMH increase in the ovarian tissues of PCOS rat

The present study aimed to build a DHEA-induced polycystic ovary syndrome (PCOS) rat model to evaluate the potential mechanism of DHEA-induced AMH rise in these rat ovarian tissues. A total of 36 female 3-week-old rats were allocated into two groups at random. The control group received merely the same amount of sesame oil for 20 days while the experimental group received 0.2 mL of sesame oil Plus DHEA 6 mg/100 g daily. Both groups' vaginal opening times were noted, and vaginal smears were taken. By using RT-qPCR and Western blot, the mRNA and protein expression of AMH, GATA4, SF1, and SOX9 in the ovarian tissues of the two groups was investigated.The rats in the experimental group appeared to have obvious disorders of the estrus cycle, as evidenced by the ratio of estrus being significantly higher than that in the control group (P < 0.05); HE staining revealed that the ovarian volume, follicular vacuoles, and follicular lumen of the rats in the experimental group increased significantly.The ELISA results revealed that T and AMH in the experimental group were higher than those in the control group at day 15 and 20. AMH、GATA4 and SF1 mRNA and protein expression were higher in the experimental group than in the control group on day 15 and 20 (P < 0.05). On day 20, the experimental group outperformed the control group (P < 0.05). In the DHEA-induced PCOS rat model, androgen may have enhanced AMH expression via increasing the expression of genes associated to the AMH promoter binding site (GATA4, SF1, SOX9).

New insights into the role of LH in early ovarian follicular growth: a possible tool to optimize follicular recruitment

Evidence shows that LH participates in enhancing transition from the early stage to the antral stage of folliculogenesis. It has been demonstrated that functional LH receptors are expressed, albeit at a very low level and even in smaller follicles, during the phase that was traditionally considered to be gonadotrophin independent, suggesting a role for LH in accelerating the rate of progression of non-growing and primary follicles to the preantral/antral stage. Hypogonadotropic hypogonadism, together with other clinical conditions of pituitary suppression, has been associated with reduced functional ovarian reserve. The reduction in LH serum concentration is associated with a low concentration of anti-Müllerian hormone. This is the case in hypothalamic amenorrhoea, pregnancy, long-term GnRH-analogue therapy and hormonal contraception. The effect seems to be reversible, such that after pregnancy and after discontinuation of drugs, the functional ovarian reserve returns to the baseline level. Evidence suggests that women with similar primordial follicle reserves could present with different numbers of antral follicles, and that gonadotrophins may play a fundamental role in permitting a normal rate of progression of follicles through non-cyclic folliculogenesis. The precise role of gonadotrophins in early folliculogenesis, as well as their use to modify the functional ovarian reserve, must be investigated.

Cystic endometrial hyperplasia-pyometra syndrome impairs the preantral follicle reserve in domestic bitches (Canis familiaris)

Cystic endometrial hyperplasia (CEH)-pyometra syndrome is the most common uterine pathological condition reported in breeding bitches, however, their described effects on fertility are limited to uterine disorders and conception rates. As the preantral follicle population represents the available reserve of gametes recruited during the lifespan, the aim of this study was to evaluate the effects of CEH-pyometra syndrome on the: (i) preantral follicle morphology, (ii) developing follicle rates, and (iii) preantral follicle and stromal cell densities. Ovarian fragments from bitches subjected to elective or therapeutic ovariohysterectomy were allocated according to uterine diagnosis as follows: control (n = 7, clinically healthy), CEH-mucometra (n = 8, uterine lumen filled with a sterile mucus), and pyometra (n = 17, presence of a purulent mucus) groups. Overall, the control group had 3.4 and 4.1-fold higher probability (P < 0.0001) of the presence of normal preantral follicles compared with CEH-mucometra and pyometra groups, respectively. Moreover, ovarian fragments from the pyometra group showed an increase in the percentage of developing follicles (P < 0.05) compared to the control. Both CEH-mucometra and pyometra groups showed lower (P < 0.05) preantral follicle and stromal cell densities (P < 0.05) compared to the control. In summary, the CEH-pyometra syndrome decreased the percentage of morphologically normal follicles and enhanced the developing follicle rates. Additionally, a reduction of preantral follicle and stromal cell densities suggests that the inappropriate uterine environment induced by CEH-pyometra syndrome can lead to premature depletion of ovarian reserve.

Stem-Cell-Derived Extracellular Vesicles: Unlocking New Possibilities for Treating Diminished Ovarian Reserve and Premature Ovarian Insufficiency

Despite advancements in assisted reproductive technology (ART), achieving successful pregnancy rates remains challenging. Diminished ovarian reserve and premature ovarian insufficiency hinder IVF success-about 20% of in vitro fertilization (IVF) patients face a poor prognosis due to a low response, leading to higher cancellations and reduced birth rates. In an attempt to address the issue of premature ovarian insufficiency (POI), we conducted systematic PubMed and Web of Science research, using keywords "stem cells", "extracellular vesicles", "premature ovarian insufficiency", "diminished ovarian reserve" and "exosomes". Amid the complex ovarian dynamics and challenges like POI, stem cell therapy and particularly the use of extracellular vesicles (EVs), a great potential is shown. EVs trigger paracrine mechanisms via microRNAs and bioactive molecules, suppressing apoptosis, stimulating angiogenesis and activating latent regenerative potential. Key microRNAs influence estrogen secretion, proliferation and apoptosis resistance. Extracellular vesicles present a lot of possibilities for treating infertility, and understanding their molecular mechanisms is crucial for maximizing EVs' therapeutic potential in addressing ovarian disorders and promoting reproductive health.

Anti-Müllerian hormone beyond an ovarian reserve marker: the relationship with the physiology and pathology in the life-long follicle development

Anti-Müllerian hormone (AMH), an indirect indicator of the number of remaining follicles, is clinically used as a test for ovarian reserve. Typically, a decline suggests a decrease in the number of remaining follicles in relation to ovarian toxicity caused by interventions, which may implicate fertility. In contrast, serum AMH levels are elevated in patients with polycystic ovary syndrome. AMH is produced primarily in the granulosa cells of the preantral and small antral follicles. Thus it varies in association with folliculogenesis and the establishment and shrinking of the follicle cohort. Ovarian activity during the female half-life, from the embryonic period to menopause, is based on folliculogenesis and maintenance of the follicle cohort, which is influenced by developmental processes, life events, and interventions. AMH trends over a woman's lifetime are associated with in vivo follicular cohort transitions that cannot be observed directly.

Potential factors result in diminished ovarian reserve: a comprehensive review

The ovarian reserve is defined as the quantity of oocytes stored in the ovary or the number of oocytes that can be recruited. Ovarian reserve can be affected by many factors, including hormones, metabolites, initial ovarian reserve, environmental problems, diseases, and medications, among others. With the trend of postponing of pregnancy in modern society, diminished ovarian reserve (DOR) has become one of the most common challenges in current clinical reproductive medicine. Attributed to its unclear mechanism and complex clinical features, it is difficult for physicians to administer targeted treatment. This review focuses on the factors associated with ovarian reserve and discusses the potential influences and pathogenic factors that may explain the possible mechanisms of DOR, which can be improved or built upon by subsequent researchers to verify, replicate, and establish further study findings, as well as for scientists to find new treatments.

Effect of IGF1 and FSH on the function of granulosa cells from prehierarchal follicles in chickens†

Insulin-like growth factor 1 (IGF1) is an essential regulator of mammalian follicle development and synergizes with follicle-stimulating hormone (FSH) to amplify its effects. In avian preovulatory follicles, IGF1 increases the expression of genes involved in steroidogenesis and progesterone and inhibin A production. The role of IGF1 in prehierarchal follicles has not been well studied in chickens. The aim of this study was to investigate the role of IGF1 in granulosa cells from prehierarchal follicles and to determine whether IGF1 and FSH synergize to promote follicle development. Granulosa cells of 3-5 and 6-8 mm prehierarchal follicles were cultured with IGF1 (0, 10, 100 ng/mL) in the presence or absence of FSH (0, 10 ng/mL). Cell proliferation, expression of genes important in follicle development (FSHR, IGF1R, AMH, STAR, CYP11A1, INHA, and INHBA), and progesterone production were evaluated following treatment. IGF1 treatment alone significantly increased STAR, CYP11A1, and INHBA mRNA expression and cell proliferation in granulosa cells of 6-8 mm follicles. IGF1 and FSH synergized to increase STAR mRNA expression in 6-8 mm follicles. IGF1 and FSH co-treatment were necessary to increase INHA mRNA expression in 6-8 mm follicles. Although IGF1 significantly increased the expression of genes involved in steroidogenesis, progesterone production in granulosa cells of 6-8 mm follicles was not affected. IGF1 did not affect AMH mRNA expression, although FSH significantly decreased AMH expression in granulosa cells of 3-5 mm follicles. These results suggest that IGF1 may act with FSH to promote follicle selection at the prehierarchal follicle stage.

Copper exposure induces ovarian granulosa cell apoptosis by activating the caspase-dependent apoptosis signaling pathway and corresponding changes in microRNA patterns

Environmental copper (Cu) contamination is a complex worldwide public health problem. However, information on the effects of Cu pollution on human reproduction is limited. Although our previous studies have indicated that Cu exposure disrupts ovarian folliculogenesis, the underlying mechanism needs to be further explored. In this study, human luteinized ovarian granulosa cells and a rat animal model were used to investigate whether Cu exposure affects ovarian follicle development by inducing apoptosis and to elucidate the possible mechanisms. The results showed that Cu exposure from weaning to sexual maturity significantly decreased the proportion of preantral follicles but increased the proportion of atretic follicles (P < 0.05). In addition, 6 mg/kg Cu increased the proportion of antral follicles, while 12 and 25 mg/kg Cu decreased it (P < 0.05). We also found that 6 mg/kg Cu exposure inhibited apoptosis of ovarian granulosa cells, while 12 and 25 mg/kg Cu promoted apoptosis (P < 0.05). Experiments on primary human luteinized ovarian granulosa cells suggested that higher levels of Cu exposure induced a significant increase in the mRNA levels of Bcl2 Bax , Fas, Caspase8, and Caspase3 (P < 0.05), and the protein levels of BAX, BCL2, CASPASE3, CASPASE8, CLE-CASPASE3, CLE-CASPASE8 and BAX/BCL2 were also increased (P < 0.05). miRNA chip analyses identified a total of 95 upregulated and 10 downregulated miRNAs in human luteinized granulosa cells exposed to Cu. Hsa-miR-19b-3p, hsa-miR-19a-3p, miR-548ar-3p, hsa-miR-652-5p, and hsa-miR-29b-5p were decreased after Cu exposure (P < 0.05). Additionally, the level of hsa-miR-144-5p was increased (P < 0.05). Together, our results reveal that Cu exposure induces abnormal ovarian folliculogenesis by inducing ovarian granulosa cell apoptosis, which is triggered by the caspase-dependent apoptosis signaling pathway, and that miRNAs may be involved in this process.

The Aging Ovary and the Tales Learned Since Fetal Development

BACKGROUND

While the term "aging" implies a process typically associated with later life, the consequences of ovarian aging are evident by the time a woman reaches her forties, and sometimes earlier. This is due to a gradual decline in the quantity and quality of oocytes which occurs over a woman's reproductive lifespan. Indeed, the reproductive potential of the ovary is established even before birth, as the proper formation and assembly of the ovarian germ cell population during fetal life determines the lifetime endowment of oocytes and follicles. In the ovary, sophisticated molecular processes have been identified that regulate the timing of ovarian aging and these are critical to ensuring follicular maintenance.

SUMMARY

The mechanisms thought to contribute to overall aging have been summarized under the term the "hallmarks of aging" and include such processes as DNA damage, mitochondrial dysfunction, telomere attrition, genomic instability, and stem cell exhaustion, among others. Similarly, in the ovary, molecular processes have been identified that regulate the timing of ovarian aging and these are critical to ensuring follicular maintenance. In this review, we outline critical processes involved in ovarian aging, highlight major achievements for treatment of ovarian aging, and discuss ongoing questions and areas of debate.

KEY MESSAGES

Ovarian aging is recognized as what may be a complex process in which age, genetics, environment, and many other factors contribute to the size and depletion of the follicle pool. The putative hallmarks of reproductive aging outlined herein include a diversity of plausible processes contributing to the depletion of the ovarian reserve. More research is needed to clarify if and to what extent these putative regulators do in fact govern follicle and oocyte behavior, and how these signals might be integrated in order to control the overall pattern of ovarian aging.

The role of anti-Mullerian hormone and other correlates in patients with polycystic ovary syndrome

BACKGROUND

Anti-Müllerian hormone (AMH) has recently emerged as a promising biomarker for the detection of polycystic ovarian morphology. In polycystic ovary syndrome (PCOS), an elevated level of AMH has been suggested to add value to the Rotterdam criteria in cases of diagnostic uncertainty. In this study, we evaluated the correlation between AMH and PCOS, and the potential role of AMH in PCOS diagnosis.

METHODS

A case-control study was performed on a total of 200 females, 100 of which were diagnosed with PCOS as per Rotterdam revised criteria (2003) and 100 as the control (non-PCOS group). Patient medical records were therefore retrieved for clinical, biochemical and ultrasound markers for PCOS diagnosis. Sensitivity, specificity, area under receiver operating characteristic (AUROC) curve, and multivariate linear regression models were applied to analyze our data.

RESULTS

Mean serum levels of LH and AMH, and LH/FSH ratio were significantly different between compared groups. In the PCOS group, the mean serum AMH level was 6.78 ng/mL and LH/FSH ratio was 1.53 while those of controls were 2.73 ng/mL and 0.53, respectively (p < .001). The most suitable compromise between 81% specificity and 79% sensitivity was obtained with a cutoff value of 3.75 ng/mL (26.78 pmol/L) serum AMH concentration for PCOS prediction, with an AUROC curve of 0.9691.

CONCLUSION

Serum AMH cutoff level of 3.75 ng/mL was identified as a convenient gauge for the prediction of PCOS and an adjuvant to the Rotterdam criteria.

AMH and other markers of ovarian function in patients with Turner syndrome - a single center experience of transition from pediatric to gynecological follow up

Turner syndrome (TS) is a chromosomal disorder that affects about 1 in 2500 female births and is characterized by the partial or complete absence of the second X chromosome. Depending on karyotype, TS is associated with primary ovarian insufficiency (POI). Approximately 50% of girls with a mosaic 45, X/46, XX karyotype may enter puberty spontaneously, but only 5-10% of women with TS achieve pregnancy without egg donation. In this review, we will evaluate the clinical use of markers of ovarian function in TS patients. Based on longitudinal studies of serum concentrations of reproductive hormones as well as ovarian morphology in healthy females and patients with TS, we will evaluate how they can be applied in a clinical setting. This is important when counseling patients and their families about future ovarian function essential for pubertal development and fertility. Furthermore, we will report on 20 years of experience of transition from pediatric to gynecological and adult endocrinological care in our center at Rigshospitalet, Copenhagen, Denmark.

Recombinant anti-Mullerian hormone treatment attenuates primordial follicle loss after ovarian cryopreservation and transplantation

PURPOSE

The foremost drawback of ovarian tissue cryopreservation and re-transplantation (OTCT) technique is the rapid loss of the primordial follicle (PF) pool. In recent studies, we have demonstrated that post-transplantation burnout of the PFs occurs due to the altered expression of the activatory and inhibitory proteins that control PF reserve, and rapamycin prevented it.

METHODS

Here, we investigated whether anti-Mullerian hormone administration in the bilateral oophorectomy and transplantation group and internal AMH in the unilateral oophorectomy and transplantation group protect follicle reserve by regulating the expression of the molecules that control follicle growth after OTCT in mice.

RESULTS

After 14 days of OTCT, PF reserve is significantly reduced in both unilateral oophorectomy and transplantation and bilateral oophorectomy and transplantation groups, while anti-Mullerian hormone treatment attenuates PF loss after bilateral oophorectomy and transplantation. The expression of KitL, Bmp-15, and p27 decreased after unilateral oophorectomy and transplantation and bilateral oophorectomy and transplantation, yet recombinant anti-Mullerian hormone treatment did not restore the expression of these proteins in the BLO-T group.

CONCLUSION

Exogenous recombinant anti-Mullerian hormone administration in the BLO-T group preserved the expressions of Tsc1 and Gdf-9 in PF and p-s6k and Gdf-9 in growing follicles after OTCT. Nonetheless, recombinant anti-Mullerian hormone administration did not affect granulosa cell proliferation and death rates in the growing follicles. These findings suggest a novel hormonal replacement strategy for fertility preservation by restoring anti-Mullerian hormone to regulate Tsc1 and p-s6k, thereby linking this hormone with the mTOR pathway and Gdf-9 signaling.

Follicular Atresia, Cell Proliferation, and Anti-Mullerian Hormone in Two Neotropical Primates (Aotus nancymae and Sapajus macrocephalus)

This study evaluated the follicular atresia, cell proliferation, and anti-Mullerian hormone action in Aotus nancymae and Sapajus macrocephalus during three sexual phases (follicular, luteal, and gestational). Follicular quantification and immunolocalization of Caspase-3 protein, B-cell lymphoma 2 (BCL-2), proliferating cell nuclear antigen (PCNA), and anti-Mullerian hormone (AMH) were performed. A significant difference in the quantification between preantral and antral follicles, with a progressive decrease in the antrals, was identified. Protein and hormonal markers varied significantly between follicle cell types (A. nancymae p = 0.001; S. macrocephalus, p = 0.002). Immunostaining in the preantral and antral follicles was present in all sexual phases; for Caspase-3, in granulosa cells, oocytes, and stroma; for BCL-2, in granulosa cells, oocytes, and theca; and for PCNA and AMH, in oocytes and granulosa cells. The immunostaining for Caspase-3 was more expressive in the preantral follicles (follicular phase, p < 0.05), while that for BCL-2 and PCNA was more expressive in the antral follicles of the follicular phase. The AMH was more expressive in the primary and antral follicles of nonpregnant females, in both the follicular and luteal phases. Our results contribute to understanding the ovarian follicular selection, recruitment, and degeneration of these species.

Nasal immunization with AMH-INH-RFRP DNA vaccine for improving follicle development and fertility in buffaloes

Introduction

Inhibin DNA vaccine has already been proven to improve the fertility of animals. This study aimed to investigate the effects of a novel Anti-Müllerian hormone (AMH)-Inhibin (INH)-RF-amide-related peptides (RFRP) DNA vaccine on immune response and reproductive performance in buffalo.

Methods

A total of 84 buffaloes were randomly divided into four groups and nasally immunized twice a day with 10 ml of either AMH-INH-RFRP DNA vaccines (3 × 1010 CFU/ml in group T1, 3 × 109 CFU/ml in group T2, and 3 × 108 CFU/ml in group T3) or PBS (as a control) for 3 days, respectively. All animals received a booster dose at an interval of 14 days.

Results

ELISA assay revealed that primary and booster immunization significantly increased the anti-AMH, anti-INH, and anti-RFRP antibody titers in the T2 group compared with that in the T3 group. After the primary immunization, the antibody positive rate was significantly higher in the T2 group than that in the T3 group. In addition, ELISA results indicated that concentrations of E2, IFN-γ, and IL-4 were significantly higher in the antibody-positive (P) group compared to the antibody-negative (N) group. In contrast, there was no significant difference in the concentrations of P4 between the P and N groups. Ultrasonography results revealed a highly significant increase of 2.02 mm in the diameter of ovulatory follicles in the P group compared to the N group. In parallel, growth speed of dominant follicles was significantly higher in the P group than that in the N group (1.33 ± 1.30 vs 1.13 ± 0.12). Furthermore, compared to N group, the rates of oestrus, ovulation, and conception were also significantly higher in the P group.

Conclusion

The novel AMH-INH-RFRP DNA vaccine improves the proportion of oestrus, ovulation, and conception in buffalo by promoting the production of E2 and the growth of follicles.

Serum Anti-Müllerian Hormone Levels and Estrous Monitoring of GnRH Agonist Deslorelin-Induced Estrus in Bitches: A Pilot Study

This study was performed to monitor estrous patterns and, more importantly, changes in anti-Müllerian hormone (AMH) concentrations during the peri-ovulatory period in deslorelin-induced estrous bitches. Healthy anestrous bitches (n = 4) were used. Estrus and ovulation were monitored after deslorelin implantation. Blood samples were collected for analysis of progesterone, estradiol-17ß and AMH concentrations before implantation (day 0) and on days 6, 8, 10, 12, 14, 16, 18, 20 and 22 after implantation. Six days following treatment, all bitches showed estrus signs. Ovulation took place between days 12 and 15. Circulating AMH concentrations varied among bitches from 0.12 to 3.08 ng/mL. However, no significant differences in AMH levels (mean ± SD) were observed between day 0 and days following post-implantation (p > 0.05). There were no significant correlations between AMH and estradiol or AMH and progesterone (p > 0.05). Ultrasonographically, the number of clearly identifiable ovarian follicles was higher before ovulation and the area of ovaries increased after ovulation (p < 0.05). Except for AMH, changes in vaginal cytology, estradiol-17ß and progesterone levels observed in our study were similar to naturally occurring estrus. Large intra- and inter-individual variation in AMH were observed suggesting that AMH is currently not suitable as a canine fertility marker to monitor ovarian response to deslorelin treatment for estrus induction.

AMH concentrations in infancy and mid-childhood predict ovarian activity in adolescence: A long-term longitudinal study of healthy girls

BACKGROUND

Anti-Müllerian hormone (AMH) is produced by granulosa cells in small growing ovarian follicles. In adult women, serum concentrations of AMH reflect the ovarian reserve of resting primordial follicles, and low AMH is associated with risk of early menopause. In contrast, patients with polycystic ovary syndrome (PCOS) have elevated AMH. The primary aim of this study was to evaluate the individual tracking of serum AMH concentrations, as well as whether AMH in early childhood reflects ovarian activity in adolescence.

METHODS

In this large longitudinal study of healthy girls were examined from infancy to adolescence (1997-2019) including physical examination, assessment of serum concentrations of reproductive hormones (in infancy, median age 0.3 yrs; mid-childhood, 7.2 yrs; puberty, 11.3 yrs; and adolescence, 15.9 yrs), transabdominal ultrasound (TAUS, puberty and adolescence) and magnetic resonance imaging (MRI, puberty) of the ovaries.

FINDINGS

Each girl maintained her relative AMH concentration (expressed as standard deviation (SD) scores) over time; mean variation of individual age adjusted AMH concentrations was 0.56 ± 0.31 SD.Serum concentrations of AMH in adolescence correlated with AMH in infancy and childhood; infancy: r = 0.347; mid-childhood: r = 0.637; puberty: r = 0.675, all p < 0.001.AMH correlated negatively with FSH concentrations in all age groups (infancy: r = -0.645, p < 0.001; mid-childhood: r = -0.222, p < 0.001; puberty: r = -0.354, p < 0.001; adolescence: n = 275, r = -0.175, p = 0.004).Serum AMH concentrations in mid-childhood correlated with the number of follicles in puberty (TAUS and MRI) as well as in adolescence (TAUS); e.g. total number of follicles: TAUS puberty (r = 0.607), MRI puberty (r = 0.379), TAUS adolescence (r = 0.414), all p < 0.001.AMH concentration in infancy as well as in mid-childhood predicted low AMH (<10 pmol/L) in adolescence; AMH infancy <7.5 pmol/L as predictor of low AMH in adolescence: sensitivity 0.71, specificity 0.70, AUC 0.759; AMH mid-childhood < 8.4 pmol/L as predictor of low AMH in adolescence: sensitivity 0.88, specificity 0.87, AUC 0.949.Girls with high serum AMH concentration in mid-childhood (AMH >30.0 pmol/L vs. other girls) had higher adolescent LH (median 4.53 vs. 3.29 U/L p = 0.041), LH/FSH ratio (1.00 vs 0.67, p = 0.019), testosterone (1.05 vs 0.81 nmol/L, p = 0.005), total number of follicles (23 vs. 19, p = 0.004), and higher prevalence of irregular cycles (10/15 = 67% vs. 28/113 = 25%, p = 0.002).

INTERPRETATION

The present findings suggest remarkably stable ovarian activity from small growing follicles in healthy girls, supporting AMH in early life as a useful clinical tool to predict future ovarian activity.

FUNDING

The work was supported by The Center on Endocrine Disruptors (CeHoS) under The Danish Environmental Protection Agency and The Ministry of Environment and Food (grant number: MST-621-00 065), the EU (QLK4-CT1999-01422; QLK4-2001-00269), the Novo Nordisk Foundation and The Danish Ministry of Science Technology and Innovation (2107-05-0006). A.S.B. is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 464240267. KM receives honoraria from Novo Nordisk A/S for teaching at the Danish annual postgraduate course of pituitary diseases.

Age-related changes in Folliculogenesis and potential modifiers to improve fertility outcomes - A narrative review

Reproductive aging is characterized by a decline in oocyte quantity and quality, which is directly associated with a decline in reproductive potential, as well as poorer reproductive success and obstetrical outcomes. As women delay childbearing, understanding the mechanisms of ovarian aging and follicular depletion have become increasingly more relevant. Age-related meiotic errors in oocytes are well established. In addition, it is also important to understand how intraovarian regulators change with aging and how certain treatments can mitigate the impact of aging. Individual studies have demonstrated that reproductive pathways involving antimullerian hormone (AMH), vascular endothelial growth factor (VEGF), neurotropins, insulin-like growth factor 1 (IGF1), and mitochondrial function are pivotal for healthy oocyte and cumulus cell development and are altered with increasing age. We provide a comprehensive review of these individual studies and explain how these factors change in oocytes, cumulus cells, and follicular fluid. We also summarize how modifiers of folliculogenesis, such as vitamin D, coenzyme Q, and dehydroepiandrosterone (DHEA) may be used to potentially overcome age-related changes and enhance fertility outcomes of aged follicles, as evidenced by human and rodent studies.

Deciphering the Roles & Regulation of Estradiol Signaling during Female Mini-Puberty: Insights from Mouse Models

Mini-puberty of infancy is a short developmental phase occurring in humans and other mammals after birth. In females, it corresponds to transient and robust activation of the hypothalamo-pituitary-ovarian (HPO) axis revealed by high levels of gonadotropin hormones, follicular growth, and increased estradiol production by the ovary. The roles of estradiol signaling during this intriguing developmental phase are not yet well known, but accumulating data support the idea that it aids in the implementation of reproductive function. This review aims to provide in-depth information on HPO activity during this particular developmental phase in several mammal species, including humans, and to propose emerging hypotheses on the putative effect of estradiol signaling on the development and function of organs involved in female reproduction.

RNA-seq identifies differentially expressed genes involved in csal1 overexpression in granulosa cells of prehierarchical follicles in Chinese Dagu hens

The transcription factor csal1 is an important molecule that plays a critical regulatory function in ovarian follicle development, as confirmed by our previous data. However, the candidate genes of csal1 and its regulatory mechanism remain poorly understood in the granulosa cells (GCs) of chicken prehierarchical follicles (PFs). Six transcriptomes of csal1 and empty vector were analyzed in Chinese Dagu hens by RNA sequencing. Six cDNA libraries were constructed, with more than 42 million clean reads and 16,779 unigenes. Of these 16,779 unigenes, 2,762 differentially expressed genes (DEGs) were found in GCs, including 1,605 upregulated and 1,157 downregulated unigenes. Fourteen genes, including BMP5, TACR2, AMH, PLAG1, MYOD1, BOP1, SIPA1, NOTCH1, BCL2L1, SOX9, ADGRA2, WNT5A, SLC7A11, and GATAD2B, were related to GC proliferation and differentiation, hormone production, ovarian follicular development, regulation of reproductive processes, and signaling pathways in the PFs. Further analysis demonstrated the DEGs in GCs of ovarian follicles were enriched in neuroactive ligand-receptor interaction, cell adhesion molecules, and pathways related to cytochrome P450, indicating a critical function for csal1 in the generation of egg-laying features by controlling ovarian follicle development. For the first time, the current study represents the transcriptome analysis with ectopic csal1 expression. These findings provide significant evidence for investigating the molecular mechanism by which csal1 controls PF development in the hen ovary.

Anti-Müllerian hormone-mediated preantral follicle atresia is a key determinant of antral follicle count in mice

STUDY QUESTION

Does anti-Müllerian hormone (AMH) induce preantral follicle atresia in mice?

SUMMARY ANSWER

The present findings suggest that AMH-mediated follicle atresia only occurs in early follicles before they become sensitive to FSH.

WHAT IS KNOWN ALREADY

Most prior studies have investigated the ability of AMH to inhibit primordial follicle activation. Our previous study showed that AMH-overexpressing mice had fewer preantral follicles than expected after accounting for primordial follicle inhibition but the reason for this was not determined.

STUDY DESIGN, SIZE, DURATION

Cross-sectional-control versus transgenic/knockout mouse studies were carried out.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Studies were conducted on female wild-type (Amh+/+), AMH-knockout (Amh-/-) and AMH overexpressing (Thy1.2-AMHTg/0) mice on a C57Bl/6J background (age: 42-120 days). The follicle counts were conducted for primordial, transitioning, primary, secondary and antral follicles in Amh-/- and Amh+/+ mice. After confirming that follicle development speeds were identical (proliferating cell nuclear antigen immunohistochemistry), the ratio of follicles surviving beyond each stage of folliculogenesis was determined in both genotypes. Evidence for increased rates of preantral follicle atresia was assessed by active caspase-3 immunohistochemistry in wild-type and Thy1.2-AMHTg/0 mice.

MAIN RESULTS AND THE ROLE OF CHANCE

Amh -/- mice at 100-120 days of age had lower primordial follicle counts but higher primordial follicle activation rates compared to Amh+/+ mice. These counteracting effects led to equivalent numbers of primordial follicles transitioning to the primary stage in Amh+/+ and Amh-/- mice. Despite this, Amh+/+ mice had fewer primary, secondary, small antral and medium antral follicles than Amh-/- mice indicating differing rates of developing follicle atresia between genotypes. Cleaved caspase-3 immunohistochemistry in Thy1.2-AMHTg/0 ovaries revealed high rates of granulosa cell and oocyte apoptosis in late primary/early secondary follicles of Thy1.2-AMHTg/0 mice.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The findings were shown only in one species and additional research will be required to determine generalizability to other species.

WIDER IMPLICATIONS OF THE FINDINGS

This study is consistent with prior studies showing that Amh-/- mice have increased primordial follicle activation but these new findings demonstrate that AMH-mediated preantral follicle atresia is a predominant cause of the increased small antral follicle counts in Amh-/- mice. This suggests that the role of AMH is not to conserve the ovarian reserve to prolong fertility, but instead to prevent the antral follicle pool from becoming too large. While this study may demonstrate a new function for AMH, the biological purpose of this function requires further investigation, particularly in mono-ovulatory species.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Health Research Council of New Zealand and the University of Otago. No competing interests to declare.