Bisphenol A: Perinatal exposure and body weight

COMBINED DEVELOPMENTAL EXPOSURE TO ESTROGENIC ENDOCRINE DISRUPTOR AND NUTRITIONAL IMBALANCE INDUCES LONG TERM ADULT PROSTATE INFLAMMATION THROUGH INFLAMMASOME ACTIVATION

Increasing number of studies suggested that environmental deleterious impacts (such as estrogen-like endocrine disruptors, EDCs, unhealthy diet) during early human development affect the risk of developing non-communicable diseases including prostate cancer (PCa) later in life. To test if the combination of EDCs and unhealthy induces adult prostate lesions, we developed an experimental model of adult male Sprague Dawley rats exposed during gestation (from day 7) to weaning to high fat diet (HFD 60% fat), or to a xenoestrogen (estradiol benzoate, EB, 2.5µg/d) from post-natal days 1 to 5, or to a combination of both. EB and EB+HFD exposures induced decreased prostate weight in adult rats along with inflammatory status. A white blood cell infiltrate was observed after EB exposure and more dramatic lesions were observed with the combined exposure, along with a gland destruction. The lesions, following EB or EB+HFD exposure, are associated with elevated mRNA levels for TNFa, IL6 and CCL2/MCP1 pro-inflammatory cytokines while the levels of the anti-inflammatory IL10 cytokine remained unchanged. This activation of NLRP3 and elevated levels of CASP1 were observed following EB or EB+HFD exposures associated with elevated mRNA levels for IL1b, substrates for the NLRP3 complex. HFD exposure alone has mild if not pro-inflammatory effects in adult prostate. In conclusion, we showed that developmental combined exposure to EB and HFD programmed prostate inflammatory lesions in adult prostate. Since proliferative inflammatory atrophy and chronic inflammation of prostate may drive cell to become cancer cells, our model might be useful for study onset of PCa.

Impact of Bisphenol A exposure on maternal gut microbial homeostasis, placental function, and fetal development during pregnancy

Pregnancy is extremely vulnerable to external environmental influences. Bisphenol A, an endocrine-disrupting chemical, poses a significant environmental hazard to individuals of all ages and stages, particularly during pregnancy. The placenta is a temporary organ facilitating the connection between the mother and fetus. While it can detoxify certain exogenous substances, it is also vulnerable to the impacts of endocrine disruptors. Likewise, the intestinal flora is highly sensitive to exogenous stresses and environmental pollutants. The regulation of gut microbiota plays a crucial role in ensuring the health of both the mother and the fetus. The gut-placental axis connects the gut, gut microbes, placenta, and fetus. Exploring possible effects on placental function and fetal development involves analyzing changes in gut microbiota composition. Given that bisphenol A may cross the intestine and affect intestinal function, gut microorganisms, and their metabolites, as well as its potential impact on the placenta, resulting in impaired placental function and fetal development, this study aims to establish a link between bisphenol A exposure, intestinal microorganisms, placental function, and fetal development. This paper seeks to analyze the effects of maternal exposure to bisphenol A during pregnancy on the balance of the maternal gut microbiota, placental function, and fetal development, considering the key role of the gut-placental axis. Additionally, this paper proposes potential directions for future research emphasizing the importance of mitigating the adverse outcomes of bisphenol A exposure during pregnancy in both human and animal studies.

Maternal Exposure to Low-Dose BDE-47 Induced Weight Gain and Impaired Insulin Sensitivity in the Offspring

Polybrominated diphenyl ethers (PBDEs), commonly used as synthetic flame retardants, are present in a variety of consumer products, including electronics, polyurethane foams, textiles, and building materials. Initial evidence from epidemiological and experimental studies suggests that maternal PBDE exposure may be associated with a higher BMI in children, with disturbance of energy metabolism and an increased risk of Type 2 diabetes. However, the causality between early exposure to real-life PBDE concentrations and increased weight as well as mechanisms underlying impaired metabolic pathways in the offspring remain elusive. Here, using a mouse model we examined the effect of maternal exposure to 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47), the most abundant congener in human samples, on offspring weight gain and energy homeostasis using a mouse model. Maternal exposure to BDE-47 at low dose resulted in weight gain in female offspring together with an impaired glucose and insulin tolerance in both female and male mice. In vitro and in vivo data suggest increased adipogenesis induced by BDE-47, possibly mediated by DNA hypermethylation. Furthermore, mRNA data suggest that neuronal dysregulation of energy homeostasis, driven via a disturbed leptin signaling may contribute to the observed weight gain as well as impaired insulin and glucose tolerance.

Maternal Exposure to Endocrine-Disrupting Chemicals: Analysis of Their Impact on Infant Gut Microbiota Composition

Endocrine disruptors (EDCs) are chemicals that interfere with the endocrine system. EDC exposure may contribute to the development of obesity, type 2 diabetes, and cardiovascular diseases by impacting the composition of an infant's gut microbiota during the first 1000 days of life. To explore the relationship between maternal urinary levels of Bisphenol-A and phthalates (UHPLC-MS/MS), and the composition of the infant gut microbiota (16S rDNA) at age 12 months (T3) and, retrospectively, at birth (T0), 1 month (T1), and 6 months (T2), stool samples from 20 infants breastfed at least once a day were analyzed. Metataxonomic bacteria relative abundances were correlated with EDC values. Based on median Bisphenol-A levels, infants were assigned to the over-exposed group (O, n = 8) and the low-exposed group (B, n = 12). The B-group exhibited higher gut colonization of the Ruminococcus torques group genus and the O-group showed higher abundances of Erysipelatoclostridium and Bifidobacterium breve. Additionally, infants were stratified as high-risk (HR, n = 12) or low-risk (LR, n = 8) exposure to phthalates, based on the presence of at least three phthalates with concentrations exceeding the cohort median values; no differences were observed in gut microbiota composition. A retrospective analysis of gut microbiota (T0-T2) revealed a disparity in β-diversity between the O-group and the B-group. Considering T0-T3, the Linear Discriminant Effect Size indicated differences in certain microbes between the O-group vs. the B-group and the HR-group vs. the LR-group. Our findings support the potential role of microbial communities as biomarkers for high EDC exposure levels. Nevertheless, further investigations are required to deeply investigate this issue.

Bisphenols-A Threat to the Natural Environment

Negative public sentiment built up around bisphenol A (BPA) follows growing awareness of the frequency of this chemical compound in the environment. The increase in air, water, and soil contamination by BPA has also generated the need to replace it with less toxic analogs, such as Bisphenol F (BPF) and Bisphenol S (BPS). However, due to the structural similarity of BPF and BPS to BPA, questions arise about the safety of their usage. The toxicity of BPA, BPF, and BPS towards humans and animals has been fairly well understood. The biodegradability potential of microorganisms towards each of these bisphenols is also widely recognized. However, the scale of their inhibitory pressure on soil microbiomes and soil enzyme activity has not been estimated. These parameters are extremely important in determining soil health, which in turn also influences plant growth and development. Therefore, in this manuscript, knowledge has been expanded and systematized regarding the differences in toxicity between BPA and its two analogs. In the context of the synthetic characterization of the effects of bisphenol permeation into the environment, the toxic impact of BPA, BPF, and BPS on the microbiological and biochemical parameters of soils was traced. The response of cultivated plants to their influence was also analyzed.

Effects of BPA Exposure and Recovery on the Expression of Genes Involved in the Hepatic Lipid Metabolism in Male Mice

Exposure to Bisphenol A (BPA) has led to an increased risk of obesity and nonalcoholic fatty liver diseases (NAFLDs). However, it is as yet unclear if the damage caused by BPA is able to be repaired sufficiently after exposure has ceased. Therefore, this project aims to investigate the effects of BPA on the hepatic lipid metabolism function and its potential mechanisms in mice by comparing the BPA exposure model and the BPA exposure + cessation of drug treatment model. Herein, the male C57BL/6 mice were exposed in the dose of 50 μg/kg/day and 500 μg/kg/day BPA for 8 weeks, and then transferred to a standard chow diet for another 8 weeks to recover. Based on our previous RNA-seq study, we examined the expression patterns of some key genes. The results showed that the mice exposed to BPA manifested NAFLD features. Importantly, we also found that there was a significant expression reversion for SCD1, APOD, ANGPT4, PPARβ, LPL and G0S2 between the exposure and recovery groups, especially for SCD1 and APOD (p < 0.01). Notably, BPA could significantly decrease the level of APOD protein (p < 0.01) whereas there was an extremely significant increase after the exposure ceased. Meanwhile, APOD over-expression suppressed TG accumulation in the AML12 cells. In conclusion, the damage caused by BPA is able to be repaired by the upregulation of APOD and exposure to BPA should be carefully examined in chronic liver metabolic disorders or diseases.

Physiological, biochemical, and hormonal changes in rats exposed to bottled water left in a hot car and the freezer

The aim of this study was to investigate the effects of bottled water left in the car and those left in the refrigerator on the physiological and biochemical parameters of male rats. Eighteen male albino rats were randomly divided into control, warmed bottled water (WBW), and cooled bottled water (CBW) groups. The concentrations of bisphenol A (BPA) and antimony (Sb) in the water samples were measured. Results showed that the levels of BPA and Sb were higher in bottled water left in the car and those kept at room temperature (control), relative to the bottled water samples kept in the fridge. Bodyweight, some metabolic indicators, cTnT and CRP levels, hematological parameters, testosterone level, and sperm quality were significantly affected by storage conditions. These results indicate that storage conditions can potentially affect the quality of bottled water, which in turn can affect the biological parameters of living organisms. Moreover, since the concentrations of BPA and Sb were least in bottled water kept in the refrigerator, we recommend that manufacturers and households should endeavor to keep bottled water under cold storage.

Bacterial degradation of bisphenol analogues: an overview

Bisphenol A (BPA) is one of the most produced synthetic monomers in the world and is widespread in the environment. BPA was replaced by bisphenol analogues (BP) because of its adverse effects on life. Bacteria can degrade BPA and other bisphenol analogues (BP), diminishing their environmental concentrations. This study aimed to summarize the knowledge and contribute to future studies. In this review, we surveyed papers on bacterial degradation of twelve different bisphenol analogues published between 1987 and June 2022. A total of 102 original papers from PubMed and Google Scholar were selected for this review. Most of the studies (94.1%, n = 96) on bacterial degradation of bisphenol analogues focused on BPA, and then on bisphenol F (BPF), and bisphenol S (BPS). The number of studies on bacterial degradation of bisphenol analogues increased more than six times from 2000 (n = 2) to 2021 (n = 13). Indigenous microorganisms and the genera Sphingomonas, Sphingobium, and Cupriavidus could degrade several BP. However, few studies focussed on Cupriavidus. The acknowledgement of various aspects of BP bacterial biodegradation is vital for choosing the most suitable microorganisms for the bioremediation of a single BP or a mixture of BP.

Early-life exposure to bisphenol A induces dysregulation of lipid homeostasis by the upregulation of SCD1 in male mice

Exposure of Bisphenol A (BPA) is closely associated with an increased prevalence of obesity-related metabolic syndrome. However, the potential mechanism of BPA-induced adipogenesis remains to be fully elucidated. Herein, potential mechanisms of BPA-induced adipogenesis in 3T3-L1 preadipocytes were evaluated using RNA-Seq. Then, using an early-life BPA exposure model, we further evaluated the effects of BPA exposure on lipid and glucose homeostasis. The results showed that lipid content in 3T3-L1 adipocytes was significantly increased after BPA exposure (p < 0.01) and male C57BL/6 mice with the dose of 500 μg/kg/day BPA by once-a-day oral administration for 8 weeks displayed a NAFLD-like phenotype. RNA-Seq analysis of preadipocytes showed that BPA exposure affected multiple biological processes including glycosphingolipid biosynthesis, regulation of lipolysis in adipocytes, PPAR signaling pathway and fatty acid metabolism. The dysregulation in a series of genes of mice was associated to de novo lipogenesis and lipid transport, which was linked to obesity. Importantly, we also found a significant expression increase of stearoyl-CoA desaturase 1 (SCD1) and a significant decrease of apolipoprotein D (APOD) in both fat (p < 0.01) and livers (p < 0.01) of male mice. Besides, the dysregulation of pro-inflammatory genes (TNF-α,IL-6 and SAA3) showed that BPA exposure promoted progression of hepatic inflammation. In conclusion, this study elucidated a novel mechanism in which obesity associated with BPA exposure by targeting SCD1. Exposure to BPA should be carefully examined in the chronic liver metabolic diseases.

Effects of gestational exposure to bisphenol A on the hepatic transcriptome and lipidome of rat dams: Intergenerational comparison of effects in the offspring

Our previous studies demonstrated that prenatal bisphenol A (BPA) exposure affected the hepatic transcriptome and lipidome in rat offspring in a sex- and age-dependent manner. In this study, we investigated the effects of gestational exposure to BPA on the rat dams, after weaning period, and compared them with those of their offspring. Our results showed alterations in hepatic transcriptome related to insulin signaling, circadian rhythm, and infectious disease pathways in BPA-treated dams even 4 weeks after the exposure, whereas slight modifications on the lipid profile were found. Alterations in lipid and transcriptome profiles were more prominent in the prenatally BPA-exposed offspring at postnatal day (PND) 1 and 21 than those in the dams, suggesting that in utero exposure to BPA is more serious than exposure in the adulthood. Cryptochrome-1 (Cry1) and peroxisome proliferator-activated receptor delta (Ppard) were commonly altered in both dams and offspring. Nevertheless, the results of DIABLO (Data Integration Analysis for Biomarker discovery using Latent cOmponents), showed that multi-omics data successfully distinguished the exposed dams from the corresponding controls and their offspring with a high level of accuracy. The accuracy rates in BPA50 models (including control and 50 μg BPA/kg bw/day exposed groups) were smaller than those in BPA5000 models (control and 5000 μg BPA/kg bw/day exposed groups), suggesting dose-dependent severity in BPA effects. Palmitic acid and genes related to circadian rhythm, insulin responses, and lipid metabolism (e.g., 1-acylglycerol-3-phosphate O-acyltransferase 2 (Agpat2), B-cell CLL/lymphoma 10 (Bcl10), Cry1, Harvey rat sarcoma virus oncogene (Hras), and NLR family member X1 (Nlrx1)) were identified through DIABLO models as novel biomarkers of effects of BPA across two generations.

Obesity II: Establishing causal links between chemical exposures and obesity

Obesity is a multifactorial disease with both genetic and environmental components. The prevailing view is that obesity results from an imbalance between energy intake and expenditure caused by overeating and insufficient exercise. We describe another environmental element that can alter the balance between energy intake and energy expenditure: obesogens. Obesogens are a subset of environmental chemicals that act as endocrine disruptors affecting metabolic endpoints. The obesogen hypothesis posits that exposure to endocrine disruptors and other chemicals can alter the development and function of the adipose tissue, liver, pancreas, gastrointestinal tract, and brain, thus changing the set point for control of metabolism. Obesogens can determine how much food is needed to maintain homeostasis and thereby increase the susceptibility to obesity. The most sensitive time for obesogen action is in utero and early childhood, in part via epigenetic programming that can be transmitted to future generations. This review explores the evidence supporting the obesogen hypothesis and highlights knowledge gaps that have prevented widespread acceptance as a contributor to the obesity pandemic. Critically, the obesogen hypothesis changes the narrative from curing obesity to preventing obesity.

Does bisphenol-A affect alteration of gut microbiome after bariatric/metabolic surgery?: a comparative metagenomic analysis in a long-term high-fat diet induced-obesity rat model

Purpose

Bisphenol A (BPA) is a widely used environmental contaminant that is associated with type 2 diabetes mellitus and a shift of gut microbial community. However, little is known about the influence of BPA on gut microbial changes related to bariatric surgery. We investigated whether long-term exposure to dietary BPA causing alterations of gut microbiome occurred after bariatric surgery.

Methods

Six-week-old male Wistar rats were fed either a high-fat diet (HFD) or HFD + BPA for 40 weeks. Then sleeve gastrectomy (SG) or Roux-en Y gastric bypass (RYGB) was performed in each diet group and observed for 12 weeks postoperatively. Fecal samples were collected at the 40th weeks and 12th postoperative weeks. Using 16S ribosomal RNA gene sequencing analysis on fecal samples, a comparative metagenomic analysis on gut microbiome composition was performed.

Results

Long-term exposure to HFD with BPA showed higher body weight change and higher level of fasting blood sugar after 40 weeks-diet challenge than those of the HFD only group. After bariatric surgeries, mean body weight of the HFD with BPA group was significantly higher than the HFD only group, but there was no difference between the SG and RYGB groups. The metagenomic analyses demonstrated that long-term exposure to dietary BPA did not affect significant alterations of gut microbiome before and after bariatric surgery, compared with the HFD groups.

Conclusion

Our results highlighted that BPA was a risk factor for obesity and may contribute to glucose intolerance, but it did not affect alterations of gut microbiome after bariatric/metabolic surgery.

Metagenomic analysis of microbial communities continuously exposed to Bisphenol A in mangrove rhizosphere and non-rhizosphere soils

Bisphenol A (BPA) is widely distributed in littoral zones and may cause adverse impacts on mangrove ecosystem. Biodegradation and phytoremediation are two primary processes for BPA dissipation in mangrove soils. However, the rhizosphere effects of different mangrove species on BPA elimination are still unresolved. In this study, three typical mangrove seedlings, namely Avicennia marina, Bruguiera gymnorrhiza (L.) and Aegiceras corniculatum, were cultivated in soil microcosms for four months and then subjected to 28-day continuous BPA amendment. Un-planted soil microcosms (as control) were also set up. The BPA residual rates and root exudates were monitored, and the metabolic pathways as well as functional microbial communities were also investigated to decipher the rhizosphere effects based on metagenomic analysis. The BPA residual rates in all planted soils were significantly lower than that in un-planted soil on day 7. Both plantation and BPA dosage had significant effects on bacterial abundance. A distinct separation of microbial structure was found between planted and un-planted soil microcosms. Genera Pseudomonas and Lutibacter got enriched with BPA addition and may play important roles in BPA biodegradation. The shifts in bacterial community structure upon BPA addition were different among the microcosms with different mangrove species. Genus Novosphingobium increased in Avicennia marina and Bruguiera gymnorrhiza (L.) rhizosphere soils but decreased in Aegiceras corniculatum rhizosphere soil. Based on KEGG annotation and binning analysis, the proposal of BPA degradation pathways and the quantification of relevant functional genes were achieved. The roles of Pseudomonas and Novosphingobium may differ in lower BPA degradation pathways. The quantity variation patterns of functional genes during the 28-day BPA amendment were different among soil microcosms and bacterial genera.

Bisphenol A exposure induces neurobehavioral deficits and neurodegeneration through induction of oxidative stress and activated caspase-3 expression in zebrafish brain

Bisphenol A (BPA) is noted for its adversative effects by inducing oxidative stress, carcinogenicity, neurotoxicity, inflammation, etc. However, the likely act of BPA in inducing neurodegenerative phenotypes remains elusive in the available literature. Hence, the present study was conducted to decipher the neurodegenerative potential of BPA in inducing Parkinson's disease like phenotypes in zebrafish. Zebrafish were subjected to chronic waterborne exposure to BPA for 56 days. Locomotor activities and neurobehavioral response were assessed by the NTDT (novel tank diving test), OFT (open field test), and LDPT (light-dark preference test). The oxidative stress markers and histopathological observation for pyknosis and chromatin condensation were carried out. Immunohistochemistry for activated caspase-3 and targeted proteins expression study was performed. The basic findings reveal that chronic BPA exposure significantly induces locomotor dysfunction through a significant decline in mean velocity and total distance traveled. As a measure of pyknosis and chromatin condensation, pyknotic and Hoechst positive neurons in telencephalon and diencephalon significantly increased by BPA exposure. A higher concentration of BPA adversely affects the neurobehavioral response, antioxidant status, and neuromorphology in zebrafish. Parkinson-relevant targeted protein expression viz. alpha-synuclein and LRRK2, were significantly upregulated, whereas tyrosine hydroxylase, NeuN, and Nurr1 were significantly downregulated in the zebrafish brain. As an indicator of cell death by apoptosis, the expression of activated caspase-3 was significantly increased in the BPA-exposed zebrafish brain. These basic results of the current study indicate that chronic waterborne exposure to BPA induces neuropathological manifestation leading to the development of motor dysfunction and Parkinsonism-like neurodegenerative phenotypes in zebrafish.

Resveratrol Butyrate Esters Inhibit Obesity Caused by Perinatal Exposure to Bisphenol A in Female Offspring Rats

Resveratrol butyrate esters (RBE) are derivatives of resveratrol (RSV) and butyric acid and exhibit biological activity similar to that of RSV but with higher bioavailability. The aim of this study was designed as an animal experiment to explore the effects of RBE on the serum biochemistry, and fat deposits in the offspring rats exposed to bisphenol A (BPA), along with the growth and decline of gut microbiota. We constructed an animal model of perinatal Bisphenol A (BPA) exposure to observe the effects of RBE supplementation on obesity, blood lipids, and intestinal microbiota in female offspring rats. Perinatal exposure to BPA led to weight gain, lipid accumulation, high levels of blood lipids, and deterioration of intestinal microbiota in female offspring rats. RBE supplementation reduced the weight gain and lipid accumulation caused by BPA, optimised the levels of blood lipids, significantly reduced the Firmicutes/Bacteroidetes (F/B) ratio, and increased and decreased the abundance of S24-7 and Lactobacillus, respectively. The analysis of faecal short-chain fatty acid (SCFA) levels revealed that BPA exposure increased the faecal concentration of acetate, which could be reduced via RBE supplementation. However, the faecal concentrations of propionate and butyrate were not only significantly lower than that of acetate, but also did not significantly change in response to BPA exposure or RBE supplementation. Hence, RBE can suppress BPA-induced obesity in female offspring rats, and it demonstrates excellent modulatory activity on intestinal microbiota, with potential applications in perinatological research.

Wood emissions and asthma development: Results from an experimental mouse model and a prospective cohort study

BACKGROUND

Increased use of renewable resources like sustainably produced wood in construction or for all sorts of long-lived products is considered to contribute to reducing society's carbon footprint. However, as a natural, biological material, wood and wood products emit specific volatile organic compounds (VOCs). Therefore, the evaluation of possible health effects due to wood emissions is of major interest.

OBJECTIVES

We investigated the effects of an exposure to multiple wood-related VOCs on asthma development.

METHODS

A murine asthma model was used to evaluate possible allergic and inflammatory effects on the lung after short- or long-term and perinatal exposure to pinewood or oriented strand board (OSB). In addition, wood-related VOCs were measured within the German prospective mother-child cohort LINA and their joint effect on early wheezing or asthma development in children until the age of 10 was estimated by Bayesian kernel machine regression (BKMR) stratifying also for family history of atopy (FHA).

RESULTS

Our experimental data show that neither pinewood nor OSB emissions even at high total VOC levels and a long-lasting exposure period induce significant inflammatory or asthma-promoting effects in sensitized or non-sensitized mice. Moreover, an exposure during the vulnerable time window around birth was also without effect. Consistently, in our mother-child cohort LINA, an exposure to multiple wood-related VOCs during pregnancy or the first year of life was not associated with early wheezing or asthma development in children independent from their FHA.

CONCLUSION

Our findings indicate that emissions from wood and wood products at levels commonly occurring in the living environment do not exert adverse effects concerning wheezing or asthma development.

Effects on the liver lipidome of rat offspring prenatally exposed to bisphenol A

Bisphenol A (BPA) is a well-known endocrine disruptor that has obesogenic properties. We have previously reported sex- and age-dependent changes in hepatic transcriptome and proteome of several lipid homeostasis-related genes in rat offspring prenatally exposed to BPA. To further understand the impacts of prenatal BPA exposure, we analyzed lipidomic profiles in the postnatal day (PND) 21 and 60 rats using a high-resolution QTOF mass spectrometer coupled with a HPLC system. We found that the total lipid content was significantly decreased in PND21 females prenatally exposed to 5000 μg/kg bw/day of BPA. Levels of total fatty acids, acylcarnitines, and monoacylglycerols significantly increased in both female and male BPA-exposed rats at PND21. An elevation in total cholesterol esters and reductions in triacylglycerols and monogalactosyl diacylglycerols were found only in PND21 females prenatally exposed to BPA. Interestingly, opposite responses were observed for phospholipids and sphingolipids between PND21 females and males following BPA exposure. The effects on the body weight and total lipid content were mitigated in the latter stage, although the alterations of lipid profiles continued until PND60. A Data Integration Analysis for Biomarker discovery using Latent cOmponents (DIABLO) revealed a high correlation of the lipidome with our previously published transcriptome data. DIABLO also identified potential biomarkers of prenatal exposure to BPA; glycerol-3-phosphate dehydrogenase 1 (Gpd1) and glyceronephosphate O-acyltransferase (Gnpat), which are involved in the glycerophospholipid metabolism, in females and males, respectively. Collectively, we highlighted the sex- and age-dependent effects of prenatal BPA exposure on hepatic lipid homeostasis in rat offspring.

Independent and combined effects of Bisphenol A and Diethylhexyl Phthalate on gestational outcomes and offspring development in Sprague-Dawley rats

Bisphenol A (BPA) and Diethylhexyl Phthalate (DEHP) are well-studied endocrine disrupting chemicals (EDCs), however, the effects of mixtures of these EDCs are not. To assess the consequences of prenatal exposure to a mixture of these EDCs, dams were orally administered either saline (control), BPA (5 μg/kg BW/day), high dose DEHP (HD-D; 7.5 mg/kg BW/day), or a combination of BPA with HD-D in experiment 1; saline, BPA (5 μg/kg BW/day), low-dose DEHP (LD-D; 5 μg/kg BW/day) or a combination of BPA with LD-D in experiment 2. Gestational weights, number of abortions, litter size and weights, number of live births and stillbirths were recorded. Morphometric measures were obtained at birth and body weight, food and water intake were monitored weekly from postnatal weeks 3-12. Offspring were sacrificed at 16-24 weeks of age and organ weights were measured. The abortion rate of dams exposed to HD-D and the mixtures, BPA + LD-D and BPA + HD-D were higher at 9, 14 and 27% respectively. Prenatal exposure to BPA or HD-D significantly decreased relative thymus weights in male but not female offspring. Apoptotic cells were detected in thymus sections of both male and female offspring prenatally exposed to DEHP. Relative heart weights increased in BPA + HD-D exposed male offspring compared to the other groups. The results indicate that a mixture of BPA and DEHP, produced a pronounced effect on pregnancy outcomes. Male offspring appear to be more susceptible to the programming effects of these EDCs or their mixture suggesting a need to reconsider the possible additive, antagonistic or synergistic effects of EDC mixtures.

Advances in BPA-induced Oxidative Stress and Related Effects and Mechanisms in Liver, 1991-2017

Bisphenol A (BPA) is a widely spreading environmental endocrine disruptor . Its characteristics, including small doses and frequent contact, make it easy to enter human body through drinking water, food, air and other pathways, leading to tumors, infertility, and liver damage. The present review summarizes the underlying mechanism of oxidative stress and its related effects induced by BPA in the liver. The progress of the mechanism for oxidative stress induced by BPA is summarized, including mitochondrial dysfunction, lipid peroxidation and inflammation reaction, liver dyslipidemia, apoptosis, and cell death mechanism. In the future, it is necessary to elucidate the molecular mechanisms and timing of oxidative stress to clarify the effects on different exposures to different genders and growth stages. Besides, studying the toxic effects on BPA surrogates, BPA metabolites and BPA combined with other pollutants in the environment is beneficial to clarify the environmental and human health effects of BPA and provide technical reference for the development of practical control measures.

Effects of Nigella sativa oil and thymoquinone against bisphenol A-induced metabolic disorder in rats

The underlying mechanisms of bisphenol A (BPA)-induced metabolic disorder and the protective impact of Nigella sativa oil (NSO) and thymoquinone (TQ) against BPA-induced metabolic disorder were investigated. Rats were treated as follows: Control, BPA (10 mg/kg), TQ (2 mg/kg), NSO (84 μL/kg), BPA + TQ (0.5, 1, 2 mg/kg), and BPA + NSO (21, 42, 84 μL/kg). BPA was administered by gavage, while, TQ and NSO were injected intraperitoneally (daily, 54 days). The weight, blood pressure, serum parameters [glucose, lipid profile, hepatic enzymes, insulin, interlukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), leptin, adiponectin], malondialdehyde (MDA), glutathione (GSH) and insulin signaling pathways [insulin receptor substrate (p-IRS,IRS); kinase (p-Akt,Akt); glycogen synthase kinase (p-GS3K,GS3K)] were measured. BPA increased the blood pressure, MDA, lipid profile, hepatic enzymes, insulin, IL-6, TNF-α, and leptin, and decreased the GSH and phosphorylated forms of IRS, Akt, GS3K but did not alter weight, glucose, IRS, AKT, and GS3K in the liver. Administration of NSO or TQ with BPA reduced the blood pressure, liver level of MDA, lipid profile, hepatic enzymes, insulin, IL-6, TNF-α, leptin, and increased the liver level of GSH and p-IRS, p-AKT, p-GS3K. TQ and NSO are thought to be effective in controlling metabolic disorders induced by BPA.

Juvenile Toxicity Rodent Model to Study Toxicological Effects of Bisphenol A (BPA) at Dose Levels Derived From Italian Children Biomonitoring Study

Bisphenol A (BPA) is a plasticizer with endocrine disrupting properties particularly relevant for children health. Recently BPA has been associated with metabolic dysfunctions but no data are yet available in specific, long-term studies. This study aimed to evaluate BPA modes of action and hazards during animal juvenile life-stage, corresponding to childhood. Immature Sprague-Dawley rats of both sexes were orally treated with 0 (vehicle only-olive oil), 2, 6, and 18 mg/kg bw per day of BPA for 28 days, from weaning to sexual maturity. Dose levels were obtained from the PERSUADED biomonitoring study in Italian children. Both no-observed-adverse-effect-level (NOAEL)/low-observed-adverse-effect-level (LOAEL) and estimated benchmark dose (BMD) approaches were applied. General toxicity, parameters of sexual development, endocrine/reproductive/functional liver and kidney biomarkers, histopathology of target tissues, and gene expression in hypothalamic-pituitary area and liver were studied. No mortality or general toxicity occurred. Sex-specific alterations were observed in liver, thyroid, spleen, leptin/adiponectin serum levels, and hypothalamic-pituitary gene expression. Thyroid homeostasis and liver were the most sensitive targets of BPA exposure in the peripubertal phase. The proposed LOAEL was 2 mg/kg bw, considering as critical effect the liver endpoints, kidney weight in male and adrenal histomorphometrical alterations and osteopontin upregulation in female rats. The BMD lower bounds were 0.05 and 1.33 mg/kg bw in males and females, considering liver and thyroid biomarkers, respectively. Overall, BPA evaluation at dose levels derived from children biomonitoring study allowed to identify sex-specific, targeted toxicological effects that may have significant impact on risk assessment for children.

Study on the Release Potential of BPA and Steroid Estrogens in the Sediments of Erhai Lake, a Typical Plateau Lake of China

On-site sampling analysis and laboratory-scale experiments were conducted to study the pollution status and release potential of EDCs in Erhai Lake. We found that nitrogen and phosphorus pollution in Erhai Lake sediment were both at a high level, as well as EDCs pollution. The concentrations of BPA, E2α, E1, E2β, EE2, and E3 were 36.84 ng/g(DW), 13.04 ng/g(DW), 128.97 ng/g(DW), 52.57 ng/g(DW), 18.48 ng/g(DW) and 5.36 ng/g(DW), respectively. The concentrations of E2α, E1, E2β and EE2 in the bottom water were higher than the surface water due to the impact of sediment release. The results of the 20 days release test indicated that BPA release from the sediment had a greater correlation with the original concentration and the particle size of sediment, while the steroid EDCs had no obvious correlation with these two factors, probably due to the difference in hydrophobicity between them. Under hydraulic disturbance and aerobic conditions, the release process of EDCs was accompanied by a large amount of microbial degradation, and degradation amount > released amount. BPA was released quickly, 9.56% was released in 20 days, but only 3.37% of steroid EDCs released. In comparison, the release process of steroids was longer and posed a greater threat to aquatic ecology.

Involvement of NMDAR/PSD-95/nNOS-NO-cGMP pathway in embryonic exposure to BPA induced learning and memory dysfunction of rats

Bisphenol A (BPA), can lead to learning and memory impairment, but the underlying mechanism is poorly understood. Researchers have indicated that the N-methyl-D-aspartate receptor (NMDAR)/postsynaptic density protein 95 (PSD-95)/neuronal nitric oxide synthase (nNOS)-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway greatly contributes to learning and memory process. Pregnant rats were exposed to 0, 0.05, 0.5, 5 and 50 mg/kg/day BPA via oral gavage from gestational day (GD) 5 to GD 19. Morris water maze, transmission electron microscope, western blot, real time PCR, biochemical analysis and ELISA were used to analyze the changes in behavior, synaptic ultrastructure, protein and gene expression of NMDAR, PSD-95, nNOS, together with nNOS activity, NO (Nitrate reductase method) and cGMP levels of the rat pups at different growth stages. Results of this research displayed that exposure to 0.5 mg/kg/day BPA could damage the spatial learning ability of rats at postnatal day (PND) 56. However, spatial memory ability could be affected by exposure to BPA at doses up to 5 mg/kg/day. Moreover, the thickness of the postsynaptic density decreased after exposure to BPA at doses of 5 and 50 mg/kg/day. Levels of NR1, NR2A, PSD-95 protein and mRNA were downregulated to some extent after exposure to BPA, whereas the expression of NR2B increased at GD 20 but decreased at PND 21 and 56. Contrarily, the nNOS expression along with the enzyme activity were promoted after exposure to BPA. Meanwhile, the NO and cGMP levels were suppressed at GD 20 but promoted at PND 21 and 56. In conclusion, these results demonstrated that NMDAR/PSD-95/nNOS-NO-cGMP pathway could be affected by embryonic exposure to BPA, which may involve in the spatial learning and memory dysfunction of rats in later life.

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.

Chronic exposure of bisphenol A impairs carbohydrate and lipid metabolism by altering corresponding enzymatic and metabolic pathways

Bisphenol-A (BPA), a widespread endocrine-disrupting chemical, has been recognized as a risk factor for metabolic disorders. BPA is considered to be involved in the impairment of carbohydrate and lipid metabolism but the underlying mechanisms still need to be elucidated. Present study was aimed to investigate the impact of BPA exposure on enzymatic and metabolic pathways that are responsible to regulate the carbohydrate and lipid metabolism. Experimental rats were exposed to different doses of BPA (50, 500, 2500 and 5000 μg/kg/day orally) dissolved in 1.5% dimethyl sulfoxide for a period of 3 months. Serum level of key metabolic enzymes (α-amylase, α-glucosidase, hexokinase, glucose-6-phosphatase and HMG-CoA-reductase) was measured by ELISA method. BPA-exposure suppressed the mRNA expression of gene encoding insulin resulting in poor insulin production. While hexokinase, acetyl-CoA carboxylase and squalene epoxide were up-regulated upon BPA exposure that justified the increased lipid profile. Moreover, BPA exposure showed considerably decreased glucose uptake through insulin signaling via Akt/GLUT4 pathways. There was a significant (p < 0.001) reduction in tissue level of glucose transporters. BPA significantly (p < 0.001) decreased the serum levels of oxidative stress biomarkers (GSH, CAT, and SOD). Serum levels of leptin, TNF-α, and IL-6 were rapidly increased upon exposure to BPA (p < 0.001). It was clearly evident from this study that BPA disturbed the carbohydrate and lipid metabolism after chronic exposure. It also accelerated the inflammatory processes by increasing the oxidative stress which ultimately lead towards the insulin resistance and impaired carbohydrate and lipid metabolism.

Effects of prenatal bisphenol A exposure on the hepatic transcriptome and proteome in rat offspring

Developmental exposure to bisphenol A (BPA) is associated with liver dysfunction and diseases in adulthood. The aims of this study were to assess the effects of prenatal BPA exposure on the hepatic transcriptome and proteome in female and male offspring and to understand adverse outcome pathways (AOPs) to observed phenotypic effects. Pregnant Wistar rats were exposed to 50 or 5000 μg BPA/kg bw/day, or 17β-estradiol (E2, 50 μg/kg bw/day) from embryonic day 3 to 18. The liver transcriptome and proteome profiles were analyzed in the newborn (postnatal day 1; PND1) and weaning (PND21) rat offspring. Based on the differentially expressed genes/proteins derived from transcriptome and proteome profiles, we performed pathway, transcription factor, and disease enrichment analyses. A principal component analysis of transcriptome data demonstrated that prenatal BPA exposure caused masculinization of the hepatic transcriptome in females. Both of transcriptomic and proteomic data showed that prenatal BPA exposure led to the disruption of cell cycle, lipid homeostasis, and hormone balance in offspring. Most of the effects at the transcript level were extended from newborn to weaning in males, but were moderated until weaning in females. The alterations at the transcript and protein levels were accordant with the observation of increases in body weight and anogenital distance and changes in hepatosomatic index in the offspring. Collectively, we constructed AOPs with evidence of sex- and age-specific actions of prenatal BPA exposure in the offspring.

Endocrine disruption and obesity: A current review on environmental obesogens

Obesity represents an important public health concern because it substantially increases the risk of multiple chronic diseases and thereby contributing to a decline in both quality of life and life expectancy. Besides unhealthy diet, physical inactivity and genetic susceptibility, environmental pollutants also contribute to the rising prevalence of obesity epidemic. An environmental obesogen is defined as a chemical that can alter lipid homeostasis to promote adipogenesis and lipid accumulation whereas an endocrine disrupting chemical (EDC) is defined as a synthetic chemical that can interfere with the endocrine function and cause adverse health effects. Many obesogens are EDCs that interfere with normal endocrine regulation of metabolism, adipose tissue development and maintenance, appetite, weight and energy balance. An expanding body of scientific evidence from animal and epidemiological studies has begun to provide links between exposure to EDCs and obesity. Despite the significance of environmental obesogens in the pathogenesis of metabolic diseases, the contribution of synthetic chemical exposure to obesity epidemic remains largely unrecognised. Hence, the purpose of this review is to provide a current update on the evidences from animal and human studies on the role of fourteen environmental obesogens in obesity, a comprehensive view of the mechanisms of action of these obesogens and current green and sustainable chemistry strategies to overcome chemical exposure to prevent obesity. Designing of safer version of obesogens through green chemistry approaches requires a collaborative undertaking to evaluate the toxicity of endocrine disruptors using appropriate experimental methods, which will help in developing a new generation of inherently safer chemicals.

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Many environmental obesogens are endocrine disrupting chemicals that interfere with normal endocrine regulation of metabolism.

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Understanding the role of environmental obesogens in the epidemics of obesity is in an infant stage.

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Green chemistry approach aims to design a safer version of these chemicals by understanding their hazardous effects.

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Further studies are necessary to fully establish the hazardous effects of obesogens and their association to human obesity.

Mechanisms of action, chemical characteristics, and model systems of obesogens

There is increasing evidence for the role of environmental endocrine disrupting contaminants, coined obesogens, in exacerbating the rising obesity epidemic. Obesogens can be found in everyday items ranging from pesticides to food packaging. Although research shows that obesogens can have effects on adipocyte size, phenotype, metabolic activity, and hormone levels, much remains unknown about these chemicals. This review will discuss what is currently known about the mechanisms of obesogens, including expression of the PPARs, hormone interference, and inflammation. Strategies for identifying obesogenic chemicals and their mechanisms through chemical characteristics and model systems will also be discussed. Ultimately, research should focus on improving models to discern precise mechanisms of obesogenic action and to test therapeutics targeting these mechanisms.

Maternal paraben exposure triggers childhood overweight development

Parabens are preservatives widely used in consumer products including cosmetics and food. Whether low-dose paraben exposure may cause adverse health effects has been discussed controversially in recent years. Here we investigate the effect of prenatal paraben exposure on childhood overweight by combining epidemiological data from a mother–child cohort with experimental approaches. Mothers reporting the use of paraben-containing cosmetic products have elevated urinary paraben concentrations. For butyl paraben (BuP) a positive association is observed to overweight within the first eight years of life with a stronger trend in girls. Consistently, maternal BuP exposure of mice induces a higher food intake and weight gain in female offspring. The effect is accompanied by an epigenetic modification in the neuronal Pro-opiomelanocortin (POMC) enhancer 1 leading to a reduced hypothalamic POMC expression. Here we report that maternal paraben exposure may contribute to childhood overweight development by altered POMC-mediated neuronal appetite regulation.

Parabens are preservatives widely used in consumer products including cosmetics and food. Here the authors demonstrate that maternal paraben exposure may contribute to childhood overweight development by an altered neuronal appetite regulation.

Prenatal BPA and its analogs BPB, BPF, and BPS exposure and reproductive axis function in the male offspring of Sprague Dawley rats

Research in the past has indicated associated long-term and low levels of exposure of bisphenol A (BPA) in early life and neuroendocrine disorders, such as obesity, precocious puberty, diabetes, and hypertension. BPA and its analogs bisphenol B (BPB), bisphenol F (BPF), and bisphenol S (BPS) have been reported to have similar or even more toxic effect as compared to BPA. Exposure of rats to BPA and its analogs BPB, BPF, and BPS resulted in decreased sperm production, testosterone secretion, and histological changes in the reproductive tissues of male rats. In the present study, BPA, BPB, BPF, and BPS were administered in drinking water at concentrations of (5, 25, and 50 μg/L) from pregnancy day (PD) 1 to PD 21. Body weight (BW), hormonal concentrations, antioxidant enzymes, and histological changes were determined in the reproductive tissues. BPA and its analogs prenatal exposure to female rats induced significant statistical difference in the antioxidant enzymes, plasma testosterone, and estrogen concentrations in the male offspring when compared with the control. Histological parameters of both testis and epididymis revealed prominent changes in the reproductive tissues. The present study suggests that BPA and its analogs BPB, BPF, and BPS different concentrations led to marked alterations in the development of the male reproductive system.

Wnt pathway: A mechanism worth considering in endocrine disrupting chemical action

Endocrine disrupting chemicals (EDCs) are defined as exogenous substances that can alter the development and functioning of the endocrine system. The Wnt signaling pathway is an evolutionarily conserved pathway consisting of proteins that transmit cell-to-cell receptors through cell surface receptors, regulating important aspects of cell migration, polarity, neural formation, and organogenesis, which determines the fate of the cell during embryonic development. Although the effects of EDCs have been studied in terms of many molecular mechanisms; because of its critical role in embryogenesis, the Wnt pathway is of special interest in EDC exposure. This review provides information about the effects of EDC exposure on the Wnt/β-catenin pathway focusing on studies on bisphenol A, di-(2-ethylhexyl) phthalate, diethylstilbestrol, cadmium, and 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Combined Exposure to Fructose and Bisphenol A Exacerbates Abnormal Lipid Metabolism in Liver of Developmental Male Rats

The aim of this study was to investigate whether combined exposure to fructose and bisphenol A (BPA) has a synergistic effect on abnormal lipid metabolism in the liver of developmental male rats and its possible mechanism. Fifty weaned male Wistar rats were divided into five groups: the control, 13% fructose, 20% fructose, 1 µg/mL BPA, and 13% fructose + 1 µg/mL BPA (combined exposure). Rats were exposed to fructose and/or BPA through drinking water for eight weeks. Genes or proteins regulating lipid metabolism include sterol regulatory element binding protein 1 (SREBP1), adipose triglyceride lipase (ATGL), hormone sensitive lipase (HSL), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FAS), zinc α 2 glycoprotein (ZAG) and estrogen receptor α (ERα), and the expression of proteins regulating inflammatory response, such as TLR4 and NF-κB, were determined. Serum total cholesterol (T-CHO), triglyceride (TG), low, high density lipoprotein cholesterol (LDL-C, HDL-C), blood glucose, insulin, IL-17 and TNF-α levels were also measured. Liver tissue morphology was observed by H&E staining. The results showed that the levels of gene and protein catalyzing lipogenesis were increased (SREBP1, ACC1 and FAS), while those catalyzing lipolysis were decreased (ATGL, HSL and ZAG), accompanied by dyslipidemia, insulin resistance and hepatic fat accumulation, and there were higher expression of TLR4 and NF-κB protein and lower expression of ERα protein in liver, and increased serum IL-17 and TNF-α levels in fructose and/or BPA exposed rats compared with controls. Moreover, the above indicators were more serious in combined exposure group than in single exposure group. Therefore, abnormal lipid metabolism in the liver of developmental rats could be exacerbated by combined exposed to fructose and BPA.

Mothers and children are related, even in exposure to chemicals present in common consumer products

BACKGROUND

Phthalates, bisphenol A (BPA) and triclosan (TCS) are detectable in the vast majority of people. Most humans are continuously exposed to these chemicals due to their presence in food or in everyday consumer products. The measurement of these compounds in family members may help to explore the impact of major lifestyle factors on exposure. Mothers and (young) children are especially interesting to study, as they mostly share considerable parts of daily life together.

MATERIALS AND METHODS

Phthalate metabolites, bisphenol A (BPA) and triclosan (TCS) were measured in first morning void urine, collected in mother-child pairs (n = 129) on the same day. The mothers (27-45y) and their children (6-11y) were recruited in the Brussels agglomeration and rural areas of Belgium in the context of the European COPHES-DEMOCOPHES human biomonitoring project. Face-to-face questionnaires gathered information on major exposure sources and lifestyle factors. Exposure determinants were assessed by multiple linear regression analysis.

RESULTS

The investigated compounds were detectable in nearly all mothers (92.8-100%) and all children (95.2-100%). The range (P₉₀ vs. P₁₀) of differences in urinary concentrations within each age group was for most compounds around 10-20 fold, and was very high for TCS up to 35 and 350-fold in children and mothers respectively. Some participants exceeded the tolerable daily intake guidelines as far as they were available from the European Food Safety Authority (EFSA). Overall, for BPA, the urinary concentrations were similar among both age groups. Most urinary phthalate metabolites were higher in children compared to the mothers, except for monoethyl phthalate (MEP). TCS levels were generally higher in the mothers. Despite the difference in mothers' and children's urinary concentrations, the creatinine-corrected levels were correlated for all biomarkers (Spearman rank r = 0.32 to 0.66, p < 0.001). Furthermore, for phthalates, similar home and lifestyle factors were associated with the urinary concentrations in both age groups: home renovation during last two years or redecoration during the last year for di-ethyl phthalate (DEP); PVC in home for di-n-butyl phthalate (DnBP), di-iso-butyl phthalate (DiBP) and butyl benzyl phthalate (BBzP), and personal care products use for DiBP and DnBP. Based on questionnaire information on general food type consumption patterns, the exposure variability could not be explained. However, comparing the phthalate intake from the current study with earlier assessed Belgian food intake calculations for both ages, food in general was estimated to be the major intake source for di-ethyl hexyl phthalate (DEHP), with diminishing importance for BBzP, DiBP and DnBP.

CONCLUSION

Our results confirm, that children and their mothers, sharing diets and home environments, also share exposure in common consumer products related chemicals. By collecting morning urine levels on the same day, and using basic questionnaires, suspected exposure routes could be unraveled.

Identification of metabolic pathways related to the bisphenol A-induced adipogenesis in differentiated murine adipocytes by using RNA-sequencing

We evaluated the effect of bisphenol A and its metabolites on the 3T3-L1 cells, in terms of glucose and lipid metabolism. We also aimed to obtain the information on the genome-wide expression changes in the 3T3-L1 cells treated with Bisphenol A by using RNA-seq, which involves whole-transcriptome sequencing. Differentially Expressed Genes (DEGs) collected from RNA-seq can be used to produce a complete picture of related metabolism pathways. The KEGG pathway was extracted based on the DEGs. Bisphenol A significantly increased the mRNA level of Sterol regulatory element binding transcription factor 1 (Srebf1) and CCAAT/enhancer binding protein alpha (Cebpa). Lipoprotein lipase (Lpl) was also significantly influenced by bisphenol A and its metabolites. Acetyl-Coenzyme A carboxylase beta (Acacb) and Fatty acid synthase (Fasn) mRNA levels were elevated by bisphenol A and its metabolites. The insulin signaling pathway, neurotrophin signaling pathway, and endometrial cancer-related pathway were focused by the functional enrichment analyses, and the pathways were well coincided with recent previous reports. DEGs collected from RNA-seq were confirmed as a reliable evidence in the exposure to the chemicals such as bisphenol A. Collecting pieces of the puzzles obtained from the RNA-seq will help us to produce a complete picture of the metabolic pathway for such chemicals.

Effects of Bauhinia forficata on glycaemia, lipid profile, hepatic glycogen content and oxidative stress in rats exposed to Bisphenol A

Bisphenol A (BPA) is an abundant raw material applied in the production of daily necessities, such as food cans, baby bottles, electronic and medical equipment. Phytotherapeutic use of plant preparations has long been known for multiple target medicinal uses. The species Bauhinia forficata is widely used as hypoglycemic, anti-inflammatory, antioxidant, diuretic and hypocholesterolemic agent. The aim of this study was to verify the effects of B. forficata extract in association with BPA exposure on serological parameters, hepatic antioxidant status and glycogen store capacity in Wistar rats. B. forficata was able to reduce BPA-induced glucose levels; it also prevented the early glucose elevation in control and BPA-exposed animals after the glucose provocative test. This effect was related to the hepatic glycogen content; while BPA reduced the hepatic glycogen deposits B. forficata treatment contributed to minimize it. BPA and B. forficata singly caused elevation in triacylglycerol and VLDL levels and reduction in cholesterol and LDL concentrations. BPA increased hepatic malondialdehyde levels and reduced catalase activity, thus inducing liver oxidative stress. Conversely, B. forficata treatment reduced malondialdehyde concentration without interfering with catalase activity; this antioxidant capacity is attributed to the flavonoids content (e.g., kaempferol and myricetin). Based on these results, we demonstrated that B. forficata commercial extract has hypoglycemic and antioxidant properties capable of minimizing the effects of BPA. However, it should be considered that the consumption of herbal commercial extract must be judicious to avoid deleterious health effects.

The protective activity of nanomicelle curcumin in bisphenol A-induced cardiotoxicity following subacute exposure in rats

Bisphenol A (BPA), an estrogenic compound, is used in manufacture of polycarbonate plastics and epoxy resins. Curcumin, the active ingredient of turmeric, is a potent protective compound against cardiac diseases. In this study the protective effect of nanomicelle curcumin on BPA-induced subchronic cardiotoxicity in rats was evaluated. Rats were divided into 6 groups including control, nanomicelle curcumin (50 mg/kg, gavage), BPA (50 mg/kg, gavage), nanomicelle curcumin (10, 25, and 50 mg/kg) plus BPA. The treatments were continued for 4 weeks. Results revealed that BPA significantly induced histophatological injuries including focal lymphatic inflammation, nuclear degenerative changes and cytoplasmic vacuolation, increased body weight, systolic and diastolic blood pressures, malondialdehyde and Creatine phosphokinase-MB level and decreased glutathione content in comparison with control group. In addition, in electrocardiographic graph, RR, QT, and PQ intervals were increased by BPA. Western blot analysis showed that BPA up-regulated phosphorylated p38 (p38-mitogen-activated protein kinase) and JNK (c-jun NH2 terminal kinases), while down-regulated phosphorylated AKT (Protein Kinase B) and ERK1/2 (extracellular signal-regulated protein kinases 1 and 2). However, nanomicelle curcumin (50 mg/kg) significantly improved these toxic effects of BPA in rat heart tissue. The results provide evidence that nanomicelle curcumin showed preventive effects on subchronic exposure to BPA induced toxicity in the heart tissue in rats.

Bisphenol A decreases the spontaneous contractions of rat uterus in vitro through a nitrergic mechanism

BACKGROUND

Bisphenol A (BPA), a chemical used in the manufacture of plastics, has toxic effects on various systems of the human body including the reproductive system. BPA possesses estrogenic activity and is implicated in altering oogenesis, ovulation, and fertility. In addition to ovulatory changes, uterine contractility is an important factor for fertility. However, the effects of BPA on myometrial contractions are not known. Therefore, we examined the effect of BPA on rat uterine contractions.

METHODS

The uterus was isolated from adult rats showing estrous phase, and spontaneous in vitro contractions were recorded (35±1 °C). The effect of cumulative concentrations of BPA was determined. Further, the involvement of nitric oxide (NO) and guanylyl cyclase (GC) for the BPA-induced changes on uterine contractility was evaluated using the NO synthase inhibitor (L-NAME) or GC inhibitor (methylene blue).

RESULTS

BPA decreased the amplitude and frequency of spontaneous uterine contractions in a concentration-dependent manner. A decrease of 50% occurred at 1 and 3 μM for amplitude and frequency, respectively. L-NAME (N-ω-nitro-l-arginine methyl ester) blocked the BPA-induced decrease in amplitude at all concentrations but antagonized the frequency only at the maximum concentration (10 μM). Methylene blue (a GC inhibitor) did not block the BPA-induced responses but for the frequency at 10 μM of BPA.

CONCLUSIONS

The results indicate that BPA decreased the amplitude and frequency of spontaneous uterine contractions by involving the nitrergic mechanism; however, the GC mechanism is not involved in the depression.

Melatonin attenuates bisphenol A-induced toxicity of the adrenal gland of Wistar rats

This study investigated the role of melatonin (MLT) on adrenal gland toxicity induced by bisphenol A (BPA). Adult male rats were divided into four groups of seven animals each: Group I (control) received oral 0.2 ml canola oil; group II received intra-peritoneal 10 mg/kg BW/day MLT; and group III received oral BPA (10 mg/kg BW/day). Group IV rats were treated with same dose of BPA as group III with a concomitant intra-peritoneal 10 mg/kg BW/day MLT. All treatments lasted for 14 days. BPA significantly increased (P < 0.05) adrenal index, circulating levels of corticosterone and adrenocorticotropic hormone (ACTH) in the rats. BPA caused marked vascular congestion, hyperplasia, cellular distortion, increased lipid peroxidation, decreased antioxidant enzymes, and decreased expression of αSmooth muscle actin as well as vimentin proteins. The concomitant treatment with MLT ameliorated these BPA-induced alterations. It is likely that melatonin attenuates BPA-induced alterations of the adrenal gland of rats through the antioxidant defense mechanism.

Prenatal Bisphenol A Exposure in Mice Induces Multitissue Multiomics Disruptions Linking to Cardiometabolic Disorders

The health impacts of endocrine-disrupting chemicals (EDCs) remain debated, and their tissue and molecular targets are poorly understood. In this study, we leveraged systems biology approaches to assess the target tissues, molecular pathways, and gene regulatory networks associated with prenatal exposure to the model EDC bisphenol A (BPA). Prenatal BPA exposure at 5 mg/kg/d, a dose below most reported no-observed-adverse-effect levels, led to tens to thousands of transcriptomic and methylomic alterations in the adipose, hypothalamus, and liver tissues in male offspring in mice, with cross-tissue perturbations in lipid metabolism as well as tissue-specific alterations in histone subunits, glucose metabolism, and extracellular matrix. Network modeling prioritized main molecular targets of BPA, including Pparg, Hnf4a, Esr1, Srebf1, and Fasn as well as numerous less studied targets such as Cyp51 and long noncoding RNAs across tissues, Fa2h in hypothalamus, and Nfya in adipose tissue. Lastly, integrative analyses identified the association of BPA molecular signatures with cardiometabolic phenotypes in mouse and human. Our multitissue, multiomics investigation provides strong evidence that BPA perturbs diverse molecular networks in central and peripheral tissues and offers insights into the molecular targets that link BPA to human cardiometabolic disorders.

Endocrine Disrupting Chemicals: An Occult Mediator of Metabolic Disease

Endocrine disrupting chemicals (EDCs), a heterogeneous group of exogenous chemicals that can interfere with any aspect of endogenous hormones, represent an emerging global threat for human metabolism. There is now considerable evidence that the observed upsurge of metabolic disease cannot be fully attributed to increased caloric intake, physical inactivity, sleep deficit, and ageing. Among environmental factors implicated in the global deterioration of metabolic health, EDCs have drawn the biggest attention of scientific community, and not unjustifiably. EDCs unleash a coordinated attack toward multiple components of human metabolism, including crucial, metabolically-active organs such as hypothalamus, adipose tissue, pancreatic beta cells, skeletal muscle, and liver. Specifically, EDCs' impact during critical developmental windows can promote the disruption of individual or multiple systems involved in metabolism, via inducing epigenetic changes that can permanently alter the epigenome in the germline, enabling changes to be transmitted to the subsequent generations. The clear effect of this multifaceted attack is the manifestation of metabolic disease, clinically expressed as obesity, metabolic syndrome, diabetes mellitus, and non-alcoholic fatty liver disease. Although limitations of EDCs research do exist, there is no doubt that EDCs constitute a crucial parameter of the global deterioration of metabolic health we currently encounter.

Bisphenol A induced abnormal DNA methylation of ovarian steroidogenic genes in rare minnow Gobiocypris rarus

Bisphenol A (BPA), an ubiquitous environmental endocrine disruptor chemical, disturbs the mRNA expressions of steroidogenic genes and subsequently steroid hormone synthesis in mammals and aquatic species. However, the underlying regulation mechanisms are barely understood, especially in fish. To explore the regulation mechanism, we exposed female rare minnow Gobiocypris rarus (G. rarus) to BPA at a nominal concentration of 15 μg/L for 7 and 14 days in the present study. Results showed significant increase of gonad somatic index (GSI) and serum estradiol (E2) levels in response to BPA at day 14. The 7-day BPA exposure notably repressed the expression of two ovarian steroidogenic genes (star and hsd11b2) and suppressed their capacity of estrogen response elements (ERE) to recruit estrogen receptor (ER), while the 14-day BPA treatment remarkably induced transcript of hsd3b and enhanced the capacity of ERE to recruitment ER in ovaries. Furthermore, the 7-day BPA exposure caused DNA hypermethylation of star (CpGs: -742 bp and -719 bp) and hsd11b2 (CpG: -1788 bp). However, 14-day BPA exposure resulted in DNA hypomethylation of hsd3b (CpG: -181 bp). Correlation analysis revealed that the DNA methylation levels at specific CpGs in star, hsd3b and hsd11b2 were significantly correlated to their mRNA levels and ER-EREs interactions. These findings suggest that the disturbed steroidogenesis and the transcripts of ovarian steroidogenic genes might attribute to the altered DNA methylation status of these ovarian steroidogenic genes in response to BPA.

In vivo and in vitro bisphenol A exposure effects on adiposity

In utero exposure to the ubiquitous plasticizer, bisphenol A (BPA) is associated with offspring obesity. As adipogenesis is a critical factor contributing to obesity, we determined the effects of in vivo maternal BPA and in vitro BPA exposure on newborn adipose tissue at the stem-cell level. For in vivo studies, female rats received BPA before and during pregnancy and lactation via drinking water, and offspring were studied for measures of adiposity signals. For in vitro BPA exposure, primary pre-adipocyte cell cultures from healthy newborns were utilized. We studied pre-adipocyte proliferative and differentiation effects of BPA and explored putative signal factors which partly explain adipose responses and underlying epigenetic mechanisms mediated by BPA. Maternal BPA-induced offspring adiposity, hypertrophic adipocytes and increased adipose tissue protein expression of pro-adipogenic and lipogenic factors. Consistent with in vivo data, in vitro BPA exposure induced a dose-dependent increase in pre-adipocyte proliferation and increased adipocyte lipid content. In vivo and in vitro BPA exposure promotes the proliferation and differentiation of adipocytes, contributing to an enhanced capacity for lipid storage. These findings reinforce the marked effects of BPA on adipogenesis and highlight the susceptibility of stem-cell populations during early life with long-term consequence on metabolic homeostasis.

Dose-dependent transcriptomic responses of zebrafish eleutheroembryos to Bisphenol A

Despite the abundant literature on the adverse effects of Bisphenol A (BPA) as endocrine disruptor, its toxicity mechanisms are still poorly understood. We present here a study of its effects on the zebrafish eleutheroembryo transcriptome at concentrations ranging from 0.1 to 4 mg L^-1, this latter representing the lowest observed effect concentration (LOEC) found in our study at three different macroscopical endpoints (survival, hatching and swim bladder inflation). Multivariate data analysis methods identified both monotonic and bi-phasic patterns of dose-dependent responses. Functional analyses of genes affected by BPA exposure suggest an interaction of BPA with different signaling pathways, being the estrogenic and retinoid receptors two likely targets. In addition, we identified an apparently unrelated inhibitory effect on, among others, visual function genes. We interpret our data as the result of a sum of underlying, independent molecular mechanisms occurring simultaneously at the exposed animals, well below the macroscopic LOEC, but related to at least some of the observed morphological alterations, particularly in eye size and yolk sac resorption. Our data supports the idea that the physiological effects of BPA cannot be only explained by its rather weak interaction with the estrogen receptor, and that multivariate analyses are required to analyze the effects of toxicants like BPA, which interact with different cellular targets producing complex phenotypes.

Bisphenol A (BPA) and bisphenol S (BPS) alter the promoter activity of the ABCB1 gene encoding P-glycoprotein in the human placenta in a haplotype-dependent manner

Exposure to bisphenols (BPA and BPS) during pregnancy can significantly affect fetal development and increase risk of adverse health consequences, however the underlying mechanisms are not fully elucidated. In human placenta, the efflux transporter P-glycoprotein (P-gp), encoded by the ABCB1 gene, extrudes its substrates from the trophoblasts back into the maternal circulation. Alterations in levels of placental P-gp could therefore significantly affect fetal exposure to xenobiotics that are P-gp substrates. The ABCB1 promoter contains many single nucleotide polymorphisms (SNPs). In the genome, SNPs are not arrayed as independent variants but as combinations forming defined haplotypes. Recently, we determined the haplotype sequences encompassing the ABCB1 promoter SNPs and found that promoter haplotypes differentially affect ABCB1 promoter activity. Here we investigate the effect of BPA and BPS on ABCB1 promoter activity by testing the hypothesis that BPA and BPS exposure affect ABCB1 promoter activity in a haplotype-dependent manner. Our data indicate that acute exposure to 50 nM BPA induced a significant haplotype-dependent increase in ABCB1 promoter activity (P < .05). However, acute exposure to 0.5 nM BPS induced a significant decrease (P < .05) in promoter activity that was haplotype-dependent. Chronic exposure to BPA and BPS individually (5 nM and 0.3 nM, respectively) or as a mixture (5 nM BPA:1.5 nM BPS) induced significant haplotype-dependent increases (P < .01) in ABCB1 promoter activity. Our data indicate that BPA and BPS significantly alter ABCB1 promoter activity in a haplotype- and exposure type- dependent manners. Such alteration could significantly impact placental P-gp levels and alter fetal exposure to many therapeutic and environmental xenobiotics.

Acrylamide induces adipocyte differentiation and obesity in mice

Obesity is a critical risk factor for various diseases including type II diabetes, cerebral infarction, cardiovascular diseases, and various cancers. Acrylamide (ACR) is present in wide range of foods, including fried potato products, root vegetables, bakery products, chips, cakes, cereals, and coffee. In this study, ACR treatment dramatically increased the accumulation of lipid droplets. We also examined expression levels of peroxisome proliferator-activated receptors γ (PPARγ), CCAAT enhancer binding protein α (c/EBPα), and CCAAT enhancer binding protein β (c/EBPβ) as adipogenic transcription factors for adipocyte differentiation. They were dose-dependently increased by treatment of ACR. Moreover, effects of ACR on mitogen-activated protein kinases (MAPKs) and 5' AMP-activated protein kinase (AMPK)-Acetyl-CoA carboxylase (ACC) activation were investigated. Results also showed that ACR induced phosphorylation of MAPKs and AMPK-ACC. ACR also induced expression of adipocyte fatty acid-binding protein (aP2), lipoprotein lipase (LPL), sterol regulatory element-binding protein (SREBP)-1c, and fatty acid synthase (FAS). Exposure of ACR to high fat diet (HFD)-fed mice significantly increased body weight, organ weight, and fat mass of mice. Collectively, these result showed that ACR can act as an enhancer of adipocyte. Therefore, we suggest that up-regulation of the adipogenesis by ACR may be related to the regulation of the MAPKs and AMPK-ACC pathway.

Reproductive and developmental F1 toxicity following exposure of pubescent F0 male mice to bisphenol A alone and in a combination with X-rays irradiation

Exposure to environmental toxicants may affect reproduction and development of subsequent generations. This study was aimed at determining the male-mediated F1 effects induced following 8-weeks of subchronic exposure of F0 male mice to bisphenol A (BPA) alone and in a combination with X-rays irradiation (IR) started during their puberty. 4.5 weeks old F0 male mice were exposed to BPA dissolved in ethyl alcohol and diluted in drinking water at the following doses: 5 mg/kg bw, 10 mg/kg bw, 20 mg/kg bw or irradiated with X-rays (0.05 Gy) or exposed to a combination of low doses of both agents (0.05 Gy + 5 mg/kg bw BPA). Immediately after the end of the 8 weeks exposure F0 males were caged with two unexposed females each. Three quarters of the mated females from each group were sacrificed 1 day before expected parturition for examination of prenatal development of the offspring. The remainder of the females from each group were allowed to deliver and rear litters. Pups of exposed males were monitored for postnatal development for 8 weeks. At 8-9 weeks of age 6-8 males from each group of F1 generation were sacrificed to determine sperm count and quality. The current results, compared to the earlier results, showed that exposure of pubescent males to BPA alone or in combination with irradiation may be more damaging to their offspring than the exposure of adult males. The exposure of pubescent males to BPA alone and in combination with irradiation significantly increased the frequency of abnormal skeletons of surviving fetuses, increased the percent of mortality of pups in the F1 generation, reduced the sperm motility of F1 males and may induce obesity. Additionally, the combined BPA and irradiation exposure reduced the number of total and live implantations, whereas the exposure to BPA alone disturbed the male:female sex ratio. The above results may be caused by genetic or by epigenetic mechanisms. Limitation of use of products including BPA, especially by children and teenagers, is strongly recommended.

Low-dose developmental bisphenol A exposure alters fatty acid metabolism in Fischer 344 rat offspring

BACKGROUND

Bisphenol A (BPA) is an endocrine disruptor and also a suggested obesogen and metabolism-disrupting chemical. Accumulating data indicates that the fatty acid (FA) profile and their ratios in plasma and other metabolic tissues are associated with metabolic disorders. Stearoyl-CoA desaturase 1 (SCD-1) is a key regulator of lipid metabolism and its activity can be estimated by dividing the FA product by its precursor measured in blood or other tissues.

OBJECTIVE

The primary aim of this study was to investigate the effect of low-dose developmental BPA exposure on tissue-specific FA composition including estimated SCD-1 activity, studied in 5- and 52-week (wk)-old Fischer 344 (F344) rat offspring.

METHODS

Pregnant F344 rats were exposed to BPA via their drinking water corresponding to 0: [CTRL], 0.5: [BPA0.5], or 50 µg/kg BW/day: [BPA50], from gestational day 3.5 until postnatal day 22.

RESULTS

BPA0.5 increased SCD-16 (estimated as the 16:1n-7/16:0 ratio) and SCD-18 (estimated as the 18:1n-9/18:0 ratio) indices in inguinal white adipose tissue triglycerides (iWAT-TG) and in plasma cholesterol esters (PL-CE), respectively, in 5-wk-old male offspring. In addition, BPA0.5 altered the FA composition in male offspring, e.g. by decreasing levels of the essential polyunsaturated FA linoleic acid (18:2n-6) in iWAT-and liver-TG. No differences were observed regarding the studied FAs in 52-wk-old offspring, although a slightly increased BW was observed in 52-wk-old female offspring.

CONCLUSIONS

Low-dose developmental BPA exposure increased SCD-16 in iWAT-TG and SCD-18 in PL-CE of male offspring, which may reflect higher SCD-1 activity in these tissues. Altered desaturation activity and signs of altered FA composition are novel findings that may indicate insulin resistance in the rat offspring. These aforementioned results, together with the observed increased BW, adds to previously published data demonstrating that BPA can act as a metabolism disrupting chemical.

In vivo maternal and in vitro BPA exposure effects on hypothalamic neurogenesis and appetite regulators

In utero exposure to the ubiquitous plasticizer, bisphenol A (BPA) is associated with offspring obesity. As food intake/appetite is one of the critical elements contributing to obesity, we determined the effects of in vivo maternal BPA and in vitro BPA exposure on newborn hypothalamic stem cells which form the arcuate nucleus appetite center. For in vivo studies, female rats received BPA prior to and during pregnancy via drinking water, and newborn offspring primary hypothalamic neuroprogenitor (NPCs) were obtained and cultured. For in vitro BPA exposure, primary hypothalamic NPCs from healthy newborns were utilized. In both cases, we studied the effects of BPA on NPC proliferation and differentiation, including putative signal and appetite factors. Maternal BPA increased hypothalamic NPC proliferation and differentiation in newborns, in conjunction with increased neuroproliferative (Hes1) and proneurogenic (Ngn3) protein expression. With NPC differentiation, BPA exposure increased appetite peptide and reduced satiety peptide expression. In vitro BPA-treated control NPCs showed results that were consistent with in vivo data (increase appetite vs satiety peptide expression) and further showed a shift towards neuronal versus glial fate as well as an increase in the epigenetic regulator lysine-specific histone demethylase1 (LSD1). These findings emphasize the vulnerability of stem-cell populations that are involved in life-long regulation of metabolic homeostasis to epigenetically-mediated endocrine disruption by BPA during early life.

Possible Obesogenic Effects of Bisphenols Accumulation in the Human Brain

Evidence of bisphenols’ obesogenic effects on humans is mixed and inconsistent. We aimed to explore the presence of bisphenol A (BPA), bisphenol F (BPF) and chlorinated BPA (ClBPA), collectively called the bisphenols, in different brain regions and their association with obesity using post-mortem hypothalamic and white matter brain material from twelve pairs of obese (body mass index (BMI) >30 kg/m²) and normal-weight individuals (BMI <25 kg/m²). Mean ratios of hypothalamus:white matter for BPA, BPF and ClBPA were 1.5, 0.92, 0.95, respectively, suggesting no preferential accumulation of the bisphenols in the grey matter (hypothalamic) or white matter-enriched brain areas. We observed differences in hypothalamic concentrations among the bisphenols, with highest median level detected for ClBPA (median: 2.4 ng/g), followed by BPF (2.2 ng/g) and BPA (1.2 ng/g); similar ranking was observed for the white matter samples (median for: ClBPA-2.5 ng/g, BPF-2.3 ng/g, and BPA-1.0 ng/g). Furthermore, all bisphenol concentrations, except for white-matter BPF were associated with obesity (p < 0.05). This is the first study reporting the presence of bisphenols in two distinct regions of the human brain. Bisphenols accumulation in the white matter-enriched brain tissue could signify that they are able to cross the blood-brain barrier.

The development of a pregnancy PBPK Model for Bisphenol A and its evaluation with the available biomonitoring data

Recent studies suggest universal fetal exposure to Bisphenol A (BPA) and its association with the adverse birth outcomes. Estimation of the fetal plasma BPA concentration from the maternal plasma BPA would be highly useful to predict its associated risk to this specific population. The objective of current work is to develop a pregnancy-physiologically based pharmacokinetic (P-PBPK) model to predict the toxicokinetic profile of BPA in the fetus during gestational growth, and to evaluate the developed model using biomonitoring data obtained from different pregnancy cohort studies. To achieve this objective, first, the adult PBPK model was developed and validated with the human BPA toxicokinetic data. This validated human PBPK model was extended to develop a P-PBPK model, which included the physiological changes during pregnancy and the fetus sub-model. The developed model would be able to predict the BPA pharmacokinetics (PKs) in both mother and fetus. Transplacental BPA kinetics parameters for this study were taken from the previous pregnant mice study. Both oral and dermal exposure routes were included into the model to simulate total BPA internal exposure. The impact of conjugation and deconjugation of the BPA and its metabolites on fetal PKs was investigated. The developed P-PBPK model was evaluated against the observed BPA concentrations in cord blood, fetus liver and amniotic fluid considering maternal blood concentration as an exposure source. A range of maternal exposure dose for the oral and dermal routes was estimated, so that simulation concentration matched the observed highest and lowest mother plasma concentration in different cohorts' studies. The developed model could be used to address the concerns regarding possible adverse health effects in the fetus being exposed to BPA and might be useful in identifying critical windows of exposure during pregnancy.