Occupational exposures to chemicals as a possible etiology in premature ovarian failure: a critical analysis of the literature

PDCD4 deficiency improved 4-vinylcyclohexene dioxide-induced mouse premature ovarian insufficiency

RESEARCH QUESTION

What role does programmed cell death 4 (PDCD4) play in premature ovarian insufficiency (POI)?

DESIGN

A PDCD4 gene knockout (PDCD4-/-) mouse model was constructed, a POI mouse model was established similar to human POI with 4-vinylcyclohexene dioxide (VCD), a PDCD4-overexpressed adenovirus was designed and the regulatory role in POI in vitro and in vivo was investigated.

RESULTS

PDCD4 expression was significantly increased in the ovarian granulosa cells of patients with POI (P ≤ 0.002 protein and mRNA) and mice with VCD-induced POI (P < 0.001 protein expression in both mouse ovaries and granulosa cells). In POI-induced mice model, PDCD4 knockouts significantly increased anti-Müllerian hormone, oestrodiol and numbers of developing follicles, and the PI3K-AKT-Bcl2/Bax signalling pathway is involved in it.

CONCLUSION

The expression and regulation of PDCD4 significantly affects the POI pathology in a mouse model. This effect is closely related to the regulation of Bcl2/Bax and the activation of the PI3K-AKT signalling pathway.

HNF1A gene mutations and premature ovarian failure (POF): evidence from a clinical paradigm combining MODY 3 and POF

Premature ovarian failure (POF) defines the occurrence of ovarian failure prior to the age of 40. It occurs in one out of 100 women but is very rare before age 20 (1:10,000). Maturity-onset diabetes of the young (MODY), caused by mutations in the HNF1A gene, is also a rare disorder; all types of MODY account for 1-2% of adult diabetic cases. These two rare nosologic entities coexisted in an adolescent girl evaluated for delayed puberty. Although this combination could represent a chance association, an interrelation might exist. We examined HNF1A expression in human fetal and adult ovaries by immunohistochemistry using a polyclonal HNF1A antibody. HNF1A protein was expressed in both the fetal and adult human ovaries. Based on these findings, we hypothesize that HNF1A participates in ovarian organogenesis and/or function and that mutations in the HNF1A gene might represent another molecular defect causing POF, possibly in combination with other genetic factors. The study underlines the importance of rare clinical paradigms in leading the way to elucidation of the pathogenetic mechanisms of rare diseases.

Epigenetic regulation in premature ovarian failure: A literature review

Premature ovarian failure (POF), or premature ovarian insufficiency (POI), is a multifactorial and heterogeneous disease characterized by amenorrhea, decreased estrogen levels and increased female gonadotropin levels. The incidence of POF is increasing annually, and POF has become one of the main causes of infertility in women of childbearing age. The etiology and pathogenesis of POF are complex and have not yet been clearly elucidated. In addition to genetic factors, an increasing number of studies have revealed that epigenetic changes play an important role in the occurrence and development of POF. However, we found that very few papers have summarized epigenetic variations in POF, and a systematic analysis of this topic is therefore necessary. In this article, by reviewing and analyzing the most relevant literature in this research field, we expound on the relationship between DNA methylation, histone modification and non-coding RNA expression and the development of POF. We also analyzed how environmental factors affect POF through epigenetic modulation. Additionally, we discuss potential epigenetic biomarkers and epigenetic treatment targets for POF. We anticipate that our paper may provide new therapeutic clues for improving ovarian function and maintaining fertility in POF patients.

Impact of benzo[a]pyrene with other pollutants induce the molecular alternation in the biological system: Existence, detection, and remediation methods

The exposure of benzo [a]pyrene (BaP) in recent times is rather unavoidable than ever before. BaP emissions are sourced majorly from anthropogenic rather than natural provenance from wildfires and volcanic eruptions. A major under-looked source is via the consumption of foods that are deep-fried, grilled, and charcoal smoked foods (meats in particular). BaP being a component of poly aromatic hydrocarbons has been classified as a Group I carcinogenic agent, which has been shown to cause both systemic and localized effects in animal models as well as in humans; has been known to cause various forms of cancer, accelerate neurological disorders, invoke DNA and cellular damage due to the generation of reactive oxygen species and involve in multi-generational phenotypic and genotypic defects. BaP's short and accumulated exposure has been shown in disrupting the fertility of gamete cells. In this review, we have discussed an in-depth and capacious run-through of the various origins of BaP, its economic distribution and its impact as well as toxicological effects on the environment and human health. It also deals with a mechanism as a single compound and its ability to synergize with other chemicals/materials, novel sensitive detection methods, and remediation approaches held in the environment.

Position statement on the diagnosis and management of premature/primary ovarian insufficiency (except Turner Syndrome)

Premature ovarian insufficiency (POI) is a rare pathology affecting 1-2% of under-40 year-old women, 1 in 1000 under-30 year-olds and 1 in 10,000 under-20 year-olds. There are multiple etiologies, which can be classified as primary (chromosomal, genetic, auto-immune) and secondary or iatrogenic (surgical, or secondary to chemotherapy and/or radiotherapy). Despite important progress in genetics, more than 60% of cases of primary POI still have no identifiable etiology; these cases are known as idiopathic POI. POI is defined by the association of 1 clinical and 1 biological criterion: primary or secondary amenorrhea or spaniomenorrhea of>4 months with onset before 40 year of age, and elevated follicle-stimulating hormone (FSH)>25IU/L on 2 assays at>4 weeks' interval. Estradiol level is low, and anti-Müllerian hormone (AMH) levels have usually collapsed. Initial etiological work-up comprises auto-immune assessment, karyotype, FMR1 premutation screening and gene-panel study. If all of these are normal, the patient and parents may be offered genome-wide analysis under the "France Génomique" project. The term ovarian insufficiency suggests that the dysfunction is not necessarily definitive. In some cases, ovarian function may fluctuate, and spontaneous pregnancy is possible in around 6% of cases. In confirmed POI, hormone replacement therapy is to be recommended at least up to the physiological menopause age of 51 years. Management in a rare diseases center may be proposed.

Urinary cadmium concentrations and risk of primary ovarian insufficiency in women: a case-control study

Cadmium, a toxic heavy metal that occurs in the environment in large quantities through human activities, has been shown to have adverse effects on female reproductive health. However, the association between cadmium exposure and primary ovarian insufficiency (POI), one of the most prevalent ovarian diseases in women, has not been examined yet. This case-control study involving 169 POI cases and 209 healthy controls was conducted in Zhejiang Province, China. The urinary concentrations of cadmium were determined by inductively coupled plasma mass spectrometry (ICP-MS). In addition, serum levels of reproductive hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), anti-Mullerian hormone (AMH) and estradiol, were measured. The median concentration of urinary cadmium in POI cases (0.43 μg/L, 0.58 μg/g for creatinine adjustment) was significantly higher than that of controls (0.29 μg/L, 0.43 μg/g for creatinine adjustment). The results of binary logistic regression models showed that the concentrations of urinary cadmium were positively significantly correlated with the odds ratio (ORs) of POI before the adjustment of confounders. After the adjustment, a significantly positive association was still present between the increased concentrations of cadmium and the ORs of POI (2.50, 95% CIs: 1.34-4.65 for the third tertile, p for trend = 0.001). The serum levels of FSH and LH were positively associated with urinary cadmium, while AMH and estradiol levels were inversely correlated. To the best of our knowledge, this is the first reported positive association of cadmium exposure with the risk of POI in women.

Effects of coenzyme Q10 on ovarian surface epithelium-derived ovarian stem cells and ovarian function in a 4-vinylcyclohexene diepoxide-induced murine model of ovarian failure

BACKGROUND

Several studies have shown that coenzyme Q10 (CoQ10) can rescue ovarian aging and that ovarian surface epithelium (OSE)-derived ovarian stem cells (OSCs) are useful for treating infertility due to ovarian aging. However, few studies have examined the effect of CoQ10 on OSCs. This study was aimed to investigate whether CoQ10 activates OSCs and recovers ovarian function in a 4-vinylcyclohexene diepoxide (VCD)-induced mouse model of ovarian failure.

METHODS

Forty female C57BL/6 mice aged 6 weeks were randomly divided into four groups (n = 10/group): a control group administered saline orally, a CoQ10 group administered 150 mg/kg/day of CoQ10 orally in 1 mL of saline daily for 14 days, a VCD group administered 160 mg/kg/day of VCD i.p. in 2.5 mL of saline/kg for 5 days, and a VCD + CoQ10 group administered VCD i.p. for 5 days injection and CoQ10 (150 mg/kg/day) orally for 14 days. After treatment, follicle counts were evaluated by hematoxylin and eosin (H&E) staining, and ovarian mRNA expressions of Bmp-15, Gdf-9, and c-Kit were examined by quantitative real-time PCR. Serum FSH, AMH, and ROS levels were also measured. Oocyte-like structure counts and the expressions of Oct-4 and MVH were also evaluated after culturing OSE for 3 weeks. In a second experiment, 32 female mice were administered CoQ10 as described above, induced to superovulate using PMSG and hCG, and mated. Numbers of zygotes and embryo development rate were examined.

RESULTS

Postcultured OSE showed significant increases in the numbers of oocyte-like structure and that the expression of Oct-4 and MVH were higher in the VCD + CoQ10 group than in the VCD group (p < 0.05). Numbers of surviving follicles from primordial to antral follicles, numbers of zygotes retrieved and embryo development rate to blastocyst were significantly greater in the VCD + CoQ10 group than in the VCD group (p < 0.01). Serum AMH level and ovarian expressions of Bmp-15, Gdf-9 and c-Kit were also significantly greater in the VCD + CoQ10 group than in the VCD group (p < 0.05). In contrast, serum ROS level was significantly lower in the VCD + CoQ10 group than in the VCD group (p < 0.05).

CONCLUSION

This study shows that CoQ10 stimulates the differentiation of OSE-derived OSCs and confirms that CoQ10 can reduce ROS levels and improve ovarian function and oocyte quality in mice with VCD-induced ovarian failure.

Ovarian Toxicity and Epigenetic Mechanisms of Phthalates and Their Metabolites

Ovary plays an important role in the female reproductive system. The maintenance and regulation of ovarian function are affected by various physical and chemical factors. With the development of industrialization, environmental pollutants have caused great harm to public health. Phthalates, as a class of endocrine-disrupting chemicals (EDCs), are synthesized and used in large quantities as plasticizers due to their chemical properties. They are easily released into environment because of their noncovalent interactions with substances, causing human exposure and possibly impairing ovary. In recent years, more and more attention has been paid to the role of epigenetics in the occurrence and development of diseases. And it is urgent to study the role of methylation, gene imprinting, miRNA, and other epigenetic mechanisms in reproductive toxicology.

Associations of age at natural menopause and occupations in Chinese female workers: A cross-sectional study

AIMS

To investigate the impact of occupation types on age at natural menopause.

METHODS

This is a nation-wide cross-sectional study based on 17,948 female workers aged over 40, who come from different industries or organizations. A face-to-face standardized questionnaire was conducted in all participants with the help of occupational hygienists. Occupational titles were coded according to the International Standard Classification of Occupations (2008) (ISCO08). Cox regression model was used to assess the association between each independent occupation and menopausal timing. Models were adjusted for marriage, education, average annual family income, parity, cigarette smoking, alcohol consumption.

RESULTS

Higher risks of earlier age at natural menopause was found among legislators and senior officials (ISCO Minor group:111, HR = 2.328, P < 0.001), among other health associated professionals (ISCO Minor group: 325, HR = 1.477, P = 0.003), the workers involved in mining and mineral processing (ISCO Minor group: 811, HR = 1.515, P = 0.048) and metal processing and finishing (ISCO Minor group: 812, HR = 1.722, P < 0.001). Reduced risks of earlier age at natural menopause, including: finance professionals (ISCO Minor group: 241, HR = 0.751, P = 0.021), manufacturing and construction supervisors (ISCO Minor group: 312, HR = 0.477, P = 0.002), administrative and specialized secretaries (ISCO Minor group: 334, HR = 0.788, P = 0.045), cleaners and helpers (ISCO Minor group: 911, HR = 0.633, P = 0.01).

CONCLUSIONS

This is the first study to address the influence of occupation types on reproductive aging, showing some specific occupations could be associated with age at natural menopause. Further investigations are necessary to clarify whether it is chance finding or a true association.

Concentrated exosomes from menstrual blood-derived stromal cells improves ovarian activity in a rat model of premature ovarian insufficiency

Background

Premature ovarian insufficiency (POI) is one of the major causes of infertility. We previously demonstrated that transplantation of menstrual blood-derived stromal cells (MenSCs) effectively improved ovarian function in a murine model of POI. Recent studies indicated that mesenchymal stem cell-derived exosomes were important components in tissue repair. In this study, we investigated the therapeutic effects of MenSCs-derived exosomes (MenSCs-Exos) in a rat model of POI and its mechanism in restoring ovulation.

Methods

Ovaries of 4.5-day-old Sprague Dawley rats (SD rats) were cultured in vitro to evaluate the effects of MenSCs-Exos exposure on early follicle development. Furthermore, POI in rats was induced by intraperitoneal administration of 4-vinylcyclohexene diepoxide (VCD). Forty-eight POI rats were randomly assigned to four groups, each receiving a different treatment: PBS, MenSCs, MenSCs-Exos, and Exo-free culture supernatant of MenSCs. Estrous cyclicity, ovarian morphology, follicle dynamics, serum hormones, pregnancy outcomes, and molecular changes were investigated.

Results

Exposure to MenSCs-Exos promoted the proliferation of granulosa cells in primordial and primary follicles in vitro and increased the expression of early follicle markers Deleted In Azoospermia Like (DAZL) and Forkhead Box L2 (FOXL2) while inhibiting follicle apoptosis. In vivo, MenSCs-Exos transplantation effectively promoted follicle development in the rat model of POI and restored the estrous cyclicity and serum sex hormone levels, followed by improving the live birth outcome. In addition, transplantation of MenSCs-Exos regulated the composition of the ovarian extracellular matrix and accelerated the recruitment of dormant follicles in the ovarian cortex and increased proliferation of granulosa cells in these follicles.

Conclusion

MenSCs-Exos markedly promoted follicle development in vitro and in vivo and restored fertility in POI rats, suggesting a restorative effect on ovarian functions. The therapeutic effect of MenSCs-Exos transplantation was sustainable, consistent with that of MenSCs transplantation. Our results suggested that MenSCs-Exos transplantation may be a promising cell-free bioresource in the treatment of POI.

Next Generation Sequencing Should Be Proposed to Every Woman With "Idiopathic" Primary Ovarian Insufficiency

Context

Primary ovarian insufficiency (POI) affects 1% of women under 40 years of age. POI is idiopathic in more than 70% of cases. Though many candidate genes have been identified in recent years, the prevalence and pathogenicity of abnormalities are still difficult to establish.

Objective

Our primary objective was to evaluate the prevalence of gene variations in a large prospective multicentric POI cohort. Our secondary objective was to evaluate the correlation between phenotype and genotype.

Methods

Two hundred and sixty-nine well-phenotyped POI patients were screened for variants of 18 known POI genes (BMP15, DMC1, EIF2S2, FIGLA, FOXL2, FSHR, GDF9, GPR3, HFM1, LHX8, MSH5, NOBOX, NR5A1, PGRMC1, STAG3, XPNPEP2, BHLB, and FSHB) by next generation sequencing (NGS). Abnormalities were classified as "variant" or "variant of unknown signification" (VUS) according to available functional tests or algorithms (SIFT, Polyphen-2, MutationTaster).

Results

One hundred and two patients (38%) were identified as having at least 1 genetic abnormality. Sixty-seven patients (25%) presented at least 1 variant. Forty-eight patients presented at least 1 VUS (18%). Thirteen patients (5%) had combined abnormalities. NOBOX variants were the most common gene variants involved in POI (9%). Interestingly, we saw no significant differences in the previous family history of POI, ethnic origin, age at onset of POI, primary amenorrhea, or secondary menstrual disturbances between the different genotypes.

Conclusion

In our study, a high percentage of patients presented gene variants detected by NGS analysis (38%). Every POI patient should undergo NGS analysis to improve medical cares of the patients.

Idiopathic primary ovarian insufficiency is associated with anogenital distance, a marker for prenatal environment

OBJECTIVE

In a significant number of women diagnosed with primary ovarian insufficiency (POI), the underlying cause cannot be found. On the other hand, the ovarian reserve set prenatally has been shown to be affected by intrauterine nutrition, environmental and hormonal factors. We aimed to evaluate the relationship between anogenital distance (AGD), which is considered as a biomarker for prenatal hormonal environment, and idiopathic POI in adolescents and young women.

STUDY DESIGN

This case control study was conducted between September 2018 and December 2019. The study group consisted of patients between the ages of 15-30, who developed POI following menarche without any identified genetic or iatrogenic cause. Controls were patients of the same age range who were having regular menstrual periods and were not diagnosed with polycystic ovary syndrome or endometriosis. Patients were excluded from the study if they were pregnant, had vaginal delivery or genital surgery. Distance between the anterior clitoral surface and the upper verge of the anus (AGD_AC), and between the posterior fourchette and the upper verge of the anus (AGD_AF) were measured in all subjects.

RESULTS

In total, 37 POI patients and 44 controls were included in the study. Two groups were similar for demographic parameters such as age and body mass index (BMI). Shorter AGD_AC and AGD_AF measurements were found to be associated with idiopathic POI.

CONCLUSION

Our results provide the first evidence of a strong association between shorter AGD measurements and the presence of idiopathic POI suggesting that prenatal environment may have role in the development of POI.

Anti-mullerian hormone levels in indian women seeking infertility treatment: Are Indian women facing early ovarian senescence?

Background:

Antimullerian hormone (AMH) is a key marker of ovarian reserve and predictor of response to fertility treatment.

Aim:

To understand the prevalence of low ovarian reserve in Indian women seeking infertility treatment, compare their AMH with age-matched fertile Indian controls and understand ethnic differences with Caucasian women.

Setting and Design:

Retrospective observational study done as collaboration between our in vitro fertilization centre and a laboratory with Pan-India presence.

Materials and Methods:

Women aged 20–44 years were selected as Group A (seeking infertility treatment n = 54,473), Group B (conceived naturally in the past; n = 283) and Group C (data of Caucasian women; n = 718). Serum AMH levels were measured and descriptive analysis done.

Statistical Analysis:

Descriptive statistics and Chi-square test.

Results:

In Group A, 28.7%, 48.7% and 70.6% of women aged <30 years, 30–34 years and 35–39 years had serum AMH levels ≤2 ng/mL and the proportions were higher than Group B. The rate at which median AMH decreased was 1.1–2 times faster in Group B as compared to Group C. The decrease in median AMH across age groups in Group A was similar to Group B.

Conclusions:

Indian women in their late twenties and early thirties visiting fertility centers showed a worrisome trend of low AMH. Our study can be used as a reference for those women considering postponing pregnancy. It may be time to look at intangible cultural factors linked to social habits, ethnicity, diet, genetic predispositions, and environmental factors like endocrine disrupting chemicals contributing to premature ovarian senescence.

A critical analysis of the impact of endocrine disruptors as a possible etiology of primary ovarian insufficiency

Primary ovarian insufficiency is a cause of infertility that affects about 1% of women under 40 years old, and is considered as idiopathic in 75% of cases. This review aims to carry out a critical synthesis of the knowledge of the chemical agents likely to affect follicular stock in humans and / or animals, by direct toxicity to follicles, or by increasing their recruitments. For the majority of toxic agents, only experimental data are currently available. We propose a strategy to encourage progress in identifying occupational factors responsible for premature ovarian failure.

Possible role of n-hexane as an endocrine disruptor in occupationally exposed women at reproductive age

Human exposure to n-hexane has been associated with subfertility and, experimentally, with a decrease in follicular development. In order to assess occupational exposure to n-hexane on ovarian function and gonadotropic hormones, we studied Mexican women labouring in a leather shoe factory (n = 34). Individual environmental levels for seven solvents, n-hexane included, were measured; also, urinary 2,5-hexanedione (2,5-HD) was determined. For ovarian function and hormonal status, FSH, LH, oestradiol and anti-Müllerian hormone (AMH) levels were determined. We performed all determinations also in a reference group, administrative workers with no exposure to solvents (n = 32). Results: N-hexane and urinary 2,5-HD levels were higher in exposed group (p < 0.001). More cases of oligomenorrhea as well as longer time for getting pregnant were observed in exposed women compared with controls; a positive association was found between menstrual cycle length and "time for getting pregnant" (p = 0.010); significant associations between FSH serum levels and 2,5-HD urinary levels (post-shift sample) were observed in non-smokers participants presenting oligomenorrhea from exposed group. Also, we found a trend for lower oestradiol levels in exposed participants with current smoking habit (p = 0.059). Conclusions: 2,5-HD urinary levels are associated with decreased gonadotropins levels; hence, n-hexane should be considered an endocrine disruptor in reproductive-age women.

Establishment and depletion of the ovarian reserve: physiology and impact of environmental chemicals

The reproductive life span in women starts at puberty and ends at menopause, following the exhaustion of the follicle stockpile termed the ovarian reserve. Increasing data from experimental animal models and epidemiological studies indicate that exposure to a number of ubiquitously distributed reproductively toxic environmental chemicals (RTECs) can contribute to earlier menopause and even premature ovarian failure. However, the causative relationship between environmental chemical exposure and earlier menopause in women remains poorly understood. The present work, is an attempt to review the current evidence regarding the effects of RTECs on the main ovarian activities in mammals, focusing on how such compounds can affect the ovarian reserve at any stages of ovarian development. We found that in rodents, strong evidence exists that in utero, neonatal, prepubescent and even adult exposure to RTECs leads to impaired functioning of the ovary and a shortening of the reproductive lifespan. Regarding human, data from cross-sectional surveys suggest that human exposure to certain environmental chemicals can compromise a woman's reproductive health and in some cases, correlate with earlier menopause. In conclusion, evidences exist that exposure to RTECs can compromise a woman's reproductive health. However, human exposures may date back to the developmental stage, while the adverse effects are usually diagnosed decades later, thus making it difficult to determine the association between RTECs exposure and human reproductive health. Therefore, epidemiological surveys and more experimental investigation on humans, or alternatively primates, are needed to determine the direct and indirect effects caused by RTECs exposure on the ovary function, and to characterize their action mechanisms.

Outcomes of random start versus clomiphene citrate and gonadotropin cycles in occult premature ovarian insufficiency patients, refusing oocyte donation: a retrospective cohort study

The aim of this study is to present the clinical outcomes of a random start, a spontaneous folliculogenesis protocol versus Clomiphene Citrate and Gonadotropin treatment in women with occult premature ovarian insufficiency. Women underwent treatment between 1 February 2009, and 30 May 2016. 41 women were treated with the random start protocol while 48 cases received ovarian stimulation with clomiphene and gonadotropins. All included cases met the criteria of 4 months of oligo-ovulation, follicular-stimulating hormone levels over 30 IU/L and anti-Mullerian hormone levels below 0.30 ng/mL. The random start protocol involved following the subjects for up to 6 months until spontaneous folliculogenesis occurred. The mean number of oocytes collected, mature oocytes, fertilized oocytes, and grade II embryos were significantly higher in the random start protocol (p < .05). The doses of gonadotropin administration and hCG were significantly lower in the random start protocol (p < .05). The clinical pregnancy and live birth rates were significantly higher in the random start protocol (p < .05). Likely stimulation is of little benefit in women with occult premature ovarian insufficiency. Observation while waiting for spontaneous folliculogenesis results in better outcomes, and less oocyte collections.

Environmental pollutants, a possible etiology for premature ovarian insufficiency: a narrative review of animal and human data

BACKGROUND

Because only 25% of cases of premature ovarian insufficiency (POI) have a known etiology, the aim of this review was to summarize the associations and mechanisms of the impact of the environment on this pathology. Eligible studies were selected from an electronic literature search from the PUBMED database from January 2000 to February 2016 and associated references in published studies. Search terms included ovary, follicle, oocyte, endocrine disruptor, environmental exposure, occupational exposure, environmental contaminant, pesticide, polyaromatic hydrocarbon, polychlorinated biphenyl PCB, phenol, bisphenol, flame retardant, phthalate, dioxin, phytoestrogen, tobacco, smoke, cigarette, cosmetic, xenobiotic. The literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We have included the human and animal studies corresponding to the terms and published in English. We have excluded articles that included results that did not concern ovarian pathology and those focused on ovarian cancer, polycystic ovary syndrome, endometriosis or precocious puberty. We have also excluded genetic, auto-immune or iatrogenic causes from our analysis. Finally, we have excluded animal data that does not concern mammals and studies based on results from in vitro culture. Data have been grouped according to the studied pollutants in order to synthetize their impact on follicular development and follicular atresia and the molecular pathways involved. Ninety-seven studies appeared to be eligible and were included in the present study, even though few directly address POI. Phthalates, bisphenol A, pesticides and tobacco were the most reported substances having a negative impact on ovarian function with an increased follicular depletion leading to an earlier age of menopause onset. These effects were found when exposure occured at different times throughout the lifetime from the prenatal to the adult period, possibly due to different mechanisms. The main mechanism seemed to be an increase in atresia of pre-antral follicles.

CONCLUSION

Environmental pollutants are probably a cause of POI. Health officials and the general public must be aware of this environmental effect in order to implement individual and global preventive actions.

Maternal exposure to di(2-ethylhexyl)phthalate (DEHP) promotes the transgenerational inheritance of adult-onset reproductive dysfunctions through the female germline in mice

Endocrine disruptors (EDs) are compounds known to promote transgenerational inheritance of adult-onset disease in subsequent generations after maternal exposure during fetal gonadal development. This study was designed to establish whether gestational and lactational exposure to the plasticizer di(2-ethylhexyl)phthalate (DEHP) at environmental doses promotes transgenerational effects on reproductive health in female offspring, as adults, over three generations in the mouse. Gestating F0 mouse dams were exposed to 0, 0.05, 5mg/kg/day DEHP in the diet from gestational day 0.5 until the end of lactation. The incidence of adult-onset disease in reproductive function was recorded in F1, F2 and F3 female offspring. In adult F1 females, DEHP exposure induced reproductive adverse effects with: i) altered ovarian follicular dynamics with reduced primordial follicular reserve and a larger growing pre-antral follicle population, suggesting accelerated follicular recruitment; ii) reduced oocyte quality and embryonic developmental competence; iii) dysregulation of the expression profile of a panel of selected ovarian and pre-implantation embryonic genes. F2 and F3 female offspring displayed the same altered reproductive morphological phenotype and gene expression profiles as F1, thus showing transgenerational transmission of reproductive adverse effects along the female lineage. These findings indicate that in mice exposure to DEHP at doses relevant to human exposure during gonadal sex determination significantly perturbs the reproductive indices of female adult offspring and subsequent generations. Evidence of transgenerational transmission has important implications for the reproductive health and fertility of animals and humans, significantly increasing the potential biohazards of this toxicant.

Akt activation by Evodiae Fructus extract protects ovary against 4-vinylcyclohexene diepoxide-induced ovotoxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Evodiae Fructus (EF) is the dried, unripe fruit of Evodia rutaecarpa Benth., and one of the main components of traditional herbal prescriptions issued for the treatment of sterility caused by irregular menstruation in Korea. However, scientific evidence regarding the efficacy and action mechanism of EF is lacking.

AIM OF THE STUDY

In this study, the authors established an in vitro screening tool to identify promising new drug candidates in herbal medicines for the prevention and treatment of premature ovarian failure. The protective effects of EF extracts against 4-vinylcyclohexene diepoxide (VCD)-induced ovotoxicity were investigated and the molecular mechanism responsible was sought.

MATERIAL AND METHODS

EF extract was prepared by boiling EF in water and its quality was confirmed by high performance liquid chromatography. CHO-K1 (Chinese hamster ovary cells) and COV434 (human ovarian granulosa cells) cells were plated, pretreated with EF extract for 2h and then treated with 1.5mM or 0.5mM VCD for 24h, respectively. Cell viabilities were measured using an MTT assay, and protein levels were determined by western blotting.

RESULTS

VCD significantly suppressed the viability of both CHO-K1 and COV434 cells in a dose-dependent manner and induced the apoptosis of CHO-K1 cells at 1.5mM. EF extract dose-dependently blocked the ovotoxicity induced by treatment with VCD. Furthermore, EF extract significantly activated Akt and downstream effectors such as mTOR and GSK-3β in CHO-K1 cells. The ability of EF extract to prevent cytotoxicity by VCD was antagonized by pretreatment of LY294002, a PI3K/Akt inhibitor.

CONCLUSION

EF has the ability to protect ovary cells against VCD-induced ovotoxicity, probably via Akt activation. These results suggest that the beneficial effects of EF might be useful for preventing premature ovarian failure or unexplained infertility caused by environmental factors.

Toward a multi-country monitoring system of reproductive health in the context of endocrine disrupting chemical exposure

BACKGROUND

Worrying trends regarding human reproductive endpoints (e.g. semen quality, reproductive cancers) have been reported and there is growing circumstantial evidence for a possible causal link between these trends and exposure to endocrine disrupting chemicals (EDCs). However, there is a striking lack of human data to fill the current knowledge gaps. To answer the crucial questions raised on human reproductive health, there is an urgent need for a reproductive surveillance system to be shared across countries.

METHODS

A multidisciplinary network named HUman Reproductive health and Global ENvironment Network (HURGENT) was created aiming at designing a European monitoring system for reproductive health indicators. Collaborative work allowed setting up the available knowledge to design such a system. Furthermore we conducted an overview of 23 potential indicators, based upon a weight of evidence (WoE) approach according to their potential relation with EDC exposure.

RESULTS

The framework and purposes of the surveillance system are settled as well as the approach to select suitable reproductive indicators. The indicators found with the highest scores according to the WoE approach are prostate and breast cancer incidence, sex ratio, endometriosis and uterine fibroid incidence, indicators related to the testicular dysgenesis syndrome, precocious puberty incidence and reproductive hormone levels.

CONCLUSION

Not only sentinel health endpoints, but also diseases with high burdens in public health are highlighted as prior indicators in the context of EDC exposure. Our work can serve as a basis to construct, as soon as possible, the first multi-country reproductive monitoring system.

Dynamics of the ovarian reserve and impact of genetic and epidemiological factors on age of menopause

The narrow standard age range of menopause, ∼50 yr, belies the complex balance of forces that govern the underlying formation and progressive loss of ovarian follicles (the "ovarian reserve" whose size determines the age of menopause). We show here the first quantitative graph of follicle numbers, distinguished from oocyte counts, across the reproductive lifespan, and review the current state of information about genetic and epidemiological risk factors in relation to possible preservation of reproductive capacity. In addition to structural X-chromosome changes, several genes involved in the process of follicle formation and/or maintenance are implicated in Mendelian inherited primary ovarian insufficiency (POI), with menopause before age 40. Furthermore, variants in a largely distinct cohort of reported genes-notably involved in pathways relevant to atresia, including DNA repair and cell death-have shown smaller but additive effects on the variation in timing of menopause in the normal range, early menopause (age <45), and POI. Epidemiological factors show effect sizes comparable to those of genetic factors, with smoking accounting for about 5% of the risk of early menopause, equivalent to the summed effect of the top 17 genetic variants. The identified genetic and epidemiological factors underline the importance of early detection of reproductive problems to enhance possible interventions.

Risks associated with premature ovarian failure in Han Chinese women

In this retrospective study, the relationship between demographic characteristics, past medical history, general lifestyle habits and susceptibility of premature ovarian failure (POF) in Han Chinese population was investigated. Five hundred and fifty-three patients with POF and 400 women with normal ovarian function were recruited. A questionnaire was designed to gather information from responders. Logistic regression was carried out to calculate odds ratios (OR), 95% confidence intervals (95% CI) and P-values. History of pelvic surgery, mumps, having relatives with menstrual abnormalities and exposure to chemical agents were significantly associated with increased risk of POF (OR 5.53 [2.15 to 14.23]; 3.26 [2.38 to 4.47]; 28.12 [8.84 to 89.46]; 4.47 [2.09 to 9.58]). Vegetarian diet, tea and mineral water consumption reduced the risk of POF (OR 0.27 [0.19 to 0.37]; 0.04 [0.03 to 0.07]; 0.63 [0.47 to 0.85], respectively). Heredity, pelvic surgery, mumps and exposure to chemical agents were identified as risk factors for POF, whereas vegetarian diet, tea consumption and mineral water drinking were protective. Therefore, genetic consultation could help those women whose relatives manifested an early or premature menopause to avoid the consequences of possible premature ovarian function cessation. Avoidance of exposure to endocrine disrupters and flavonoids intake should be considered.

[Premature ovarian failures]

Premature ovarian failure (POF) is clinically suspected by amenorrhea and confirmed by an elevated FSH serum level above 40 mUI/L (even 20 mUI/L) twice, in a woman before the age of 40. Prevalence of POF is between 1 to 2% in women. In 90% of cases, no aetiology is identified. Obvious causes are chemotherapy, pelvic radiotherapy, ovarian surgery and diethylstilbestrol exposure in utero. A karyotype should be performed as Turner Syndrome is the most frequent genetic cause of POF. Some X abnormalities such as X deletion or X autosome translocation can be found. FMR1 pre-mutation (fragile X syndrome) should be searched for, even though no cases of mental retardation are known, in the family. Other genetic abnormalities can be suggested by associated symptoms (i.e.: FOXL2, SF1 mutations). Auto-immune aetiology can be suspected if other auto-immune features are present, however, there are no reliable auto-antibodies to confirm auto-immunity in POF. Treatment of POF is based on hormonal replacement therapy in order to avoid estrogen deficiency, suppress vasomotor symptoms and avoid bone loss as well as cardiovascular risk. Estrogens should be associated with progesterone or a progestin, at least up to the age of 51. Patients with POF should be informed that spontaneous pregnancies may occur (in 5% of cases). In case of desire of pregnancy, the patient should be oriented to a specialized unit for in vitro fertilization with oocyte donation. Psychological support is essential and should be part of the treatment. POF is associated with an increased risk of emotional distress and depression. No preventive treatment of POF is available so far.