Effects of Bisphenol S on hypothalamic neuropeptides regulating feeding behavior and apelin/APJ system in mice

Algal toxicity and food chain transport characteristics of three common bisphenols and their mixtures

Various bisphenols (BPs) have been frequently detected in the aquatic environment and coexist in the form of mixtures with potential huge risks. As we all know, food chain is a media by which BPs mixtures and their mixtures probably enter the organisms at different trophic levels due to their environmental persistence. As a result, the concentrations of BPs and their mixtures may continuously magnify to varying degrees, which can produce higher risks to different levels of organisms, and even human health. However, the related researches about mixtures are few due to the complexity of mixtures. So, the ternary BP mixtures were designed by the uniform design ray method using bisphenol A (BPA), bisphenol S (BPS) and bisphenol F (BPF) to investigate their food chain effects including bioconcentration and biomagnification. Here, Chlorella pyrenoidosa (C. pyrenoidosa) and Daphnia magna (D. magna) were selected to construct a food chain. The toxic effects of single BPs and their mixtures were also systematically investigated by the time-dependent microplate toxicity analysis (t-MTA) method. Toxicity interaction within the ternary mixture was analyzed by the concentration addition model (CA) and the deviation from the CA model (dCA). The results show that the C. pyrenoidosa and D. magna had obvious bioconcentration and biomagnification effects on BPs and their mixture. The mixture had the potential to enrich at higher nutrient levels. And BPF had the largest bioconcentration effect (BCF1 = 481.86, BCF2 = 772.02) and biomagnification effect (BMF = 1.6). Three BPs were toxic to C. pyrenoidosa by destroying algal cells and decreasing protein and chlorophyll contents, and their toxicity order was BPF > BPA > BPS. Moreover, their ternary mixture exhibits synergism with time/concentration-dependency. The obtained results are of significant reference value for objectively and accurately assessing the ecological and environmental risks of bisphenol pollutants.

Effects of Acute and Developmental Exposure to Bisphenol S on Chinese Medaka (Oryzias sinensis)

Bisphenol S (BPS), one of the substitutes for bisphenol A (BPA), is widely used in various commodities. The BPS concentrations in surface water have gradually increased in recent years, making it a predominant bisphenol analogue in the aquatic environment and raising concerns about its health and ecological effects on aquatic organisms. For this study, we conducted a 96 h acute toxicity test and a 15-day developmental exposure test to assess the adverse effects of BPS exposure in Chinese medaka (Oryzias sinensis), a new local aquatic animal model. The results indicate that the acute exposure of Chinese medaka embryos to BPS led to relatively low toxicity. However, developmental exposure to BPS was found to cause developmental abnormalities, such as decreased hatching rate and body length, at 15 dpf. A transcriptome analysis showed that exposure to different concentrations of bisphenol S often induced different reactions. In summary, environmental concentrations of BPS can have adverse effects on the hatching and physical development of Chinese medaka, and further attention needs to be paid to the potential toxicity of environmental BPS.

Association of urinary bisphenols with thyroid function in the general population: a cross-sectional study of an industrial park in China

Bisphenols (BPs) are potential thyroid disruptors that are widely used in many consumer products, leading to their widespread exposure in the general population. Current cross-sectional and case-control studies have found associations between exposure to BPs and serum thyroid function, but the results were contradictory. The objectives of this study are to describe demographic characteristics, BP exposure levels, and thyroid function measurements in potentially exposed and control districts and to investigate the association of urinary BPs with thyroid function. Data were collected from a general population aged 3-79 years (N = 281) recruited by the Zhejiang Human Biomonitoring Program (ZJHBP). The concentrations of 10 kinds of BPs in urine and serum free triiodothyronine (FT3), total triiodothyronine (TT3), free thyroxine (FT4), total thyroxine (TT4), thyroid-stimulating hormone (TSH), thyroglobulin (Tg), thyroglobulin antibodies (TgAb), thyroid peroxidase antibodies (TPOAb), and thyrotropin receptor antibody (TRAb) in serum were measured. Multiple linear regression and weighted quantile sum (WQS) regression were used to estimate the relationship between single and mixed exposure of BPs and thyroid function. Bisphenol A (BPA), bisphenol S (BPS), and bisphenol P (BPP) were detected, respectively, in 82.73%, 94.24%, and 55.40% of the population in the exposed area and 81.69%, 61.27%, and 43.66% of the population in the control area. Among adult females, serum TT3 was negatively associated with urinary BPA (β = -0.033, 95% CI = -0.071, -0.008, P = 0.021). Among minor females, FT4 and Tg levels were negatively associated with the urinary BPA (β = -0.026, 95% CI = -0.051, -0.002, P = 0.032 for FT4; β = -0.129, 95% CI = -0.248, -0.009, P = 0.035 for Tg), and TPOAb was positively associated with urinary BPA (β = 0.104, 95% CI = 0.006, 0.203, P = 0.039). In WQS models, BPs mixture was positively associated with FT3 (βWQS = 0.022, 95% CI = 0.002, 0.042) and TT3 (βWQS = 0.033, 95% CI = 0.004, 0.062), and negatively associated with FT4 (βWQS = -0.024, 95% CI = -0.044, 0.004). We found widespread exposure to BPA, BPS, and BPP in the general population of Zhejiang province and found an association between BPA and thyroid hormones. This association is gender- and age-dependent and needs to be confirmed in further studies.

Influence of bisphenol A and its analog bisphenol S on cocaine- and amphetamine-regulated transcript peptide-positive enteric neurons in the mouse gastrointestinal tract

Introduction

Bisphenol A (BPA) is used in large quantities for the production of plastics and is present in various everyday objects. It penetrates living organisms and shows multidirectional adverse influence on many internal organs. For this reason, BPA is often replaced in plastic production by other substances. One of them is bisphenol S (BPS), whose effects on the enteric nervous system (ENS) have not been explained.

Methods

Therefore, the present study compares the influence of BPA and BPS on the number of enteric neurons immunoreactive to cocaine-and amphetamine-regulated transcript (CART) peptide located in the ENS of the stomach, jejunum and colon with the use of double immunofluorescence method.

Results

The obtained results have shown that both bisphenols studied induced an increase in the number of CART-positive enteric neurons, and the severity of changes depended on the type of enteric ganglion, the dose of bisphenols and the segment of the digestive tract. The most visible changes were noted in the myenteric ganglia in the colon. Moreover, in the colon, the changes submitted by BPS are more noticeable than those observed after BPA administration. In the stomach and jejunum, bisphenol-induced changes were less visible, and changes caused by BPS were similar or less pronounced than those noted under the impact of BPA, depending on the segment of the gastrointestinal tract and ganglion type studied.

Discussion

The results show that BPS affects the enteric neurons containing CART in a similar way to BPA, and the BPS impact is even stronger in the colon. Therefore, BPS is not neutral for the gastrointestinal tract and ENS.

Changes Caused by Bisphenols in the Chemical Coding of Neurons of the Enteric Nervous System of Mouse Stomach

Bisphenol A (BPA), an organic chemical compound which is widely used in the production of plastics, can severely damage live organisms. Due to these findings, the plastic industry has started to replace it with other substances, most often with bisphenol S (BPS). Therefore, during the present investigation, with the use of double immunofluorescence labeling, we compared the effect of BPA and BPS on the enteric nervous system (ENS) in the mouse corpus of the stomach. The obtained results show that both studied toxins impact the amount of nerve cells immunoreactive to substance P (SP), galanin (GAL), vesicular acetylcholine transporter (VAChT is used here as a marker of cholinergic neurons) and vasoactive intestinal polypeptide (VIP). Changes observed under the impact of both bisphenols depended on the neuronal factor, the type of the enteric ganglion and the doses of bisphenols studied. Generally, the increase in the percentage of neurons immunoreactive to SP, GAL and/or VIP, and the decrease in the percentage of VAChT-positive neurons, was noted. Severity of changes was more visible after BPA administration. However, the study has shown that long time exposure to BPS also significantly affects the ENS.

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

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

New insight on the mechanism of eating disorder in females based on metabolic differences of bisphenol S in female and male zebrafish

The different capacity of glucuronic acid metabolism might lead to the difference of bisphenol S (BPS) residual in tissues of male and female zebrafish. This may be the fundamental reason why BPS causes different effects in females and males. Here, adult zebrafish are exposed to 1, 10 and 100 μg/L BPS for 35 days to explore the main effect on females. After exposure, the liver of females showed stronger BPS metabolism ability than males, resulting in the accumulation of BPS in the gut of females. The results of neurotransmitters in gut of females revealed that the content of serotonin was decreased by BPS treatments. In addition, the mRNA expression levels of tryptophan 5-monooxygenase (Tph1) that regulated serotonin synthesis was reduced in gut of females in all BPS groups, and Tph1 protein has very high affinity with BPS molecule. Adult females treated with BPS exhibited symptoms including overeating, a decrease of serotonin in the gut, hypoglycemia and hyperlipidemia, a similar effect of Tph1 protein inhibitor LP533401 on adult females. This hypoglycemia stimulates brain agrp/pomc and orexin neurons to induce overfeeding behavior, causing intestinal homeostasis imbalance and hyperlipidemia. Our data elucidate a potential pathogenesis of eating disorder under pollutant stress.

Effects of the long-term influence of bisphenol A and bisphenol S on the population of nitrergic neurons in the enteric nervous system of the mouse stomach

Bisphenol A (BPA) is an endocrine disruptor commonly used in the production of plastics. Due to its relatively well-known harmful effects on living organisms, BPA is often replaced by its various analogues. One of them is bisphenol S (BPS), widely used in the plastics industry. Until recently, BPS was considered completely safe, but currently, it is known that it is not safe for various internal organs. However, knowledge about the influence of BPS on the nervous system is scarce. Therefore, the aim of this study was to investigate the influence of two doses of BPA and BPS on the enteric nitrergic neurons in the CD1 strain mouse stomach using the double-immunofluorescence technique. The study found that both substances studied increased the number of nitrergic neurons, although changes under the impact of BPS were less visible than those induced by BPA. Therefore, the obtained results, for the first time, clearly indicate that BPS is not safe for the innervation of the gastrointestinal tract.

The Comparison of the Influence of Bisphenol A (BPA) and Its Analogue Bisphenol S (BPS) on the Enteric Nervous System of the Distal Colon in Mice

Bisphenol A (BPA), commonly used as a plasticizer in various branches of industry has a strong negative effect on living organisms. Therefore, more and more often it is replaced in production of plastics by other substances. One of them is bisphenol S (BPS). This study for the first time compares the impact of BPA and BPS on the enteric neurons using double immunofluorescence technique. It has been shown that both BPA and BPS affect the number of enteric neurons containing substance P (SP), galanin (GAL), vasoactive intestinal polypeptide (VIP), neuronal isoform of nitric oxide synthase (nNOS-a marker of nitrergic neurons) and/or vesicular acetylcholine transporter (VAChT- a marker of cholinergic neurons). The changes noted under the impact of both bisphenols are similar and consisted of an increase in the number of enteric neurons immunoreactive to all neuronal factors studied. The impact of BPS on some populations of neurons was stronger than that noted under the influence of BPA. The obtained results clearly show that BPS (similarly to BPA) administered for long time is not neutral for the enteric neurons even in relatively low doses and may be more potent than BPA for certain neuronal populations.

Cytogenetic and developmental toxicity of bisphenol A and bisphenol S in Arbacia lixula sea urchin embryos

Bisphenol S (BP-S) is one of the most important substitutes of bisphenol A (BP-A), and its environmental occurrence is predicted to intensify in the future. Both BP-A and BP-S were tested for adverse effects on early life stages of Arbacia lixula sea urchins at 0.1 up to 100 µM test concentrations, by evaluating cytogenetic and developmental toxicity endpoints. Embryonic malformations and/or mortality were scored to determine embryotoxicity (72 h post-fertilization). It has been reported in academic dataset that bisphenols concentration reached μg/L in aquatic environment of heavily polluted areas. We have chosen concentrations ranging from 0.1-100 μM in order to highlight, in particular, BP-S effects. Attention should be paid to this range of concentrations in the context of the evaluation of the toxicity and the ecological risk of BP-S as emerging pollutant. Cytogenetic toxicity was measured, using mitotic activity and chromosome aberrations score in embryos (6 h post-fertilization). Both BP-A and BP-S exposures induced embryotoxic effects from 2.5 to 100 µM test concentrations as compared to controls. Malformed embryo percentages following BP-A exposure were significantly higher than in BP-S-exposed embryos from 0.25 to 100 µM (with a ~5-fold difference). BP-A, not BP-S exhibited cytogenetic toxicity at 25 and 100 µM. Our results indicate an embryotoxic potential of bisphenols during critical periods of development with a potent rank order to BP-A vs. BP-S. Thus, we show that BP-A alternative induce similar toxic effects to BP-A with lower severity.

Maternal exposure to bisphenol S induces neuropeptide signaling dysfunction and oxidative stress in the brain, and abnormal social behaviors in zebrafish (Danio rerio) offspring

Recent studies show that bisphenol S (BPS) induces multiple adverse effects in exposed organisms; however, the maternal effects of BPS exposure remain poorly understood. Here, we expose adult female zebrafish to environmentally relevant concentrations of BPS (0, 1, 10, 30 μg/L) and 1 μg/L of 17-β-estradiol (E2) as a positive control for 60 days. Females were then paired with BPS-unexposed males and their offspring were raised in control water for 6 months. Maternal exposure to BPS was found to alter social behavior and anxiety response in a dose-specific manner in male offspring. Group preferences and social cohesion were significantly reduced by maternal exposure to 1 and 10 μg/L BPS, respectively. Additionally, maternal exposure to 1 and 30 μg/L BPS and E2 decreased offspring stress responses during the novel tank test. The impaired social behavior was associated with elevated arginine-vasotocin (AVT) level as well as with the altered expression of genes involved in AVT signaling pathway (AVT, avpr1aa) and enzymatic antioxidant genes (cat and Mn-sod) in the brain. Collectively, these results suggest that maternal exposure to environmentally relevant concentrations of BPS alters social behavior in zebrafish offspring, which is likely mediated by oxidative stress and disruption of neuropeptide signaling pathways in the brain.

Bisphenol S induces Agrp expression through GPER1 activation and alters transcription factor expression in immortalized hypothalamic neurons: A mechanism distinct from BPA-induced upregulation

The increasing prevalence of obesity around the world has brought concern upon ubiquitously present obesogenic environmental compounds, such as bisphenol A (BPA). Increasingly tightened regulations on the industrial use of BPA have prompted a transition to a structurally similar alternative, bisphenol S (BPS). BPS displays endocrine-disrupting behaviours similar to those of BPA and increases body weight, food intake and the hypothalamic expression of Agrp in vivo. However, the mechanisms behind this deleterious effect are unclear. Here, we report an increase in the mRNA level of Agrp at 4 h following BPS treatment in immortalized murine hypothalamic cell lines of embryonic and adult origin (mHypoE-41, mHypoA-59). BPS-induced changes in the expression of transcription factors and estrogen receptors that occurred concurrently with Agrp upregulation demonstrated similarities to BPA-induced changes, however, there were also changes that were unique to BPS. Specifically, while Chop, Atf3, Atf4, Atf6, Klf4, and Creb1 were upregulated and Gper1 was downregulated by both BPA and BPS, Esr1 mRNA levels were upregulated and Foxo1 and Stat3 levels remained unchanged by BPS. Finally, inhibition of GPER1 by G15 prevented BPS-mediated Agrp upregulation, independent of Atf3 and Klf4 upregulation. Overall, our results demonstrate the ability of BPS to increase Agrp mRNA expression through GPER1 signaling and to alter transcription factor expression in hypothalamic neurons, further elucidating the endocrine-disrupting potential of this alternative industrial chemical.

Bisphenol S favors hepatic steatosis development via an upregulation of liver MCT1 expression and an impairment of the mitochondrial respiratory system

Bisphenol S (BPS) is a common substitute of bisphenol A (BPA). Recent data suggest that BPS acts as an obesogenic endocrine disruptor with emerging implications in the physiopathology of metabolic syndrome. However, the effects of BPS on monocarboxylate transporters (acting as carriers for lactate, pyruvate, and ketone bodies) and the mitochondrial respiratory system in the liver remain limited. For this purpose, male Swiss mice were treated with BPS at 100 µg/kg/day for 10 weeks, in drinking water. An increase in body weight and food intake was observed with no increase in locomotor activity. Moreover, data show that BPS increases hepatic MCT1 (a key energetic fuel transporter) mRNA expression accompanied by hepatic steatosis initiation and lipid accumulation, while disrupting mitochondrial function and oxidative stress parameters. Furthermore, BPS produced a significant increase in lactate dehydrogenase and creatine kinase activities. We can suggest that BPS contributes to hepatic steatosis in mice by upregulating monocarboxylate transporters and affecting the bioenergetic status characterized by an impaired mitochondrial respiratory system. Thus, our data highlight a new mechanism putatively implicated in hepatic steatosis development during BPS-induced obesity involving lactate metabolism.

Are BPA Substitutes as Obesogenic as BPA?

Metabolic diseases, such as obesity, Type II diabetes and hepatic steatosis, are a significant public health concern affecting more than half a billion people worldwide. The prevalence of these diseases is constantly increasing in developed countries, affecting all age groups. The pathogenesis of metabolic diseases is complex and multifactorial. Inducer factors can either be genetic or linked to a sedentary lifestyle and/or consumption of high-fat and sugar diets. In 2002, a new concept of “environmental obesogens” emerged, suggesting that environmental chemicals could play an active role in the etiology of obesity. Bisphenol A (BPA), a xenoestrogen widely used in the plastic food packaging industry has been shown to affect many physiological functions and has been linked to reproductive, endocrine and metabolic disorders and cancer. Therefore, the widespread use of BPA during the last 30 years could have contributed to the increased incidence of metabolic diseases. BPA was banned in baby bottles in Canada in 2008 and in all food-oriented packaging in France from 1 January 2015. Since the BPA ban, substitutes with a similar structure and properties have been used by industrials even though their toxic potential is unknown. Bisphenol S has mainly replaced BPA in consumer products as reflected by the almost ubiquitous human exposure to this contaminant. This review focuses on the metabolic effects and targets of BPA and recent data, which suggest comparable effects of the structural analogs used as substitutes.

Regulatory and academic studies to derive reference values for human health: The case of bisphenol S

The close structural analogy of bisphenol (BP) S with BPA, a recognized endocrine-disrupting chemical and a substance of very high concern in the European Union, highlights the need to assess the extent of similarities between the two compounds and carefully scrutinize BPS potential toxicity for human health. This analysis aimed to investigate human health toxicity data regarding BPS, to find a point of departure for the derivation of human guidance values. A systematic and transparent methodology was applied to determine whether European or international reference values have been established for BPS. In the absence of such values, the scientific literature on human health effects was evaluated by focusing on human epidemiological and animal experimental studies. The results were analyzed by target organ/system: male and female reproduction, mammary gland, neurobehavior, and metabolism/obesity. Academic experimental studies were analyzed and compared to regulatory data including subchronic studies and an extended one-generation and reproduction study. In contrast to the regulatory studies, which were performed at dose levels in the mg/kg bw/day range, the academic dataset on specific target organs or systems showed adverse effects for BPS at much lower doses (0.5-10 μg/kg bw/day). A large disparity between the lowest-observed-adverse-effect levels (LOAELs) derived from regulatory and academic studies was observed for BPS, as for BPA. Toxicokinetic data on BPS from animal and human studies were also analyzed and showed a 100-fold higher oral bioavailability compared to BPA in a pig model. The similarities and differences between the two bisphenols, in particular the higher bioavailability of BPS in its active (non-conjugated) form and its potential impact on human health, are discussed. Based on the available experimental data, and for a better human protection, we propose to derive human reference values for exposure to BPS from the N(L)OAELs determined in academic studies.

Low-dose bisphenol S exposure induces hypospermatogenesis and mitochondrial dysfunction in rats: A possible implication of StAR protein

A wide variety of environmental chemicals/xenobiotics including bisphenol A (BPA) has been shown to cause male reproductive dysfunctions and infertility. Recently, bisphenol S (BPS) replaces BPA, in several products, including foodstuffs, under the BPA-free label. However, several studies have raised inquietude about the potential adverse effects of BPS. The present study was conducted to evaluate sperm parameters, biochemical parameters, mitochondrial function, and histopathological patterns after post-lactation BPS exposure at a low dose. Male rats (21 days old) were exposed to water containing BPS at 50 μg/L in drinking water for 10 weeks. Results showed no significant alteration in the gonadosomatic index (GSI) and relative reproductive organs weight. However, a significant reduction in epididymal sperm parameters (number, viability, and mobility) with morphological abnormalities were observed in the BPS group compared to control. An increase of malondialdehyde (MDA) level accompanied by antioxidant defense alteration particularly, in glutathione peroxidase activity, as well as a defective mitochondrial function were observed in testicular tissues of BPS treated rats. More importantly, in histopathological diagnosis, BPS treatment induces hypospermatogenesis and alteration in Sertoli cells. In silico docking studies illustrated BPS binds with steroidogenic acute regulatory (StAR) protein thereby affecting the transport of cholesterol into mitochondria resulting in decreased steroidogenesis. These results reflect a reprotoxic effect of BPS vould potentially lead to fertility reduction, in sexually maturity age. We highlighted that post-lactation exposure to BPS, equivalent in humans to the period covering childhood and adolescent stages, disrupt male reproduction function.

Multigenerational study of the obesogen effects of bisphenol S after a perinatal exposure in C57BL6/J mice fed a high fat diet

BACKGROUND

Bisphenol S is an endocrine disruptor exhibiting metabolic disturbances, especially following perinatal exposures. To date, no data are available on the obesogen effects of BPS in a mutligenerational issue.

OBJECTIVES

We investigated obesogen effects of BPS in a multigenerational study by focusing on body weight, adipose tissue and plasma parameters in male and female mice.

METHODS

Pregnant C57BL6/J mice were exposed to BPS (1.5 μg/kg bw/day ie a human equivalent dose of 0.12 μg/kg bw/day) by drinking water from gestational day 0 to post natal day 21. All offsprings were fed with a high fat diet during 15 weeks. Body weight was monitored weekly and fat mass was measured before euthanasia. At euthanasia, blood glucose, insuline, triglyceride, cholesterol and no esterified fatty acid plasma levels were determined and gene expressions in visceral adipose tissue were assessed. F1 males and females were mated to obtain the F2 generation. Likewise, the F2 mice were cross-bred to obtain F3. The same analyses were performed.

RESULTS

In F1 BPS induced an overweight in male mice associated to lipolysis gene expressions upregulation. In F1 females, dyslipidemia was observed. In F2, BPS exposure was associated to an increase in body weight, fat and VAT masses in males and females. Several plasma parameters were increased but with a sex related pattern (blood glucose, triglycerides and cholesterol in males and NEFA in females). We observed a down-regulation in mRNA expression of gene involved in lipogenesis and in lipolysis for females but only in the lipogenesis for males. In F3, a decrease in VAT mass and an upregulation of lipogenesis gene expression occurred only in females.

CONCLUSIONS

BPS perinatal exposure induced sex-dependent obesogen multigenerational effects, the F2 generation being the most impacted. Transgenerational disturbances persisted only in females.

Chronic exposure to bisphenol S induces oxidative stress, abnormal anxiety, and fear responses in adult zebrafish (Danio rerio)

Bisphenol S (BPS) is increasingly used in a wide range of industrial and consumer products, resulting in its ubiquitous distribution across the environment, including aquatic ecosystems. Although it is commonly known as a weak/moderate estrogenic compound, there has been a growing acknowledgment of the potential of BPS to cause toxicity by inducing oxidative stress. Oxidative stress is a major participant in the development of anxiety-like behaviors in humans and animals. Therefore, the present study was designed to examine the impact of BPS on anxiety-like behavior and fear responses in adult zebrafish and also to elucidate the possible linkage between the BPS neurotoxicity and oxidative status of the brain. To this end, adult male and female zebrafish were exposed to 0 (control), 1, 10, and 30 μg/L of BPS and 1 μg/L of 17-β-estradiol (E2) for 75 days. Following exposure, changes in anxiety and fear-related responses were evaluated by applying a novel tank test and by exposing focal fish to chemical alarm cues. Additionally, we evaluated the expression of multiple antioxidant genes in the zebrafish brain. Our results indicate that BPS, irrespective of exposure concentration, and E2 significantly decreased bottom-dwelling behavior and the latency to enter the upper water column. Furthermore, exposure to the highest concentration of BPS and E2 induced a significant decrease in fear-related responses. The impaired anxiety and reduced fear-related responses were associated with a down-regulation in the transcription of genes involved in enzymatic antioxidant defense. Taken together, our results suggest that chronic exposure to BPS impairs anxiety and fear responses in adult zebrafish, possibly by inducing oxidative stress in the brain.

Hepatic transcriptome and DNA methylation patterns following perinatal and chronic BPS exposure in male mice

Background

Bisphenol S (BPS) is a common bisphenol A (BPA) substitute, since BPA is virtually banned worldwide. However, BPS and BPA have both endocrine disrupting properties. Their effects appear mostly in adulthood following perinatal exposures. The objective of the present study was to investigate the impact of perinatal and chronic exposure to BPS at the low dose of 1.5 μg/kg body weight/day on the transcriptome and methylome of the liver in 23 weeks-old C57BL6/J male mice.

Results

This multi-omic study highlights a major impact of BPS on gene expression (374 significant deregulated genes) and Gene Set Enrichment Analysis show an enrichment focused on several biological pathways related to metabolic liver regulation. BPS exposure also induces a hypomethylation in 58.5% of the differentially methylated regions (DMR). Systematic connections were not found between gene expression and methylation profile excepted for 18 genes, including 4 genes involved in lipid metabolism pathways (Fasn, Hmgcr, Elovl6, Lpin1), which were downregulated and featured differentially methylated CpGs in their exons or introns.

Conclusions

This descriptive study shows an impact of BPS on biological pathways mainly related to an integrative disruption of metabolism (energy metabolism, detoxification, protein and steroid metabolism) and, like most high-throughput studies, contributes to the identification of potential exposure biomarkers.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07294-3.

Maternal organophosphate flame-retardant exposure alters offspring feeding, locomotor and exploratory behaviors in a sexually-dimorphic manner in mice

Increased usage of organophosphate flame retardants (OPFRs) has led to detectable levels in pregnant women and neonates, which is associated with negative neurological outcomes. Therefore, we investigated if maternal OPFR exposure altered adult offspring feeding, locomotor, and anxiety-like behaviors on a low-fat (LFD) or high-fat diet (HFD). Wild-type C57Bl/6J dams were orally dosed with vehicle (sesame oil) or an OPFR mixture (1 mg/kg combination each of tris(1,3-dichloro-2-propyl)phosphate, triphenyl phosphate and tricresyl phosphate) from gestation day 7 to postnatal day 14. After weaning, pups were fed either a LFD or HFD until 19 weeks of age. Locomotor and anxiety-like behaviors were evaluated with the open field test, elevated plus maze, and metabolic cages. Feeding behaviors and meal patterns were analyzed by a Biological Data Acquisition System. Anogenital distance was reduced in OPFR-exposed male pups, but no effect was detected on adult body weight. We observed interactions of OPFR exposure and HFD consumption on locomotor and anxiety-like behavior in males, suggesting an anxiogenic effect while reducing overall nighttime activity. We also observed an interaction of OPFR exposure and HFD on weekly food intake and feeding behaviors. OPFR-exposed males consumed more total HFD than oil-exposed males during the 72-hour trial. However, when arcuate gene expression was analyzed, OPFR exposure induced Agrp expression in females, which would suggest greater orexigenic tone. Collectively, the implications of our study are that the behavioral effects of OPFR exposure are modulated by adult HFD consumption, which may influence the metabolic and neurological consequences of maternal OPFR exposure.

A comprehensive review of the neurobehavioral effects of bisphenol S and the mechanisms of action: New insights from in vitro and in vivo models

The normal brain development and function are delicately driven by an ever-changing milieu of steroid hormones arising from fetal, placental, and maternal origins. This reliance on the neuroendocrine system sets the stage for the exquisite sensitivity of the central nervous system to the adverse effects of endocrine-disrupting chemicals (EDCs). Bisphenol A (BPA) is one of the most common EDCs which has been a particular focus of environmental concern for decades due to its widespread nature and formidable threat to human and animal health. The heightened regulatory actions and the scientific and public concern over the adverse health effects of BPA have led to its replacement with a suite of structurally similar but less known alternative chemicals. Bisphenol S (BPS) is the main substitute for BPA that is increasingly being used in a wide array of consumer and industrial products. Although it was considered to be a safe BPA alternative, mounting evidence points to the deleterious effects of BPS on a wide range of neuroendocrine functions in animals. In addition to its reproductive toxicity, recent experimental efforts indicate that BPS has a considerable potential to induce neurotoxicity and behavioral dysfunction. This review analyzes the current state of knowledge regarding the neurobehavioral effects of BPS and discusses its potential mode of actions on several aspects of the neuroendocrine system. We summarize the role of certain hormones and their signaling pathways in the regulation of brain and behavior and discuss how BPS induces neurotoxicity through interactions with these pathways. Finally, we review potential links between BPS exposure and aberrant neurobehavioral functions in animals and identify key knowledge gaps and hypotheses for future research.

Neuro-toxic and Reproductive Effects of BPA

Background:

Bisphenol A (BPA) is one of the highest volume chemicals produced worldwide. It has recognized activity as an endocrine-disrupting chemical and has suspected roles as a neurological and reproductive toxicant. It interferes in steroid signaling, induces oxidative stress, and affects gene expression epigenetically. Gestational, perinatal and neonatal exposures to BPA affect developmental processes, including brain development and gametogenesis, with consequences on brain functions, behavior, and fertility.

Methods:

This review critically analyzes recent findings on the neuro-toxic and reproductive effects of BPA (and its ana-logues), with focus on neuronal differentiation, synaptic plasticity, glia and microglia activity, cognitive functions, and the central and local control of reproduction.

Results:

BPA has potential human health hazard associated with gestational, peri- and neonatal exposure. Beginning with BPA’s disposition, this review summarizes recent findings on the neurotoxicity of BPA and its analogues, on neuronal dif-ferentiation, synaptic plasticity, neuro-inflammation, neuro-degeneration, and impairment of cognitive abilities. Furthermore, it reports the recent findings on the activity of BPA along the HPG axis, effects on the hypothalamic Gonadotropin Releas-ing Hormone (GnRH), and the associated effects on reproduction in both sexes and successful pregnancy.

Conclusion:

BPA and its analogues impair neuronal activity, HPG axis function, reproduction, and fertility. Contrasting re-sults have emerged in animal models and human. Thus, further studies are needed to better define their safety levels. This re-view offers new insights on these issues with the aim to find the “fil rouge”, if any, that characterize BPA’s mechanism of action with outcomes on neuronal function and reproduction.

Short and long-term effects of bisphenol S (BPS) exposure during pregnancy and lactation on plasma lipids, hormones, and behavior in rats

Bisphenol S (BPS) has replaced bisphenol A (BPA), a known non-persistent endocrine disrupting chemical, in several products. Considering that little is known regarding BPS effects, especially during critical windows of ontogenetic development, and that BPA, which is quite similar to BPS, is know to be transferred to the offspring via the placenta and milk, in the present study we investigated the behavioral, biochemical and endocrine profiles of Wistar rats born from dams that were BPS-exposed [groups: BPS10 (10 μg/kg/day), BPS50 (50 μg/kg/day)] during pregnancy and lactation. Due to the non-monotonic dose-response effect of bisphenol, the data of both BPS groups were directly compared with those of the controls, not to each other. Males and females were analyzed separately. At weaning, male BPS50 offspring had hypotriglyceridemia and hyperthyroxinemia, whereas BPS50 females showed higher 25(OH)D levels. At adulthood, BPS offspring of both sexes had lower food intake. BPS males showed lower visceral adiposity. BPS50 females had smaller fat droplets in brown adipocytes. BPS males showed higher anxiety and higher locomotor activity, while BPS10 females showed lower exploration. During a food challenge test at adulthood, BPS males consumed more high-fat diet at 30 min. BPS10 females initially (at 30 min) consumed more high-fat diet but, after 12 h, less of this diet was consumed. BPS50 males had hypertriglyceridemia and lower plasma T3, while BPS females showed lower plasma T4. BPS10 females had lower progesterone, whereas BPS50 females had higher plasma 25(OH)D. Maternal BPS exposure has adverse effects on the triacylglycerol, hormones levels and behavior of the progeny. Furthermore, the increased preference for the fat-enriched diet suggests an increased risk for obesity and its health consequences in the long term.

A scoping review of the health and toxicological activity of bisphenol A (BPA) structural analogues and functional alternatives

Recent studies report widespread usage or exposure to a variety of chemicals with structural or functional similarity to bisphenol A (BPA), referred to as BPA analogues or derivatives. These have been detected in foodstuffs, house dust, environmental samples, human urine or blood, and consumer products. Compared to BPA, relatively little is known about potential toxicity of these compounds. This scoping review aimed to summarize the human, animal, and mechanistic toxicity data for 24 BPA analogues of emerging interest to research and regulatory communities. PubMed was searched from March 1, 2015 to January 5, 2019 and combined with the results obtained from literature searches conducted through March 23, 2015, in The National Toxicology Program's Research Report 4 (NTP RR-04), "Biological Activity of Bisphenol A (BPA) Structural Analogues and Functional Alternatives". Study details are presented in interactive displays using Tableau Public. In total, 5748 records were screened for inclusion. One hundred sixty seven studies were included from NTP RR-04 and 175 studies were included from the updated literature search through January 2019. In total, there are 22, 117, and 221 human epidemiological, experimental animal, or in vitro studies included. The most frequently studied BPA analogues are bisphenol S (BPS), bisphenol F (4,4-BPF), and bisphenol AF (BPAF). Notable changes in the literature since 2015 include the growing body of human epidemiological studies and in vivo studies conducted in zebrafish. Numerous new endpoints were also evaluated across all three evidence streams including diabetes, obesity, and oxidative stress. However, few studies have addressed endpoints such as neurodevelopmental outcomes or impacts on the developing mammary or prostate glands, which are known to be susceptible to disruption by BPA. Further, there remains a critical need for better exposure information in order to prioritize experimental studies. Moving forward, researchers should also ensure that full dose responses are performed for all main effects in order to support hazard and risk characterization efforts. The evidence gathered here suggests that hazard and risk characterizations should expand beyond BPA in order to consider BPA structural and functional analogues.

The occurrence, potential toxicity, and toxicity mechanism of bisphenol S, a substitute of bisphenol A: A critical review of recent progress

Bisphenol S (BPS) has been introduced into the industry as a safer alternative to bisphenol A (BPA). The distribution of BPS has recently become an important issue worldwide, but investigations on the toxicity and mechanisms of BPS remain limited. A review of the literature reveals that BPS has widespread presence in environmental media, such as indoor dust, surface water, sediments, and sewage sludge. It has been detected in plants, paper products, some food items, and even in the human body. In addition, compared to BPA, BPS has a lower acute toxicity, similar or less endocrine disruption, similar neurotoxicity and immunotoxicity, and lower reproductive and developmental toxicity. The mechanisms underlying BPS toxicity may be related to the chemical properties of BPS in the human body, including interactions with estrogen receptors, and binding to DNA and some proteins, subsequently including exerting oxidative stress. However, further investigation on the potential risks of BPS to humans and its mechanisms of toxicity should be conducted to better understand and control the risks of such novel chemicals.

Long-term bisphenol S exposure induces fat accumulation in liver of adult male zebrafish (Danio rerio) and slows yolk lipid consumption in F1 offspring

Bisphenol S (BPS), as a substitute for bisphenol A, was frequently detected in human urine and blood. It has been reported that BPS could disrupt fat metabolism in vivo and vitro although mechanisms remain unclear. Additionally, there is no study that the disruptive effect of BPS on parental fat metabolism indirectly interferes with the lipid metabolism of offspring. Here, after 120-d exposure to 1, 10, 100, and 1000 μg/L BPS, the transcription level of genes involved in lipid metabolism in liver and feeding regulation of brain-gut axis, as well as the hepatic triacylglycerol (TAG) and plasma lipid levels were investigated in both male and female zebrafish. Results showed that in male liver, fatty acid synthesis and degradation were inhibited by reducing transcription levels of srebp1 and pparα, and the synthesis of TAG was significantly increased using fatty acid as a precursor by elevating agpat4 and dgat2 mRNA expression levels. As a consequence, fat accumulation and the increased TAG levels were observed in male liver, and lipid levels were also elevated in male plasma. In female liver, there was no excessive fat accumulation and BPS exposure had a non-monotonic effect on the gene expression of fasn, dagt2, and pparα. Notably, the unexposed offspring showed a large amount of yolk lipid remain at 5 days post fertilization. This study obviously demonstrated that long-term BPS exposure increases the risk of non-alcoholic fatty liver disease in male zebrafish and life-cycle exposure hazard on offspring is noteworthy.

Bisphenol S exposure affects gene expression related to intestinal glucose absorption and glucose metabolism in mice

Bisphenol S, an industrial chemical, has raised concerns for both human and ecosystem health. Yet, health hazards posed by bisphenol S (BPS) exposure remain poorly studied. Compared to all tissues, the intestine and the liver are among the most affected by environmental endocrine disruptors. The aim of this study was to investigate the molecular effect of BPS on gene expression implicated in the control of glucose metabolism in the intestine (apelin and its receptor APJ, SGLT1, GLUT2) and in the liver (glycogenolysis and/or gluconeogenesis key enzymes (glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK)) and pro-inflammatory cytokine expression (TNF-α and IL-1β)). BPS at 25, 50, and 100 μg/kg was administered to mice in water drink for 10 weeks. In the duodenum, BPS exposure reduces significantly mRNA expression of sodium glucose transporter 1 (SGLT1), glucose transporter 2 (GLUT2), apelin, and APJ mRNA. In the liver, BPS exposure increases the expression of G6Pase and PEPCK, but does not affect pro-inflammatory markers. These data suggest that alteration of apelinergic system and glucose transporters expression could contribute to a disruption of intestinal glucose absorption, and that BPS stimulates glycogenolysis and/or gluconeogenesis in the liver. Collectively, we reveal that BPS heightens the risk of metabolic syndrome.

Neurobehavioral effects of bisphenol S exposure in early life stages of zebrafish larvae (Danio rerio)

As an alternate of bisphenol A (BPA), bisphenol S (BPS) is now widely used to produce our daily consumer goods. Some studies have shown that BPS has the potential to disrupt the reproduction and glucose homeostasis. However, the impact of BPS on the nervous system remains unclear. The purpose of this study is to investigate the impact of BPS on the nervous systems of zebrafish in their early growing stages. The 96 h-LC₅₀ value of BPS to zebrafish larvae was 323 mg/L (95%CI: 308-339 mg/L). Zebrafish embryos were exposed to BPS at concentrations of 0, 0.03, 0.3 and 3.0 mg/L until 6 days postfertilization. Our results showed that 0.3 and 3.0 mg/L BPS exposure markedly decreased locomotor behavior, accompany by the increased oxidative stress, promoted apoptosis and altered retinal structure in zebrafish. In addition, the expression levels of six neurodevelopment genes (α1-tubulin, elavl3, gap43, mbp, syn2a and gfap) were downregulated after 3.0 mg/L BPS treatment. In conclusion, BPS may affect locomotor behavior and alter retinal structure in zebrafish larvae partially by increasing oxidative stress, and by suppressing the expression levels of neurodevelopment genes.

Metabolism Disrupting Chemicals and Alteration of Neuroendocrine Circuits Controlling Food Intake and Energy Metabolism

The metabolism-disrupting chemicals (MDCs) are molecules (largely belonging to the category of endocrine disrupting chemicals, EDCs) that can cause important diseases as the metabolic syndrome, obesity, Type 2 Diabetes Mellitus or fatty liver. MDCs act on fat tissue and liver, may regulate gut functions (influencing absorption), but they may also alter the hypothalamic peptidergic circuits that control food intake and energy metabolism. These circuits are normally regulated by several factors, including estrogens, therefore those EDCs that are able to bind estrogen receptors may promote metabolic changes through their action on the same hypothalamic circuits. Here, we discuss data showing how the exposure to some MDCs can alter the expression of neuropeptides within the hypothalamic circuits involved in food intake and energy metabolism. In particular, in this review we have described the effects at hypothalamic level of three known EDCs: Genistein, an isoflavone (phytoestrogen) abundant in soy-based food (a possible new not-synthetic MDC), Bisphenol A (compound involved in the manufacturing of many consumer plastic products), and Tributyltin chloride (one of the most dangerous and toxic endocrine disruptor, used in antifouling paint for boats).