Cellular, transcriptomic and methylome effects of individual and combined exposure to BPA, BPF, BPS on mouse spermatocyte GC-2 cell line

Bisphenol F (BPF) exposure impairs sperm quality and offspring development in male zebrafish

BACKGROUND

Bisphenol F (BPF), a substitute for bisphenol A (BPA), is widely used in consumer products, increasing the potential for environmental exposure. Our study investigated the reproductive effects of BPF on adult male zebrafish and explored its toxicological mechanisms, as well as its intergenerational effects.

METHODS

Adult male zebrafish were exposed to BPF concentrations of 0, 50, 500, 2500, and 5000 nM for 21 days. We evaluated sperm cell quantity and quality, hormonal markers testosterone (T) and vitellogenin (VTG), gene expression profiles related to hormone synthesis, metabolism, apoptosis, cell cycle, sexual behavior, and offspring health metrics including survival, development and locomotion.

RESULTS

BPF exposure did not significantly affect body weight or gonadal index. However, at 500 and 2500 nM, a significant reduction in sperm count was observed. BPF exposure led to decreased serum T and increased hepatic VTG levels, indicating hormonal disruption. At 50 nM, BPF initiated sperm apoptosis, and at higher doses, it disrupted sperm meiosis, affecting cell distribution. This exposure negatively impacted sperm quality, reduced offspring survival rates, and altered sperm motility in adult fish. Offspring from BPF-exposed groups showed developmental issues, including increased mortality, delayed developmental stages, abnormal tail coiling and heart rate, which correlated with paternal sperm count and quality changes, alterations in T and VTG levels, and cell cycle phase distributions.

CONCLUSIONS

Our study demonstrated that BPF exposure significantly impacted sperm quality, characterized by reduced sperm count and altered motility patterns, leading to developmental anomalies in offspring. These novel findings highlight the need for further research into BPF's reproductive and developmental toxicity, emphasizing the potential risks to aquatic ecosystems and human health. The observed effects on sperm quality, hormonal balance, and offspring development provide new insights into the reproductive toxicity profile of BPF.

The risk of prenatal bisphenol A exposure in early life neurodevelopment: Insights from epigenetic regulation

Bisphenols are mainly used as protective coatings for plastics and resin-based materials in various consumer products. Industrial producers have a high demand for bisphenol A (BPA) among all bisphenol substitutes for various consumer products. However, according to reports, prolonged exposure to BPA can cause multiple health issues, including neurodevelopmental disorders in young children. BPA exposure during pregnancy has been considered as the primary cause of increasing the risk of neurological disorders in children as their neural systems are designed to respond to any environmental changes during prenatal life. Recently, there has been an increased focus on the effects of prenatal exposure to BPA, as it has been found to alter gene expression related to epigenetic mechanisms like DNA methylation, histone modification, and microRNA expression. Based on the evidence, frequent interactions can lead to inherited changes in an individual's neural profile. In this review, we delve into the current knowledge regarding the toxicity mechanism of BPA for expecting mothers. Next, we will discuss the possible action of BPA on the epigenetic mechanism during brain development. This is especially important to portray an overview on the role of epigenetic modification caused by prenatal BPA exposure and next, give future directions for improving human health risk assessment caused by BPA exposure.

Bisphenol A: Epigenetic effects on the male reproductive system and male offspring

Bisphenol A (BPA) is a commonly used organic compound. Over the past decades, many studies have examined the mechanisms of BPA toxicity, with BPA-induced alterations in epigenetic modifications receiving considerable attention. Particularly in the male reproductive system, abnormal alterations in epigenetic markers can adversely affect reproductive function. Furthermore, these changes in epigenetic markers can be transmitted to offspring through the father. Here, we review the effects of BPA exposure on various epigenetic markers in the male reproductive system, including DNA methylation, histone modifications, and noncoding RNA, as well as associated changes in the male reproductive function. We also reviewed the effects of father's exposure to BPA on offspring epigenetic modification patterns.

Bisphenol A and selenium deficiency exposure induces pyroptosis and myogenic differentiation disorder in chicken muscle stomach

Bisphenol A (BPA), which is commonly found in the environment due to its release from the use of plastics and food overpacks, has become a major stressor for environmental sustainability and livestock and poultry farming health. Selenium (Se) deficiency causes structural damage and inflammatory responses to the digestive system and muscle tissue, and there is a potential for concurrent space-time exposure to nutritional deficiency diseases and environmental toxicants in livestock and poultry. The mechanisms of damage to chicken muscular stomach from BPA or/and Se deficiency treatment are still not known. Here, we established a chicken model of BPA (20 mg/kg) or/and Se deficiency (0.039 mg/kg) exposure, and detected histopathological changes in the muscular stomach tissue, the levels of iNOS/NO pathway, IL-6/JAK/STAT3 pathway, pyroptosis, and myogenic differentiation by H&E staining, immunofluorescence staining, real-time quantitative PCR, and western blot methods. The data revealed that BPA or Se deficiency exposure caused gaps between muscle fibers with inflammatory cell infiltration; up-regulation of the iNOS/NO pathway and IL-6/JAK/STAT3 pathway; up-regulation of NLRP3/Caspase-1-dependent pyroptosis related genes; down-regulation of muscle-forming differentiation (MyoD, MyoG, and MyHC) genes. The combination of BPA and Se deficiency was associated with higher toxic impairment than alone exposure. In conclusion, we discovered that BPA and Se deficiency caused myogastric pyroptosis and myogenic differentiation disorder. These findings provide a theoretical basis for the co-occurrence of animal nutritional deficiency diseases and environmental toxicant exposures in livestock and poultry farming, and may provide important insights into limiting the production of harmful substances.

Endocrine Disruptors and Metabolic Changes: Impact on Puberty Control

OBJECTIVE

This study aims to explore the significant impact of environmental chemicals on disease development, focusing on their role in developing metabolic and endocrine diseases. The objective is to understand how these chemicals contribute to the increasing prevalence of precocious puberty, considering various factors, including epigenetic changes, lifestyle, and emotional disturbances.

METHODS

The study employs a comprehensive review of descriptive observational studies in both human and animal models to identify a degree of causality between exposure to environmental chemicals and disease development, specifically focusing on endocrine disruption. Due to ethical constraints, direct causation studies in human subjects are not feasible; therefore, the research relies on accumulated observational data.

RESULTS

Puberty is a crucial life period with marked physiological and psychological changes. The age at which sexual characteristics develop is changing in many regions. The findings indicate a correlation between exposure to endocrine-disrupting chemicals and the early onset of puberty. These chemicals have been shown to interfere with normal hormonal processes, particularly during critical developmental stages such as adolescence. The research also highlights the interaction of these chemical exposures with other factors, including nutritional history, social and lifestyle changes, and emotional stress, which together contribute to the prevalence of precocious puberty.

CONCLUSION

Environmental chemicals significantly contribute to the development of certain metabolic and endocrine diseases, particularly in the rising incidence of precocious puberty. Although the evidence is mainly observational, it adequately justifies regulatory actions to reduce exposure risks. Furthermore, these findings highlight the urgent need for more research on the epigenetic effects of these chemicals and their wider impact on human health, especially during vital developmental periods.

Integrative analysis of DNA methylome and transcriptome reveals epigenetic regulation of bisphenols-induced cardiomyocyte hypertrophy

Cardiac hypertrophy, a kind of cardiomyopathic abnormality, might trigger heart contractile and diastolic dysfunction, and even heart failure. Currently, bisphenols (BPs) including bisphenol A (BPA), and its alternatives bisphenol AF (BPAF), bisphenol F (BPF) and bisphenol S (BPS) are ubiquitously applied in various products and potentially possess high cardiovascular risks for humans. However, the substantial experimental evidences of BPs on heart function, and their structure-related effects on cardiomyocyte hypertrophy are still urgently needed. DNA methylation, a typical epigenetics, play key roles in BPs-induced transcription dysregulation, thereby affecting human health including cardiovascular system. Thus, in this study, we performed RNA-seq and reduced representation bisulfite sequencing (RRBS) to profile the landscapes of BPs-induced cardiotoxicity and to determine the key roles of DNA methylation in the transcription. Further, the capabilities of three BPA analogues, together with BPA, in impacting heart function and changing DNA methylation and transcription were compared. We concluded that similar to BPA, BPAF, BPF and BPS exposure deteriorated heart function in a mouse model, and induced cardiomyocyte hypertrophy in a H9c2 cell line. BPAF, BPF and BPS all played BPA-like roles in both transcriptive and methylated hierarchies. Moreover, we validated the expression levels of four cardiomyocyte hypertrophy related candidate genes, Psmc1, Piptnm2, Maz and Dusp18, which were all upregulated and with DNA hypomethylation. The findings on the induction of BPA analogues on cardiomyocyte hypertrophy and DNA methylation revealed their potential detrimental risks in heart function of humans.

Combination of Bisphenol A and Its Emergent Substitute Molecules Is Related to Heart Disease and Exerts a Differential Effect on Vascular Endothelium

Plastic production, disposal, and recycling systems represent one of the higher challenges for the planet's health. Its direct consequence is the release of endocrine disruptors, such as bisphenol A (BPA), and its emerging substitute molecules, bisphenol F and S (BPF and BPS), into the environment. Consequently, bisphenols are usually present in human biological fluids. Since BPA, BPS, and BPF have structural analogies and similar hormonal activity, their combined study is urgently needed. The present manuscript studied the effect of the mixture of bisphenols (BPmix) in one of the world's largest human cohorts (NHANES cohort). Descriptive and comparative statistics, binomial and multinomial logistic regression, weighted quantile sum regression, quantile g-computation, and Bayesian kernel machine regression analysis determined a positive association between BPmix and heart disease, including confounders age, gender, BMI, ethnicity, Poverty/Income Ratio, and serum cotinine. Endothelial dysfunction is a hallmark of cardiovascular disease; thus, the average ratio of bisphenols found in humans was used to conduct murine aortic endothelial cell studies. The first results showed that BPmix had a higher effect on cell viability than BPA, enhancing its deleterious biological action. However, the flow cytometry, Western blot, and immunofluorescence assays demonstrated that BPmix induces a differential effect on cell death. While BPA exposure induces necroptosis, its combination with the proportion determined in the NHANES cohort induces apoptosis. In conclusion, the evidence suggests the need to reassess research methodologies to study endocrine disruptors more realistically.

The State of Research and Weight of Evidence on the Epigenetic Effects of Bisphenol A

Bisphenol A (BPA) is a high-production-volume chemical with numerous industrial and consumer applications. BPA is extensively used in the manufacture of polycarbonate plastics and epoxy resins. The widespread utilities of BPA include its use as internal coating for food and beverage cans, bottles, and food-packaging materials, and as a building block for countless goods of common use. BPA can be released into the environment and enter the human body at any stage during its production, or in the process of manufacture, use, or disposal of materials made from this chemical. While the general population is predominantly exposed to BPA through contaminated food and drinking water, non-dietary exposures through the respiratory system, integumentary system, and vertical transmission, as well as other routes of exposure, also exist. BPA is often classified as an endocrine-disrupting chemical as it can act as a xenoestrogen. Exposure to BPA has been associated with developmental, reproductive, cardiovascular, neurological, metabolic, or immune effects, as well as oncogenic effects. BPA can disrupt the synthesis or clearance of hormones by binding and interfering with biological receptors. BPA can also interact with key transcription factors to modulate regulation of gene expression. Over the past 17 years, an epigenetic mechanism of action for BPA has emerged. This article summarizes the current state of research on the epigenetic effects of BPA by analyzing the findings from various studies in model systems and human populations. It evaluates the weight of evidence on the ability of BPA to alter the epigenome, while also discussing the direction of future research.

N-acetylcysteine rescues meiotic arrest during spermatogenesis in mice exposed to BDE-209

Deca-bromodiphenyl ethers (BDE-209) has been widely used in electronic devices and textiles as additives to flame retardants. Growing evidence showed that BDE-209 exposure leads to poorer sperm quality and male reproductive dysfunction. However, the underlying mechanisms of BDE-209 exposure caused a decline in sperm quality remains unclear. This study aimed to evaluate the protective effects of N-acetylcysteine (NAC) on meiotic arrest in spermatocytes and decreased sperm quality in BDE-209-exposed mice. In the study, mice were treated with NAC (150 mg/kg BW) 2 h before administrated with BDE-209 (80 mg/kg BW) for 2 weeks. For the in vitro studies, spermatocyte cell line GC-2spd cells were pretreated with NAC (5 mM) 2 h before treated with BDE-209 (50 μM) for 24 h. We found that pretreatment with NAC attenuated the oxidative stress status induced by BDE-209 in vivo and in vitro. Moreover, pretreatment with NAC rescued the testicular histology impairment and decreased the testicular organ coefficient in BDE-209-exposed mice. In addition, NAC supplement partially promoted meiotic prophase and improved sperm quality in BDE-209-exposed mice. Furthermore, NAC pretreatment effectively improved DNA damage repair by recovering DMC1, RAD51, and MLH1. In conclusion, BDE-209 caused spermatogenesis dysfunction related to the meiotic arrest medicated by oxidative stress, decreasing sperm quality.

Multiple circRNAs regulated by QKI5 conjointly spongemiR-214-3p to antagonize bisphenol A-inducedspermatocyte toxicity

Although circular RNAs (circRNAs) are found to play important roles in many pathophysiological processes, the canonical theory that they act as microRNA sponges is now more and more challenged, given that most circRNAs only have few binding sites in a particular microRNA. Our previous study revealed that some up-regulated circRNAs play protective roles in bisphenol A (BPA)-induced toxicity in GC-2 germ cells. Here by CCK-8 assay, apoptosis assay, qRT-PCR and western blot analysis, we further discover that circRNAs (represented by circDcbld2, circMapk1 and circTbcld20) can cooperatively sponge miR-214-3p and then up-regulate AKT1 in ameliorating BPA-induced reproductive toxicity. They share binding sites with miR-214-3p and collectively reinforce the sponging effects. In addition, the upstream regulation mechanism, proven by bioinformatics analysis and in vitro gain- and loss-of-function study, shows that down-regulation of RNA binding protein QKI5 after BPA exposure can increase the expressions of these protective circRNAs, and thus activate the cell protective process. The QKI5-circDcbld2/circMapk1/circTblcd20-miR-214-3p-AKT1 axis ameliorates the toxic effect of BPA on GC-2 cells. Many other circRNAs up-regulated upon BPA treatment and QKI5 down-regulation also show binding sites with miR-214-3p. Thus the above axis may also be extrapolated to other circRNAs. Our results enrich the context of circRNA sponge mode and may provide new ideas in future multiple nucleic acid therapy.

Effects of bisphenol A and estradiol in adult rat testis after prepubertal and pubertal exposure

Over the past few decades, male fertility has been decreasing worldwide. Many studies attribute this outcome to endocrine disruptors exposure such as bisphenol A (BPA), which is a chemical compound used in plastics synthesis and exhibiting estrogenic activity. In order to assess how the window of exposure modulates the effects of BPA on the testis, prepubertal (15 dpp to 30 dpp) and pubertal (60 dpp to 75 dpp) male Sprague-Dawley rats were exposed to BPA (50 µg/kg bw/day), 17-β-estradiol (E2) (20 µg/kg bw/day) as a positive control, or to a combination of these compounds. For both periods of exposure, the rats were sacrificed and their testes were collected at 75 dpp. The histological analysis and the quantification of the gene expression of testis cell markers by RT-qPCR confirmed the complete spermatogenesis in all groups for both periods of exposure. However, our results suggest a deleterious effect of BPA on the blood-testis barrier in adults after pubertal exposure as BPA and BPA+E2 treatments induced a decrease in caveolin-1 and connexin-43 gene expression; which are proteins of the junctional complexes. As none of these effects were found after a prepubertal exposure, these results suggested the reversibility of BPA's effects. Caution must be taken when transposing this finding to humans and further studies are needed in this regard. However, from a regulatory perspective, this study emphasizes the importance of taking into account different periods of exposure, as they present different sensitivities to BPA exposure.

Knowledge Gap in Understanding the Steroidogenic Acute Regulatory Protein Regulation in Steroidogenesis Following Exposure to Bisphenol A and Its Analogues

The use of bisphenols has become extremely common in our daily lives. Due to the extensive toxic effects of Bisphenol A (BPA), the industry has replaced this endocrine-disrupting chemical (EDC) with its analogues, which have been proven to decrease testosterone levels via several mechanisms, including targeting the steroidogenic acute regulatory (StAR) protein. However, when exposed to BPA and its analogues, the specific mechanism that emerges to target StAR protein regulations remains uncertain. Hence, this review discusses the effects of BPA and its analogues in StAR protein regulation by targeting cAMP-PKA, PLC-PKC, EGFR-MAPK/ERK and Ca²⁺-Nur77. BPA and its analogues mainly lead to decreased LH in blood and increased ERK expression and Ca²⁺ influx, with no relationship with the StAR protein regulation in testicular steroidogenesis. Furthermore, the involvement of the cAMP-PKA, PLC-PKC, and Nur77 molecules in StAR regulation in Leydig cells exposed to BPA and its analogues remains questionable. In conclusion, although BPA and its analogues have been found to disrupt the StAR protein, the evidence in connecting the signaling pathways with the StAR regulations in testicular steroidogenesis is still lacking, and more research is needed to draw a solid conclusion.

Double-dose responses of Scenedesmus capricornus microalgae exposed to humic acid

Dissolved organic matter (DOM) has been found to attenuate the ecotoxicity of various environmental pollutants, but research on its own toxic effects in aquatic ecosystems has been very limited. Herein, the toxic effects of humic acid (HA), a represent DOM typically found in natural waters, on the freshwater alga Scenedesmus capricornus were investigated. As result, HA exerted a double-dose effect on the growth of Scenedesmus capricornus. At HA concentrations below 2.0 mgC/L, the growth of Scenedesmus capricornus was slightly promoted, as was the synthesis of chlorophyll and macromolecules in the algae. Moreover, S. capricornus can maintain its growth by secreting fulvic acid as a nutrient carbon source. However, the growth of Scenedesmus capricornus was significantly inhibited when HA was beyond 2.0 mgC/L. The main mechanisms of humic acid's toxicity were membrane damage and oxidative stress. Particularly, when the oxidative stress exceeds the algae's carrying capacity, the synthesis of EPS is greatly inhibited and HA damage results. Taken together, DOM may have both positive and negative effects on aquatic ecosystems.

Disrupted metabolic pathways and potential human diseases induced by bisphenol S

Although the toxicity of bisphenol S has been studied in some species, the global metabolic network disrupted by bisphenol S remains unclear. To this end, published datasets related to the genes, proteins, and metabolites disturbed by bisphenol S were investigated through omics methods. The dataset revealed that bisphenol S at high concentrations tended to downregulate biomolecules, while low concentrations of bisphenol S tended to enhance metabolic reactions. The results showed that exposure to bisphenol S upregulated estrogen and downregulated androgen metabolism in humans, mice, rats, and zebrafish. Fatty acid metabolism and phospholipid metabolism in mice were upregulated. Reactions in amino acid metabolism were upregulated, with the exception of the suppressive conversion of arginine to ornithine. In zebrafish, fatty acid synthesis was promoted, while nucleotide metabolism was primarily depressed through the downregulation of pyruvate 2-o-phosphotransferase. The interference in amino acid metabolism by bisphenol S could trigger Alzheimer's disease, while its disturbance of glucose metabolism was associated with type II diabetes. Disturbed glycolipid metabolism and vitamin metabolism could induce Alzheimer's disease and diabetes. These findings based on omics data provide scientific insight into the metabolic network regulated by bisphenol S and the diseases triggered by its metabolic disruption.

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

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

Bisphenol F promotes the secretion of pro-inflammatory cytokines in macrophages by enhanced glycolysis through PI3K-AKT signaling pathway

Bisphenol F (BPF) is a member of endocrine disrupting chemicals (EDCs). As a substitute of bisphenol A (BPA), BPF is widely used in various consumer products, leading to an increased risk of people's exposure. However, there are few studies on the immunotoxicity and mechanism of BPF. This study aimed to investigate the effect of BPF on the secretion of pro-inflammatory cytokines by macrophages and explore its mechanism. In our study, RAW264.7 macrophages were treated with different concentrations of BPF (0, 5, 10 and 20 μM) for 24 h. The results showed that the secretion of pro-inflammatory cytokines (IL-6, TNF-α and IL-1β) and the production of lactate were increased in a dose-dependent manner. BPFalso led to the activation of the PI3K-AKT signaling pathway. After pretreatment with glycolysis inhibitor (2-DG) and exposure to BPF (20 μM), the secretion of pro-inflammatory cytokines induced by BPF was inhibited. PI3K inhibitor (LY294002) and estrogen receptor (ER) antagonist (ICI 182,780) could also inhibit the above effects induced by BPF (20 μM). In conclusion, our results suggested that BPF can enhance glycolysis through ER mediated PI3K-AKT signaling pathway, and the enhanced glycolysis further promoted the secretion of pro-inflammatory cytokines. Our research provides basic data for future studies on bisphenol exposure and immunotoxicity.

Effects of bisphenol S and bisphenol F on human spermatozoa: An in vitro study

Bisphenol A (BPA), the main chemical monomer of epoxy resins and polycarbonate plastics, has generated concerns about its endocrine disruptor properties, along with the reported possible links with several human health disorders. Accordingly, some restrictions on its use have been recommended. Bisphenol S (BPS) and bisphenol F (BPF) are the main replacements to BPA, with which they share homologies in chemical structure. However, to date, little is known about their possible adverse effects for human reproduction. As the in vitro exposure of human spermatozoa to BPA induces oxidative/pro-apoptotic effects, the aim of the present study was to verify whether BPS and BPF could represent safer compounds for human sperm functions. The exposure of motile sperm suspensions to scalar concentrations of BPS or BPF for 4 h did not significantly reduce sperm motility (as assessed by computer-aided semen analysis) and viability. At flow cytometry, no changes in mitochondrial membrane potential, or mitochondrial generation of reactive oxygen species were detected by using the JC-1 and MitoSOX red probes, respectively. Interestingly, it nor even the combination of both BPS and BPF at the highest concentrations impaired sperm mitochondrial functions. In conclusion, BPS and BPF seem to be safer alternatives to BPA for sperm biology, as they do not affect mitochondrial functions, sperm motility and viability. These findings could help regulatory agencies to identify more secure chemicals to replace BPA in industrial production of plastics.

Oxidative stress-mediated apoptosis is involved in bisphenol S-induced reproductive toxicity in male C57BL/6 mice

The reproductive toxicity of bisphenol S (BPS) in male mammals and its possible mechanism are not clear. We investigated the effects and possible mechanism of action of BPS on adult male C57BL/6 mice. We found that exposure to 200-mg/kg BPS resulted in a significant decrease in the sperm count in the caput/corpus and cauda epididymis, significantly decreased sperm motility, and significantly increased the sperm deformity. Histological evaluation revealed that BPS exposure caused a decrease of spermatozoa in the lumen of seminiferous tubules and a reduction in the proportion of Stage VII or VIII seminiferous tubules in the BPS-treated groups. Furthermore, ultrastructure analysis revealed BPS-induced mitochondrial damage and apoptosis in spermatogenic cells. Moreover, BPS exposure-induced oxidative stress in testicular tissues. Further, dUTP-biotin nick end labeling (TUNEL) assay showed that BPS induced the apoptosis of spermatogenic cells in a dose-dependent manner. BPS also significantly upregulated cleaved caspase-8, cleaved caspase-9, cleaved caspase-3, Fas, and FasL and significantly downregulated the Bcl-2/Bax ratio. These results suggest that BPS-induced oxidative stress in the testis and spermatogenic cell apoptosis potentially impairs spermatogenesis and sperm function, which may be the mechanism of the reproductive toxicity of BPS. The Fas/FasL and mitochondrial signal pathways may be involved in BPS-induced oxidative stress-related apoptosis. These results suggest that BPS-induced oxidative stress in the testis and spermatogenic cell apoptosis potentially impairs spermatogenesis and sperm function, which may be the mechanism of the reproductive toxicity of BPS. The Fas/FasL and mitochondrial signal pathways may be involved in BPS-induced oxidative stress-related apoptosis.

Environmental pollutants exposure and male reproductive toxicity: The role of epigenetic modifications

Male fertility rates have shown a progressive decrease in recent decades. There is a growing concern about the male reproductive dysfunction caused by environmental pollutants exposure, however the underlying molecular mechanisms are still not well understood. Epigenetic modifications play a key role in the biological responses to external stressors. Therefore, this review discusses the roles of epigenetic modifications in male reproductive toxicity induced by environmental pollutants, with a particular emphasis on DNA methylation, histone modifications and miRNAs. The available literature proposed that environmental pollutants can directly or cause oxidative stress and DNA damage to induce a variety of epigenetic changes, which lead to gene dysregulation, mitochondrial dysfunction and consequent male reproductive toxicity. However, future studies focusing on more kinds of epigenetic modifications and their crosstalk as well as epidemiological data are still required to fill in the current research gaps. In addition, the intrinsic links between pollutants-mediated epigenetic regulations and male reproduction-related physiological responses deserve to be further explored.

Exposure to phthalates and bisphenol analogues among childbearing-aged women in Korea: Influencing factors and potential health risks

Phthalates and bisphenol A (BPA), widely applied in industrial and consumer products, can affect hormones associated with the human reproductive system. Because the incidence of reproductive diseases is increasing, a comprehensive exposure assessment of phthalates and bisphenol analogues (BPs) is required for childbearing-aged women. Phthalate metabolites and BPs were measured in urine samples collected from 509 childbearing-aged women (20-48 years) in Korea to investigate their current exposure status, profiles, influencing factors, and potential health risks. DEHP metabolites and BPA were the dominant compounds found, indicating that they are highly consumed in daily life. Bisphenol S (BPS), as an alternative to BPA, was detected in most urine samples. Total concentrations of phthalate metabolites and BPs ranged from 3.42 to 3570 (GM: 45.6) ng/mL and from <LOQ to 80.3 (0.91) ng/mL, respectively, which were within the ranges observed in women in previous studies. Exposure to diethyl phthalate (DEP) was significantly associated with the use of cosmetics and personal care products such as perfume, body lotion, and sunscreen. Higher ratios of urinary BPS/BPA were observed in younger and more highly educated women and in women living in urbanized regions than others. This result suggests that a shift in consumption from BPA to BPS was preferentially occurring in urbanized regions. The assessment of the cumulative risk posed by phthalates and BPs showed that they pose only a small health risk to Korean women. This study provides baseline data on exposure levels, profiles, and influencing factors for phthalates and BPs in childbearing-aged women.

Quercetin exerts bidirectional regulation effects on the efficacy of tamoxifen in estrogen receptor-positive breast cancer therapy: An in vitro study

Tamoxifen was widely applied in the therapy of estrogen receptor (ER)-positive breast cancer. With the purpose of determining the potential impacts of quercetin on its effectiveness, MCF-7 cells were selected as the in vitro model and several cellular biological behaviors (ie, cell proliferation, migration, invasion, cycle, apoptosis, and oxidative stress) were investigated. As results, quercetin showed contrasting dose-response to cellular behaviors dependent on the ROS-regulated p53 signaling pathways. In detail, quercetin promoted cell proliferation and inhibited cell apoptosis at low concentrations, whereas high-concentration resulted in apoptosis induction. Moreover, quercetin at a low concentration significantly inhibited tamoxifen-induced antiproliferation in MCF-7 cells, whereas high concentrations enhanced cell apoptosis in a synergetic manner. The real-time quantitative polymerase chain reaction analysis further implied that quercetin exerted its dual roles in tamoxifen-induced antiproliferative effects by regulated the gene expression involved in cell metastasis, cycle, and apoptosis through the ER pathways. Our present study provides a considerable support to the combination of quercetin and tamoxifen on human ER-positive breast carcinoma management.

Prenatal Exposure to Bisphenol A, E, and S Induces Transgenerational Effects on Male Reproductive Functions in Mice

This study was performed to examine the transgenerational effects of bisphenol (BP) A analogs, BPE, and BPS on male reproductive functions using mice as a model. CD-1 mice (F0) were orally exposed to control treatment (corn oil), BPA, BPE, or BPS (0.5 or 50 µg/kg/day) from gestational day 7 (the presence of vaginal plug = 1) to birth. Mice from F1 and F2 offspring were used to generate F3 males. Prenatal exposure to BPA, BPE, and BPS decreased sperm counts and/or motility and disrupted the progression of germ cell development as morphometric analyses exhibited an abnormal distribution of the stages of spermatogenesis in F3 males. Dysregulated serum levels of estradiol-17β and testosterone, as well as expression of steroidogenic enzymes in F3 adult testis were also observed. In the neonatal testis, although apoptosis and DNA damage were not affected, mRNA levels of DNA methyltransferases, histone methyltransferases, and their associated factors were increased by BP exposure. Furthermore, BP exposure induced immunoreactive expression of DNMT3A in Sertoli cells, strengthened DNMT3B, and weakened H3K9me2 and H3K9me3 in germ cells of the neonatal testis, whereas DNMT1, H3K4me3, and H3K27ac were not affected. In adult testis, stage-specific DNMT3B was altered by BP exposure, although DNMT3A, H3K9me2, and H3K9me3 expression remained stable. These results suggest that prenatal exposure to BPA, BPE, and BPS induces transgenerational effects on male reproductive functions probably due to altered epigenetic modification following disruption of DNMTs and histone marks in the neonatal and/or adult testis.

Discrepant dose responses of bisphenol A on oxidative stress and DNA methylation in grass carp ovary cells

Bisphenol A (BPA), is a common contaminant in diverse environmental compartments and its endocrine disruptive effect on living organisms has been widely reported. Further works are still required to facilitate the research on cytotoxicity and genotoxicity. In the present study, grass carp ovary (GCO) cells were used to investigate cellular oxidative stress and genomic DNA methylation under BPA exposure. Results showed that BPA exposure for 48 h arrested cell proliferation and viability. The oxidative stress was distinctly enhanced with increased reactive oxygen species (ROS), malondialdehyde level, and oxidation of reduced glutathione (GSH) in 30 μM BPA group. Furthermore, the global 5-methylcytosine (5 mC) level was elevated and showed inverted U-shaped responses to the BPA doses. Besides, one-carbon metabolism and de novo GSH synthesis were disrupted at 30 μM BPA. Current data suggested that low dose of BPA exposure could exhibit hormesis in recycling circular biosynthesis of GSH and scavenging ROS to create a relatively reductive intracellular environment, and up-regulate transcripts of methyltransferases that increased the 5 mC level in GCO cells. While high dose of BPA distinctly induced oxidative stress, elevated de novo GSH synthesis, and then attenuated transmethylation activity and decreased 5 mC level. Current study highlighted the discrepant dose responses of BPA in fish ovary cells that facilitated the understanding of pleiotropic consequences in organisms.

Low doses of Bisphenol S affect post-translational modifications of sperm proteins in male mice

BACKGROUND

Bisphenol S (BPS) is increasingly used as a replacement for bisphenol A in the manufacture of products containing polycarbonates and epoxy resins. However, further studies of BPS exposure are needed for the assessment of health risks to humans. In this study we assessed the potential harmfulness of low-dose BPS on reproduction in male mice.

METHODS

To simulate human exposure under experimental conditions, 8-week-old outbred ICR male mice received 8 weeks of drinking water containing a broad range of BPS doses [0.001, 1.0, or 100 μg/kg body weight (bw)/day, BPS1-3] or vehicle control. Mice were sacrificed and testicular tissue taken for histological analysis and protein identification by nano-liquid chromatography/mass spectrometry (MS) and sperm collected for immunodetection of acetylated lysine and phosphorylated tyrosine followed by protein characterisation using matrix-assisted laser desorption ionisation time-of-flight MS (MALDI-TOF MS).

RESULTS

The results indicate that compared to vehicle, 100 μg/kg/day exposure (BPS3) leads to 1) significant histopathology in testicular tissue; and, 2) higher levels of the histone protein γH2AX, a reliable marker of DNA damage. There were fewer mature spermatozoa in the germ layer in the experimental group treated with 1 μg/kg bw (BPS2). Finally, western blot and MALDI-TOF MS studies showed significant alterations in the sperm acetylome and phosphorylome in mice treated with the lowest exposure (0.001 μg/kg/day; BPS1), although the dose is several times lower than what has been published so far.

CONCLUSIONS

In summary, this range of qualitative and quantitative findings in young male mice raise the possibility that very low doses of BPS may impair mammalian reproduction through epigenetic modifications of sperm proteins.

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.

BPA and Nutraceuticals, Simultaneous Effects on Endocrine Functions

Background

Bisphenol A (BPA) is worldwide diffused as a monomer of epoxy resins and polycarbonate plastics and has recognized activity as Endocrine Disruptor (ED). It is capable to interfere or compete with endogenous hormones in many physiological activities thus having adverse outcomes on health. Diet highly affects health status and in addition to macronutrients, provides a large number of substances with recognized pro-heath activity, and thus called nutraceuticals.

Objective

This mini-review aims at summarizing the possible opposite and simultaneous effects of BPA and nutraceuticals on endocrine functions. The possibility that diet may represent the first instrument to preserve health status against BPA damages has been discussed.

Methods

The screening of recent literature in the field has been carried out.

Results

The therapeutic and anti-oxidant properties of many nutraceuticals may reverse the adverse health effects of BPA.

Conclusion

In vitro and in vivo studies provided evidence that nutraceuticals can preserve the health. Thus, the use of nutraceuticals can be considered a support for clinical treatment. In conclusion, dietary remediation may represent a successful therapeutic approach to maintain and preserve health against BPA damage.

Bisphenols as a Legacy Pollutant, and Their Effects on Organ Vulnerability

Bisphenols are widely used in the synthesis of polycarbonate plastics, epoxy resins, and thermal paper, which are used in manufacturing items of daily use. Packaged foods and drinks are the main sources of exposure to bisphenols. These chemicals affect humans and animals by disrupting the estrogen, androgen, progesterone, thyroid, and aryl hydrocarbon receptor functions. Bisphenols exert numerous harmful effects because of their interaction with receptors, reactive oxygen species (ROS) formation, lipid peroxidation, mitochondrial dysfunction, and cell signal alterations. Both cohort and case-control studies have determined an association between bisphenol exposure and increased risk of cardiovascular diseases, neurological disorders, reproductive abnormalities, obesity, and diabetes. Prenatal exposure to bisphenols results in developmental disorders in animals. These chemicals also affect the immune cells and play a significant role in initiating the inflammatory response. Exposure to bisphenols exhibit age, gender, and dose-dependent effects. Even at low concentrations, bisphenols exert toxicity, and hence deserve a critical assessment of their uses. Since bisphenols have a global influence on human health, the need to discover the underlying pathways involved in all disease conditions is essential. Furthermore, it is important to promote the use of alternatives for bisphenols, thereby restricting their uses.

17β-estradiol at low concentrations attenuates the efficacy of tamoxifen in breast cancer therapy

Tamoxifen has been applied widely in the treatment of estrogen receptor (ER)-positive breast cancer. The impact of low concentrations of 17β-estradiol (E2) (a pervasive environmental pollutant) on its effectiveness was studied in vitro using an MCF-7 cell line. Cell proliferation, migration, invasion, and apoptosis were studied along with cell cycle progression, reactive oxygen species generation and mitochondrial membrane potentials repression. The signaling pathways involved were identified. Typical concentrations of E2 in the environment (10^-10 to 10^-8 M) were observed to promote cell growth and protect MCF-7 cells from tamoxifen's cytotoxicity. Cell migration, invasion, cell cycle progression and apoptosis all involved in reducing tamoxifen's cytotoxicity. E2 at environmental concentrations induced PI3K/Akt and MAPK/ERK signal transduction through the estrogen receptor pathways to affect cell proliferation. Taken together, the results explain how E2 in the environment may attenuate the efficacy of tamoxifen in ER-positive breast cancer therapy. They provide considerable support for E2's adverse effects on human health and cancer management.

Food up-take and reproduction performance of Daphnia magna under the exposure of Bisphenols

Because the application of Bisphenol A (BPA) was restricted, many substitutes, such as Bisphenol F (BPF) and Bisphenol S (BPS), were developed as BPA substitutes. Therefore, environmental impacts of BPA and its substitutes on aquatic organisms should be concerned, especially their combined toxicity. In this study, the impacts of BPA, BPF, BPS and their mixture on the feeding behavior, reproduction and physiological function of daphnids were synthetically evaluated, involving the duration and mode of exposure. In short-term exposure tests, feeding rates of D. magna decreased after exposure to BPA, BPF, BPS and their mixture, while the inhibition reversed into stimulation in the recovery period. It may benefit from overcompensation of D. magna. In long-term exposure tests, the inhibition effect on the reproduction and growth of the exposed D. magna was difficult to recover, and only some experimental groups have a certain recovery. In conclusion, environmental risk of BPA, BPF, BPS and their mixture on the behavior of D. magna increased with prolonged exposure time. Moreover, relative activities of trypsin, amylase (AMS), acetylcholinesterase (AChE), carbonic anhydrase (CA), glutathione peroxidase (GPx) and super oxidase dimutase (SOD) of the exposed daphnids decreased in most treatment groups, indicating the disorder of digestive, nervous and antioxidative system of D. magna. Interestingly, inhibition of enzymes activities decreased with the increase of the exposure time, which implied the tolerance may be occurred.