Bisphenol A Action Research Articles

The Evaluation of Evidence Bisphenol A Exposure and Human Reproductive Health: A review

Infertility is widespread problem defined as the inability to conceive after one year of unprotected intercourse. One of the most notable factors causing this status is the exposure to environmental contaminants. It is now recognized that many contaminants present in the environment have the ability to interfere in the action of hormones and therefore are termed endocrine disruptors (EDs). Some of these compounds are present in nature, but the majority are artificial and released into the environment by the human activities without any prior knowledge of their impact on ecosystems, animal welfare, or wildlife and human health. Many epidemiological studies have reported a radical growth in the incidence of male infertility, accompanied by decreasing sperm quality, decline in spermatozoa motility, defect in Leydig cell morphology, insufficient activity of steroidogenesis and spermatogenesis. The similar situation was observed in female, when the increased risk for endometriosis, reproductive and other endocrine-related cancer, impaired oocytes, ovarian dysfunction, or irregular menstrual cycle was confirmed. All mentioned consequences have been associated with increasing concentration of bisphenol A (BPA) in the environment. Humans are exposed to BPA not only through specific occupational circumstance, but nowadays more generally also from the ordinary day-to-day domestic and workplace lifestyles. Almost 3.4 million tons per year of BPA is used in a variety common product such as food packaging, household products, epoxy resins, dental sealants and many others. Under these endpoints, apprehensions about the reproductive dysfunctions associated with BPA action are unquestionable. In this review, we address the topic of BPA effects on reproductive function in males and females and emphasize its effects on overall health. A considerably more detailed and systematic research in EDs toxicology is required for a better understanding of risks associated with exposure to environmental toxicants.

Potential Mechanisms of Bisphenol A (BPA) Contributing to Human Disease.

Bisphenol A (BPA) is an organic synthetic compound serving as a monomer to produce polycarbonate plastic, widely used in the packaging for food and drinks, medical devices, thermal paper, and dental materials. BPA can contaminate food, beverage, air, and soil. It accumulates in several human tissues and organs and is potentially harmful to human health through different molecular mechanisms. Due to its hormone-like properties, BPA may bind to estrogen receptors, thereby affecting both body weight and tumorigenesis. BPA may also affect metabolism and cancer progression, by interacting with GPR30, and may impair male reproductive function, by binding to androgen receptors. Several transcription factors, including PPARγ, C/EBP, Nrf2, HOX, and HAND2, are involved in BPA action on fat and liver homeostasis, the cardiovascular system, and cancer. Finally, epigenetic changes, such as DNA methylation, histones modification, and changes in microRNAs expression contribute to BPA pathological effects. This review aims to provide an extensive and comprehensive analysis of the most recent evidence about the potential mechanisms by which BPA affects human health.

Hydrogen Peroxide Production by the Spot-Like Mode Action of Bisphenol A.

Bisphenol A (BPA), an intermediate chemical used for synthesizing polycarbonate plastics, has now become a wide spread organic pollutant. It percolates from a variety of sources, and plants are among the first organisms to encounter, absorb, and metabolize it, while its toxic effects are not yet fully known. Therefore, we experimentally studied the effects of aqueous BPA solutions (50 and 100 mg L−1, for 6, 12, and 24 h) on photosystem II (PSII) functionality and evaluated the role of reactive oxygen species (ROS) on detached leaves of the model plant Arabidopsis thaliana. Chlorophyll fluorescence imaging analysis revealed a spatiotemporal heterogeneity in the quantum yields of light energy partitioning at PSII in Arabidopsis leaves exposed to BPA. Under low light PSII function was negatively influenced only at the spot-affected BPA zone in a dose- and time-dependent manner, while at the whole leaf only the maximum photochemical efficiency (Fv/Fm) was negatively affected. However, under high light all PSII photosynthetic parameters measured were negatively affected by BPA application, in a time-dependent manner. The affected leaf areas by the spot-like mode of BPA action showed reduced chlorophyll autofluorescence and increased accumulation of hydrogen peroxide (H2O2). When H2O2 was scavenged via N-acetylcysteine under BPA exposure, PSII functionality was suspended, while H2O2 scavenging under non-stress had more detrimental effects on PSII function than BPA alone. It can be concluded that the necrotic death-like spots under BPA exposure could be due to ROS accumulation, but also H2O2 generation seems to play a role in the leaf response against BPA-related stress conditions.

Role of bisphenol A on calcium influx and its potential toxicity on the testis of Danio rerio

This study investigated the acute in vitro effect of low-concentration bisphenol A (BPA) on calcium (45Ca2+) influx in zebrafish (Danio rerio) testis and examined whether intracellular Ca2+ was involved in the effects of BPA on testicular toxicity. In vitro studies on 45Ca2+ influx were performed in the testes after incubation with BPA for 30 min. Inhibitors were added 15 min before the addition of 45Ca2+ and BPA to testes to study the mechanism of action of BPA. The involvement of intracellular calcium from stores on lactate dehydrogenase (LDH) release and on triacylglycerol (TAG) content were carried out after in vitro incubation of testes with BPA for 1 h. Furthermore, gamma-glutamyl transpeptidase (GGT) and aspartate aminotransferase (AST) activities were analyzed in the liver at 1 h after in vitro BPA incubation of D. rerio. Our data show that the acute in vitro treatment of D. rerio testes with BPA at very low concentration activates plasma membrane ionic channels, such as voltage-dependent calcium channels and calcium-dependent chloride channels, and protein kinase C (PKC), which stimulates Ca2+ influx. In addition, BPA increased cytosolic Ca2+ by activating inositol triphosphate receptor (IP3R) and inhibiting sarco/endoplasmic reticulum calcium ATPase (SERCA) at the endoplasmic reticulum, contributing to intracellular Ca2+ overload. The protein kinases, PKC, MEK 1/2 and PI3K, are involved in the mechanism of action of BPA, which may indicate a crosstalk between the non-genomic initiation effects mediated by PLC/PKC/IP3R signaling and genomic responses of BPA mediated by the estrogen receptor (ESR). In vitro exposure to a higher concentration of BPA caused cell damage and plasma membrane injury with increased LDH release and TAG content; both effects were dependent on intracellular Ca2+ and mediated by IP3R. Furthermore, BPA potentially induced liver damage, as demonstrated by increased GGT activity. In conclusion, in vitro effect of BPA in a low concentration triggers cytosolic Ca2+ overload and activates downstream protein kinases pointing to a crosstalk between its non-genomic and genomic effects of BPA mediated by ESR. Moreover, in vitro exposure to a higher concentration of BPA caused intracellular Ca2+-dependent testicular cell damage and plasma membrane injury. This acute toxicity was reinforced by increased testicular LDH release and GGT activity in the liver.

Effects of Prenatal Exposure to a Low-Dose of Bisphenol A on Sex Differences in Emotional Behavior and Central Alpha2-Adrenergic Receptor Binding.

Prenatal exposure to bisphenol A (BPA) influences the development of sex differences neurologically and behaviorally across many species of vertebrates. These effects are a consequence of BPA’s estrogenic activity and its ability to act as an endocrine disrupter even, at very low doses. When exposure to BPA occurs during critical periods of development, it can interfere with the normal activity of sex steroids, impacting the fate of neurons, neural connectivity and the development of brain regions sensitive to steroid activity. Among the most sensitive behavioral targets of BPA action are behaviors that are characterized by a sexual dimorphism, especially emotion and anxiety related behaviors, such as the amount of time spent investigating a novel environment, locomotive activity and arousal. Moreover, in some species of rodents, BPA exposure affected males’ sexual behaviors. Interestingly, these behaviors are at least in part modulated by the catecholaminergic system, which has been reported to be a target of BPA action. In the present study we investigated the influence of prenatal exposure of mice to a very low single dose of BPA on emotional and sexual behaviors and on the density and binding characteristics of alpha2 adrenergic receptors. Alpha2 adrenergic receptors are widespread in the central nervous system and they can act as autoreceptors, inhibiting the release of noradrenaline and other neurotransmitters from presynaptic terminals. BPA exposure disrupted sex differences in behavioral responses to a novel environment, but did not affect male mice sexual behavior. Importantly, BPA exposure caused a change in the binding affinity of alpha2 adrenergic receptors in the locus coeruleus and medial preoptic area (mPOA) and it eliminated the sexual dimorphism in the density of the receptors in the mPOA.

Bisphenol A and S impaired ovine granulosa cell steroidogenesis.

Bisphenols, plasticisers used in food containers, can transfer to food. Bisphenol A (BPA) has been described as an endocrine disruptor and consequently banned from the food industry in several countries. It was replaced by a structural analogue, Bisphenol S (BPS). BPA action on the steroidogenesis is one of the mechanisms underlying its adverse effects on the efficiency of female reproduction. This study aimed to determine whether BPS is a safe alternative to BPA regarding GC functions. Antral follicles (2-6 mm), of approximatively 1000 adult ewe ovaries, were aspired and GC purified. For 48 h, ovine GC were treated with BPA or BPS (from 1 nM to 200 µM) and the effects on cell viability, proliferation, steroid production, steroidogenic enzyme expression and signalling pathways were investigated. Dosages at and greater than 100 μM BPA and 10 µM BPS decreased progesterone secretion by 39% (P < 0.001) and 22% (P = 0.040), respectively. BPA and BPS 10 μM and previously mentioned concentrations increased oestradiol secretion two-fold (P < 0.001 and P = 0.082, respectively). Only 100 µM BPA induced a decrease (P < 0.001) in gene expression of the enzymes of steroidogenesis involved in the production of progesterone. BPA reduced MAPK3/1 phosphorylation and ESR1 and ESR2 gene expression, effects that were not observed with BPS. BPA and BPS altered steroidogenesis of ovine GC. Thus, BPS does not appear to be a safe alternative for BPA. Further investigations are required to elucidate BPA and BPS mechanisms of action.

Effects of bisphenol A and its alternative bisphenol F on Notch signaling and intestinal development: A novel signaling by which bisphenols disrupt vertebrate development

We previously found bisphenol A (BPA) alternative, bisphenol F (BPF) upregulated Notch-related gene expression in intestines of the African clawed frog Xenopus laevis, suggesting an agonistic action on Notch signaling, a crucial signaling in multiple biological processes during development. Here, we aimed to confirm the actions of BPA and BPF on Notch signaling and to reveal their effects on intestinal development. Using X. laevis, an excellent model for developmental biology, we found that 10–1000 nM BPA and BPF significantly elevated Notch-related gene expression in a concentration-dependent manner. Subsequently, exceptional cell proliferation as well as intestinal histological changes were observed in treated intestines. Importantly, Notch inhibitor markedly suppressed the effects of BPA and BPF described above. Furthermore, we employed rat intestinal epithelium cells (IEC-6), an ideal in vitro model of intestinal epithelial cell differentiation, to confirm the effects of bisphenols. As expected, BPA and BPF upregulated Notch-related gene expression and induced the translocation of the Notch intracellular domain to the nucleus, followed by exceptional cell proliferation and differentiation, whereas Notch inhibitor antagonized the effects caused by BPA and BPF. All results strongly demonstrate that both BPA and BPF activate Notch signaling and subsequently disrupt intestinal development in vertebrates. Given its fundamental roles in multiple developmental processes, we propose that Notch signaling is an important and general target signaling of bisphenols in many developing tissues of vertebrates including humans.

Lipid profile of blood serum in mice under conditions of bisphenol a administration and vitamin a different suplementation

The purpose of the study was to determine the lipid profile of blood serum and glucose tolerance in mice under conditions of bisphenol A (BPA) administration and different vitamin A consumption. The experimental animals were wild type mice with normal retinoids supplementation and transgenic mice (Lrat-/-) that are unable to esterify of retinol and do not have retinoid stores in liver. BPA, dissolved in corn oil (used as a vehicle), was administered per os daily for 3 days at a dose of 50 mg/kg body weight. Vitamin A overconsumption was modeled by administration of retinyl acetate in a very high dose of 3000 IU at 12 h intervals for 3 days. In the present study dyslipidemia was observed in the mice received 50 mg/kg BPA represented by significant higher triglycerides (at 1,4-fold), total cholesterol (at 2,2-fold), LDL-C, VLDL-C and HDL-C (46%, 39% and 2,8-fold respectively) than those mice of control group received vehicle. Administration of BPA also resulted in disruptions of glucose homeostasis, consisting of hyperglycemia (11±1.11 mmol/l) and glucose intolerance of animals. These BPA’s actions were attributed to its ability of binding to nonclassical membrane estrogen receptor as well as the G-protein coupled-receptor 30 (GPR30) and to act through nongenomic pathways. In knockout mice that did not have retinoid stores in the liver, indicators of both lipid profiles and glucose homeostasis were not significantly different from identical indicators of vehicle-treated mice. Additional 3000 IU retinyl acetate expose simultaneously with administration of 50 mg/kg BPA enhanced the lipogenic effect of xenobiotics in the wild type animals and induce its obesonic adverse effect in Lrat-/- mice. Thus, BPA exposure results in metabolic disorders consisting of hyperglycemia, glucose intolerance, hypercholesterolemia and hyperlipidemia. Retinoids enhanced the BPA action as an obesogen.

Metabonomics reveals bisphenol A affects fatty acid and glucose metabolism through activation of LXR in the liver of male mice

Bisphenol-A (BPA) is a representative environmental endocrine disrupting chemical that is widely used in the production of polycarbonate plastics and epoxy resins. Many studies have confirmed BPA to be closely associated with metabolic diseases, reproductive system diseases, and sex hormone-dependent cancers. In this study, we aimed to systematically elucidate the molecular action of BPA on liver fatty acid and glucose metabolism and the reasons for BPA-induced hypoglycemia through a metabonomics approach. C57BL/6 mice were orally treated with BPA (1, 10, 50, 250 μg/kg) for 35 days and the liver metabonomics and histopathology, molecular docking, mRNA expression levels and activities of enzymes were analyzed. Based on the high-resolution mass spectrometry (MS) for metabonomics and on various software and bioinformatic analysis methods, we found that BPA could affect fatty acid and glucose metabolism, block the TCA cycle, and BPA also regulated the nuclear receptor LXR caused hypoglycemia, thereby affecting the normal metabolic functions of the liver.

Low-dose Bisphenol-A regulates inflammatory cytokines through GPR30 in mammary adipose cells.

The dramatic rise in obesity and metabolic syndrome can be related, at least in part, to environmental chemical factors such as Bisphenol-A (BPA). In this study, we aimed to understand the effects of low-dose Bisphenol-A on the human mature adipocytes and stromal vascular fraction (SVF) cells, obtained from subcutaneous mammary adipose tissue of overweight female patients, undergoing surgical mammary reduction. 24 and/or 48-h exposure to BPA 0.1 nM elicited significant increase of the inflammatory molecules interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemo-attractant protein 1α (MCP1α) and induced G protein-coupled estrogen receptor 30 (GPR30) levels more than two-fold both in mature adipocytes and SVF cells. These effects were similar to that obtained in the presence of GPR30-specific agonist G1 (100 nM) and were reverted by G15 (1 µM), a GPR30-selective antagonist. As a result of BPA-GPR30 signaling activation, fatty acid synthase (FAS) and leptin mRNA levels were significantly higher upon BPA exposure (P < 0.05) in mature adipocytes, with an opposite effect on adiponectin (ADIPOQ). In addition, an increase in SVF cell proliferation and ERK1/2 phosphorylation, was observed, compared to untreated cells. G15 reverted all of these effects. Interestingly, the action of BPA on SVF cell growth was mimicked by IL-8 treatment and was reverted by incubation with anti-IL8 antibodies. All these data suggest that BPA at 0.1 nM, a ten times lower concentration than environmental exposure, increases the expression of pro-inflammatory cytokines via GPR30 both in mature mammary adipocytes and in SVF cells with a possible involvement of IL-8.

Understanding the molecular mechanisms of bisphenol A action in spermatozoa.

Bisphenol A (BPA) is an endocrine-disrupting chemical that is capable of interfering with the normal function of the endocrine system in the body. Exposure to this chemical from BPA-containing materials and the environment is associated with deleterious health effects, including male reproductive abnormalities. A search of the literature demonstrated that BPA, as a toxicant, directly affects the cellular oxidative stress response machinery. Because of its hormone-like properties, it can also bind with specific receptors in target cells. Therefore, the tissue-specific effects of BPA mostly depend on its endocrine-disrupting capabilities and the expression of those particular receptors in target cells. Although studies have shown the possible mechanisms of BPA action in various cell types, a clear consensus has yet to be established. In this review, we summarize the mechanisms of BPA action in spermatozoa by compiling existing information in the literature.

Dichotomy of bisphenol A-induced expression of peroxisome proliferator-activated receptors in hepatic and testicular tissues in mice

Environmental and dietary exposure to bisphenol A (BPA) and its toxicological consequences are extensively reported. BPA has multiple cellular targets. One of the mechanisms of action of BPA involves interaction with and activation of nuclear receptors (NRs) including peroxisome proliferator activated-receptors (PPARs). PPARs regulate genes involved in adipogenesis, and metabolism of glucose, lipid and cholesterol. Study of tissue and dose specific PPAR expression may decipher the toxicity outcome of BPA exposure. We studied expression of three forms of PPARs in mouse liver and testes exposed to BPA for 14 days. mRNA and protein expression of all forms of PPAR increased linearly (monotonic) with the dose in the liver while non-monotonic but dose specific effects were observed in the testes showing a differential pattern of expression. However, histopathological study showed a dose-dependent pattern of changes in liver as well as testes demonstrating a monotonic effect. These findings imply that other PPAR-independent mechanisms may play a role in BPA-induced pathological changes. The present study warrants exploration of the role of PPARs in BPA-induced effects on male reproductive functions and offers an insight into the peculiar response of BPA at low subchronic levels which may be helpful in designing appropriate risk assessment framework.

Oestrogen receptor β mediates the actions of bisphenol-A on ion channel expression in mouse pancreatic beta cells.

Bisphenol-A (BPA) is a widespread endocrine-disrupting chemical that has been associated with type 2 diabetes development. Low doses of BPA modify pancreatic beta cell function and induce insulin resistance; some of these effects are mediated via activation of oestrogen receptors α (ERα) and β (ERβ). Here we investigated whether low doses of BPA regulate the expression and function of ion channel subunits involved in beta cell function. Microarray gene profiling of isolated islets from vehicle- and BPA-treated (100μg/kg per day for 4days) mice was performed using Affymetrix GeneChip Mouse Genome 430.2 Array. Expression level analysis was performed using the normalisation method based on the processing algorithm 'robust multi-array average'. Whole islets or dispersed islets from C57BL/6J or oestrogen receptor β (ERβ) knockout (Erβ-/-) mice were treated with vehicle or BPA (1nmol/l) for 48h. Whole-cell patch-clamp recordings were used to measure Na+ and K+ currents. mRNA expression was evaluated by quantitative real-time PCR. Microarray analysis showed that BPA modulated the expression of 1440 probe sets (1192 upregulated and 248 downregulated genes). Of these, more than 50 genes, including Scn9a, Kcnb2, Kcnma1 and Kcnip1, encoded important Na+ and K+ channel subunits. These findings were confirmed by quantitative RT-PCR in islets from C57BL/6J BPA-treated mice or whole islets treated ex vivo. Electrophysiological measurements showed a decrease in both Na+ and K+ currents in BPA-treated islets. The pharmacological profile indicated that BPA reduced currents mediated by voltage-activated K+ channels (Kv2.1/2.2 channels) and large-conductance Ca2+-activated K+ channels (KCa1.1 channels), which agrees with BPA's effects on gene expression. Beta cells from ERβ-/- mice did not present BPA-induced changes, suggesting that ERβ mediates BPA's effects in pancreatic islets. Finally, BPA increased burst duration, reduced the amplitude of the action potential and enlarged the action potential half-width, leading to alteration in beta cell electrical activity. Our data suggest that BPA modulates the expression and function of Na+ and K+ channels via ERβ in mouse pancreatic islets. Furthermore, BPA alters beta cell electrical activity. Altogether, these BPA-induced changes in beta cells might play a role in the diabetogenic action of BPA described in animal models.

BPA activates EGFR and ERK1/2 through PPARγ to increase expression of steroidogenic acute regulatory protein in human cumulus granulosa cells

Bisphenol A (BPA) negatively affects steroid production in human luteinized granulosa cells (GC). This study was designed to address two important questions: (1) whether BPA exerts the same disruptive effect in human cumulus granulosa cells (hCGC) and (2) to reveal the molecular mechanism underlying the BPA's action on steroidogenesis. We used cultured hCGC since these cells exert the properties of GC from early antral follicles. Results showed that BPA at 100 μM decreased estradiol level and CYP19A1 mRNA, but increased progesterone production, steroidogenic acute regulatory protein (STAR) and peroxisome proliferator-activated receptor gamma (PPARγ) mRNA expression after 48 h. Shorter (6 h) exposure to BPA elevated PPARγ mRNA level in hCGC. Addition of ERK1/2 (U0126), EGFR (AG1478) and PPARγ (GW9662) inhibitors prevented the BPA-induced STAR and PPARγ mRNA expression. Western blot analysis showed that BPA induced a rapid EGFR and ERK1/2 activation. The BPA-induced EGFR phosphorylation was prevented by addition of the PPARγ inhibitor, whereas the BPA-induced ERK1/2 activation was prevented by addition of the EGFR or PPARγ inhibitor. These data show that BPA increases the progesterone and decreases the estradiol biosynthetic pathway in hCGC. Augmentation of the progesterone biosynthetic pathway is mediated through the PPARγ-dependent activation of EGFR and ERK1/2, leading to increased expression of STAR mRNA.

Acute toxicity of bisphenol A and its structural analogues and transcriptional modulation of the ecdysone-mediated pathway in the brackish water flea Diaphanosoma celebensis

Bisphenol A (BPA) is a representative endocrine disrupting chemical (EDC) that has estrogenic effects in aquatic animals. In recent years, due to the continuing usage of BPA, its analogues have been developed as alternative substances to replace its use. The molting process is a pivotal point in the development and reproduction of crustaceans. However, studies of the effects of EDCs on molting in crustaceans at the molecular level are scarce. In the present study, we examined the acute toxicity of BPA and its analogues bisphenol F (BPF) and S (BPS) to the brackish water flea Diaphanosoma celebensis. We further identified four ecdysteroid pathway - related genes (cyp314a1, EcRA, EcRB, and USP) in D. celebensis, and investigated the transcriptional modulation of these genes during molting and after exposure to BPA and its analogues for 48 h. Sequencing and phylogenetic analyses revealed that these four genes are highly conserved among arthropods and may be involved in development and reproduction in the adult stage. The mRNA expression patterns of cyp314a1, EcRA and USP were matched with the molting cycle, suggesting that these genes play a role in the molting process in the adult stage in cladocerans. Following relative real-time polymerase chain reaction (RT-PCR) analyses, BPA and its analogues were found to modulate the expression of each of these four genes differently, indicating that these compounds can disrupt the normal endocrine system function of D. celebensis. This study improves our understanding of the molecular mode of action of BPA and its analogues in D. celebensis.

Bisphenol A, but not Bisphenol S, exposure increases lipid deposition by acting on the PI3K pathway in vivo

Bisphenol A (BPA) is an endocrine disrupter present in many daily products including food and beverage packaging. BPA exposure has been linked to many disorders in humans including cancer, neurological disorders, diabetes and obesity and has therefore been declared toxic and a partial ban is in effect in several countries. Recently the plastic industry has come with a bisphenol analog as a substitute for BPA in BPA free products: BPS. However to date, little is known regarding the toxicity of BPS in vivo. In this study, we used the zebrafish as a vertebrate model to understand the mechanism of action of BPA and BPS in lipid usage during embryogenesis. Zebrafish embryos exposed to the extreme low dose 1 nM BPA (over 6,000‐fold lower than the accepted human daily exposure), have a 65% increase in lipid deposition. Interestingly, BPS exposure, at the same concentration, has no effect on lipid deposition. BPA is classified as an estrogenic compound however, pharmacological blockage of the nuclear estrogen receptors does not suppress the induced lipid deposition. To identify which pathway might be involved in this increased lipid deposition, we performed a full embryo lipidomic analysis. This revealed that BPA exposed embryos had a dramatic increase of diacylglycerol (DAG) and Phosphatidylinositol (PI) lipids. Strikingly, lipidomic analysis of BPS exposed embryos showed a decrease of DAGs and PIs. This is the first study to demonstrate a phenotypical difference between BPA and BPS at similar doses. Double exposure of BPA and LY294002, a strong inhibitor of phosphoinositide 3‐kinases, abolishes the BPA induced increase in lipid deposition and lipid usage. At the molecular level, BPA exposure increases the expression of key enzymes of the PI3K pathway such as: cdipt, plcb3, vps34p and p110. Our study allows us to propose a model in which BPA, but not BPS, at very low concentration can activate the PI3K pathway leading to an accumulation of lipid during embryogenesis in an estrogen receptors independent manner. Our results confirm that, at least in terms a of lipid usages, BPS is safer than BPA exposure and support the ban on BPA from consumer merchandise.Support or Funding InformationThis project was supported by an Australian Diabetes Research Trust (DART) research grant to YGThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Cardiogenesis impairment promoted by bisphenol A exposure is successfully counteracted by epigallocatechin gallate

Exposure to the emerging contaminant bisphenol A (BPA) is ubiquitous and associated with cardiovascular disorders. BPA effect as endocrine disruptor is widely known but other mechanisms underlying heart disease, such as epigenetic modifications, remain still unclear. A compound of green tea, epigallocatechin gallate (EGCG), may act both as anti-estrogen and as inhibitor of some epigenetic enzymes. The aims of this study were to analyze the molecular processes related to BPA impairment of heart development and to prove the potential ability of EGCG to neutralize the toxic effects caused by BPA on cardiac health. Zebrafish embryos were exposed to 2000 and 4000 μg/L BPA and treated with 50 and 100 μM EGCG. Heart malformations were assessed at histological level and by confocal imaging. Expression of genes involved in cardiac development, estrogen receptors and epigenetic enzymes was analyzed by qPCR whereas epigenetic modifications were evaluated by whole mount immunostaining. BPA embryonic exposure led to changes in cardiac phenotype, induced an overexpression of hand2, a crucial factor for cardiomyocyte differentiation, increased the expression of estrogen receptor (esr2b), promoted an overexpression of a histone acetyltransferase (kat6a) and also caused an increase in histone acetylation, both mechanisms being able to act in sinergy. EGCG treatment neutralized all the molecular alterations caused by BPA, allowing the embryos to go on with a proper heart development. Both molecular mechanisms of BPA action (estrogenic and epigenetic) likely lying behind cardiogenesis impairment were successfully counteracted by EGCG treatment.

Effects of adolescent Bisphenol-A exposure on memory and spine density in ovariectomized female rats: Adolescence vs adulthood

The endocrine disruptor, Bisphenol-A (BPA), alters many behavioral and neural parameters in rodents. BPA administration to gonadally intact adolescent rats increases anxiety, impairs spatial memory, and decreases dendritic spine density when measured in adulthood. Since BPA's action seems to be mediated through gonadal steroid receptors, the current experiments were done in ovariectomized (OVX) female rats to examine the effects on behavior and spine density of adolescent BPA exposure under controlled hormone conditions. OVX (postnatal day, PND, 21) female Sprague-Dawley rats (n = 66) received subcutaneous injections of BPA (40 μg/kg/bodyweight), 17β-Estradiol (E2, 50 μg/kg/bodyweight), or saline during adolescence (PND 38–49). Following the last injection brains were processed for Golgi impregnation (Exp1), behavioral and spine density in adolescence (Exp2), or in adulthood (Exp3). In Exp1, E2 increased spine density in CA1 pyramidal cells and BPA decreased spine density in granule cells of the dentate gyrus (DG). In Exp2, BPA impaired spatial memory on the object placement (OP) task, E2 increased spine density in CA1, BPA decreased spine density in the DG and the medial prefrontal cortex (mPFC). When measured in adulthood (Exp3), BPA impaired OP and object recognition (OR) performance, E2 increased spine density in CA1, and BPA decreased spine density in CA1, the mPFC and the DG. Results provide novel data on the effects of adolescent BPA in an OVX model and are compared to data in intact animals and within the context of understanding the importance of the profound neuronal alterations occurring during adolescent development.

Effects of bisphenol A on gap junctions in HaCaT cells as mediated by the estrogen receptor pathway.

Bisphenol A (BPA) is widely used as the raw material for the production of plastics and paper products. People can be exposed to BPA through dermal contact, particularly for cashiers in contact with thermal paper every day. BPA is a known endocrine disruptor that has been shown to be carcinogenic. Many tumors show weak gap junctional intercellular communication (GJIC) function. The aim of this study was to investigate the effects and possible mechanisms of BPA's action on GJIC of human HaCaT skin cells. The results showed that BPA increased cell proliferation rates, prolonged GJIC photobleaching fluorescence recovery times and reduced overall fluorescence recovery rates at 0.01, 0.1 and 1μm. BPA downregulated connexin (Cx)26 mRNA level at 0.1μm. Estrogen receptor (ER) antagonist ICI 182780 at 5nm partially blocked the above effects of BPA indicating involvement of the ER pathway with BPA exposure. However, BPA did not influence Cx43 mRNA and protein levels. Our immunofluorescence data showed that Cx26 was expressed in the cytoplasm and plasma membrane, and was involved in the formation of gap junctions between adjacent cells, while Cx43 was expressed only in the cytoplasm. Therefore, our data indicate that Cx26 gap junctions may be involved in the GJIC inhibition caused by BPA. In conclusion, our results indicate that BPA can promote human skin cell proliferation, inhibit skin cell GJIC function but not formation and downregulate Cx26 mRNA levels partially through the ER pathway. We hypothesize that BPA can exhibit carcinogenicity by inhibiting GJIC.

Bisphenol A exposure during early pregnancy impairs uterine spiral artery remodeling and provokes intrauterine growth restriction in mice

Endocrine disrupting chemicals are long suspected to impair reproductive health. Bisphenol A (BPA) has estrogenic activity and therefore the capacity of interfering with endocrine pathways. No studies dissected its short-term effects on pregnancy and possible underlying mechanisms. Here, we studied how BPA exposure around implantation affects pregnancy, particularly concentrating on placentation and uterine remodeling. We exposed pregnant female mice to 50 µg/kg BPA/day or 0.1% ethanol by oral gavage from day 1 to 7 of gestation. High frequency ultrasound was employed to document the presence and size of implantations, placentas and fetuses throughout pregnancy. Blood velocity in the arteria uterina was analyzed by Doppler measurements. The progeny of mothers exposed to BPA was growth-restricted compared to the controls; this was evident in vivo as early as at day 12 as analyzed by ultrasound and confirmed by diminished fetal and placenta weights observed after sacrificing the animals at day 14 of gestation. The remodeling of uterine spiral arteries (SAs) was considerably impaired. We show that short-term exposure to a so-called “safe” BPA dose around implantation has severe consequences. The intrauterine growth restriction observed in more than half of the fetuses from BPA-treated mothers may owe to the direct negative effect of BPA on the remodeling of uterine SAs that limits the blood supply to the fetus. Our work reveals unsuspected short-term effects of BPA on pregnancy and urges to more studies dissecting the mechanisms behind the negative actions of BPA during early pregnancy.