Differential activity of BPA, BPAF and BPC on zebrafish estrogen receptors in vitro and in vivo

Assessment of toxicity and endocrine-disrupting activity of bisphenol analogues during ozone and UV treatments in zebrafish eleutheroembryos

In recent decades, increased regulations on the use of bisphenol A (BPA) have prompted a surge in the use of BPA alternatives. Consequently, a widespread occurrence of BPA substitutes in aquatic environments is currently being detected. While some evidence exists about the degradation of these compounds through various water treatment technologies, the evolution of the resulting toxicity and endocrine-disrupting activity during these processes remains scarcely evaluated. In this study, the acute toxicity and transcriptomic responses in zebrafish eleutheroembryos exposed to selected bisphenols (BPA, bisphenol AF (BPAF) and bisphenol CCl (BPC-Cl)) were assessed during their oxidation by ozone. In addition, the response of zebrafish eleutheroembryos exposed to BPC-Cl treated with UV radiation was also investigated. Results showed that both ozonation and UV treatment effectively reduced the intrinsic toxicity of the studied bisphenols. This was observed with the increase of the survival and swim bladder inflation rates of zebrafish eleutheroembryos, reaching control levels. In concordance with these results, the initially altered mRNA levels in genes related to xenobiotic stimulus (cyp2k18); lipid homeostasis and transport (apoa1a); retinoid metabolism (aldh1a2); neutrophil differentiation (alas1); and oxygen transport (hbae3) in zebrafish eleutheroembryos were generally mitigated during the ozonation and UV treatment of bisphenols. Similarly, the high estrogenicity of these bisphenols, observed by elevated mRNA levels of cyp19a1b, decreased significantly during the ozonation treatment, reaching control levels. On the contrary, an increase in mRNA levels of fads2 and cyp19a1b was observed in animals exposed to BPC-Cl treated with UV radiation. These results suggest that the photolysis products of BPC-Cl may induce disruption of the lipid biosynthesis and estrogenicity. This was further confirmed with RNA-sequencing analysis, which revealed that embryos exposed to BPC-Cl treated with UV radiation presented alterations in mRNA levels of genes specifically related to estrogenic stimulus.

Genetic Evidence for Estrogenic Effects of Benzophenone-2 on Zebrafish Neurodevelopment and Its Signaling Mechanism

Estrogens play a crucial role in regulating various biological responses during the early stages of neurodevelopment. Benzophenone-2 (BP2), a widely used organic ultraviolet (UV) filter, has been proven as an estrogenic compound, whereas the estrogenic effects of BP2 on neurodevelopment remain largely unknown. Here, we investigated the neurodevelopmental toxicity of BP2 by exposing zebrafish embryos from 2 to 120 h postfertilization (hpf) at environmentally relevant concentrations. We demonstrated that early life exposure to BP2 induced multiple concentration-dependent impairments in the nervous system, including hypoactivity, abnormal brain morphology, impaired neurocyte proliferation, shortened axon, and increased neurocyte apoptosis. Moreover, metabolomic profiling revealed a decrease in dopamine (DA) and its metabolites in BP2-treated larvae. Using E2 treatment and morpholino knockdown assays, we provided strong genetic evidence that the BP2-induced behavioral disorders were associated with estrogen-dependent signaling, especially estrogen receptors 2a and 2b (esr2). Subsequently, transcriptomic profiling indicated that the activation of esr2 further inhibited the expression of LIM homeobox transcription factor 1 β a (lmx1ba), which is vital for normal neurodevelopment. Consistently, the overexpression of lmx1ba and inhibition of esr2 obviously alleviated BP2-caused neurotoxicity, uncovering a seminal role of esr2 and lmx1ba in BP2-induced neurodevelopmental toxicity. Our findings provide the first evidence in fish that BP2 can induce neurodevelopmental deficits and brain dysfunction and offer novel insights into the mechanisms of toxicity of BP2 as well as other emerging benzophenones.

Sociodemographic and dietary predictors of maternal and placental mycoestrogen concentrations in a US pregnancy cohort

BACKGROUND

Zearalenone (ZEN) is a mycotoxin contaminating grains and processed foods. ZEN alters nuclear estrogen receptor α/β signaling earning its designation as a mycoestrogen. Experimental evidence demonstrates that mycoestrogen exposure during pregnancy is associated with altered maternal sex steroid hormones, changes in placental size, and decreases in fetal weight and length. While mycoestrogens have been detected in human biospecimens worldwide, exposure assessment of ZEN in US populations, particularly during pregnancy, is lacking.

OBJECTIVE

To characterize urinary and placental concentrations of ZEN and its metabolites in healthy US pregnant people and examine demographic, perinatal, and dietary predictors of exposure.

METHODS

Urine samples were collected in each trimester from pregnant participants in the UPSIDE study and placenta samples were collected at delivery (Rochester, NY, n = 317). We used high performance liquid chromatography and high-resolution tandem mass spectrometry to measure total urinary (ng/ml) and placental mycoestrogens (ng/g). Using linear regression and linear mixed effect models, we examined associations between mycoestrogen concentrations and demographic, perinatal, and dietary factors (Healthy Eating Index [HEI], ultra-processed food [UPF] consumption).

RESULTS

Mycoestrogens were detected in 97% of urines (median 0.323 ng/ml) and 84% of placentas (median 0.012 ng/g). Stability of urinary mycoestrogens across pregnancy was low (ICC: 0.16-0.22) and did not correlate with placental levels. In adjusted models, parity (multiparous) and pre-pregnancy BMI (higher) predicted higher urinary concentrations. Birth season (fall) corresponded with higher placental mycoestrogens. Dietary analyses indicated that higher HEI (healthier diets) predicted lower exposure (e.g., Σmycoestrogens %∆ -2.03; 95%CI -3.23, -0.81) and higher percent calories from UPF predicted higher exposure (e.g., Σmycoestrogens %∆ 1.26; 95%CI 0.29, 2.24).

IMPACT

The mycotoxin, zearalenone (ZEN), has been linked to adverse health and reproductive impacts in animal models and livestock. Despite evidence of widespread human exposure, relatively little is known about predictors of exposure. In a pregnant population, we observed that maternal ZEN concentrations varied by maternal pre-pregnancy BMI and parity. Consumption of ultra-processed foods, added sugars, and refined grains were linked to higher ZEN concentrations while healthier diets were associated with lower levels. Our research suggests disparities in exposure that are likely due to diet. Further research is needed to understand the impacts of ZEN on maternal and offspring health.

Bisphenol A Disrupts Ribosome Function during Ovarian Development of Mice

This study examines the impact of Bisphenol A (BPA), a prevalent environmental estrogenic toxicant, on the ovarian development of mice. Mice were exposed to varying BPA doses from in utero to postnatal stages, up to weaning (day 21, PND 21) and puberty (day 45, PND 45). The BPA content in the serum of the offspring mice on PND 45 was higher than that of the mice sacrificed at PND 21. However, the ovary organ index of the mice of PND 21 was significantly increased, and the ovarian structure was damaged when exposed to BPA. In contrast, the mice with PND 45 did not show apparent ovarian lesions. On the other hand, granulosa cell apoptosis was detected in both PND 21 and PND 45 mice ovaries, and ERβ was increased under the influence of BPA. Transcriptomic analysis revealed BPA's significant impact on ribosomal gene expression, marked downregulation of Rpl21 and Rpsa, and upregulation of Rps2 in both age groups. These transcriptomic alterations were further corroborated by real-time PCR, highlighting a dose-dependent effect of BPA on Rps2. Our findings confirm BPA's detrimental effects on ovarian health, with more pronounced damage in younger mice, suggesting heightened vulnerability in this group. The study underscores ribosomes as critical targets in BPA-induced ovarian developmental disruptions.

Interaction of Bisphenol A and Its Analogs with Estrogen and Androgen Receptor from Atlantic Cod (Gadus morhua)

The widespread use of bisphenol A (BPA) in polycarbonate plastics and epoxy resins has made it a prevalent environmental pollutant in aquatic ecosystems. BPA poses a significant threat to marine and freshwater wildlife due to its documented endocrine-disrupting effects on various species. Manufacturers are increasingly turning to other bisphenol compounds as supposedly safer alternatives. In this study, we employed in vitro reporter gene assays and ex vivo precision-cut liver slices from Atlantic cod (Gadus morhua) to investigate whether BPA and 11 BPA analogs exhibit estrogenic, antiestrogenic, androgenic, or antiandrogenic effects by influencing estrogen or androgen receptor signaling pathways. Most bisphenols, including BPA, displayed estrogenic properties by activating the Atlantic cod estrogen receptor alpha (gmEra). BPB, BPE, and BPF exhibited efficacy similar to or higher than that of BPA, with BPB and BPAF being more potent agonists. Additionally, some bisphenols, like BPG, induced estrogenic effects in ex vivo liver slices despite not activating gmEra in vitro, suggesting structural modifications by hepatic biotransformation enzymes. While only BPC2 and BPAF activated the Atlantic cod androgen receptor alpha (gmAra), several bisphenols exhibited antiandrogenic effects by inhibiting gmAra activity. This study underscores the endocrine-disrupting impact of bisphenols on aquatic organisms, emphasizing that substitutes for BPA may pose equal or greater risks to both the environment and human health.

The Dicentrarchus labrax estrogen screen test: A relevant tool to screen estrogen-like endocrine disrupting chemicals in the aquatic environment

In response to the need for the diversification of regulatory bioassays to screen estrogen-like endocrine disrupting chemical (EEDC) in the environment, we propose the use of a reporter gene assay involving all nuclear estrogen receptors from Dicentrarchus labrax (i.e., sbEsr1, sbEsr2a, or sbEsr2b). Named DLES test (D. labrax estrogen screen), it aims at complementing existing standardized in vitro tests by implementing more estrogen receptors notably those that do not originate from humans. Positive responses were obtained with all three estrogen receptors, and-consistently with observations from other species-variations in sensitivity to E2 were measured. Sensitivity and EC50 values could be classified as follows: sbEsr2b < sbEsr2a < sbEsr1. The pharmacological characterization with a human estrogen receptor antagonist (fulvestrant) successfully validated the specific involvement of each sbEsr and evidenced the capacity of the DLES test to highlight antagonist interactions. The DLES test was applied to WWTP contaminant extracts. A positive response was detected in the inflow sample in accordance with the YES test, but not in the outflow sample. Notwithstanding, the DLES test (sbEsr2b) exhibited greater sensitivity for the screening of those samples. This study demonstrates the need for more comprehensive testing including representatives of marine species for a better detection of EEDCs. The DLES test appears as a pertinent tool to predict adverse effects and to widen the scope of screening and hazard assessment of EEDCs in the environment.

Associations between mycoestrogen exposure and sex steroid hormone concentrations in maternal serum and cord blood in the UPSIDE pregnancy cohort

Zearalenone (ZEN) is a fungal-derived toxin found in global food supplies including cereal grains and processed foods, impacting populations worldwide through diet. Because the chemical structure of ZEN and metabolites closely resembles 17β-estradiol (E2), they interact with estrogen receptors α/β earning their designation as 'mycoestrogens'. In animal models, gestational exposure to mycoestrogens disrupts estrogen activity and impairs fetal growth. Here, our objective was to evaluate relationships between mycoestrogen exposure and sex steroid hormone concentrations in maternal circulation and cord blood for the first time in humans. In each trimester, pregnant participants in the UPSIDE study (n = 297) provided urine for mycoestrogen analysis and serum for hormone analysis. At birth, placental mycoestrogens and cord steroids were measured. We fitted longitudinal models examining log-transformed mycoestrogen concentrations in relation to log-transformed hormones, adjusting for covariates. Secondarily, multivariable linear models examined associations at each time point (1st, 2nd, 3rd trimesters, delivery). We additionally considered effect modification by fetal sex. ZEN and its metabolite, α-zearalenol (α-ZOL), were detected in >93% and >75% of urine samples; >80% of placentas had detectable mycoestrogens. Longitudinal models from the full cohort exhibited few significant associations. In sex-stratified analyses, in pregnancies with male fetuses, estrone (E1) and free testosterone (fT) were inversely associated with ZEN (E1 %Δ: -6.68 95%CI: -12.34, -0.65; fT %Δ: -3.22 95%CI: -5.68, -0.70); while α-ZOL was positively associated with E2 (%Δ: 5.61 95%CI: -1.54, 9.85) in pregnancies with female fetuses. In analysis with cord hormones, urinary mycoestrogens were inversely associated with androstenedione (%Δ: 9.15 95%CI: 14.64, -3.30) in both sexes, and placental mycoestrogens were positively associated with cord fT (%Δ: 37.13, 95%CI: 4.86, 79.34) amongst male offspring. Findings support the hypothesis that mycoestrogens act as endocrine disruptors in humans, as in animal models and livestock. Additional work is needed to understand impacts on maternal and child health.

Exploring BPA alternatives - Environmental levels and toxicity review

Bisphenol A alternatives are manufactured as potentially less harmful substitutes of bisphenol A (BPA) that offer similar functionality. These alternatives are already in the market, entering the environment and thus raising ecological concerns. However, it can be expected that levels of BPA alternatives will dominate in the future, they are limited information on their environmental safety. The EU PARC project highlights BPA alternatives as priority chemicals and consolidates information on BPA alternatives, with a focus on environmental relevance and on the identification of the research gaps. The review highlighted aspects and future perspectives. In brief, an extension of environmental monitoring is crucial, extending it to cover BPA alternatives to track their levels and facilitate the timely implementation of mitigation measures. The biological activity has been studied for BPA alternatives, but in a non-systematic way and prioritized a limited number of chemicals. For several BPA alternatives, the data has already provided substantial evidence regarding their potential harm to the environment. We stress the importance of conducting more comprehensive assessments that go beyond the traditional reproductive studies and focus on overlooked relevant endpoints. Future research should also consider mixture effects, realistic environmental concentrations, and the long-term consequences on biota and ecosystems.

Hydroxyl radical and UV-induced reactions of bisphenol analogues in water: Kinetics, transformation products and estrogenic activity estimation

There is currently a concern about the endocrine-disrupting capacity of many bisphenol A substitutes, such as BPAF, BPAP, BPB, BPC, BPC-Cl, BPE, BPF, BPS and BPZ in natural waters. However, fundamental data (i.e., kinetics and mechanisms) about the performance of advanced oxidation processes and UV radiation for water decontamination are scarce. In this study, the removal of bisphenol A substitutes was evaluated by UV/H2O2 and UV treatments under neutral pH conditions. Reactivity of hydroxyl radical (·OH) with bisphenol analogues was studied by competition kinetics and their quantum yield was determined at 254 nm. Results revealed similar values of the second-order rate constants of ·OH with all bisphenols (5.89-14.1 × 109 M-1 s-1), as well as comparable values of the quantum yields (4.8-28.7 × 10-3 mol E-1), except for BPC-Cl. This compound showed a remarkably high quantum yield (4.7 × 10-1 mol E-1), which resulted in a removal higher than 60 % at typical UV disinfection doses (ca. 40 mJ cm-2). The transformation products formed by ·OH and UV-induced reactions were also assessed. Catechol and ortho-quinone derivatives were suggested as the main intermediates from the reaction of bisphenols with ·OH. Excluding BPC-Cl, the resulting photolysis products of bisphenols coincided with those from the ·OH reaction. A distinguished mechanism was proposed for the formation of the photolysis products of BPC-Cl, based on the favoured cleavage of the C-Cl bonds under UV irradiation. Phenanthrene-3,6-diol was suggested as main initial photolysis byproduct of BPC-Cl. Estrogenicity of bisphenols and detected intermediates was predicted using a Quantitative Structure-Activity Relationship (QSAR) approach. Certain byproducts produced during bisphenols reaction with ·OH, such as catechol derivatives, may exhibit estrogenic activity, as they were predicted as very strong binders. Similarly, all photolysis intermediates of BPC-Cl were predicted as very strong binders as well, suggesting that estrogenicity could persist after the treatment.

Physiology-informed toxicokinetic model for the zebrafish embryo test developed for bisphenols

Zebrafish embryos (ZFE) is a widely used model organism, employed in various research fields including toxicology to assess e.g., developmental toxicity and endocrine disruption. Variation in effects between chemicals are difficult to compare using nominal dose as toxicokinetic properties may vary. Toxicokinetic (TK) modeling is a means to estimate internal exposure concentration or dose at target and to enable extrapolation between experimental conditions and species, thereby improving hazard assessment of potential pollutants. In this study we advance currently existing TK models for ZFE with physiological ZFE parameters and novel experimental bisphenol data, a class of chemicals with suspected endocrine activity. We developed a five-compartment model consisting of water, plastic, chorion, yolk sack and embryo in which surface area and volume changes as well as the processes of biotransformation and blood circulation influence mass fluxes. For model training and validation, we measured internal concentrations in ZFE exposed individually to BPA, bisphenol AF (BPAF) and Z (BPZ). Bayesian inference was applied for parameter calibration based on the training data set of BPZ. The calibrated TK model predicted internal ZFE concentrations of the majority of external test data within a 5-fold error and half of the data within a 2-fold error for bisphenols A, AF, F, and tetrabromo bisphenol A (TBBPA). We used the developed model to rank the hazard of seven bisphenols based on predicted internal concentrations and measured in vitro estrogenicity. This ranking indicated a higher hazard for BPAF, BPZ, bisphenol B and C (BPB, BPC) than for BPA.

Genetic and Epigenetic Evidence for Nonestrogenic Disruption of Otolith Development by Bisphenol A in Zebrafish

Bisphenol A (BPA) is a well-known endocrine-disrupting chemical (EDC) that has estrogenic activities. In addition to disrupting reproductive development and function via estrogenic signaling pathways, BPA can also interfere with nonreproductive functions through nonestrogenic pathways; however, the mechanisms underlying such nonestrogenic activities are not well understood. In this study, we demonstrated that BPA could disrupt otolith formation during the early development of zebrafish with long-lasting ethological effects. Using multiple mutants of estrogen receptors, we provided strong genetic evidence that the BPA-induced otolith malformation was independent of estrogen signaling. Transcriptome analysis revealed that two genes related to otolith development, otopetrin 1 (otop1) and starmaker (stm), decreased their expression significantly after BPA exposure. Knockout of both otop1 and stm genes could phenocopy the BPA-induced otolith malformation, while microinjection of their mRNAs could rescue the BPA-induced abnormalities of otolith formation. Further experiments showed that BPA inhibited the expression of otop1 and stm by activating the MEK/ERK-EZH2-H3K27me3 signaling pathway. Taken together, our study provided comprehensive genetic and molecular evidence that BPA induced the otolith malformation through nonestrogenic pathway during zebrafish early development and its activities involved epigenetic control of key genes (e.g., otop1 and stm) participating in otolith formation.

4-Methylbenzylidene camphor triggers estrogenic effects via the brain-liver-gonad axis in zebrafish larvae

4-Methylbenzylidene camphor (4-MBC), an emerging contaminant, is a widely-used ultraviolet (UV) filter incorporated into cosmetics because it protects the skin from UV rays and counters photo-oxidation. Despite the well-established estrogenic activity of 4-MBC, the link between this activity and its effects on neurobehavior and the liver remains unknown. Thus, we exposed zebrafish larvae to environmentally relevant concentrations of 4-MBC with 1.39, 4.17, 12.5 and 15.4 μg/mL from 3 to 5 days postfertilization. We found that 4-MBC produced an estrogenic effect by intensifying fluorescence in the transgenic zebrafish, which was counteracted by co-exposure with estrogen receptor antagonist. 4-MBC-upregulated estrogen receptor alpha (erα) mRNA, and an interaction between 4-MBC and ERα suggested ERα's involvement in the 4-MBC-induced estrogenic activity. RNA sequencing unearthed 4-MBC-triggered responses in estrogen stimulus and lipid metabolism. Additionally, 4-MBC-induced hypoactivity and behavioral phenotypes were dependent on the estrogen receptor (ER) pathway. This may have been associated with the disruption of acetylcholinesterase and acetylcholine activities. As a result, 4-MBC increased vitellogenin expression and caused lipid accumulation in the liver of zebrafish larvae. Collectively, this is the first study to report 4-MBC-caused estrogenic effects through the brain-liver-gonad axis. It provides novel insight into how 4-MBC perturbs the brain and liver development.

In silico simulations and molecular descriptors to predict in vitro transactivation potencies of Baikal seal estrogen receptors by environmental contaminants

Baikal seals (Pusa sibirica) are vulnerable to high levels of organic pollutants. Here, we evaluated the transactivation potencies of bisphenols (BPs) and hydroxylated polychlorinated biphenyls (OH-PCBs) via the Baikal seal estrogen receptor α and β (bsERα and bsERβ) using in vitro and in silico approaches. In vitro reporter gene assays showed that most BPs and OH-PCBs exhibited estrogenic activity with bsER sub-type-specific potency. Among the BPs tested, bisphenol AF showed the lowest EC50 for both bsERs. 4'-OH-CB50 and 4'-OH-CB30 showed the lowest EC50 among OH-PCBs tested for bsERα and bsERβ, respectively. 4-((4-Isopropoxyphenyl)-sulfonyl)phenol, 4'-OH-CB72, and 4'-OH-CB121 showed weak bsERα-specific transactivation. Only 4-OH-CB107 did not affect both bsERs. In silico docking simulations revealed the binding affinities of these chemicals to bsERs and partially explained the in vitro results. Using the in silico simulations and molecular descriptors as explanatory variables and the in vitro results as objective variables, the quantitative structure-activity relationship (QSAR) models constructed for classification and regression accurately separated bsER-active compounds from non-active compounds and predicted the in vitro bsERα- and bsERβ-transactivation potencies, respectively. The QSAR models also suggested that chemical polarity, van der Waals surface area, bridging atom structure, position of the phenolic-OH group, and ligand interactions with key residues of the ligand binding pocket are critical variables to account for the bsER transactivation potency of the test compounds. We also succeeded in constructing computational models for predicting in vitro transactivation potencies of mouse ERs in the same manner, demonstrating the applicability of our approach independent of species-specific responses.

Bisphenol A effects on the host Biomphalaria alexandrina and its parasite Schistosoma mansoni

Bisphenol A (BPA) is one of the most potent endocrine-disrupting chemicals (EDCs) that adversely affect aquatic organisms. The present investigation explored the effects of exposure to BPA at 0.1 and 1 mgL-1 concentrations on the fecundity of Biomphalaria alexandrina, snail's infection with Schistosoma mansoni, and histology of the ovotestis and topographical structure of S. mansoni cercariae emerged from exposed snails. The 24 h LC50 and LC90 values of BPA against B. alexandrina were 8.31 and 10.88 mgL-1 BPA, respectively. The exposure of snails to 0.1 or 1 mgL-1 BPA did not affect the snail's survival. However, these concentrations caused an increase in the reproductive rate (Ro) of infected snails. A slight decrease in egg production was observed in snails exposed to 0.1 mgL-1 BPA after being infected (infected then exposed). However, a significant increase in egg production was noted in snails exposed to 1 mgL-1 BPA after infection with S. mansoni. Histopathological investigations indicated a clear alteration in the ovotestis tissue structure of exposed and infected-exposed groups compared to the control snails. Chronic exposure to BPA caused pathological alterations in the gametogenic cells. SEM preparations of S. mansoni cercariae emerged from infected-exposed snails showed obvious body malformations. From a public health perspective, BPA pollution may negatively impact schistosomiasis transmission, as indicated by the disturbance in cercarial production and morphology. However, it has adverse effects on the reproduction and architecture of reproductive organs of exposed snails, indicating that B. alexandrina snails are sensitive to sublethal BPA exposure.

A comparative study of human and zebrafish glucocorticoid receptor activities of natural and pharmaceutical steroids

Introduction

The action of environmental steroids on the human glucocorticoid receptor (hGR) has been pointed out with the risk to impair physiological immune and metabolic processes regulated by this nuclear receptor. However, there is still a lack of mechanistic information regarding their ability to interact with GR in aquatic species.

Methods

To investigate ligand activation differences between hGR and zebrafish GR (zfGR), we tested several natural and synthetic steroids using reporter cell lines expressing hGR or zfGR.

Results and discussion

Almost all the glucocorticoids tested (dexamethasone, cortisol, bimedrazol, medrol, cortivazol and fluticasone) are agonists of the two receptors with similar potencies. The dissociated glucocorticoids, RU24782 and RU24858 are agonists of both zfGR and hGR but with a better potency for the latter. On the other hand, the synthetic glucocorticoid forbimenol and the mineralocorticoid aldosterone are agonist on hGR but antagonist on zfGR. The other steroids tested, androgens and progestins, are all antagonists of both GRs with equal or lower potency on zfGR than on hGR. Surprisingly, the lower efficacy and potency on zfGR of aldosterone, forbimenol and the dissociated glucocorticoids is not related to their affinity for the receptors which would suggest that it could be related to less efficacious recruitment of coactivators by zfGR compared to hGR.

Optimized extraction and analysis methods using liquid chromatography-tandem mass spectrometry for zearalenone and metabolites in human placental tissue

Zearalenone and its metabolites, a group of endocrine disrupting mycotoxins, have been linked to adverse reproductive health effects. They cross the placental barrier, potentially reaching the fetus. In this study, we adapted and optimized our protocol previously used for urine, to measure these mycotoxins in human placentas. We combined a supported liquid extraction step using Chem Elut cartridges with solid phase extraction on Discovery® DSC-NH2 tubes. The optimized extraction efficiencies were between 68 and 80% for all metabolites. Analysis was performed by UHPLC-HRMS using a Betasil™ Phenyl-Hexyl column eluted with a gradient of acetonitrile-methanol-water. The chromatography method separated all analytes in under 15 min. Validation experiments confirmed the method's sensitivity, with LODs ranging from 0.0055 to 0.011 pg/mg tissue. The method was linear over a range of 0.0025-1.5 pg/mg tissue with R2 values ≥ 0.994. Precision and accuracy calculations ranged from 4.7-7.9% and 0.6-6.7% respectively. The method was then successfully applied to a subset of placenta samples (n = 25) collected from an ongoing prospective birth cohort. Interestingly, 92% of the samples contained at least one measurable zearalenone metabolite, providing initial indication of potentially widespread exposure during pregnancy.

Estrogenic and non-estrogenic effects of bisphenol A and its action mechanism in the zebrafish model: An overview of the past two decades of work

Bisphenol A (BPA) is the most simple and predominant component of the Bisphenol family. BPA is widely present in the environment and the human body as a result of its extensive usage in the plastic and epoxy resins of consumer goods like water bottles, food containers, and tableware. Since the 1930s, when BPA's estrogenic activity was first observed, and it was labeled as a "mimic hormone of E2", studies on the endocrine-disrupting effects of BPA then have been widely conducted. As a top vertebrate model for genetic and developmental studies, the zebrafish has caught tremendous attention in the past two decades. By using the zebrafish, the negative effects of BPA either through estrogenic signaling pathways or non-estrogenic signaling pathways were largely found. In this review, we tried to draw a full picture of the current state of knowledge on the estrogenic and non-estrogenic effects of BPA with their mechanisms of action through the zebrafish model of the past two decades, which may help to fully understand the endocrine-disrupting effects of BPA and its action mechanism, and give a direction for the future studies.

Bisphenol C induces developmental defects in liver and intestine through mTOR signaling in zebrafish (Danio rerio)

Bisphenol A (BPA) was widely used in the plastic products and banned in infant food containers in many countries due to the environmental and biological toxicity. As a common substitute of BPA to manufacture products, Bisphenol C (BPC) is frequently detected in human samples like infants and toddlers' urine, indicating infants and young children are at risk of BPC exposure. However, the understanding of effects of BPC exposure on early development is limited. Herein, we evaluated the early developmental toxicity of BPC and studied the underlying mechanism in a zebrafish model. We found BPC exposure leading to liver and intestinal developmental defects in zebrafish, which occurred via disruption of GPER-AKT-mTOR-RPS6 pathway. Specifically, BPC downregulated phosphorylated and total levels of mTOR, which synergistically reduced the phosphorylation of RPS6, suppressing the translation of genes essential for cell proliferation in liver and intestine such as yap1 and tcf4. Collectively, our results not only observed clear toxicity of BPC during liver and intestinal development but also demonstrated the underlying mechanism of BPC-mediated defects via disrupting the GPER-AKT-mTOR-RPS6 pathway.

In vivo and in silico assessments of estrogenic potencies of bisphenol A and its analogs in zebrafish (Danio rerio): Validity of in silico approaches to predict in vivo effects

This study assessed the estrogen-like potencies of bisphenol A (BPA) and its analogs (BPs) using in vivo and in silico approaches in zebrafish. Zebrafish embryos were exposed to 16 BPs, most of which concentration-dependently induced cytochrome P450 19A1b (CYP19A1b) expression. BPs-induced CYP19A1b expression was suppressed by fulvestrant, a nonselective high affinity antagonist for estrogen receptor (Esr) subtypes. For BPs that concentration-dependently induced CYP19A1b expression, we estimated their 50 % effective concentration (EC₅₀) and relative potencies (REPs) with respect to the potency of BPA for inducing CYP19A1b expression. BP C2, Bis-MP, and BPAF showed lower EC₅₀ than BPA, BPE, and BPF, while BPZ and BPB showed moderate EC₅₀. The REP order of the BPs was BP C2 (26) > Bis-MP (24) > BPAF (21) > BPZ (5.8) > BPB (2.7) > BPE (1.5) > BPF (0.63) > 2,4'-BPF (0.22), indicating that some BPs showed greater estrogenic potencies than BPA in our system. We also constructed in silico homology models of ligand binding domains for zebrafish Esr subtypes, including Esr1, Esr2a, and Esr2b. Molecular docking simulations of ligands with the Esr subtypes revealed the interaction energies of some BPs were lower than that of BPA. The interaction energies showed significant positive correlations with their EC₅₀ values for inducing CYP19A1b expression in vivo. This study showed that some BPA analogs have greater estrogenic potencies than BPA and that in silico simulations of interactions between ligands and Esr subtypes may help predict in vivo estrogenic potencies of untested chemicals.

Early-life bisphenol AP exposure impacted neurobehaviors in adulthood through microglial activation in mice

Bisphenol AP (BPAP), a structural analog of bisphenol A (BPA), has been widely detected in environment and biota. BPAP was reported to interfere with hormone and metabolism, while limited data were available about its effects on neurobehavior, especially exposure to it during early-life time. A mouse model of early-life BPAP exposure was established to evaluate the long-term neurobehaviors in offspring. Collectively, early-life BPAP exposure caused anxiety-like behaviors and impaired learning and memory in adult offspring. Through brain bulk RNA-sequencing (RNA-seq), we found differential expressed genes were enriched in pathways related to behaviors and neurodevelopment, which were consistent with the observed phenotype. Besides, single-nucleus RNA-sequencing (snRNA-seq) showed BPAP exposure altered the transcriptome of microglia in hippocampus. Mechanistically, BPAP exposure induced inflammations in hippocampus through upregulating Iba-1 and activating the microglia. In addition, we observed that BPAP exposure could activate peripheral immunity and promote proportion of macrophages and activation of dendritic cells in the offspring. In conclusion, early-life exposure to BPAP impaired neurobehaviors in adult offspring accompanied with excessive activation of hippocampal microglia. Our findings provide new clues to the underlying mechanisms of BPAP's neurotoxic effects and therefore more cautions should be taken about BPAP.

A PBPK model to evaluate zebrafish eleutheroembryos' actual exposure: bisphenol A and analogs' (AF, F, and S) case studies

The zebrafish eleutheroembryo model is increasingly used to assess the toxicity and developmental adverse effects of xenobiotics. However, the actual exposure is seldom measured (poorly accessible), while a predictive model could estimate these concentrations. The predictions with a new eleutheroembryo physiologically based pharmacokinetic (PBPK) model have been evaluated using datasets obtained from literature data for several bisphenols. The model simulated the toxicokinetics of bisphenols A (BPA), AF, F, and S through the eleutheroembryo tissues while considering the body and organ growth. We further improved the predictions by adding dynamic flows through the embryo and/or its chorion, impact of experimental temperature, metabolic clearance, and saturation of the absorption by Bayesian calibration. The model structure was determined using the BPA dataset and generalized to the other bisphenols. This model revealed the central role of the chorion in the compound uptake in the first 48 h post-fertilization. The predictions for the BPA substitutes estimated by our PBPK model were compared to available toxicokinetics data for zebrafish embryos, and 63% and 88% of them were within a twofold and fivefold error intervals of the corresponding experimental values, respectively. This model provides a tool to design new eleutheroembryo assays and evaluate the actual exposure.

Bisphenol AF Promoted the Growth of Uterus and Activated Estrogen Signaling Related Targets in Various Tissues of Nude Mice with SK-BR-3 Xenograft Tumor

Environmental estrogens can promote the growth, migration, and invasion of breast cancer. However, few studies evaluate adverse health impacts of environmental estrogens on other organs of breast cancer patients. Therefore, the present study investigated the effects of environmental estrogen bisphenol AF (BPAF) on the main organs of female Balb/cA nude mice with SK-BR-3 xenograft tumor by detecting the organ development and gene expression of targets associated with G protein-coupled estrogen receptor 1 (GPER1)-mediated phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) and mitogen-activated protein kinase (MAPK) signaling pathways in hypothalamus, ovary, uterus, liver, and kidney. The results showed that BPAF at 20 mg/kg bw/day markedly increased the uterine weight and the uterine coefficient of nude mice compared to SK-BR-3 bearing tumor control, indicating that BPAF promoted the growth of uterus due to its estrogenic activity. Additionally, BPAF significantly up-regulated the mRNA relative expression of most targets related to nuclear estrogen receptor alpha (ERα) and GPER1-mediated signaling pathways in the hypothalamus, followed by the ovary and uterus, and the least in the liver and kidney, indicating that BPAF activated different estrogen activity related targets in different tissues. In addition, BPAF markedly up-regulated the mRNA expression of GPER1 in all tested tissues, and the molecular docking showed that BPAF could dock into GPER1. Because gene change is an early event of toxicity response, these findings suggested that BPAF might aggravate the condition of breast cancer patients through exerting its estrogenic activity via the GPER1 pathway in various organs.

The masculinization steroid milieu caused by fluorene-9-bisphenol disrupts sex-typical courtship behavior in female zebrafish (Danio rerio)

In vertebrates, the behavior of congenital sex differences between males and females is highly dependent on steroid signals and hormonal milieu. The presence of endocrine disrupting chemicals (EDCs) in the environment generally plays a similar role to sex hormones, so its interference with aquatic organism population stability can not be ignored and is worth studying. Fluorene-9-bisphenol (BHPF) has been clarified as an endocrine disruptor on organisms by several studies but its mechanism in perturbation of courtship behavior of female zebrafish is not clear. Here, we proposed an automated multi-zebrafish tracking method quantifying the courtship process and reported that zebrafish females exposed to BHPF, are not receptive to males but rather court females, and lose normal ovarian function with an altered sex steroid milieu. Our results showed that BHPF damaged 17β-estradiol synthesis by down-regulation of sox3 and cyp19a1a, linking apoptosis with ovary development and female fecundity. The down-regulated expression of estrogen signaling through an estrogen receptor, esr2b, caused the induction of masculinization of female courtship behavior and sexual preference in zebrafish females after BHPF treatment. This process might be mediated by inhibiting the transcription of a neuropeptide B (npb) in the brain. Our study reveals that the estrogen signaling pathway may play an important role in classical courtship behavior and sexual preference of zebrafish. This study provided evidence that anti-estrogenic chemical exposure caused adverse effects on the regulation of the brain-gonad-estrogen axis of aquatic organisms, which should be of concern and highlighted the importance of controlling environmental contamination.

Species Differences in Response to Binding Interactions of Bisphenol A and its Analogs with the Modeled Estrogen Receptor 1 and In Vitro Reporter Gene Assay in Human and Zebrafish

Adverse impacts associated with the interactions of numerous endocrine-disruptor chemicals (EDCs) with estrogen receptor 1 play a pivotal role in reproductive dysfunction. The predictive studies on these interactions thus are crucial in the risk assessment of EDCs but rely heavily on the accuracy of specific protein structure in three dimensions. As the three-dimensional (3D) structure of zebrafish estrogen receptor 1 (zEsr1) is not available, the 3D structure of zEsr1 ligand-binding domain (zEsr1-LBD) was generated using MODELLER and its quality was assessed by the PROCHECK, ERRAT, ProSA, and Verify-3D tools. After the generated model was verified as reliable, bisphenol A and its analogs were docked on the zEsr1-LBD and human estrogen receptor 1 ligand-binding domain (hESR1-LBD) using the Discovery Studio and Autodock Vina programs. The molecular dynamics followed by molecular docking were simulated using the Nanoscale Molecular Dynamics program and compared to those of the in vitro reporter gene assays. Some chemicals were bound with an orientation similar to that of 17β-estradiol in both models and in silico binding energies showed moderate or high correlations with in vitro results (0.33 ≤ r²  ≤ 0.71). Notably, hydrogen bond occupancy during molecular dynamics simulations exhibited a high correlation with in vitro results (r²  ≥ 0.81) in both complexes. These results show that the combined in silico and in vitro approaches is a valuable tool for identifying EDCs in different species, facilitating the assessment of EDC-induced reproductive toxicity. Environ Toxicol Chem 2022;41:2431-2443. © 2022 SETAC.

Endocrine-Disrupting Effects of Bisphenol A on the Cardiovascular System: A Review

Currently, the plastic monomer and plasticizer bisphenol A (BPA) is one of the most widely used chemicals. BPA is present in polycarbonate plastics and epoxy resins, commonly used in food storage and industrial or medical products. However, the use of this synthetic compound is a growing concern, as BPA is an endocrine-disrupting compound and can bind mainly to estrogen receptors, interfering with different functions at the cardiovascular level. Several studies have investigated the disruptive effects of BPA; however, its cardiotoxicity remains unclear. Therefore, this review’s purpose is to address the most recent studies on the implications of BPA on the cardiovascular system. Our findings suggest that BPA impairs cardiac excitability through intracellular mechanisms, involving the inhibition of the main ion channels, changes in Ca²⁺ handling, the induction of oxidative stress, and epigenetic modifications. Our data support that BPA exposure increases the risk of developing cardiovascular diseases (CVDs) including atherosclerosis and its risk factors such as hypertension and diabetes. Furthermore, BPA exposure is also particularly harmful in pregnancy, promoting the development of hypertensive disorders during pregnancy. In summary, BPA exposure compromises human health, promoting the development and progression of CVDs and risk factors. Further studies are needed to clarify the human health effects of BPA-induced cardiotoxicity.

The alternative analog plasticizer BPS displays similar phenotypic and metabolomic responses to BPA in HepG2 and INS-1E cells

Bisphenols A (BPA) and S (BPS) are endocrine-disrupting chemicals that affect energy metabolism, leading to impairment of glucose and lipid homeostasis. We aimed at identifying metabolic pathways regulated by both compounds in human liver cells and rat pancreatic β-cells that could impair energy homeostasis regulation. We assessed the effects on growth, proliferation, and viability of hepatocarcinoma (HepG2) and insulinoma (INS-1E) cells exposed to either BPA or BPS in a full range concentration between 0.001 and 100 μM. Both the dose and duration of exposure caused a differential response on growth and viability of both cells. Effects were more pronounced on HepG2, as these cells exhibited non-linear dose-responses following exposure to xenobiotics. For INS-1E, effect was observed only at the highest concentration. In addition, we profiled their intracellular state by untargeted metabolomics at 24, 48, and 72 h of exposure. This analysis revealed time- and dose-dependently molecular changes for HepG2 and INS-1E that were similar between BPA and BPS. Both increased levels of inflammatory mediators, such as metabolites pertaining to linolenic and linoleic acid metabolic pathway. In summary, this study shows that BPS also disrupts molecular functions in cells that regulate energy homeostasis, displaying similar but less pronounced responses than BPA.

Transcriptomic and physiological analysis of endocrine disrupting chemicals Impacts on 3D Zebrafish liver cell culture system

In recent decades, extensive efforts have focused on developing in vitro platforms mimicking fish livers to better understand the acute or chronic effects of toxicants on lower aquatic vertebrates. Fish liver cell lines have emerged as a promising culture system for these in vitro platforms because they complement the currently limited in vitro tools that mostly consist of mammalian cell lines and adhere to the 3Rs: replacement, reduction, and refinement of living animal tests. However, monolayer cell lines have lower transcriptional and physiological responses upon exposure to toxic chemicals than freshly isolated primary cells. To overcome this challenge, we utilized a three-dimensional (3D) spheroid-based in vitro platform, in which hepatocyte cells had self-organized into spheroid forms via E-cadherin bonds. This platform exhibited augmented transcriptomic and phenotypic regulation of liver cells in comparison to monolayer cells. We examined the organoid platform using the zebrafish liver (ZFL) cell line as a model system. ZFL cells spontaneously clustered into 3D spheroids with long-term viability by optimizing cell seeding density on a non-adherent substrate. Interestingly, 3D ZFL spheroids treated with estrogenic chemicals were activated to synthesize a higher level of vitellogenin (Vtg) than monolayer cells. Whole-transcriptome sequencing analysis confirmed that 3D ZFL spheroids had greater transcriptional regulation of genes related to reproductive toxicological response and liver functions, such as the urea cycle, estrogen receptors, and vitellogenin, compared to monolayer cells. These results may contribute to the engineering of novel 3D in vitro platforms for screening harmful chemicals and improving understanding of the underlying liver toxicity mechanisms at the molecular and cellular levels.

Emerging concepts and opportunities for endocrine disruptor screening of the non-EATS modalities

Endocrine disrupting chemicals (EDCs) are ubiquitous in the environment and involve diverse chemical-receptor interactions that can perturb hormone signaling. The Organization for Economic Co-operation and Development has validated several EDC-receptor bioassays to detect endocrine active chemicals and has established guidelines for regulatory testing of EDCs. Focus on testing over the past decade has been initially directed to EATS modalities (estrogen, androgen, thyroid, and steroidogenesis) and validated tests for chemicals that exert effects through non-EATS modalities are less established. Due to recognition that EDCs are vast in their mechanisms of action, novel bioassays are needed to capture the full scope of activity. Here, we highlight the need for validated assays that detect non-EATS modalities and discuss major international efforts underway to develop such tools for regulatory purposes, focusing on non-EATS modalities of high concern (i.e., retinoic acid, aryl hydrocarbon receptor, peroxisome proliferator-activated receptor, and glucocorticoid signaling). Two case studies are presented with strong evidence amongst animals and human studies for non-EATS disruption and associations with wildlife and human disease. This includes metabolic syndrome and insulin signaling (case study 1) and chemicals that impact the cardiovascular system (case study 2). This is relevant as obesity and cardiovascular disease represent two of the most significant health-related crises of our time. Lastly, emerging topics related to EDCs are discussed, including recognition of crosstalk between the EATS and non-EATS axis, complex mixtures containing a variety of EDCs, adverse outcome pathways for chemicals acting through non-EATS mechanisms, and novel models for testing chemicals. Recommendations and considerations for evaluating non-EATS modalities are proposed. Moving forward, improved understanding of the non-EATS modalities will lead to integrated testing strategies that can be used in regulatory bodies to protect environmental, animal, and human health from harmful environmental chemicals.

Use of Reporter Genes to Analyze Estrogen Response: The Transgenic Zebrafish Model

In vivo models to detect estrogenic compounds are very valuable for screening for endocrine disruptors. Here we describe the use of transgenic estrogen reporter zebrafish as an in vivo model for the identification of estrogenic properties of compounds. Live imaging of these transgenic fish provides knowledge of estrogen receptor specificity of different ligands as well as dynamics of estrogen signaling. Coupled to image analysis, the model can provide quantitative concentration-response information on estrogenic activity of chemical compounds.

Environmental persistence, detection, and mitigation of endocrine disrupting contaminants in wastewater treatment plants – a review with a focus on tertiary treatment technologies

Endocrine disrupting chemicals are a group of contaminants that have severe effects on humans and animals when exposed, like cancer and alterations to the nervous and reproductive systems.

Interspecies Differences in Activation of Peroxisome Proliferator-Activated Receptor γ by Pharmaceutical and Environmental Chemicals

Endocrine disrupting chemicals (EDCs) are able to deregulate the hormone system, notably through interactions with nuclear receptors (NRs). The mechanisms of action and biological effects of many EDCs have mainly been tested on human and mouse but other species such as zebrafish and xenopus are increasingly used as a model to study the effects of EDCs. Among NRs, peroxisome proliferator-activated receptor γ (PPARγ) is a main target of EDCs, for which most experimental data have been obtained from human and mouse models. To assess interspecies differences, we tested known human PPARγ ligands on reporter cell lines expressing either human, mouse, zebrafish, or xenopus PPARγ. Using these cell lines, we were able to highlight major interspecies differences. Known hPPARγ pharmaceutical ligands modulated hPPARγ and mPPARγ activities in a similar manner, while xPPARγ was less responsive and zfPPARγ was not modulated at all by these compounds. On the contrary, human liver X receptor (hLXR) ligands GW 3965 and WAY-252623 were only active on zfPPARγ. Among environmental compounds, several molecules activated the PPARγ of the four species similarly, e.g., phthalates (MEHP), perfluorinated compounds (PFOA, PFOS), and halogenated derivatives of BPA (TBBPA, TCBPA), but some of them like diclofenac and the organophosphorus compounds tri-o-tolyl phosphate and triphenyl phosphate were most active on zfPPARγ. This study confirms or shows for the first time the h, m, x, and zfPPARγ activities of several chemicals and demonstrates the importance of the use of species-specific models to study endocrine and metabolism disruption by environmental chemicals.

Teratogenicity and toxicity of the new BPA alternative TMBPF, and BPA, BPS, and BPAF in chick embryonic development

Bisphenol A (BPA) is a widely known, yet controversial reproductive toxin, capable of inducing reproductive, developmental, and somatic growth defects across species. Due to scientific findings and public concern, companies have developed BPA alternatives remarkably similar to BPA. However, these alternatives have had much less testing and oversight, yet they are already being mass-produced and used across industries from plastics to food-contact coatings. The newest one, tetramethyl bisphenol F (TMBPF), is the least well-studied and has never been investigated in embryological models, however it continues to be mass produced and found in various products. Here, we used the chicken embryotoxicity screening test to compare the toxicities and potencies of several BPA analogs including TMBPF. We exposed developing chicken (Gallus gallus domesticus) embryos in ovo, from embryonic day 5 to 12 (E5-12), to increasing concentrations of BPA, bisphenol S (BPS), bisphenol AF (BPAF), and TMBPF, from 0.003 to 30 μM, and analyzed their developmental and toxic effects. The bisphenols significantly impaired development, growth, and survival in a dose-dependent manner, even at low, environmentally relevant concentrations of 3-30 nM. There was severely reduced growth and developmental delay, with exposed embryos averaging half the size and weight of control vehicle-treated embryos. The most common and severe dysmorphologies were craniofacial, eye, gastrointestinal, and body pigmentation abnormalities. The bisphenols caused dose-dependent toxicity with the lowest LC₅₀s (lethal concentration with 50% survival) ever demonstrated in chick embryos, at 0.83-2.92 μM. Notably, TMBPF was the second-most toxic and teratogenic of all chemicals tested (rank order of BPAF > TMBPF > BPS > BPA). These results underscore the adverse effects of BPA replacements on early embryo development and may have implications for reproductive health and disease across species, including pregnancy exposures in humans.

Bisphenol AF exposure causes fasting hyperglycemia in zebrafish (Danio rerio) by interfering with glycometabolic networks

Bisphenol AF (BPAF), one of the main alternatives to bisphenol A, has been frequently detected in various environmental media, including the human body, and is an emerging contaminant. Epidemiological investigations have recently shown the implications of exposure to BPAF in the incidence of diabetes mellitus in humans, indicating that BPAF may be a potential diabetogenic endocrine disruptor. However, the effects of BPAF exposure on glucose homeostasis and their underlying mechanisms in animals remain largely unknown, which may limit our understanding of the health risks of BPAF. To this end, zebrafish (Danio rerio), an emerging and valuable model in studying animal glycometabolism and diabetes, were exposed to environmentally relevant concentrations (5 and 50 μg/L) and 500 μg/L BPAF for 28 d. Several key toxicity endpoints of blood glucose metabolism were detected in our study, and the results showed significantly increased fasting blood glucose levels, hepatic glycogen contents and hepatosomatic indexes and decreased muscular glycogen contents in the BPAF-exposed zebrafish. The results of quantitative real-time PCR showed the abnormal expression of genes involved in glycometabolic networks, which might promote hepatic gluconeogenesis and inhibit glycogenesis and glycolysis in the muscle and/or liver. Furthermore, the failure of insulin regulation, including plasma insulin deficiency and impaired insulin signaling pathways in target tissues, may be a potential mechanism underlying BPAF-induced dysfunctional glycometabolism. In summary, our results provide novel in vivo evidence that BPAF can cause fasting hyperglycemia by interfering with glycometabolic networks, which emphasizes the potential health risks of environmental exposure to BPAF in inducing diabetes mellitus.

Individual and combined effects of BPA, BPS and BPAF on the cardiomyocyte differentiation of embryonic stem cells

Exposure to many kinds of bisphenols (BPs) is common, and the effects of BP mixtures may differ from those of individual BPs. Therefore, evaluating combined exposure effects is necessary. Our study evaluated the individual and combined exposure effects of bisphenol A (BPA), bisphenol S (BPS) and bisphenol AF (BPAF) on embryonic development using an embryonic stem cell test (EST) and a concentration additive (CA) model at relatively high doses to uncover the interaction model of the three BPs. Environmentally relevant concentrations were then used to evaluate the possible effects of the individual and combined BPs at actual human exposure levels. Exposure to relatively high-dose BPA, BPS and BPAF inhibited embryonic stem cell differentiation into cardiomyocytes and exhibited weak embryo toxicity. Individually, BPA, BPS and BPAF inhibited endoderm, mesoderm and ectoderm marker expression but enhanced pluripotency marker expression. Combined exposure to BPs had an additive effect on cardiomyocyte differentiation and embryonic stem cell proliferation based on the CA model. Environmentally relevant individual or combined BP doses (10 ng/ml individual BPA, BPS and BPAF doses or 1 ng/ml and 10 ng/ml BP mixture doses) failed to cause oxidative stress, DNA damage or apoptosis changes in stem cell differentiation. The cardiomyocyte differentiation ratio also did not change significantly. Individual and combined exposure to environmentally relevant BP doses led to a significant increase in collagen expression. BPAF and the combination of BPs increased the type 1 collagen level, while the combination also increased the type 3 collagen level, which may be related to p38 pathway activation. The p38 pathway inhibitor SB203580 inhibited the increase in collagen during cardiomyocyte differentiation caused by low-dose BPs. These results suggest that relatively high-dose BPs in combination have an additive effect on cardiomyocyte differentiation. Low-dose BPs individually and in combination may affect cardiomyocyte collagen through the p38 pathway.

Impact of Fusarium-Derived Mycoestrogens on Female Reproduction: A Systematic Review

Contamination of the world's food supply and animal feed with mycotoxins is a growing concern as global temperatures rise and promote the growth of fungus. Zearalenone (ZEN), an estrogenic mycotoxin produced by Fusarium fungi, is a common contaminant of cereal grains and has also been detected at lower levels in meat, milk, and spices. ZEN's synthetic derivative, zeranol, is used as a growth promoter in United States (US) and Canadian beef production. Experimental research suggests that ZEN and zeranol disrupt the endocrine and reproductive systems, leading to infertility, polycystic ovarian syndrome-like phenotypes, pregnancy loss, and low birth weight. With widespread human dietary exposure and growing experimental evidence of endocrine-disrupting properties, a comprehensive review of the impact of ZEN, zeranol, and their metabolites on the female reproductive system is warranted. The objective of this systematic review was to summarize the in vitro, in vivo, and epidemiological literature and evaluate the potential impact of ZEN, zeranol, and their metabolites (commonly referred to as mycoestrogens) on female reproductive outcomes. We conducted a systematic review (PROSPERO registration CRD42020166469) of the literature (2000-2020) following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The data sources were primary literature published in English obtained from searching PubMed, Web of Science, and Scopus. The ToxR tool was applied to assess risk of bias. In vitro and in vivo studies (n = 104) were identified and, overall, evidence consistently supported adverse effects of mycoestrogens on physiological processes, organs, and tissues associated with female reproduction. In non-pregnant animals, mycoestrogens alter follicular profiles in the ovary, disrupt estrus cycling, and increase myometrium thickness. Furthermore, during pregnancy, mycoestrogen exposure contributes to placental hemorrhage, stillbirth, and impaired fetal growth. No epidemiological studies fitting the inclusion criteria were identified.

Bisphenol AF induces apoptosis via estrogen receptor beta (ERβ) and ROS-ASK1-JNK MAPK pathway in human granulosa cell line KGN

Bisphenol AF (BPAF) is an emerging environmental pollutant. Although BPAF is widely spread in the environment and human surroundings, its interference with ovarian function has not been fully elucidated. The aim of this study was to identify the mechanism underlying the effect of BPAF on the apoptosis of KGN cells, which maintain the physiological characteristics of ovarian granulosa cells. Our results indicated that BPAF induces KGN cell apoptosis in a concentration- and time-dependent manner. Meanwhile, BPAF exposure significantly promoted the expression of pro-apoptotic proteins, including Bax, Bid and Bak, while the expression of anti-apoptotic proteins, such as Bcl-2, Bcl-xL and Mcl-1, decreased significantly. We further detected a significant increase in intracellular ROS levels in response to high concentrations of BPAF exposure. After blocking the corresponding pathway, it was found that ROS mediates ASK1 and JNK activation. Furthermore, the role of Ca²⁺ overload and estrogen receptor β (ERβ) in BPAF-induced KGN cell apoptosis was also confirmed by using inhibitors. These results suggest that BPAF has potential reproductive toxicity for females, and ROS-ASK1-JNK axis may play a key role in BPAF-induced ovarian dysfunction. In addition, Ca²⁺ overload and ERβ pathway activation may also be an important mechanism of reproductive toxicity of BPAF.

Bisphenol A induces apoptosis through GPER-dependent activation of the ROS/Ca2+-ASK1-JNK pathway in human granulosa cell line KGN

Bisphenol A (BPA) is widely distributed in the environment and human surroundings and is closely related to the occurrence of many chronic diseases including female infertility. Although BPA-induced granulosa cell apoptosis has been widely reported, the underlying mechanisms remain unknown. In this study, we evaluated the induction effect of BPA exposure on apoptosis and mechanisms of regulation in KGN cells (a human granulosa-like tumor cell line). Our results indicated that BPA induced apoptosis of KGN cells in a dose- and time-dependent manner. BPA exposure significantly promoted the expression of pro-apoptotic proteins and decreased mitochondrial membrane potential. We also observed that high concentrations of BPA significantly promoted the generation of reactive oxygen species (ROS) and calcium ion (Ca²⁺) accumulation. The involvement of ROS and Ca²⁺ in BPA-induced KGN cell apoptosis was confirmed by pretreatment with NAC (an antioxidant) and BAPTA-AM (a calcium chelator). After inhibitors pretreatment to block the corresponding signaling pathways, it was found that BPA-induced phosphorylation of JNK and ASK1 proteins and apoptosis of KGN cells were significantly inhibited. We pretreated with G15 (a GPER inhibitor) and found that BPA-induced ROS generation and Ca²⁺ accumulation and apoptosis were significantly inhibited. These results suggest that BPA exposure induces KGN cell apoptosis through GPER-dependent activation of the ROS/Ca²⁺-ASK1-JNK signaling pathway. Our study provides mechanisms by which BPA induced apoptosis of granulosa cells and ovarian dysfunction.

Acute toxicity of Bisphenol A (BPA) to tropical marine and estuarine species from different trophic groups

BPA is chemical pollutant of very high concern due to its toxicity to the environment and risks for human health. Environmental concern consists in BPA entrance into aquatic ecosystems due to acute and chronic toxicity to invertebrates and vertebrates. This study aimed to determine acute BPA toxicity to tropical estuarine-marine species of four trophic levels and integrate BPA toxicity values using species sensitivity distribution (SSD) analysis. Our hypothesis is that BPA toxicity increases towards higher trophic levels. Microalga (Tetraselmis sp.), zooplanktonic grazer (Artemia salina), deposit-feeder invertebrate (Heleobia australis), and omnivorous fish (Poecilia vivipara) were chosen as experimental models. Tetraselmis sp. showed the highest BPA tolerance, without a concentration-dependent response. Species sensitivity have increased from A. salina (LC_50,96h = 107.2 mg L^-1), followed by H. australis (LC_50,96h = 11.53.5 mg L^-1), to P. vivipara (LC_50,96h = 3.5 mg L^-1). Despite the toxicity hierarchy towards trophic levels, which partially supported our hypothesis, SSD did not evidence a clear pattern among estuarine-marine trophic groups. Our study disclosed the sensitivity of not yet investigated species to BPA and, in an integrative way, highlighted BPA toxic effects at different trophic levels. Although estimated acute hazardous concentration (HC5 = 1.18 mg L^-1) for estuarine and marine species was higher than environmentally relevant concentrations, sublethal adverse effects induced by BPA exposure may lead to unbalances in population levels and consequently affect the ecological functioning of tropical coastal systems.

Acute and long-term metabolic consequences of early developmental Bisphenol A exposure in zebrafish (Danio rerio)

Bisphenol A (BPA) is an estrogenic contaminant linked to metabolic disruption. Developmental BPA exposure is of particular concern, as organizational effects may irreversibly disrupt metabolism at later life-stages. While BPA exposures in adult fish elicit metabolic perturbations similar to effects described in rodents, the metabolic effects of developmental BPA exposure in juvenile fish remain largely unknown. Following embryonic zebrafish exposure to BPA (0.1, 1 and 4 mg/L) and EE₂ (10 ng/L) from 2 to 5 dpf, we assessed the metabolic phenotype in larvae (4-6 dpf) and juveniles (43-49 dpf) which had been divided into regular-fed and overfed groups at 29 dpf. Developmental BPA exposure in larvae dose-dependently reduced food-intake and locomotion and increased energy expenditure. Juveniles (29 dpf) exhibited a transient increase in body weight after developmental BPA exposure and persistent diet-dependent locomotion changes (43-49 dpf). At the molecular level, glucose and lipid metabolism-related transcript abundance clearly separated BPA exposed fish from controls and EE₂ exposed fish at the larval stage, in juveniles on a regular diet and, to a lesser extent, in overfed juveniles. In general, the metabolic endpoints affected by BPA exposure were not mimicked by EE₂ treatment. We conclude that developmental BPA exposure elicits acute metabolic effects in zebrafish larvae and fewer transient and persistent effects in juveniles and that these metabolic effects are largely independent of BPA's estrogenicity.