The estrogen receptor relative binding affinities of 188 natural and xenochemicals: structural diversity of ligands

Chemistry domain of applicability evaluation against existing estrogen receptor high-throughput assay-based activity models

Introduction

The U. S. Environmental Protection Agency's Endocrine Disruptor Screening Program (EDSP) Tier 1 assays are used to screen for potential endocrine system-disrupting chemicals. A model integrating data from 16 high-throughput screening assays to predict estrogen receptor (ER) agonism has been proposed as an alternative to some low-throughput Tier 1 assays. Later work demonstrated that as few as four assays could replicate the ER agonism predictions from the full model with 98% sensitivity and 92% specificity. The current study utilized chemical clustering to illustrate the coverage of the EDSP Universe of Chemicals (UoC) tested in the existing ER pathway models and to investigate the utility of chemical clustering to evaluate the screening approach using an existing 4-assay model as a test case. Although the full original assay battery is no longer available, the demonstrated contribution of chemical clustering is broadly applicable to assay sets, chemical inventories, and models, and the data analysis used can also be applied to future evaluation of minimal assay models for consideration in screening.

Methods

Chemical structures were collected for 6,947 substances via the CompTox Chemicals Dashboard from the over 10,000 UoC and grouped based on structural similarity, generating 826 chemical clusters. Of the 1,812 substances run in the original ER model, 1,730 substances had a single, clearly defined structure. The ER model chemicals with a clearly defined structure that were not present in the EDSP UoC were assigned to chemical clusters using a k-nearest neighbors approach, resulting in 557 EDSP UoC clusters containing at least one ER model chemical.

Results and Discussion

Performance of an existing 4-assay model in comparison with the existing full ER agonist model was analyzed as related to chemical clustering. This was a case study, and a similar analysis can be performed with any subset model in which the same chemicals (or subset of chemicals) are screened. Of the 365 clusters containing >1 ER model chemical, 321 did not have any chemicals predicted to be agonists by the full ER agonist model. The best 4-assay subset ER agonist model disagreed with the full ER agonist model by predicting agonist activity for 122 chemicals from 91 of the 321 clusters. There were 44 clusters with at least two chemicals and at least one agonist based upon the full ER agonist model, which allowed accuracy predictions on a per-cluster basis. The accuracy of the best 4-assay subset ER agonist model ranged from 50% to 100% across these 44 clusters, with 32 clusters having accuracy ≥90%. Overall, the best 4-assay subset ER agonist model resulted in 122 false-positive and only 2 false-negative predictions compared with the full ER agonist model. Most false positives (89) were active in only two of the four assays, whereas all but 11 true positive chemicals were active in at least three assays. False positive chemicals also tended to have lower area under the curve (AUC) values, with 110 out of 122 false positives having an AUC value below 0.214, which is lower than 75% of the positives as predicted by the full ER agonist model. Many false positives demonstrated borderline activity. The median AUC value for the 122 false positives from the best 4-assay subset ER agonist model was 0.138, whereas the threshold for an active prediction is 0.1.

Conclusion

Our results show that the existing 4-assay model performs well across a range of structurally diverse chemicals. Although this is a descriptive analysis of previous results, several concepts can be applied to any screening model used in the future. First, the clustering of the chemicals provides a means of ensuring that future screening evaluations consider the broad chemical space represented by the EDSP UoC. The clusters can also assist in prioritizing future chemicals for screening in specific clusters based on the activity of known chemicals in those clusters. The clustering approach can be useful in providing a framework to evaluate which portions of the EDSP UoC chemical space are reliably covered by in silico and in vitro approaches and where predictions from either method alone or both methods combined are most reliable. The lessons learned from this case study can be easily applied to future evaluations of model applicability and screening to evaluate future datasets.

Assessment of developmental toxicity and the potential mode of action underlying single and binary exposure to estrogenic endocrine disrupting chemicals in zebrafish (Danio rerio)

The current study investigated the effect of single and binary exposure to distinct xenoestrogens, including diethylstilbestrol (DES) and zearalenone (ZEN), on zebrafish embryos subjected to continuous exposure for 4 days starting from 4 h post fertilization. Noteworthy impact on cumulative mortality, hatchability, spinal and tail curvature, pericardial edema, and reduction in blood circulation were observed in DES-treated embryos, with lower incidence and intensity shown for ZEN at the same nominal concentration (3 μM). An interactive effect was seen for the combined exposure to DES and ZEN, in which deformities and circulatory failure mediated by DES were mitigated by co-treatment with low concentrations of ZEN. Similarly, ZEN-induced spinal and tail curvature, pericardial edema, and blood flow reduction declined dramatically following DES co-exposure at low concentrations. A significant counteracting effect has been observed against DES- and ZEN-induced developmental anomalies following co-treatment with an estrogen receptor (ER) antagonist, fulvestrant (FUL). The assessment of the aromatase gene (CYP19A1b) showed that DES strongly upregulated mRNA expression of CYP19A1b with a lower EC50 (1.1 × 10-3 nM) than a natural estrogen, 17β-estradiol (2.5 nM). Similarly, ZEN induced CYP19A1b mRNA expression with an EC50 of 57 nM. Exposure to 10 or 20 μM FUL inhibited the expression of CYP19A1b induced by a single treatment of DES or ZEN. Overall, the competitive action against ER could be the main mechanism underlying the developmental toxicity induced by DES and ZEN.

Reversible female contraceptives: historical, current, and future perspectives†

Contraception is a practice with extensive and complicated social and scientific histories. From cycle tracking, to the very first prescription contraceptive pill, to now having over-the-counter contraceptives on demand, family planning is an aspect of healthcare that has undergone and will continue to undergo several transformations through time. This review provides a comprehensive overview of current reversible hormonal and non-hormonal birth control methods as well as their mechanism of action, safety, and effectiveness specifically for individuals who can become pregnant. Additionally, we discuss the latest Food and Drug Administration (FDA)-approved hormonal method containing estetrol and drospirenone that has not yet been used worldwide as well as the first FDA-approved hormonal over-the-counter progestin-only pills. We also review available data on novel hormonal delivery through microchip, microneedle, and the latest FDA-approved non-hormonal methods such as vaginal pH regulators. Finally, this review will assist in advancing female contraceptive method development by underlining constructive directions for future pursuits. Information was gathered from the NCBI and Google Scholars databases using English and included publications from 1900 to present. Search terms included contraceptive names as well as efficacy, safety, and mechanism of action. In summary, we suggest that investigators consider the side effects and acceptability together with the efficacy of contraceptive candidate towards their development.

Comparative study on estrogen receptor alpha dimerization and transcriptional activity of parabens

Parabens are used as preservatives in various household products, including oral products, cosmetics, and hair/body washes. In recent years, the widespread use of parabens has raised concerns due to the potential health risks associated with their estrogenic effects. In the present study, we evaluated and compared the estrogenic activity of parabens using two cell-based in vitro tests: (1) bioluminescence resonance energy transfer (BRET)-based estrogen receptor alpha (ERα) dimerization using HEK293 cells that were stably transfected with ERα-fused NanoLuc luciferase (Nluc) and HaloTag (HT) expression vector, and (2) stably transfected transcriptional activation (STTA) assays using ERα-HeLa9903 cells. The following parabens were tested using the BRET-based ERα dimerization assay and showed estrogenic activity (PC20 values): methyl paraben (MP, 5.98 × 10-5 M), ethyl paraben (EP, 3.29 × 10-5 M), propylparaben (PP, 3.09 × 10-5 M), butyl paraben (BP, 2.58 × 10-5 M), isopropyl paraben (IsoPP, 1.37 × 10-5 M), and isobutyl paraben (IsoBP, 1.43 × 10-5 M). Except MP, all other parabens tested using the STTA assay also showed estrogenic activity: EP, 7.57 × 10-6 M; PP, 1.18 × 10-6 M; BP, 3.02 × 10-7 M; IsoPP, 3.58 × 10-7 M; and IsoBP, 1.80 × 10-7 M. Overall, EP, PP, BP, IsoPP, and IsoBP tested positive for estrogenic activity using both assays. These findings demonstrate that most parabens, albeit not all, induce ERα dimerization and possess estrogenic activity.

Increased Endocrine Activity of Xenobiotic Chemicals as Mediated by Metabolic Activation

The US Environmental Protection Agency (USEPA) is faced with long lists of chemicals that require hazard assessment. The present study is part of a larger effort to develop in vitro assays and quantitative structure-activity relationships applicable to untested chemicals on USEPA inventories through study of estrogen receptor (ER) binding and estrogen-mediated gene expression in fish. The present effort investigates metabolic activation of chemicals resulting in increased estrogenicity. Phenolphthalin (PLIN) was shown not to bind rainbow trout (Oncorhynchus mykiss) ER (rtER) in a competitive binding assay, but vitellogenin (Vtg) expression was induced in trout liver slices exposed to 10-4 and 10-3.7 M PLIN. Phenolphthalein (PLEIN), a metabolite of PLIN, was subsequently determined to be formed when slices were exposed to PLIN. It binds rtER with a relative binding affinity to 17β-estradiol of 0.020%. Slices exposed to PLEIN expressed Vtg messenger RNA (mRNA) at 10-4.3 , 10-4 , and 10-3.7 M, with no detectable PLIN present. Thus, Vtg expression noted in PLIN slice exposures was explained by metabolism to PLEIN in trout liver slices. A second model chemical, 4,4'-methylenedianiline (MDA), was not shown to bind rtER but did induce Vtg mRNA production in tissue slices at 10-4.3 , 10-4 , and 10-3.7 M in amounts nearly equal to reference estradiol induction, thus indicating metabolic activation of MDA. A series of experiments were performed to identify a potential metabolite responsible for the observed increase in activity. Potential metabolites hydroxylamine-MDA, nitroso-MDA, azo-MDA, and azoxy-MDA were not observed. However, acetylated MDA was observed and tested in both ER-binding and tissue slice Vtg induction assays. Environ Toxicol Chem 2023;42:2747-2757. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

The G Protein-Coupled Estrogen Receptor (GPER): A Critical Therapeutic Target for Cancer

Estrogens have been implicated in the pathogenesis of various cancers, with increasing concern regarding the overall rising incidence of disease and exposure to environmental estrogens. Estrogens, both endogenous and environmental, manifest their actions through intracellular and plasma membrane receptors, named ERα, ERβ, and GPER. Collectively, they act to promote a broad transcriptional response that is mediated through multiple regulatory enhancers, including estrogen response elements (EREs), serum response elements (SREs), and cyclic AMP response elements (CREs). Yet, the design and rational assignment of antiestrogen therapy for breast cancer has strictly relied upon an endogenous estrogen-ER binary rubric that does not account for environmental estrogens or GPER. New endocrine therapies have focused on the development of drugs that degrade ER via ER complex destabilization or direct enzymatic ubiquitination. However, these new approaches do not broadly treat all cancer-involved receptors, including GPER. The latter is concerning since GPER is directly associated with tumor size, distant metastases, cancer stem cell activity, and endocrine resistance, indicating the importance of targeting this receptor to achieve a more complete therapeutic response. This review focuses on the critical importance and value of GPER-targeted therapeutics as part of a more holistic approach to the treatment of estrogen-driven malignancies.

Development of a framework for risk assessment of dietary carcinogens

Although there are a number of guidance documents and frameworks for evaluation of carcinogenicity, none of the current methods fully reflects the state of the science. Common limitations include the absence of dose-response assessment and not considering the impact of differing exposure patterns (e.g., intermittent, high peaks vs. lower, continuous exposures). To address these issues, we have developed a framework for risk assessment of dietary carcinogens. This framework includes an enhanced approach for weight of evidence (WOE) evaluation for genetic toxicology data, with a focus on evaluating studies based on the most recent testing guidance to determine whether a chemical is a mutagen. Included alongside our framework is a discussion of resources for evaluating tissue dose and the temporal pattern of internal dose, taking into account the chemical's toxicokinetics. The framework then integrates the mode of action (MOA) and associated dose metric category with the exposure data to identify the appropriate approach(es) to low-dose extrapolation and level of concern associated with the exposure scenario. This framework provides risk managers with additional flexibility in risk management and risk communication options, beyond the binary choice of linear low-dose extrapolation vs. application of uncertainty factors.

Hormonal contraceptive exposure relates to changes in resting state functional connectivity of anterior cingulate cortex and amygdala

Introduction

Hormonal contraceptives (HCs), nowadays one of the most used contraceptive methods, downregulate endogenous ovarian hormones, which have multiple plastic effects in the adult brain. HCs usually contain a synthetic estrogen, ethinyl-estradiol, and a synthetic progestin, which can be classified as androgenic or anti-androgenic, depending on their interaction with androgen receptors. Both the anterior cingulate cortex (ACC) and the amygdala express steroid receptors and have shown differential functionality depending on the hormonal status of the participant and the use of HC. In this work, we investigated for the first time the relationship between ACC and amygdala resting state functional connectivity (rs-FC) and HC use duration, while controlling for progestin androgenicity.

Methods

A total of 231 healthy young women participated in five different magnetic resonance imaging studies and were included in the final analysis. The relation between HC use duration and (i) gray matter volume, (ii) fractional amplitude of low-frequency fluctuations, and (iii) seed-based connectivity during resting state in the amygdalae and ACC was investigated in this large sample of women.

Results

In general, rs-FC of the amygdalae with frontal areas, and between the ACC and temporoparietal areas, decreased the longer the HC exposure and independently of the progestin's androgenicity. The type of HC's progestin did show a differential effect in the gray matter volume of left ACC and the connectivity between bilateral ACC and the right inferior frontal gyrus.

Role of Estrogen and Estrogen Receptor in GH-Secreting Adenomas

Acromegaly is a rare disease with several systemic complications that may lead to increased overall morbidity and mortality. Despite several available treatments, ranging from transsphenoidal resection of GH-producing adenomas to different medical therapies, complete hormonal control is not achieved in some cases. Some decades ago, estrogens were first used to treat acromegaly, resulting in a significant decrease in IGF1 levels. However, due to the consequent side effects of the high dose utilized, this treatment was later abandoned. The evidence that estrogens are able to blunt GH activity also derives from the evidence that women with GH deficiency taking oral estro-progestins pills need higher doses of GH replacement therapy. In recent years, the role of estrogens and Selective Estrogens Receptor Modulators (SERMs) in acromegaly treatment has been re-evaluated, especially considering poor control of the disease under first- and second-line medical treatment. In this review, we analyze the state of the art concerning the impact of estrogen and SERMs on the GH/IGF1 axis, focusing on molecular pathways and the possible implications for acromegaly treatment.

Role of Estrogen Receptor α in Aging and Chronic Disease

Estrogen receptor alpha (ERα) plays a crucial role in reproductive function in both sexes. It also mediates cellular responses to estrogens in multiple nonreproductive organ systems, many of which regulate systemic metabolic homeostasis and inflammatory processes in mammals. The loss of estrogens and/or ERα agonism during aging is associated with the emergence of several comorbid conditions, particularly in females undergoing the menopausal transition. Emerging data also suggests that male mammals likely benefit from ERα agonism if done in a way that circumvents feminizing characteristics. This has led us, and others, to speculate that tissue-specific ERα agonism may hold therapeutic potential for curtailing aging and chronic disease burden in males and females that are at high-risk of cancer and/or cardiovascular events with traditional estrogen replacement therapies. In this mini-review, we emphasize the role of ERα in the brain and liver, summarizing recent evidence that indicates these two organs systems mediate the beneficial effects of estrogens on metabolism and inflammation during aging. We also discuss how 17α-estradiol administration elicits health benefits in an ERα-dependent manner, which provides proof-of-concept that ERα may be a druggable target for attenuating aging and age-related disease burden.

Electrochemical degradation of 17α-ethinylestradiol: Transformation products, degradation pathways and in vivo assessment of estrogenic activity

Conventional water treatment methods are not efficient in eliminating endocrine disrupting compounds (EDCs) in wastewater. Electrochemical Advanced Oxidation Processes (eAOPs) offer a promising alternative, as they electro-generate highly reactive species that oxidize EDCs. However, these processes produce a wide spectrum of transformation products (TPs) with unknown chemical and biological properties. Therefore, a comprehensive chemical and biological evaluation of these remediation technologies is necessary before they can be safely applied in real-life situations. In this study, 17α-ethinylestradiol (EE2), a persistent estrogen, was electrochemically degraded using a boron doped diamond anode with sodium sulfate (Na₂SO₄) and sodium chloride (NaCl) as supporting electrolytes. Ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry was used for the quantification of EE2 and the identification of TPs. Estrogenic activity was assessed using a transgenic medaka fish line. At optimal operating conditions, EE2 removal reached over 99.9% after 120 min and 2 min, using Na₂SO₄ and NaCl, respectively. The combined EE2 quantification and in vivo estrogenic assessment demonstrated the overall estrogenic activity was consistently reduced with the degradation of EE2, but not completely eradicated. The identification and time monitoring of TPs showed that the radical agents readily oxidized the phenolic A-ring of EE2, leading to the generation of hydroxylated and/or halogenated TPs and ring-opening products. eAOP revealed to be a promising technique for the removal of EE2 from water. However, caution should be exercised with respect to the generation of potentially toxic TPs.

Trace analysis of benzophenone-type UV filters in water and their effects on human estrogen and androgen receptors

To carry out risk assessments of benzophenone-type UV filters (BPs), fast and accurate analytical methods are crucial to determine and monitor levels in the environment. This study presents an LC-MS/MS method that requires minimal sample preparation and yet can identify 10 different BPs in environmental samples such as surface or wastewater resulting in a LOQ range from 2 to 1060 ng/L. The method suitability was tested through environmental monitoring, which showed that, BP-4 is the most abundant derivative found in the surface waters of Germany, India, South Africa and Vietnam. BP-4 levels correlate with the WWTP effluent fraction of the respective river for selected samples in Germany. Peak values of 171 ng/L for 4-hydroxybenzophenone (4-OH-BP), as measured in Vietnamese surface water, already exceed the PNEC value of 80 ng/L, elevating 4-OH-BP to the status of a new pollutant that needs more frequent monitoring. Moreover, this study reveals that during biodegradation of benzophenone in river water, the transformation product 4-OH-BP is formed which contain structural alerts for estrogenic activity. By using yeast-based reporter gene assays, this study provides bio-equivalents of 9 BPs, 4-OH-BP, 2,3,4-tri-OH-BP, 4-cresol and benzoate and complements the existing structure-activities relationships of BPs and their degradation products.

Hormonal contraception and cognition: Considering the influence of endogenous ovarian hormones and genes for clinical translation

Despite the well-known influence of ovarian hormones on the brain and widespread use of hormonal contraception (HC) since the 1960s, our knowledge of HC's cognitive effects remains limited. To date, the cognitive findings have been inconsistent. In order to establish what might make HC studies more consistent, we surveyed the literature on HCs and cognition to determine whether studies considered HC formulation, phase, pharmacokinetics, duration, and gene interactions, and assessed whether oversight of these factors might contribute to variable findings. We found that synthetic HC hormones exert dose-dependent effects, the day of oral contraceptive (Pill) ingestion is critical for understanding cognitive changes, and gene-cognition relationships differ in women taking the Pill likely due to suppressed endogenous hormones. When these factors were overlooked, results were not consistent. We close with recommendations for research more likely to yield consistent findings and be therefore, translatable.

Regulation of ABC transporters by sex steroids may explain differences in drug resistance between sexes

Drug efficacy is dependent on the pharmacokinetics and pharmacodynamics of therapeutic agents. Tight junctions, detoxification enzymes, and drug transporters, due to their localization on epithelial barriers, modulate the absorption, distribution, and the elimination of a drug. The epithelial barriers which control the pharmacokinetic processes are sex steroid hormone targets, and in this way, sex hormones may also control the drug transport across these barriers. Thus, sex steroids contribute to sex differences in drug resistance and have a relevant impact on the sex-related efficacy of many therapeutic drugs. As a consequence, for the further development and optimization of therapeutic strategies, the sex of the individuals must be taken into consideration. Here, we gather and discuss the evidence about the regulation of ATP-binding cassette transporters by sex steroids, and we also describe the signaling pathways by which sex steroids modulate ATP-binding cassette transporters expression, with a focus in the most important ATP-binding cassette transporters involved in multidrug resistance.

Ex vivo effects of 17β-estradiol on the prepubertal rat testis

Although it is well established that testis produces estrogens, their precise effect is not fully documented, particularly during the prepubertal period. In a previous in vivo study, we demonstrated that an exposure of prepubertal rats (15-30 days post-partum (dpp)) to 17β-estradiol (E2) delays the establishment of spermatogenesis. In order to characterize the mechanisms of action and the direct targets of E2 on the immature testis, we developed an organotypic culture model of testicular explants obtained from prepubertal rats (15, 20 and 25 dpp). To determine the involvement of nuclear estrogen receptors (ERs) in the effect of E2, particularly that of ESR1 which is the major ER expressed in the prepubertal testis, a pre-treatment with the full antagonist of this type of ERs (ICI 182.780) was performed. Histological analyses, gene expression studies and hormonal assays were conducted to investigate the effects of E2 on steroidogenesis- and spermatogenesis-related endpoints. Testicular explants from 15 dpp rats were unresponsive to E2 exposure while E2 effects were observed in those obtained from 20 and 25 dpp rats. An E2 exposure of testicular explants obtained from 20 dpp rats seemed to accelerate the establishment of spermatogenesis, whereas an E2 exposure of 25 dpp testicular explants induced a delay of this process. These effects could be related to the E2-induced modulation of steroidogenesis, and involved both ESR1-dependent and -independent mechanisms of action. Overall, this ex vivo study demonstrated differential age- and concentration-related effects of E2 on the testis during the prepubertal period.

Benzophenone-3: Comprehensive review of the toxicological and human evidence with meta-analysis of human biomonitoring studies

BACKGROUND

Benzophenone-3 (BP-3) and its major metabolite benzophenone-1 (BP-1) are widely used as UV filters in sunscreens and cosmetics to prevent sunburn and skin damage, or as stabilizers to prevent photodegradation in many commercial products. As a result, their presence is ubiquitous in the environment, wildlife and humans. Based on endocrine disruption concerns, international regulatory agencies are performing a closer evaluation.

OBJECTIVE AND METHODS

This work aimed to comprehensively review the available human relevant evidence for safety issues in MEDLINE/PubMed in order to create a structured database of studies, as well as to conduct an integrative analysis as part of the Human Biomonitoring for Europe (HBM4EU) Initiative.

RESULTS

A total of 1,635 titles and abstracts were screened and 254 references were evaluated and tabulated in detail, and classified in different categories: i) exposure sources and predictors; ii) human biomonitoring (HBM) exposure levels to perform a meta-analysis; iii) toxicokinetic data in both experimental animals and humans; iv) in vitro and in vivo rodent toxicity studies; and v) human data on effect biomarkers and health outcomes. Our integrative analysis showed that internal peak BP-3 concentrations achieved after a single whole-body application of a commercially available sunscreen (4% w/w) may overlap with concentrations eliciting endocrine disrupting effects in vitro, and with internal concentrations causing in vivo adverse female reproductive effects in rodents that were supported by still limited human data. The adverse effects in rodents included prolonged estrous cycle, altered uterine estrogen receptor gene expression, endometrium hyperplasia and altered proliferation and histology of the mammary gland, while human data indicated menstrual cycle hormonal alterations and increased risk of uterine fibroids and endometriosis. Among the modes of action reported (estrogenic, anti-androgenic, thyroid, etc.), BP-3 and especially BP-1 showed estrogenic activity at human-relevant concentrations, in agreement with the observed alterations in female reproductive endpoints. The meta-analysis of HBM studies identified a higher concern for North Americans, showing urinary BP-3 concentrations on average 10 and 20 times higher than European and Asian populations, respectively.

DISCUSSION AND CONCLUSIONS

Our work supports that these benzophenones present endocrine disrupting properties, endorsing recent European regulatory efforts to limit human exposure. The reproducible and comprehensive database generated may constitute a point of departure in future risk assessments to support regulatory initiatives. Meanwhile, individuals should not refrain from sunscreen use. Commercially available formulations using inorganic UV filters that are practically not absorbed into systemic circulation may be recommended to susceptible populations.

Simultaneous trace determination of three natural estrogens and their sulfate and glucuronide conjugates in municipal waste and river water samples with UPLC-MS/MS

Analytical method for three natural estrogens (NEs) and their sulfate and glucuronide conjugates in waste and river waters using solid-phase extraction (SPE) coupled with ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) has been available, but problems including poor recovery exist. In order to solve these, some optimizations have been performed in this work. For sample preparation, both rinse and elution solutions were optimized, in which 6 mL of MeOH/water (1:9, v/v), MeOH/Ace/water (10:2:88, v/v/v), and MeOH/NH₄OH/water (10:2:88, v/v/v) were determined as the rinse solution, while 6 mL of 2.0% NH₄OH/MeOH was determined as the elution solution for conjugated NEs (C-NEs). For mobile phase, addition of NH₄F could obviously enhance the signal response of the nine target compounds, and the optimized addition concentration was 0.5 mmol/L. The developed efficient method was validated and showed excellent linearity for each target compound (R² > 0.998), low limit of quantifications (LOQs, 0.07-1.29 ng/L) in four different water matrices, and excellent recovery efficiencies of 81.0-116.1% in influent, effluent, ultra-pure, and river water samples with low relative standard deviations (RSDs, 0.6-13.6%). The optimized method was successfully applied to influent, effluent, and Pearl River water, among which three NEs were all detected, while five C-NEs were found in the influent, three C-NEs were detected in the effluent, and two C-NEs were found in the Pearl River water, indicating the wide distribution of NEs and C-NEs in different water environments. This work provided a reliable and efficient analytical method for simultaneous trace determination of NEs and C-NEs, which had satisfactory absolute recoveries with low RSDs, low LOQs, and time-saving for both analysis and nitrogen drying.

West African e-waste-soil assessed with a battery of cell-based bioassays

Soil samples randomly taken from major e-waste sites in West Africa (Nigeria, Benin and Ghana) were examined for an extensive range of organic contaminants. Cytotoxicity measurements and assessment of activation of xeno-sensing receptors from fish (Atlantic cod) were employed as a battery of in vitro biological assays to explore the quality and toxicity profile of West African e-waste soil. The concentrations of the measured contaminants of emerging concerns (CECs) and persistent organic pollutants (POPs) in the e-waste soil differs significantly from the reference soil with chemical profiles typically dominated by legacy polybrominated diphenyl ethers (PBDEs) (405.8 μgkg^-1) and emerging organophosphate ester flame retardant tris (1-chloro-2-propyl) phosphate (TCPP) (404 μgkg^-1), in addition to the short chain perfluorobutane sulfonate (PFBS) (275.3 μgkg^-1) and perfluorobutanoate (PFBA) (16 μgkg^-1). The study revealed that perfluorooctanoic acid (PFOA) occurred only in e-waste soil from Ghana and ranged from 2.6 to 5.0 μgkg^-1. Overall, non-polar e-waste soil-derived extracts had a stronger effect on COS-7 cell viability than the polar extracts and elutriates. The highest receptor activation was observed with single polar and non-polar extracts from the Nigeria and Benin sites, indicating hotspots with Er-, PPARa- and Ahr-agonist activities. Thus, the results obtained with our battery of in vitro biological assays underscored these e-waste sites as remarkably polluted spots with complex toxicity profiles of great concern for human and environmental health.

Oral contraceptives in the central nervous system: Basic pharmacology, methodological considerations, and current state of the field

Millions of women around the world use combined oral contraceptives (OCs), yet surprisingly little is known about their central nervous system (CNS) effects. This article provides a short overview of the basic pharmacology of OCs, emphasizing features that may be relevant to understanding their effects in the CNS. Historical and recent findings from studies of cognitive function, mood, and negative affect (depressive changes under OC use) are then reviewed. We also present data from an archival dataset from our own laboratory in which we explore dysphoric changes in women using four generations of contraceptive progestins. Current data in the field are consistent with a modest effect of OC use on CNS variables, but conclusions based on current findings must be made very cautiously because of multiple methodological issues in many published studies to date, and inconsistencies in the findings. Directions for future research over the next 10 years are suggested. (150 words).

Potential biomarker of phenol toxicity in freshwater fish C. mrigala: Serum cortisol, enzyme acetylcholine esterase and survival organ gill

In this modern industrialized era of large-scale production of agrochemicals, various emerging contaminants form the main components of waste water and sludge in most of the developing countries of the world. In this concern, phenol- an inevitable and alarming chemical pollutant in aquatic ecosystem, gains a speedy access into the water bodies as an industrial by-product. Though the detrimental effects of phenol have been studied in various aspects of aquatic life, current study is an initiative to unravel the toxic effects of phenol at molecular level in Cirrhinus mrigala. Plasma cortisol level and acetylcholine esterase activity in fish was estimated by Chemiluminescent immunoassay technique and Ellman assay respectively. Scanning electron microscopic studies were carried out to unravel the gill histopathological alterations in exposed fish. It was observed that phenol (22.32 mg/l) inhibits 50 % of acetylcholine esterase activity in brain thereby affecting the locomotion of the targeted carp. Cortisol elevated during the 7th day in exposed fish, but declined progressively on the forthcoming 21st and 28th days. Manifestations in gill encompass curling, fusion, aberrations, sloughing of gill epithelium, wider inter filamentary space and mucus coating in the primary gill filament. It concludes that the discernable deviations produced in both biochemical parameters and key organ gill can be used as a biomarker and bio-indicator respectively for assessing the existence of emerging toxicants in aquatic ecosystem.

Perinatal exposure to the fungicide ketoconazole alters hypothalamic control of puberty in female rats

INTRODUCTION

Estrogenic endocrine disrupting chemicals (EDCs) such as diethylstilbestrol (DES) are known to alter the timing of puberty onset and reproductive function in females. Accumulating evidence suggests that steroid synthesis inhibitors such as ketoconazole (KTZ) or phthalates may also affect female reproductive health, however their mode of action is poorly understood. Because hypothalamic activity is very sensitive to sex steroids, we aimed at determining whether and how EDCs with different mode of action can alter the hypothalamic transcriptome and GnRH release in female rats.

DESIGN

Female rats were exposed to KTZ or DES during perinatal (DES 3-6-12μg/kg.d; KTZ 3-6-12mg/kg.d), pubertal or adult periods (DES 3-12-48μg/kg.d; KTZ 3-12-48mg/kg.d).

RESULTS

Ex vivo study of GnRH pulsatility revealed that perinatal exposure to the highest doses of KTZ and DES delayed maturation of GnRH secretion before puberty, whereas pubertal or adult exposure had no effect on GnRH pulsatility. Hypothalamic transcriptome, studied by RNAsequencing in the preoptic area and in the mediobasal hypothalamus, was found to be very sensitive to perinatal exposure to all doses of KTZ before puberty with effects persisting until adulthood. Bioinformatic analysis with Ingenuity Pathway Analysis predicted "Creb signaling in Neurons" and "IGF-1 signaling" among the most downregulated pathways by all doses of KTZ and DES before puberty, and "PPARg" as a common upstream regulator driving gene expression changes. Deeper screening ofRNAseq datasets indicated that a high number of genes regulating the activity of the extrinsic GnRH pulse generator were consistently affected by all the doses of DES and KTZ before puberty. Several, including MKRN3, DNMT3 or Cbx7, showed similar alterations in expression at adulthood.

CONCLUSION

nRH secretion and the hypothalamic transcriptome are highly sensitive to perinatal exposure to both DES and KTZ. The identified pathways should be exploredfurther to identify biomarkers for future testing strategies for EDC identification and when enhancing the current standard information requirements in regulation.

The role of ovarian hormones in the pathophysiology of perimenopausal sleep disturbances: A systematic review

Sleep disturbance is a common clinical concern throughout the menopausal transition. However, the pathophysiology and causes of these sleep disturbances remain poorly understood, making it challenging to provide appropriate therapy. Our goal was to i) review the literature about the influence of ovarian hormones on sleep in perimenopausal women, ii) summarize the potential underlying pathophysiology of menopausal sleep disturbances and iii) evaluate the implications of these findings for the therapeutic approach to sleep disturbances in the context of menopause. A systematic literature search using the databases Embase, MEDLINE and Cochrane Library was conducted. Keywords relating to ovarian hormones, sleep disturbances and menopause were used. Ultimately, 86 studies were included. Study Quality Assessment Tools of the National Institutes of Health were used for quality assessment. Results from good-quality studies demonstrated that the postmenopausal decline in estrogen and progesterone contributes to sleep disturbances in women and that timely treatment with estrogen and/or progesterone therapy improved overall sleep quality. Direct and indirect effects of both hormones acting in the central nervous system and periphery, as well as via secondary effects (e.g. reduction in vasomotor symptoms), can contribute to improvements in sleep. To strengthen external validity, studies examining neurobiological pathways are needed.

Toxicokinetics, Percutaneous Absorption and Tissue Distribution of Benzophenone-3, an UV Filtering Agent, in Rats

The aim of this study was to evaluate in vitro skin permeation and deposition, in vivo toxicokinetics, percutaneous absorption and tissue distribution of benzophenone-3 (BP-3) in rats. Four transdermal formulations containing BP-3 were prepared and evaluated for in vitro skin permeation and deposition of BP-3 using Franz diffusion cells. A gel formulation was used in subsequent in vivo percutaneous absorption due to its high in vitro skin permeation and deposition. Compared to intravenous (i.v.) injection, the prolonged terminal t_1/2 (3.1 ± 1.6 h for i.v. injection and 18.3 ± 5.8 h for topical application) was observed indicating occurrence of flip-flop kinetics after topical application. The bioavailability of BP-3 after topical application was 6.9 ± 1.8%. The tissue-to-plasma partition coefficient (kp) for testis, considered a toxic target for BP-3, was less than 1.. Overall, findings of this study may be useful for risk assessment of BP-3.

Modeling hormonal contraception in female rats: A framework for studies in behavioral neurobiology

Research on hormonal contraceptives (HC) in animal models is lacking, and as a result, so is our understanding of the impact of HC on the brain and behavior. Here, we provide a review of the pharmacology of HC, as well as the methodology and best practices for designing a model of HC in female rats. We outline specific methodological considerations regarding dosing, route of administration, exposure time/timing, and selecting a control group. We also provide a framework outlining important levels of analysis for thinking about the impact of HC on behavioral and neurobiological outcomes. The purpose of this review is to equip researchers with foundational knowledge, and some basic elements of experimental design for future studies investigating the impact of HC on the brain and behavior of female rats.

Structure-related endocrine-disrupting potential of environmental transformation products of benzophenone-type UV filters: A review

Benzophenone-type UV filters (BPs) represent a very diverse group of chemicals that are used across a range of industrial sectors around the world. They are found within different environmental compartments (e.g. surface water, groundwater, wastewater, sediments and biota) at concentrations ranging from ng/L to mg/L. Some are known as endocrine disruptors and are currently within the scope of international regulations. A structural alert for high potential of endocrine disrupting activity was assigned to 11 BP derivatives. Due to the widespread use, distribution and disruptive effects of some BPs, knowledge of their elimination pathways is required. This review demonstrates that biodegradation and photolytic decomposition are the major elimination processes for BP-type UV filters in the environment. Under aerobic conditions, transformation pathways have only been reported for BP, BP-3 and BP-4, which are also the most common derivatives. Primary biodegradation mainly results in the formation of hydroxylated BPs, which exhibit a structure-related increase in endocrine activity when compared to their parent substances. By combining 76 literature-based transformation products (TPs) with in silico results relating to their receptor activity, it is demonstrated that 32 TPs may retain activity and that further knowledge of the degradation of BPs in the environment is needed.

Impact of preovulatory estradiol concentrations on subsequent luteal function in beef cattle

It has been hypothesized that circulating concentrations of estradiol during the preovulatory period, can impact subsequent progesterone concentrations. Ovulation was synchronized in nonlactating beef cows (n = 53). Cows that exhibited estrus before gonadotrophin-releasing hormone (GnRH)-induced ovulation (d 0) had greater (p<.01) peak concentrations of estradiol compared with cows that did not express estrus (11.5 ± 0.8 vs. 6.2 ± 0.6 pg/mL), respectively, but there was no difference in ovulatory follicle size (p= .80) or interval from GnRH2 to ovulation (p=.23). Circulating concentrations of progesterone during luteal formation (d 3-7; p=.70 and p=.77) or mid-luteal phase (d 8-14; p=.39 and p=.12) were not affected by elevated periovulatory estradiol or an interaction with day. To investigate the direct influence of estradiol on luteal function, ovulation (d 0) was synchronized in nonlactating beef cows and cows were allocated to three groups (control, n = 5; vehicle injection, n = 4; or an estradiol antagonist (Fulvestrant; ICI 182,780), n = 4. Intrafollicular injection of vehicle (100 µL) or an estradiol antagonist (25 μg Fulvestrant in 100 µL) into the largest follicle occurred on d -2. Concentrations of estradiol increased (p<.0001) from d -2 to 0 but did not differ among groups (p>.50). Furthermore, plasma concentrations of progesterone on d 0 through 20 were not affected by treatment (p=.86). These results indicate that elevated preovulatory estradiol before ovulation was not required to prepare granulosa cells for luteinization or subsequent luteal progesterone secretion but did tend to impact luteal lifespan.

Stable isotope probing reveals specific assimilating bacteria of refractory organic compounds in activated sludge

Activated sludge in wastewater treatment bioreactors contains diverse bacteria, while little is known about the community structure of bacteria responsible for degradation of refractory organic compounds (ROCs). In this study, 10 ROCs frequently detected in sewage were investigated, and the potential bacteria degrading these ROCs were analyzed by DNA stable isotope probing and high-throughput sequencing. The results showed that the bacterial communities responsible for degradation of different ROCs were largely different. A total of 84 bacterial genera were found to be involved in degrading at least one of the 10 ROCs, however, only six genera (Acinetobacter, Bacteroides, Bosea, Brevundimonas, Lactobacillus and Pseudomonas) were common to all 10 ROCs. This suggests that different ROCs may have specific assimilating bacteria in the activated sludge. Our results also showed that these ROC-degrading bacteria are difficult to isolate by conventional methods and that most of them have relatively low relative abundance in municipal wastewater treatment bioreactors. Development of new technologies to increase the abundance and activity of these bacteria may significantly improve the removal efficiency of ROCs from wastewater.

Waves of follicle development, growth and degeneration in adult ovary of zebrafish (Danio rerio) on chronic exposure to environmental estrogens in laboratory

Patterns of quantitative production of follicles, their growth, and degeneration in the adult ovary of zebrafish (Danio rerio) in response to long-term (80 days) exposure to environmental estrogens (EE) in the laboratory, were studied. Experimentally naive female D. rerio procured from fish farm were acclimated to the laboratory (natural temperature, 26 ± 1° C, photoperiod, 11.30 L:12.30 D) for two weeks and divided into 10 groups. Each group (n = 20) was housed in a separate glass aquarium containing 10 L of conditioned water (physico-chemical parameters maintained within the permissible range prescribed for zebrafish) along with either 5 ng or 10 ng/L of 17α-ethynylestradiol (EE₂) or diethylstilbestrol (DES) or bisphenol A (BPA) or estradiol 17-β (positive control) or water with no chemical (negative control). All experimental fish were fed twice daily on commercial pellets (ad libitum) supplemented with Artemia nauplius, the exposure was semi-static and chemical residues in media samples were determined by ultra-performance liquid chromatography (UPLC). Exposure of fish to estrogens increased (p < 0.05) (i) body mass and gonadosomatic indices (GSI) in E₂, EE₂ and DES groups (ii) previtellogenic and vitellogenic follicles in E₂ and EE₂ groups (iii) atretic follicles (AF) in DES and BPA groups compared to controls and (iv) decrease in total oocyte volumes (V = 4/3. π. r³) compared to those of E₂ group. These results suggest that the chronic exposure of fish to EE (at environmentally relevant concentrations) has a profound influence on ovarian follicular dynamics and the effects of individual EE are discrete on the ovary.

Diethylhexyl Phthalate and Bisphenol A Promote Vincristine and Tamoxifen Resistance in Vitro

Environmental estrogen active compounds are strong determinants of estrogen receptor (ER)-positive breast cancers, and increased evidence indicates their contribution to chemotherapy resistance. In the current study, the efficacy of vincristine and tamoxifen, with the presence of diethylhexyl phthalate (DEHP) and bisphenol A (BPA) and the possible involvement of estrogen and estrogen receptor-related mechanisms, was evaluated in an ER+ mammary tumor cancer cell line, MCF-7. Chemotherapeutics tamoxifen as an estrogen receptor modulator and vincristine as an antimitotic compound were selected for evaluation against the presence of common endocrine disrupters. BPA and DEHP preincubation at their proliferative concentrations for 4 h was found to decrease the cytotoxicity of vincristine. mRNA and protein expression of ESR1 and ESR 2 were decreased by vincristine, while this decrease was reversed by DEHP and BPA. Both BPA and DEHP were able to interfere with the cytotoxic activity of vincristine against MCF-7 cells through ESR1 and ESR2. This study provides in vitro toxicological evidence for vincristine resistance and its relation to estrogen active environmental pollutants in ER+ breast cancer cells.

Estrogenic Action in Stress-Induced Neuroendocrine Regulation of Energy Homeostasis

Estrogens are among important contributing factors to many sex differences in neuroendocrine regulation of energy homeostasis induced by stress. Research in this field is warranted since chronic stress-related psychiatric and metabolic disturbances continue to be top health concerns, and sex differences are witnessed in these aspects. For example, chronic stress disrupts energy homeostasis, leading to negative consequences in the regulation of emotion and metabolism. Females are known to be more vulnerable to the psychological consequences of stress, such as depression and anxiety, whereas males are more vulnerable to the metabolic consequences of stress. Sex differences that exist in the susceptibility to various stress-induced disorders have led researchers to hypothesize that gonadal hormones are regulatory factors that should be considered in stress studies. Further, estrogens are heavily recognized for their protective effects on metabolic dysregulation, such as anti-obesogenic and glucose-sensing effects. Perturbations to energy homeostasis using laboratory rodents, such as physiological stress or over-/under- feeding dietary regimen prevalent in today’s society, offer hints to the underlying mechanisms of estrogenic actions. Metabolic effects of estrogens primarily work through estrogen receptor α (ERα), which is differentially expressed between the sexes in hypothalamic nuclei regulating energy metabolism and in extrahypothalamic limbic regions that are not typically associated with energy homeostasis. In this review, we discuss estrogenic actions implicated in stress-induced sex-distinct metabolic disorders.

Benzotriazole Ultraviolet Stabilizers Promote Breast Cancer Cell Proliferation via Activating Estrogen-Related Receptors α and γ at Human-Relevant Levels

Benzotriazole ultraviolet stabilizers (BUVSs) are ubiquitous emerging pollutants that have been reported to show estrogenic disruption effects through interaction with the classic estrogen receptors (ERs) in the fashion of low activity. The present study aims at revealing the potential disruption mechanism via estrogen-related receptors α and γ (ERRα and ERRγ) pathways. By the competitive binding assay, we first found that BUVSs bond to ERRγ ligand binding domain (ERRγ-LBD) with Kd ranging from 0.66 to 19.27 μM. According to the results of reporter gene assays, the transcriptional activities of ERRα and ERRγ were promoted by most tested BUVSs with the lowest observed effective concentrations (LOEC) from 10 to 100 nM, which are in the range of human exposure levels. At 1 μM, most tested BUVSs showed higher agonistic activity toward ERRγ than ERRα. The most effective two BUVSs promoted the MCF-7 proliferation dependent on ERRα and ERRγ with a LOEC of 100 nM. The molecular dynamics simulation showed that most studied BUVSs had lower binding free energy with ERRγ than with ERRα. The structure-activity relationship analysis revealed that molecular polarizability, electron-donating ability, ionization potential, and softness were the main structural factors impacting the binding of BUVSs with ERRγ. Overall, our results provide novel insights into the estrogenic disruption effects of BUVSs.

Evaluation of estrogenic and antiestrogenic activity in sludge and explanation of individual compound contributions

Mixture toxicity, including agonistic and antagonistic effects, is an unrevealed environmental problem. Estrogenic endocrine disruptors are known to cause adverse effects for aquatic biota, but causative chemicals and their contributions to the total activity in sewage sludge remain unknown. Therefore, advanced analytical methods, a yeast bioassay and mixture toxicity models were concurrently applied for the characterization of 8 selected sludges with delectable estrogenic activity (and 3 sludges with no activity as blanks) out of 25 samples from wastewater treatment plants (WWTPs). The first applied full logistic model adequately explained total activity by considering the concentrations of the monitored compounds. The results showed that the activity was primarily caused by natural estrogens in municipal WWTP sludge. Nevertheless, activity in a sample originating from a car-wash facility was dominantly caused by partial agonists - nonylphenols - and only a model enabling prediction of all dose-response curve parameters of the final mixture curve explained these results. Antiestrogenic effects were negligible, and effect-directed analysis identified the causative chemicals.

Radioiodinated Ethinylestradiol Derivatives for Estrogen Receptor Targeting Breast Cancer Imaging

Two novel PEGylated ethinylestradiol (PEG = poly(ethylene glycol)) estrogen receptor (ER) targeting probes [¹³¹I]EITE and [¹³¹I]MITE were synthesized and evaluated. Both probes had a nanomolar binding affinity to the ER receptor (36.47 nM for [¹³¹I]EITE and 61.83 nM for [¹³¹I]MITE). They showed high uptake in ER-positive MCF-7 cells and tumors, which could be significantly blocked by a coinjection of excess estradiol. Their ER specificities were further demonstrated by the low uptake in ER-negative MDA-MB-231 cells and tumors. The maximum tumor-to-muscle (T/M) ratios reach to 6.59 for [¹³¹I]EITE at 1 h postinjection (p.i.) and to 3.69 for [¹³¹I]MITE at 2 h p.i. in MCF-7 tumors. Among these two probes, [¹³¹I]EITE showed a faster tumor accumulation and a higher T/M ratio indicating it could be a better candidate for the potential diagnosis of ER-positive breast cancers.

Allosteric binding on nuclear receptors: Insights on screening of non-competitive endocrine-disrupting chemicals

Endocrine-disrupting chemicals (EDCs) can compete with endogenous hormones and bind to the orthosteric site of nuclear receptors (NRs), affecting normal endocrine system function and causing severe symptoms. Recently, a series of pharmaceuticals and personal care products (PPCPs) have been discovered to bind to the allosteric sites of NRs and induce similar effects. However, it remains unclear how diverse EDCs work in this new way. Therefore, we have systematically summarized the allosteric sites and underlying mechanisms based on existing studies, mainly regarding drugs belonging to the PPCP class. Advanced methods, classified as structural biology, biochemistry and computational simulation, together with their advantages and hurdles for allosteric site recognition and mechanism insight have also been described. Furthermore, we have highlighted two available strategies for virtual screening of numerous EDCs, relying on the structural features of allosteric sites and lead compounds, respectively. We aim to provide reliable theoretical and technical support for a broader view of various allosteric interactions between EDCs and NRs, and to drive high-throughput and accurate screening of potential EDCs with non-competitive effects.

Effects of Organochlorine Pesticide Residues in Maternal Body on Infants

There are many organochlorine pollutants in the environment, which can be directly or indirectly exposed to by mothers, and as estrogen endocrine disruptors can cause damage to the lactation capacity of the mammary gland. In addition, because breast milk contains a lot of nutrients, it is the most important food source for new-born babies. If mothers are exposed to organochlorine pesticides (OCPs), the lipophilic organochlorine contaminants can accumulate in breast milk fat and be passed to the infant through breast milk. Therefore, it is necessary to investigate organochlorine contaminants in human milk to estimate the health risks of these contaminants to breastfed infants. In addition, toxic substances in the mother can also be passed to the fetus through the placenta, which is also something we need to pay attention to. This article introduces several types of OCPs, such as dichlorodiphenyltrichloroethane (DDT), methoxychlor (MXC), hexachlorocyclohexane (HCH), endosulfan, chlordane, heptachlorand and hexachlorobenzene (HCB), mainly expounds their effects on women's lactation ability and infant health, and provides reference for maternal and infant health. In addition, some measures and methods for the control of organochlorine pollutants are also described here.

The physiological role of estrogen receptor functional domains

Estrogen receptor (ER) is a member of the nuclear receptor superfamily whose members share conserved domain structures, including a DNA-binding domain (DBD) and ligand-binding domain (LBD). Estrogenic chemicals work as ligands for activation or repression of ER-mediated transcriptional activity derived from two transactivation domains: AF-1 and AF-2. AF-2 is localized in the LBD, and helix 12 of the LBD is essential for controlling AF-2 functionality. The positioning of helix 12 defines the ER alpha (ERα) ligand properties as agonists or antagonists. In contrast, it is still less well defined as to the ligand-dependent regulation of N-terminal AF-1 activity. It has been thought that the action of selective estrogen receptor modulators (SERMs) is mediated by the regulation of a tissue specific AF-1 activity rather than AF-2 activity. However, it is still unclear how SERMs regulate AF-1 activity in a tissue-selective manner. This review presents some recent observations toward information of ERα mediated SERM actions related to the ERα domain functionality, focusing on the following topics. (1) The F-domain, which is connected to helix 12, controls 4-hydroxytamoxifen (4OHT) mediated AF-1 activation associated with the receptor dimerization activity. (2) The zinc-finger property of the DBD for genomic sequence recognition. (3) The novel estrogen responsive genomic DNA element, which contains multiple long-spaced direct-repeats without a palindromic ERE sequence, is differentially recognized by 4OHT and E2 ligand bound ERα transactivation complexes.

Dietary Intake of 17α-Ethinylestradiol Promotes HCC Progression in Humanized Male Mice Expressing Sex Hormone-Binding Globulin

Hepatocellular carcinoma (HCC) is a male-oriented malignancy; its progression is affected by sex hormones. 17α-ethinylestradiol (EE2) is a synthetic estrogen widely used as an oral contraceptive; however, it is unknown whether EE2 regulates sex hormone action in HCC. We investigated whether EE2 influences HCC risk in male androgenic environments, using mice expressing human sex hormone-binding globulin (SHBG). Two-week-old male mice were injected with diethyl-nitrosamine (DEN, 25 mg/kg) and fed an EE2 diet for 10 weeks from 30 weeks of age. Development and characteristics of liver cancer were evaluated in 40-week-old mice via molecular and histological analyses. Although EE2 did not increase HCC progression in wild-type mice, SHBG mice exhibited remarkably higher HCC risk when fed EE2. The livers of EE2-treated SHBG mice exhibited substantially increased pro-inflammatory necrosis with high plasma levels of ALT and HMGB1, and intrahepatic injury and fibers. Additionally, increased androgen response and androgen-mediated proliferation in the livers of EE2-treated SHBG mice and EE2-exposed hepatocytes under SHBG conditions were observed. As a competitor of SHBG-androgen binding, EE2 could bind with SHBG and increase the bioavailability of androgen. Our results revealed that EE2 is a novel risk factor in androgen-dominant men, predisposing them to HCC risk.

Phytoestrogens (Resveratrol and Equol) for Estrogen-Deficient Skin-Controversies/Misinformation versus Anti-Aging In Vitro and Clinical Evidence via Nutraceutical-Cosmetics

The overarching theme for this review is perspective. Superfoods (a marketing term for fruits and vegetables, etc.) have a positive connotation, while many superfoods contain phytoestrogens, a term that is alarming to the public and has a negative connotation because phytoestrogens are endocrine-disruptors, even though they are strong antioxidants that have many health benefits. To understand phytoestrogens, this paper provides a brief summary of the characteristics of: (a) estrogens, (b) estrogen receptors (ER), (c) estrogen-deficient skin, (d) how perspective(s) get off track, (e) phytoestrogen food sources, and (f) misconceptions of phytoestrogens and food safety, in general, that influence person(s) away from what is true. Finally, a brief history of cosmetics to nutraceuticals is covered plus the characteristics of phytoestrogens, resveratrol and equol on: (g) estrogen receptor binding, (h) topical and oral dosing, and (i) in vitro, molecular mechanisms and select clinical evidence, where both phytoestrogens (resveratrol and equol) demonstrate promising applications to improve skin health is presented along with future directions of nutraceuticals. Perspective is paramount in understanding the controversies associated with superfoods, phytoestrogens, and endocrine-disruptors because they have both positive and negative connotations. Everyone is exposed to and consumes these molecules everyday regardless of age, gender, or geographic location around the world, and how we understand this is a matter of perspective.

Estrogens and the regulation of glucose metabolism

The main estrogens: estradiol, estrone, and their acyl-esters have been studied essentially related to their classical estrogenic and pharmacologic functions. However, their main effect in the body is probably the sustained control of core energy metabolism. Estrogen nuclear and membrane receptors show an extraordinary flexibility in the modulation of metabolic responses, and largely explain gender and age differences in energy metabolism: part of these mechanisms is already sufficiently known to justify both. With regard to energy, the estrogen molecular species act essentially through four key functions: (1) Facilitation of insulin secretion and control of glucose availability; (2) Modulation of energy partition, favoring the use of lipid as the main energy substrate when more available than carbohydrates; (3) Functional protection through antioxidant mechanisms; and (4) Central effects (largely through neural modulation) on whole body energy management. Analyzing the different actions of estrone, estradiol and their acyl esters, a tentative classification based on structure/effects has been postulated. Either separately or as a group, estrogens provide a comprehensive explanation that not all their quite diverse actions are related solely to specific molecules. As a group, they constitute a powerful synergic action complex. In consequence, estrogens may be considered wardens of energy homeostasis.

The Peculiar Estrogenicity of Diethyl Phthalate: Modulation of Estrogen Receptor α Activities in the Proliferation of Breast Cancer Cells

Phthalates comprise a group of synthetic chemicals present in the environment because of their wide use as plasticizers and as additives in products for personal care. Among others, diethyl phthalate (DEP) is largely used in products for infants, children, and adults, in which its exposure has been correlated with an increased risk of breast cancer. The adverse health outcomes deriving from phthalate exposure have been associated with their activity as endocrine disruptors (EDCs) of the steroid and thyroid hormone signaling by affecting developmental and reproductive health, and even carcinogenicity. However, the estrogen disruptor activities of DEP are still controversial, and the mechanism at the root of the estrogenic-disrupting action of DEP remains to be clarified. Here, we evaluated the DEP mechanism of action on the activation status of estrogen receptor α (ERα) by analyzing the receptor's phosphorylation as well as both nuclear and extra-nuclear pathways triggered by the receptor to modulate the proliferation of breast cancer cells. Although DEP does not bind to ERα, our results suggest that this phthalate ester exerts multiple parallel interactions with ERα signaling and emphasize the importance to determine an appropriate battery of in vitro methods that will include specific molecular mechanisms involved in the endocrine disruption.

Evidence of increased estrogenicity upon metabolism of Bisphenol F - Elucidation of the key metabolites

The increasing concern over bisphenol A (BPA) has directed much attention toward bisphenol F (BPF) and bisphenol S (BPS) as BPA alternatives for the development of "BPA-free" products. Consequently, BPS and BPF were frequently detected in surface water, sediment, sewage effluent, indoor dust, and even in food and biological fluids in humans. Thus, environmental researches start to focus on the potential environmental risks of BPA alternatives. While the estrogenically active metabolites and the specific estrogenically active structure are still unknown. In this study, the MTT assay on acute cytotoxicity and the recombinant transactivation assay were carried out to determine whether BPF and BPS are suitable alternatives to BPA. Our results show that the cytotoxic and estrogenic activities of BPS and BPF are lower than those of BPA. However, after the addition of a rat liver homogenate to simulate mammal metabolism, BPF exhibited higher estrogenic activity than BPA. To identify the chemical structures and estrogen receptor binding affinities of active estrogenic metabolites, LC-MS, MetaPrint2D(-React), and VirtualToxLab were integrated. The observed results indicated that the para-hydroxylated BPF and BPF-OCH₃ might have strong ER binding affinities. These results demonstrate that metabolization is important to consider upon investigating endocrine disruption of chemicals getting into contact with humans, such as in dental sealing or food packaging. Alternatives to potentially hazardous substances should be thoroughly tested prior to use.

Elucidation of Agonist and Antagonist Dynamic Binding Patterns in ER-α by Integration of Molecular Docking, Molecular Dynamics Simulations and Quantum Mechanical Calculations

Estrogen receptor alpha (ERα) is a ligand-dependent transcriptional factor in the nuclear receptor superfamily. Many structures of ERα bound with agonists and antagonists have been determined. However, the dynamic binding patterns of agonists and antagonists in the binding site of ERα remains unclear. Therefore, we performed molecular docking, molecular dynamics (MD) simulations, and quantum mechanical calculations to elucidate agonist and antagonist dynamic binding patterns in ERα. 17β-estradiol (E2) and 4-hydroxytamoxifen (OHT) were docked in the ligand binding pockets of the agonist and antagonist bound ERα. The best complex conformations from molecular docking were subjected to 100 nanosecond MD simulations. Hierarchical clustering was conducted to group the structures in the trajectory from MD simulations. The representative structure from each cluster was selected to calculate the binding interaction energy value for elucidation of the dynamic binding patterns of agonists and antagonists in the binding site of ERα. The binding interaction energy analysis revealed that OHT binds ERα more tightly in the antagonist conformer, while E2 prefers the agonist conformer. The results may help identify ERα antagonists as drug candidates and facilitate risk assessment of chemicals through ER-mediated responses.

Terephthalic Acid Copolyesters Containing Tetramethylcyclobutanediol for High-Performance Plastics

There is a need for high-performance applications for terephthalic acid (TPA) polyesters with high heat resistance, impact toughness, and optical clarity. Bisphenol A (BPA) based polycarbonates and polyarylates have such properties, but BPA is an endocrine disruptor. Therefore, new TPA polyesters that are less hazardous to health and the environment are becoming popular. Tetramethylcyclobutanediol (TMCD) is a difunctional monomer that can be polymerized with TPA and other diols to yield copolyesters with superior properties to conventional TPA polyesters. It has a cyclobutyl ring that makes it more rigid than cyclohexanedimethanol (CHDM) and EG. Thus, TMCD containing TPA copolyesters can have high heat resistance and impact strength. TPA can be made from abundantly available upcycled polyethylene terephthalate (PET). Therefore, this review discusses the synthesis of monomers and copolyesters, the impact of diol composition on material properties, molecular weight, effects of photodegradation, health safety, and substitution of cyclobutane diols for future polyesters.

Characterisation of (anti-)progestogenic and (anti-)androgenic activities in surface and wastewater using high resolution effectdirected analysis

The quality of surface waters is threatened by pollution with low concentrations of bioactive chemicals, among which those interfering with steroid hormone systems. Induced by reports of anti-progestogenic activity in surface waters, a two-year four-weekly survey of (anti-)progestogenic activity was performed at three surface water locations in the Netherlands that serve as abstraction points for the production of drinking water. As certain endogenous and synthetic progestogenic compounds are also potent (anti-)androgens, these activities were also investigated. Anti-progestogenic and anti-androgenic activities were detected in the majority of the monitoring samples, sometimes in concentrations exceeding effect-based trigger values, indicating the need for further research. To characterize the compounds responsible for the activities, a high resolution Effect-Directed Analysis (hr-EDA) panel was combined with PR and AR CALUX bioassays, performed in agonistic and antagonistic modes. The influent and effluent of a domestic wastewater treatment plant (WWTP) were included as effluent is a possible emission source of active compounds. As drivers for androgenic and progestogenic activities several native and synthetic steroid hormones were identified in the WWTP samples, namely androstenedione, testosterone, DHT, levonorgestrel and cyproterone acetate. The pesticides metolachlor and cyazofamid were identified as contributors to both the anti-progestogenic and anti-androgenic activities in surface water. In addition, epiconazole contributed to the anti-progestogenic activities in the rivers Rhine and Enclosed Meuse. This study showed the strength of hr-EDA for the identification of bioactive compounds in environmental samples and shed light on the drivers of (anti-)progestogenic and (anti-)androgenic activities in the aquatic environment.

Structure-based virtual screening of CYP1A1 inhibitors: towards rapid tier-one assessment of potential developmental toxicants

Cytochrome P450 1A1 (CYP1A1) metabolizes estrogens, melatonin, and other key endogenous signaling molecules critical for embryonic/fetal development. The enzyme has increasing expression during pregnancy, and its inhibition or knockout increases embryonic/fetal lethality and/or developmental problems. Here, we present a virtual screening model for CYP1A1 inhibitors based on the orthosteric and predicted allosteric sites of the enzyme. Using 1001 reference compounds with CYP1A1 activity data, we optimized the decision thresholds of our model and classified the training compounds with 68.3% balanced accuracy (91.0% sensitivity and 45.7% specificity). We applied our final model to 11 known CYP1A1 orthosteric binders and related compounds, and found that our ranking of the known orthosteric binders generally agrees with the relative activity of CYP1A1 in metabolizing these compounds. We also applied the model to 22 new test compounds with unknown/unclear CYP1A1 inhibitory activity, and predicted 16 of them are CYP1A1 inhibitors. The CYP1A1 potency and modes of inhibition of these 22 compounds were experimentally determined. We confirmed that most predicted inhibitors, including drugs contraindicated during pregnancy (amiodarone, bicalutamide, cyproterone acetate, ketoconazole, and tamoxifen) and environmental agents suspected to be endocrine disruptors (bisphenol A, diethyl and dibutyl phthalates, and zearalenone), are indeed potent inhibitors of CYP1A1. Our results suggest that virtual screening may be used as a rapid tier-one method to screen for potential CYP1A1 inhibitors, and flag them out for further experimental evaluations.

Do oral contraceptives affect young women's memory? Dopamine-dependent working memory is influenced by COMT genotype, but not time of pill ingestion

Background

Despite the widespread use of oral contraceptives (OCs), and the well-documented influence of estrogens, notably 17β-estradiol (E2), on cognition, research relating OCs to working memory is limited and mixed. Two factors may contribute to these mixed findings: 1) pharmacokinetics of oral contraceptives, which drive fluctuations in synthetic hormone levels; and 2) genetic polymorphisms related to dopamine degradation and working memory, which interact with E2. This research investigated whether the pharmacokinetics of oral contraceptives, in concert with the single nucleotide polymorphism (Val¹⁵⁸Met; rs4680) of the catechol-o-methyltransferase gene (COMT), influence working memory performance.

Methods

University-age women taking and not taking OCs were tested for working memory and genotyped for COMT. If they were not taking OCs (n = 62), sessions occurred in the early follicular (low E2) and late follicular (high E2) phase. If they were taking OCs (n = 52), sessions occurred 1–2 hours after (high ethinyl estradiol, EE) and ~24 hours after (low EE) pill ingestion. Working memory was tested using the N-back, AX-CPT, Digit Span, and Digit Ordering Tasks. Data were analyzed using multilevel models with estrogen condition, COMT, and group as predictors, controlling for mood and practice effects.

Results

For women taking OCs, time of pill ingestion did not influence performance. However, the subgroup with COMT val/val (low dopamine) were less accurate on 2-back lure trials than those with COMT met/met (high dopamine). For women not taking OCs, cycle phase moderated COMT’s influence on lure accuracy. When compared, women taking OCs had higher AX-CPT proactive control indices than those not taking OCs.

Conclusion

These findings suggest that oral contraceptives are not detrimental for young women’s working memory and that they may increase proactive control. The more pronounced effects of COMT in women taking OCs suggests that, in women taking OCs, suppressed endogenous E2–not fluctuating EE levels–may be more relevant for working memory. Future studies are needed to differentiate effects of endogenous versus synthetic estrogens on working memory.

Oxidation of benzophenone-3 in aqueous solution by potassium permanganate: kinetics, degradation products, reaction pathways, and toxicity assessment

Benzophenone-3 (BP-3) is used in a wide range of personal care products and plastics to resist ultraviolet light, which has aroused considerable public concern due to its endocrine-disrupting effects. In this work, we systematically investigated the chemical oxidation process of BP-3 by KMnO₄. The influences of several factors, such as pH, oxidant dose, temperature, coexisting water constituents, and water matrices, on BP-3 degradation efficiency were evaluated. The removal rate of 10 μM BP-3 could reach 91.3% in 2 h under the conditions of pH = 8.0, [BP-3]₀:[KMnO₄]₀ = 1:20, and T = 25 °C, with the observed rate constant (k_obs) value of 0.0202 min^-1. The presence of typical anions (Cl^-, NO₃^-, SO₄^2-) and HA could slightly increase BP-3 removal, while HCO₃^- caused a relatively significant promotion of BP-3 degradation. On the basis of mass spectrometry and theoretical calculations, hydroxylation, direct oxidation, and carbon-carbon bridge bond cleavage were mainly involved in the oxidation process. Toxicity assessment revealed that the acute and chronic toxicities were reduced significantly, which suggested KMnO₄ is a promising technique for BP-3 removal.