Signaling pathways of bisphenol A-induced apoptosis in hippocampal neuronal cells: Role of calcium-induced reactive oxygen species, mitogen-activated protein kinases, and nuclear factor-κB

Bisphenol A exposure and neurodevelopmental disorders and problems in children under 12 years of age: A systematic review and meta-analysis

BACKGROUND

Bisphenol A (BPA) exposure may lead to neurodevelopmental disorders and problems (NDPs) in children under 12 years old. In recent years, the number of relevant studies has increased, but the evidence is inconsistent. Therefore, we conducted a comprehensive systematic review and meta-analysis to determine the association between BPA exposure and NDPs and potential gender differences.

METHODS

A literature search was conducted in eight bibliographic databases for peer-reviewed research articles published from database inception to October 11, 2024. Eligible studies were epidemiological, observational studies in children under 12 years old, which evaluated the associations between BPA of biosamples and NDPs. The converted effect sizes were synthesized using multilevel random effects meta-analysis models. Meta-regression analysis, sensitivity analysis, unmeasured confounding bias, and publication bias tests were examined to substantiate the results.

RESULTS

The search identified 1090 unique studies, 32 of which involving 15,669 participants were finally included in the meta-analysis. The meta-analysis showed that BPA exposure was associated with intellectual disability (Cohen's d = 0.14, 95 %CI = 0.06-0.22), autism spectrum disorder (ASD, Cohen's d = 0.10, 95 %CI = 0.02-0.17), attention deficit and hyperactivity disorder (ADHD, Cohen's d = 0.28, 95 %CI = 0.10-0.47), and communication disorders (Cohen's d = 0.12, 95 %CI = 0.01-0.23) in all children. Gender differences exist while BPA was associated with intellectual disability, ASD, ADHD, and motor disorders in boys, and with intellectual disability and ADHD in girls.

CONCLUSION

This study indicated that BPA exposure was associated with an increased risk of NDPs in children, particularly in boys, underscoring the importance of considering BPA exposure as a potential risk factor for children's brain health.

Disruptive multiple cell death pathways of bisphenol-A

Endocrine-disrupting chemicals (EDCs) significantly contribute to health issues by interfering with hormonal functions. Bisphenol A (BPA), a prominent EDC, is extensively utilized as a monomer and plasticizer in producing polycarbonate plastic and epoxy resins, making it one of the highest-demanded chemicals in commercial use. This is the major component used in plastic products, including bottles, containers, storage items, and food serving ware. Exposure of BPA happens through oral, respiratory, transdermal routes and eye contact. As an EDC, BPA disrupts hormonal binding, leading to various health problems, such as cancers, reproductive abnormalities, metabolic syndrome, immune dysfunction, neurological effects, cardiovascular problems, respiratory issues, and obesity. BPA mimics the hormone estrogen but exhibits a weak affinity for estrogen receptors. This weak binding affinity triggers multiple cell death pathways, including necroptosis, pyroptosis, apoptosis, ferroptosis, and autophagy, across different cell types. Numerous clinical, in-vitro, and in-vivo experiments have demonstrated that BPA exposure results in unfavorable health effects. This review highlights the mechanisms of cell death pathways initiated through BPA exposure and the associated negative health consequences. The extensive use of BPA and its frequent detection in environmental and biological models underscore the urgent need for further investigation into its effects and the development of safe alternatives. Addressing the health risks posed by BPA involves a comprehensive approach that includes reducing exposure and finding novel substitutes to lessen its detrimental impact on humans.

Ferulic acid ameliorates bisphenol A (BPA)-induced Alzheimer's disease-like pathology through Akt-ERK crosstalk pathway in male rats

OBJECTIVES

This study investigated the neuroprotective effect of ferulic acid (FA) against bisphenol A (BPA) induced Alzheimer's disease-like pathology in male rats.

METHODS

Rats were allocated into four groups, control, BPA, BPA + FA, and FA, respectively, for 40 days. Spatial working memory and recognition memory were evaluated. Moreover, the brain levels of oxidative stress biomarkers, proinflammatory cytokines, extracellular signal-regulated kinase (ERK), and phosphorylated serine/threonine protein kinase (p-Akt) were measured. We also determined the brain neuropathological protein levels, including Beta-Amyloid 1-42, total Tau (tTau), and phosphorylated Tau (pTau) proteins. Furthermore, brain levels of Acetylcholinesterase (AChE) and Beta-secretase (BACE) were assessed. Brain histological investigation and immunohistochemistry determination of glial fibrillar acidic protein (GFAP) were also performed. Moreover, docking simulation was adapted to understand the inhibitory role of FA on AChE, BACE-1, and ERK1/2.

RESULTS

Interestingly, the BPA + FA treated group showed a reversal in the cognitive impairments induced by BPA, which was associated with improved brain redox status. They also exhibited a significant decrease in brain inflammatory cytokines, ERK, and p-Akt levels. Moreover, they revealed a decline in beta-amyloid 1-42 and a significant improvement in tTau expression and pTau protein levels in the brain tissue. Further, the brain levels of AChE and BACE were substantially reduced in BPA + FA rats. The neuroprotective effect of FA was confirmed by restoring the normal architecture of brain tissue, which was associated with decreasing GFAP.

CONCLUSION

FA could be a potent neuroprotectant agent against AD with a possible prospect for its therapeutic capabilities and nutritional supplement value due to its antioxidant and antiapoptotic properties.

Evaluation of Selected Folk Herbs on the Fertility of Sprague Dawley Male Rats: Biochemical, Histological, and Molecular Investigations

Scientists have shown great interest in traditional plant extracts, particularly Lepidium sativum (LS), Origanum majorana (OM), Ferula hermonis (FH), and Eruca sativa (ES), which are frequ ently used to improve health. Recently, attention has been directed toward their influence on spermatogenesis and male fertility. Hence, the objective of this study was to explore their impact on male rats' fertility. Antioxidant activity and total phenolic content (TPC) were determined, along with the identification and quantification of phenolic compounds. Oral administration of aqueous extracts was performed individually or as a mixture (MIX) at a dose of 100 mg/kg in 28 male Sprague Dawley rats over a 60-day period. Organ weight, sex hormone concentrations, sperm parameters, oxidative stress markers, histological and morphometric analysis, and protein expression levels were investigated. OM and MIX showed the highest TPC and antioxidant activities, and MIX possessed the highest polyphenolic constituents. Elevated serum testosterone, epididymal sperm concentration, testes glutathione levels, and histomorphometric parameters were manifested in all groups, especially in MIX. MIX group also displayed elevated levels of vimentin, protein kinase B, and mTOR expression in the testes, complemented by declined expression of Phosphatase and Tensin Homolog (PTEN). In conclusion, these findings propose that these extracts, especially MIX followed by OM, enhance fertility by stimulating spermatogenesis.

Tetra aniline-based polymers ameliorate BPA-induced cardiotoxicity in Sprague Dawley rats, in silico and in vivo analysis

AIMS

Bisphenol A (BPA), xenoestrogen, is an environmental toxicant, that generates oxidative stress leading to cardiotoxicity. The oxidative stress can be neutralized by natural and synthetic antioxidants. The present study elucidates the highly selective antioxidative potential of synthetic tetra aniline polymers Es-37 and L-37 against Bisphenol A-induced cardiac cellular impairments and the role of miRNA-15a-5p in the regulation of different apoptotic proteins.

MATERIALS AND METHODS

The molecular docking of L-37 and Es-37 with three proteins (p53, Cytochrome c, and Bcl-2) were performed. The dose of 1 mg/kg BW of BPA, 1 mg/kg BW Es-37 and L-37 and 50 mg/kg BW N-acetyl cysteine (NAC) was administered to Sprague Dawley rats. The miRNA and target gene expression were confirmed by qRt-PCR and Immunoblotting.

KEY FINDINGS

In our results, BPA administration significantly elevated the reactive oxygen species (ROS), p53, cytochrome c, and particularly miRNA-15a-5p expression; however: these changes were notably reversed by Es-37 and L-37 treatment. Additionally, molecular docking of synthetic polymers validated that L-37 has a greater binding affinity with the target proteins compared to Es-37, with the highest binding values reported for the enzymatic protein cytochrome c.

SIGNIFICANCE

These results suggest that both synthetic polymers Es-37 and L-37 have the potential to scavenge free radicals, boost-up antioxidant enzyme activities, and avert (BPA-induced) toxicity, thus, may serve as cardioprotective agents. Moreover, this study first time proposes that miRNA-15a-5p overexpression is associated with oxidative stress and coincides with BPA induced cardiotoxicity, thus may serve as potential therapeutic target in future.

Bisphenol A and Its Emergent Substitutes: State of the Art of the Impact of These Plasticizers on Oxidative Stress and Its Role in Vascular Dysfunction

The "One Health approach" has evidenced the significant impact of xenobiotic exposure to health, and humans are a relevant target for their toxic effects. Bisphenol A (BPA) exerts a ubiquitous exposure source in all ecosystems. Given its endocrine-disrupting and harmful consequences on health, several countries have enforced new regulations to reduce exposure to BPA. Cardiovascular diseases (CVDs) are complex conditions that lead to higher mortality worldwide, where family history, lifestyle, and environmental factors, like BPA exposure, have a remarkable contribution. This chemical compound is the most widely used in plastic and epoxy resin manufacturing and has been associated with effects on human health. Therefore, new-generation bisphenols (NGBs) are replacing BPA use, arguing that they do not harm health. Nonetheless, the knowledge about whether NGBs are secure options is scanty. Although BPA's effects on several organs and systems have been documented, the role of BPA and NGBs in CVDs has yet to be explored. This review's goals are focused on the processes of endothelial activation (EA)-endothelial dysfunction (ED), a cornerstone of CVDs development, bisphenols' (BPs) effects on these processes through oxidant and antioxidant system alteration. Despite the scarce evidence on pro-oxidant effects associated with NGBs, our review demonstrated a comparable harmful effect on BPA. The results from the present review suggest that the biological mechanisms to explain BPs cardiotoxic effects are the oxidant stress ↔ inflammatory response ↔ EA ↔ ED → atherosclerotic plate → coagulation promotion. Other effects contributing to CVD development include altered lipid metabolism, ionic channels, and the activation of different intracellular pathways, which contribute to ED perpetuation in a concerted manner.

Polyphenols Regulate the Activity of Endocrine-Disrupting Chemicals, Having Both Positive and Negative Effects

Endocrine-disrupting chemicals (EDCs) are chemical substances that can interfere with any hormone action. They are categorized according to origin and use, such as industrial chemicals like polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs), plastics like bisphenol A (BPA), plasticizers like phthalates, pesticides like dichlorodiphenyltrichloroethane (DDT), fungicides like vinclozolin, and pharmaceuticals like diethylstilbestrol (DES). Natural EDCs, such as phytoestrogens, are present in the diet of both humans and animals. Polyphenols are a large group of natural compounds derived from plants and are found in beverages and food. They are grouped based on their chemical structure into flavonoids and nonflavonoids and are reported to have many beneficial effects on health, including, but not limited to, anticancer, antioxidant, and anti-inflammatory effects. Moreover, polyphenols have both pro- and antioxidant characteristics, and due to their antioxidant and anti-inflammatory potential, they presumably have a protective effect against damage induced by EDCs. However, polyphenols may act as EDCs. In this review, we report that polyphenols regulate the activity of EDCs, having both positive and negative effects. Hence, a better understanding of the associations between EDCs and polyphenols will allow the establishment of improved approaches to protect human health from EDCs.

Prenatal low-dose Bisphenol A exposure impacts cortical development via cAMP-PKA-CREB pathway in offspring

Bisphenol A (BPA) is a widely used plasticizer known to cause various disorders. Despite a global reduction in the use of BPA-containing products, prenatal exposure to low-dose BPA, even those below established safety limits, has been linked to neurological and behavioral deficits in childhood. The precise mechanisms underlying these effects remain unclear. In the present study, we observed a significant increase in the number of cortical neurons in offspring born to dams exposed to low-dose BPA during pregnancy. We also found that this prenatal exposure to low-dose BPA led to increased proliferation but reduced migration of cortical neurons. Transcriptomic analysis via RNA sequencing revealed an aberrant activation of the cAMP-PKA-CREB pathway in offspring exposed to BPA. The use of H89, a selective PKA inhibitor, effectively rescued the deficits in both proliferation and migration of cortical neurons. Furthermore, offspring from dams exposed to low-dose BPA exhibited manic-like behaviors, including hyperactivity, anti-depressant-like responses, and reduced anxiety. While H89 normalized hyperactivity, it didn't affect the other behavioral changes. These results suggest that the overactivation of PKA plays a causative role in BPA-induced changes in neuronal development. Our data also indicate that manic-like behaviors induced by prenatal low-dose BPA exposure may be influenced by both altered neuronal development and abnormal PKA signaling in adulthood.

Bisphenol A and its structural analogues exhibit differential potential to induce mitochondrial dysfunction and apoptosis in human granulosa cells

Bisphenol A (BPA) is an endocrine disruptor strongly associated with ovarian dysfunction. BPA is being substituted by structurally similar chemicals, such as bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF). However, the toxicity of these analogues in female reproduction remains largely unknown. This study evaluated the effects of BPA and its analogues BPS, BPF, and BPAF on the mitochondrial mass and function, oxidative stress, and their potential to induce apoptosis of human granulosa cells (KGN cells). BPA and its analogues, especially BPA and BPAF, significantly decreased mitochondrial activity and cell viability. The potential of bisphenols to reduce mitochondrial mass and function differed in the following order: BPAF > BPA > BPF > BPS. Flow cytometry revealed that exposure to bisphenols significantly increased mitochondrial ROS levels and increased mitochondrial Ca2+ levels. Thus, bisphenols exposure causes mitochondrial stress in KGN cells. At the same time, bisphenols exposure significantly induced apoptosis. These results thus emphasize the toxicity of these bisphenols to cells. Our study suggests the action mechanism of BPA and its analogues in damage caused to ovarian granulosa cells. Additionally, these novel analogues may be regrettable substitutes, and the biological effects and potential risks of BPA alternatives must be evaluated.

Application of the Key Characteristics of Carcinogens to Bisphenol A

The ten key characteristics (KCs) of carcinogens are based on characteristics of known human carcinogens and encompass many types of endpoints. We propose that an objective review of the large amount of cancer mechanistic evidence for the chemical bisphenol A (BPA) can be achieved through use of these KCs. A search on metabolic and mechanistic data relevant to the carcinogenicity of BPA was conducted and web-based software tools were used to screen and organize the results. We applied the KCs to systematically identify, organize, and summarize mechanistic information for BPA, and to bring relevant carcinogenic mechanisms into focus. For some KCs with very large data sets, we utilized reviews focused on specific endpoints. Over 3000 studies for BPA from various data streams (exposed humans, animals, in vitro and cell-free systems) were identified. Mechanistic data relevant to each of the ten KCs were identified, with receptor-mediated effects, epigenetic alterations, oxidative stress, and cell proliferation being especially data rich. Reactive and bioactive metabolites are also associated with a number of KCs. This review demonstrates how the KCs can be applied to evaluate mechanistic data, especially for data-rich chemicals. While individual entities may have different approaches for the incorporation of mechanistic data in cancer hazard identification, the KCs provide a practical framework for conducting an objective examination of the available mechanistic data without a priori assumptions on mode of action. This analysis of the mechanistic data available for BPA suggests multiple and inter-connected mechanisms through which this chemical can act.

Potential involvement of ferroptosis in BPA-induced neurotoxicity: An in vitro study

BACKGROUND

Ferroptosis is a newly recognized cell death pathway having distinct characteristics compared to traditional cell death pathways such as apoptosis, necroptosis, or autophagy. However, the potential involvement of ferroptosis in bisphenol A (BPA)-induced neurotoxicity has not been well explored so far. In present study, we analyzed the relationship between ferroptosis and BPA-induced neurotoxicity.

METHODS

In this study, a human neuroblastoma cell line, SH-SY5Y, was treated with BPA, ferrostatin-1 (FS-1, ferroptosis inhibitor) and RSL-3 (ferroptosis inducer). The cell viability was measured using MTT assay. Additionally, the levels of lipid peroxidation, total iron content, reactive oxygen species (ROS) generation, and nitrite content were measured to evaluate the key markers of ferroptosis. To further confirm the involvement of ferroptosis in BPA-induced neurotoxicity, other ferroptosis markers such as glutathione peroxidase (GPx) activity, total glutathione contents and antioxidant parameters were also evaluated.

RESULTS

The cell viability of SH-SY5Y cells was down-regulated by BPA treatment in a concentration-dependent manner, the cell viability at 0.1 µM concentration was 97.63% whereas at highest BPA concentration i.e. 10 µM, the cell viability was 86.05% (p < 0.0001). Also the antioxidant parameters including catalase and superoxide dismutase activity of neuronal cells were down-regulated upon BPA exposure. However, the levels of lipid peroxidation, total iron, reactive oxygen species, and nitrite contents were increased in a concentration-dependent manner which could be rescued by FS-1 and exacerbated by RSL-3. The total iron in SH-SY5Y cells at 0.1 µM concentration was found to be 1.2 fold (p < 0.05) of control and at highest BPA concentration total iron was about 1.41 fold (p < 0.001) of control.

CONCLUSIONS

The present study indicated that, ferroptosis plays an important role in the progression of BPA-induced neurotoxicity, and ferroptosis may become a novel target in the treatment of various neurological disorders.

Isosorbide, a versatile green chemical: Elucidating its ADME properties for safe use

Isosorbide, an environmentally friendly and renewable substance, finds extensive application in diverse fields, such as a bisphenol A substitute, polymers, functional materials, organic solvents, fuels, and pharmaceuticals. Despite its increasing interest and widespread usage, there remains a notable absence of available reports regarding its absorption, distribution, metabolism, and excretion (ADME) properties. This study endeavors to investigate the ADME characteristics of isosorbide in rats. Isosorbide levels in biological samples were quantified based on the analytical method using gas chromatography-mass spectrometry (GC-MS). Following administration, isosorbide exhibited rapid absorption and elimination, with a bioavailability of 96.1%. The metabolic stability assay indicated that isosorbide remained stable during metabolism. The majority of absorbed isosorbide was promptly excreted, with urinary excretion as the primary route. This study furnishes valuable insights into the ADME of isosorbide, contributing to its safety assessment and fostering its continued application across various domains.

Potential neuroprotective effect of nanomicellar curcumin on learning and memory functions following subacute exposure to bisphenol A in adult male rats

Bisphenol A (BPA) is an endocrine-disrupting chemical commonly utilized in the manufacture of plastics, which may cause damage to brain tissue. Curcumin is a phytochemical with protective effects against neurological and mental diseases. The purpose of this research was to evaluate whether nanomicellar curcumin (NmCur) might protect rats against BPA-induced learning and memory deficits. After determining the proper dose of BPA, the animals were randomly divided into 8 groups (8 rats in each group) receiving dextrose 5% (as vehicle of NmCur) (Dex), sesame oil (as vehicle of BPA) (Sea), Sea plus Dex, NmCur (50 mg/kg), BPA (50 mg/kg), and 50 mg/kg BPA plus 10, 25, and 50 mg/kg NmCur groups, respectively. Behavioral tests performed using passive avoidance training (PAT), open-field (OF), and Morris water maze (MWM) tests. The expression of oxidative stress markers, proinflammatory cytokines, oxidative stress-scavenging enzymes, glutamate receptors, and MAPK and memory-related proteins was measured in rat hippocampus and cortical tissues. BPA up-regulated ROS, MDA, TNF-α, IL-6, IL-1β, SOD, GST, p-P38, and p-JNK levels; however, it down-regulated GSH, GPx, GR, CAT, p-AKT, p-ERK1/2, p-NR1, p-NR2A, p-NR2B, p-GluA1, p-CREB, and BDNF levels. BPA decreased step-through latency (STL) and peripheral and total, but not central, locomotor activity. It increased the time to find the hidden platform, the mean of escape latency time, and the traveled distance in the target quadrant, but decreased the time spent in the target quadrant. The combination of BPA (50 mg/kg) and NmCur (25 and 50 mg/kg) reversed all of BPA's adverse effects. Therefore, NmCur exhibited neuroprotective effects against subacute BPA-caused learning and memory impairment.

Endocrine disrupting chemicals in indoor dust: A review of temporal and spatial trends, and human exposure

Several chemicals with widespread consumer uses have been identified as endocrine-disrupting chemicals (EDCs), with a potential risk to humans. The occurrence in indoor dust and resulting human exposure have been reviewed for six groups of known and suspected EDCs, including phthalates and non-phthalate plasticizers, flame retardants, bisphenols, per- and polyfluoroalkyl substances (PFAS), biocides and personal care product additives (PCPs). Some banned or restricted EDCs, such as polybrominated diphenyl ethers (PBDEs), di-(2-ethylhexyl) phthalate (DEHP), bisphenol A (BPA), perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), are still widely detected in indoor dust in most countries, even as the predominating compounds of their group, but generally with decreasing trends. Meanwhile, alternatives that are also potential EDCs, such as bisphenol S (BPS), bisphenol F (BPF), decabromodiphenyl ethane (DBDPE) and organophosphate flame retardants (OPFRs), and PFAS precursors, such as fluorotelomer alcohols, have been detected in indoor dust with increasing frequencies and concentrations. Associations between some known and suspected EDCs, such as phthalate and non-phthalate plasticizers, FRs and BPs, in indoor dust and paired human samples indicate indoor dust as an important human exposure pathway. Although the estimated daily intake (EDI) of most of the investigated compounds was mostly below reference values, the co-exposure to a multitude of known or suspected EDCs requires a better understanding of mixture effects.

Continuous and discontinuous multi-generational disturbances of tetrabromobisphenol A on longevity in Caenorhabditis elegans

Tetrabromobisphenol A (TBBPA) is one of the most prevalently used brominated flame retardants. Due to its persistence, it is predominantly found in environmental matrices and has the potential to generate multi-generational toxicity. However, knowledge of its adaptive response or long-term residual effect in multi-generations, and molecular mechanisms remain understudied. In the current study, the model animal nematode Caenorhabditis elegans (C. elegans) was exposed to TBBPA at environmentally realistic concentrations (0.1-1000 μg L^-1) for four consecutive generations (G₀ to G₃). Degenerative age-related multiple endpoints including lifespan, locomotion behaviors, growth, reproduction, oxidative stress-related biochemical responses, cell apoptosis, and stress related gene expressions were assessed in the continuous exposure generations (G₀ and G₃) and the discontinuously exposed generations (T₃ and T'₃). The results showed that changes in degenerative age-related response monitored four generations varied in direction and magnitude depending on the TBBPA concentrations, and the response intensify ranked as G₀ > T'₃/G₃ > T₃. TBBPA at 1 μg L^-1 dosage was detected as the lowest observed effect concentration in multi-biomarkers. The underlying mechanism of aging phenotypes was that reactive oxygen species accumulation led to cell apoptosis regulated by gene ape-1, and confirmed catalase enzyme and superoxide dismutase activity played a crucial role in the detoxification process of TBBPA at the molecular level. This study provided insights into the underlying mechanism of TBBPA-interfered longevity and its environmental multi-generational potential risks.

High cytotoxicity of a degraded TBBPA, dibromobisphenol A, through apoptotic and necrosis pathways

Halogenated flame retardants comprising bisphenol A (BPA) derivatives, such as tetrabromobisphenol A (TBBPA), have been studied their adverse effects on human health. However, despite the fact that these halogenated BPAs are easily degraded in the environment, the risks to living organisms due to these degraded products have mostly been overlooked. To evaluate the potential toxicity of degraded TBBPAs and related compounds, we examined the cytotoxicity of halogenated bisphenol A derivatives possessing one to four halogen atoms in vitro. The results indicated that the degraded TBBPA derivatives exhibited strong cytotoxicity against HeLa cells than TBBPA. Interestingly, the di-halogenated BPA derivatives possessing two halogen atoms exhibited the strongest cytotoxicity among tested compounds. In addition, a lactate dehydrogenase release assay, fluorescence spectroscopy and flow cytometry results indicated that dibromo-BPA and diiodo-BPA induced both apoptotic and necrotic cell death by damaging the cell membranes of HeLa cells. Moreover, Escherichia coli growth was inhibited in the presence of dehalogenated TBBPA and related compounds. These findings suggest that halogenated BPA derivatives that leak from various flame-retardant-containing products require strict monitoring, as not only TBBPA but also its degraded products in environment can exert adverse effects to human health.

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.

Multi-omics approaches for remediation of bisphenol A: Toxicity, risk analysis, road blocks and research perspectives

In this "plastic era" with the increased use of plastic in day today's life the accumulation of its degraded products like microplastics or plastic additives such as Bisphenol A(BPA) is also increasing. BPA is an endocrine-disrupting chemical used as a plasticizing agent in clear plastic, building materials, coatings, and epoxy resin. Several enzymes including laccases and lipases have been studied for the reduction of BPA toxicity. Over the decades of encountering these toxicants, microorganisms have evolved to degrade different classes of plastic additives. Since the degradation of BPA is a long process thus meta-omics approaches have been employed to identify the active microbiota and microbial dynamics involved in the mitigation of BPA. It is also necessary to investigate the impact of processing activities on transit of BPA in food items and to limit its entrance in food world. This review summarizes a comprehensive overview on BPA sources, toxicity, bio-based mitigation approaches along with a deeper understanding of multi-omics approaches for its reduction and risk analysis. Knowledge gaps and opportunities have been comprehensively compiled that would aid the state-of-the-art information in the available literature for the researchers to further address this issue.

Developmental and Reproductive Impacts of Four Bisphenols in Daphnia magna

Bisphenol A (BPA) is a typical endocrine-disrupting chemical (EDC) used worldwide. Considering its adverse effects, BPA has been banned or strictly restricted in some nations, and many analogs have been introduced to the market. In this study, we selected three representative substitutes, BPS, BPF, and BPAF, along with BPA, to assess the developmental and reproductive effects on Daphnia magna. The F0 generation was exposed to bisphenols (BPs) at an environmentally relevant concentration (100 μg/L) for 21 d; then the embryo spawn at day 21 was collected. Behavior traits, the activity of antioxidant enzymes, and gene transcription were evaluated at three developmental stages (days 7, 14, and 21). Notably, body length, heart rate, and thoracic limb beating were significantly decreased, and D. magna behaved more sluggishly in the exposed group. Moreover, exposure to BPs significantly increased the antioxidant enzymatic activities, which indicated that BPs activated the antioxidant defense system. Additionally, gene expression indicated intergenerational effects in larvae, particularly in the BPAF group. In conclusion, BPA analogs such as BPF and BPAF showed similar or stronger reproductive and developmental toxicity than BPA in D. magna. These findings collectively deepen our understanding of the toxicity of BPA analogs and provide empirical evidence for screening safe alternatives to BPA.

Curcumin ameliorated low dose-Bisphenol A induced gastric toxicity in adult albino rats

Bisphenol A (BPA) is one of the most common worldwide chemicals involved in the industry of polycarbonate plastics, medical devices, and pharmaceuticals. Forty three-month-old albino rats were randomly classified into four groups. Group Ӏ received a daily corn oil dose (5 mL/kg/ body weight, BW) through a gastric tube for one month, Group ӀӀ received a daily dose of Curcumin (200 mg/kg body weight (B.W.) through a gastric tube for one month, Group ӀӀӀ received a daily dose of BPA (0.5 μg/kg B.W.) through a gastric tube for one month and Group ӀV received concomitant daily doses of Bisphenol A and Curcumin as the regimen described in groups ӀӀ and ӀӀӀ. The rats were sacrificed, and glandular portion of stomach was dissected and processed for light, immunohistochemical and ultrastructural study. BPA induced destructed gastric glands, dilated congested blood vessels, submucosal oedema, decreased PAS-positive reactivity, increased collagen fibres deposition, decrease in the positive BCL2 immunoexpression, increased positive PCNA immunoexpression, reduction in the gastric mucosal height and destructive changes in the enteroendocrine, chief and parietal cells. Curcumin coadministration provoked an obvious improvement in the gastric structure. BPA exposure has toxic effects on the glandular portion of the stomach in rats. Otherwise, Curcumin coadministration has exhibited protective impact on the architecture of the stomach.

Inflammatory cytokines as key players of apoptosis induced by environmental estrogens in the ovary

Natural and synthetic environmental estrogens (EEs), interfering with the physiological functions of the body's estrogens, are widespread and are rising much concern for their possible deleterious effects on human and animal health, in particular on reproduction. In fact, increasing evidence indicate that EEs can be responsible for a variety of disfunctions of the reproductive system especially in females such as premature ovarian insufficiency (POI). Because of their great structural diversity, the modes of action of EEs are controversial. One important way through which EEs exert their effects on reproduction is the induction of apoptosis in the ovary. In general, EEs can exert pro-and anti-apoptotic effects by agonizing or antagonizing numerous estrogen-dependent signaling pathways. In the present work, results concerning apoptotic pathways and diseases induced by representative EEs (such as zearalenone, bisphenol A and di-2-ethylhexyl phthalate), in ovaries throughout development are presented into an integrated network. By reviewing and elaborating these studies, we propose inflammatory factors, centered on the production of tumor necrosis factor (TNF), as a major cause of the induction of apoptosis by EEs in the mammalian ovary. As a consequence, potential strategies to prevent such EE effect are suggested.

Comparative Neurodevelopment Effects of Bisphenol A and Bisphenol F on Rat Fetal Neural Stem Cell Models

Bisphenol A (BPA) is considered as one of the most extensively synthesized and used chemicals for industrial and consumer products. Previous investigations have established that exposure to BPA has been linked to developmental, reproductive, cardiovascular, immune, and metabolic effects. Several jurisdictions have imposed restrictions and/or have banned the use of BPA in packaging material and other consumer goods. Hence, manufacturers have replaced BPA with its analogues that have a similar chemical structure. Some of these analogues have shown similar endocrine effects as BPA, while others have not been assessed. In this investigation, we compared the neurodevelopmental effects of BPA and its major replacement Bisphenol F (BPF) on rat fetal neural stem cells (rNSCs). rNSCs were exposed to cell-specific differentiation media with non-cytotoxic doses of BPA or BPF at the range of 0.05 M to 100 M concentrations and measured the degree of cell proliferation, differentiation, and morphometric parameters. Both of these compounds increased cell proliferation and impacted the differentiation rates of oligodendrocytes and neurons, in a concentration-dependent manner. Further, there were concentration-dependent decreases in the maturation of oligodendrocytes and neurons, with a concomitant increase in immature oligodendrocytes and neurons. In contrast, neither BPA nor BPF had any overall effect on cellular proliferation or the cytotoxicity of astrocytes. However, there was a concentration-dependent increase in astrocyte differentiation and morphological changes. Morphometric analysis for the astrocytes, oligodendrocytes, and neurons showed a reduction in the arborization. These data show that fetal rNSCs exposed to either BPA or BPF lead to comparable changes in the cellular differentiation, proliferation, and arborization processes.

Bisphenol A and Bisphenol S Oxidative Effects in Sheep Red Blood Cells: An In Vitro Study

Bisphenols (BPs) are plastic components widely used worldwide and occurring in the environment. Exposure to these compounds is known to be harmful for animals and humans at different levels. The aim of this study was to evaluate and compare the oxidative effects of bisphenol A (BPA) and bisphenol S (BPS) in sheep. Reactive oxygen species (ROS) production and correlated structural alterations in sheep erythrocytes were investigated in vitro. Blood samples from four ewes were collected at fasting from the jugular vein using vacuum collection tubes containing EDTA. For ROS assay in erythrocytes, blood was properly diluted and BPA or BPS was added to obtain final bisphenol concentrations in the range between 1 and 300 μM. 2′,7′-Dichlorodihydrofluorescein diacetate (H2DCF-DA) 3 μM was added to the samples, and fluorescence was read in four replicates using a microplate reader. To evaluate erythrocyte shape, blood smears of blood treated with the different concentrations of BPS and BPA were prepared. A significant increase in ROS production was observed when concentrations of BPS and BPA increased from 1 to 100 μM (p < 0.05). At the higher concentrations of the two studied BPs (300 μM of BPS and 200-300 μM of BPA), a ROS decrease was observed when compared to the control group (p < 0.01). Erythrocytes' shape alterations were observed in cells treated with BPS and BPA 200-300 μM 4 hours after the beginning of the treatment. This study confirms that BPA and BPS exhibit oxidative effects on sheep erythrocytes. At higher concentrations, BPA was able to modify erythrocytes' shape, while BPS altered their membrane as a sign of a protein clustering that could lead to eryptosis. These BPs' effects are consequent to intracellular ROS increase.

Roles of ERK/Akt signals in mitochondria-dependent and endoplasmic reticulum stress-triggered neuronal cell apoptosis induced by 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene, a major active metabolite of bisphenol A

Bisphenol A (BPA) is recognized as a harmful pollutant in the worldwide. Growing studies have reported that BPA can cause adverse effects and diseases in human, and link to a potential risk factor for development of neurodegenerative diseases (NDs). 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), which generated in the mammalian liver after BPA exposure, is a major active metabolite of BPA. MBP has been suggested to exert greater toxicity than BPA. However, the molecular mechanism of MBP on the neuronal cytotoxicity remains unclear. In this study, MBP exposure significantly reduced Neuro-2a cell viability and induced apoptotic events that MBP (5-15 μM) exhibited greater neuronal cytotoxicity than BPA (50-100 μM). The mitochondria-dependent apoptotic signals including the decrease in mitochondrial membrane potential (MMP) and the increase in cytosolic apoptosis-induced factor (AIF), cytochrome c release, and Bax protein expression were involved in MBP (10 μM)-induced Neuro-2a cell death. Exposure of Neuro-2a cells to MBP (10 μM) also triggered endoplasmic reticulum (ER) stress through the induction of several key molecules including glucose-regulated protein (GRP)78, C/EBP homologous protein (CHOP), X-box binding protein (XBP)-1, protein kinase R-like ER kinase (PERK), eukaryotic initiation factor 2α (eIF2α), inositol-requiring enzyme(IRE)-1, activation transcription factor(AFT)4 and ATF6, and caspase-12. Pretreatment with 4-PBA (an ER stress inhibitor) and specific siRNAs for GRP78, CHOP, and XBP-1 significantly suppressed the expression of these ER stress-related proteins and the activation of caspase-12/-3/-7 in MBP-exposed Neuro-2a cells. Furthermore, MBP (10 μM) exposure dramatically increased the activation of extracellular regulated protein (ERK)1/2 and decreased Akt phosphorylation. Pretreatment with PD98059 (an ERK1/2 inhibitor) and transfection with the overexpression of activation of Akt1 (myr-Akt1) effectively suppressed MBP-induced apoptotic and ER stress-related signals. Collectively, these results demonstrate that MBP exposure exerts neuronal cytotoxicity via the interplay of ERK activation and Akt inactivation-regulated mitochondria-dependent and ER stress-triggered apoptotic pathway, which ultimately leads to neuronal cell death.

Bisphenol A(BPA), BPS and BPB-induced oxidative stress and apoptosis mediated by mitochondria in human neuroblastoma cell lines

The analogues of biphenol A (BPA), including bisphenol S (BPS) and bisphenol B (BPB), are commonly used to replace the application of BPA in containers and wrappers of daily life. However, their safeties are questioned due to their similar chemical structure and possible physiological effects as BPA. To investigate the neurotoxic effects of BPA, BPS, and BPB as well as their underlying mechanism, IMR-32 cell line from male and SK-N-SH cell line from female were exposed respectively to BPA, BPS and BPB with concentrations of 1 nM, 10 nM, 100 nM, 1 μM, 10 μM, and 100 μM for 24 h. Additionally, 24 h exposure of BPA combining epigallocatechin gallate (EGCG) (4 μM and 8 μM for IMR-32 and SK-N-SH respectively) were conducted. Results demonstrated that BPs exposure could promote reactive oxygen species production and increase level of malondialdehyde (MDA) while decrease levels of superoxide dismutase (SOD). Intensive study revealed that after exposure to BPA mitochondrial membrane potential (MMP) dropped down and the protein expression levels of Bak-1, Bax, cytochrome c and Caspase-3 were up-regulated but Bcl-2 were down-regulated significantly. Moreover, apoptosis rate was raised and cell activity declined remarkably in the neuroblastoma cells. All the effects induced by BPA could be alleviated by the adding of EGCG, which similar alleviations could be inferred in IMR-32 and SK-N-SH cells induced by BPS and BPB. Furthermore, BPS showed lower neurotoxic effects compared to BPA and BPB. Interestingly, the neurotoxic effects of BPA on IMR-32 cells were significantly higher than those on SK-N-SH cells. In conclusion, the results suggested that BPA, BPS and BPB could induce oxidative stress and apoptosis via mitochondrial pathway in the neuroblastoma cells and male is more susceptible to BPs than female.

Changes in the Population Size of Calbindin D-28k-Immunoreactive Enteric Neurons in the Porcine Caecum under the Influence of Bisphenol A: A Preliminary Study

Calbindin D-28k (CB) is a calcium-binding protein widely distributed in living organisms that may act as a calcium buffer and sensory protein. CB is present in the enteric nervous system (ENS) situated in the gastrointestinal tract, which controls the majority of activities of the stomach and intestine. The influence of various doses of bisphenol A (BPA)—a chemical compound widely used in plastics production—on the number and distribution of CB-positive enteric neuronal cells in the porcine caecum was investigated with an immunofluorescence technique. The obtained results showed that low dosages of BPA resulted in an increase in the number of CB-positive neuronal cells in the myenteric (MP) and inner submucous (ISP) plexuses, whereas it did not alter the number of such neuronal cells in the outer submucous plexus (OSP). High dosages of BPA caused the increase in the amount of CB-positive perikarya in all the above-mentioned kinds of the caecal neuronal plexuses. These observations strongly suggest that CB in the ENS participates in the processes connected with the toxic activity of BPA. Most likely, the changes noted in this experiment result from the adaptive and protective properties of CB.

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

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

Boswellic Acid Synergizes With Low-Level Ionizing Radiation to Modulate Bisphenol Induced-Lung Toxicity in Rats by Inhibiting JNK/ERK/c-Fos Pathway

Bisphenol A (BPA) is a low molecular weight chemical compound that has a deleterious effect on the endocrine system. It was used in plastics manufacturing with injurious effects on different body systems. Occupational exposure to low-level ionizing radiation (<1 Gy) is shown to attenuate an established inflammatory process and therefore enhance cell protection. Therefore, the objective of this study was to investigate the protective effect of boswellic acid (BA) accompanied by whole-body low-dose gamma radiation (γ-R) against BPA-induced lung toxicity in male albino rats. BPA intoxication induced with 500 mg/kg BW. Rats received 50 mg BA/kg BW by gastric gavage concomitant with 0.5 Gy γ-R over 4 weeks. The immunoblotting and biochemical results revealed that BA and/or γ-R inhibited BPA-induced lung toxicity by reducing oxidative damage biomolecules; (MDA and NADPH oxidase gene expression), inflammatory indices (MPO, TNF-α, IL-6, and gene expression of CXCR-4). Moreover, BA and or/γ-R ameliorated the lung inflammation via regulation of the JNK/ERK/c-Fos and Nrf2/ HO-1 signaling pathways. Interestingly, our data demonstrated that BA in synergistic interaction with γ-R is efficacious control against BPA-induced lung injury via anti-oxidant mediated anti-inflammatory activities.

Transcriptomic analysis of bisphenol AF on early growth and development of zebrafish (Danio rerio) larvae

Bisphenol AF (BPAF), an alternative to bisphenol A, is widely detected in aquatic environments. Owing to health concerns, the toxic effects of BPAF on organisms are drawing attention. The present study aims to evaluate the toxicity of BPAF, combining the results of omics techniques and experiment. Employing transcriptome sequencing (RNA-seq), we obtained 391, 648, 512, and 545 differentially expressed genes (DEGs) in 0.1, 1, 10, and 100 μg/L BPAF-exposed zebrafish larvae, respectively. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment revealed the early development, stimulus-response, and MAPK signaling pathway were significantly affected by BPAF. In addition, five hub genes (fgf3, fgf4, map2k1, myca, and casp3b) were highlighted as the key genes in MAPK signaling pathway using the protein-protein interaction network. Therefore, the RNA-seq results showed that early development and stimulus-response were the main processes affected by BPAF, which was consistent with our morphological and pathological results. The hatching rate of zebrafish embryos in 1 and 10 μg/L BPAF groups was significantly inhibited, and the oxidative stress indexes, including the level of total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and lipid peroxidation (LPO), were significantly increased by the 100 μg/L BPAF treatment. Moreover, the activity of alkaline phosphatase (AKP) was significantly decreased in all BPAF exposure groups. In conclusion, exposure to BPAF at environmental relevant concentrations affected the early development and immune system of zebrafish larvae by modulating MAPK signaling pathway, and our results provide solid evidence for the future studies on the toxicity of bisphenols.

Di-2-ethylhexyl phthalate (DEHP) induces apoptosis of mouse HT22 hippocampal neuronal cells via oxidative stress

Di-2-ethylhexyl phthalate (DEHP) has been widely used as a plasticizer in industry and can affect memory; however, the underlying mechanism remains unclear. In the present study, mouse HT22 cells, an immortalized hippocampal neuronal cell line, was utilized as an in vitro model. We showed that DEHP dramatically inhibited cell viability and increased lactate dehydrogenase (LDH) release from the cells in a dose-dependent manner, suggesting that DEHP could cause cytotoxicity of mouse HT22 cells. The protein levels of cleaved Caspase-8, cleaved Caspase-3, and Bax markedly increased in the DEHP-treated cells, whereas there was a significant decrease in the Bcl-2 protein level, implying that DEHP could induce apoptosis of mouse HT22 cells. DEHP exposure significantly increased the content of malondialdehyde, whereas it markedly decreased the level of glutathione and the activities of glutathione peroxidase and superoxide dismutase, suggesting that DEHP induced oxidative stress of the cells. Compared with the DEHP-treated group, the inhibition of cell viability and the release of LDH were rescued in the N-acetyl-l-cysteine plus DEHP group. Furthermore, inhibition of oxidative stress could rescue the induction of apoptosis by DEHP. Collectively, our results indicated that DEHP could induce apoptosis of mouse HT22 cells via oxidative stress.

Protective effect of crocin on bisphenol A - induced spatial learning and memory impairment in adult male rats: Role of oxidative stress and AMPA receptor

OBJECTIVES

Bisphenol A (BPA), a xenoestrogenic endocrine disrupting agent, is widely used in the production of polycarbonate plastics and has potential adverse effects on the developing nervous system, memory and learning abilities. The protective effect of the crocin, an important active constituent in Crocus sativus L, on memory impairment induced by BPA in rat was determined through evaluation of oxidative stress and the level of NMDA (N-methyl-D-aspartate receptors) and AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole-propionicd acid) receptors.

MATERIALS AND METHODS

Rats were orally treated with BPA (100 mg/kg) or sesame seed oil in control group for 28 days. Crocin (10, 20, and 40 mg/kg, IP) was administrated in BPA-orally treated groups for 28 days. Memory and learning functions were evaluated by Morris water maze. The level of malondialdehyde (MDA) and glutathione (GSH) contents were determined in rat hippocampus. Additionally, the expression of NMDA and AMPA receptors were analyzed using Western blot method.

RESULTS

Administration of BPA significantly reduced memory and learning functions. Crocin significantly protected against learning and memory impairments induced by BPA. BPA administration markedly reduced GSH content and induced lipid peroxidation, while crocin was able to increase GSH content in rat hippocampus. The expression of NMDA receptor did not change in BPA-treated rats, while the significant reduction in AMPA receptor expression was observed. Moreover, crocin (20 mg/kg) significantly elevated the expression of AMPA receptor.

CONCLUSION

Crocin recovered spatial learning and memory defects induced by BPA in part through anti-oxidant activity and modulation the expression of AMPA receptor in rat hippocampus.

Impacts of bisphenol A analogues on zebrafish post-embryonic brain

Bisphenol A (BPA) is a widely studied and well-recognised endocrine-disrupting chemical, and one of the current issues is its safe replacement by various analogues. Using larva zebrafish as a model, the present study reveals that moderate and chronic exposure to BPA analogues such as bisphenol S, bisphenol F and bisphenol AF may also affect vertebrate neurodevelopment and locomotor activity. Several parameters of embryo-larval development were investigated, such as mortality, hatching, number of mitotically active cell, as defined by 5-bromo-2'-deoxyuridine incorporation and proliferative cell nuclear antigen labelling, aromatase B protein expression in radial glial cell and locomotor activity. Our results show that exposure to several bisphenol analogues induced an acceleration of embryo hatching rate. At the level of the developing brain, a strong up-regulation of the oestrogen-sensitive Aromatase B was also detected in the hypothalamic region. This up-regulation was not associated with effects on the numbers of mitotically active progenitors nor differentiated neurones in the preoptic area and in the nuclear recessus posterior of the hypothalamus zebrafish larvae. Furthermore, using a high-throughput video tracking system to monitor locomotor activity in zebrafish larvae, we show that some bisphenol analogues, such as bisphenol AF, significantly reduced locomotor activity following 6 days of exposure. Taken together, our study provides evidence that BPA analogues can also affect the neurobehavioural development of zebrafish.

Protective effects of lycopene on hippocampal neurotoxicity and memory impairment induced by bisphenol A in rats

Bisphenol A (BPA) is used to produce polycarbonate plastic and epoxy resins which are used in many consumer products. Most people encounter BPA in their daily routines. However, it has been heavily reported that BPA has a neurotoxic effect. The present study aimed to investigate the effect of lycopene on cognitive deficits induced by a high dose of BPA focusing on mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway, oxidative stress, apoptosis, and memory retrieval in adult male rats. Therefore, 72 rats were divided into four groups: control group, BPA group (50 mg/kg body weight (bw)) 3 days a week for 42 days, lycopene group (10 mg/kg bw) daily for 42 days, and lycopene + BPA group. Concurrent treatment of lycopene with BPA improved the learning and cognition memory in Morris water maze and novel object recognition tests along with an increase in acetylcholine esterase activity as well as inhibition of oxidative stress by restoring reduced glutathione and suppressing malondialdehyde hippocampal level to their normal levels. Mechanistically, lycopene upregulated the protein expression of tyrosine receptor kinase B, which resulted in an upsurge in its downstream cascades MAPK/ERK1/2/cAMP response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) signaling pathway in the hippocampus of BPA-intoxicated rats. Furthermore, concurrent treatment of lycopene with BPA prevented apoptosis by marked decrease in Bcl-2 associated X protein (Bax) gene expression and caspase 3 activity while restoring B-cell leukemia/lymphoma-2 (Bcl-2) gene expression. In conclusion, the present study provided evidence that lycopene exerted a neuroprotective effect against BPA intoxication in hippocampi of rats via its antioxidant properties, activation of MAPK/ERK pathway, and inhibiting a neuronal apoptosis which reflected on improving the learning and cognition memory.

Cell Cycle Deficits in Neurodegenerative Disorders: Uncovering Molecular Mechanisms to Drive Innovative Therapeutic Development

Cell cycle dysregulation has been implicated in the pathogenesis of neurodegenerative disorders. Specialised function obligates neuronal cells to subsist in a quiescent state of cell cycle once differentiated and therefore the circumstances and mechanisms underlying aberrant cell cycle activation in post-mitotic neurons in physiological and disease conditions remains an intriguing area of research. There is a strict requirement of concurrence to cell cycle regulation for neurons to ensure intracellular biochemical conformity as well as interrelationship with other cells within neural tissues. This review deliberates on various mechanisms underlying cell cycle regulation in neuronal cells and underscores potential implications of their non-compliance in neural pathology. Recent research suggests that successful duplication of genetic material without subsequent induction of mitosis induces inherent molecular flaws that eventually assert as apoptotic changes. The consequences of anomalous cell cycle activation and subsequent apoptosis are demonstrated by the increased presence of molecular stress response and apoptotic markers. This review delineates cell cycle events under normal physiological conditions and deficits amalgamated by alterations in protein levels and signalling pathways associated with cell-division are analysed. Cell cycle regulators essentially, cyclins, CDKs, cip/kip family of inhibitors, caspases, bax and p53 have been identified to be involved in impaired cell cycle regulation and associated with neural pathology. The pharmacological modulators of cell cycle that are shown to impart protection in various animal models of neurological deficits are summarised. Greater understanding of the molecular mechanisms that are indispensable to cell cycle regulation in neurons in health and disease conditions will facilitate targeted drug development for neuroprotection.

Spinosin protects N2a cells from H2 O2 -induced neurotoxicity through inactivation of p38MAPK

OBJECTIVES

Previous studies have suggested that spinosin (SPI) exerted neuroprotective effects through inhibition of oxidative damage, but the underlying mechanisms are still unclear. Herein, the mechanisms underlying the protective effects of SPI against oxidative stress induced by hydrogen peroxide (H₂ O₂ ) were examined in neuro-2a (N2a) mouse neuroblastoma cells.

METHODS

N2a cells were pretreated with H₂ O₂ for 2 h, followed by a 24-h incubation with SPI. Intracellular reactive oxygen species (ROS) production was analysed by flow cytometry. Levels of Aβ_1-42 production were determined by ELISA assay. Levels of expression of c-Jun N-terminal kinase (JNK), p-JNK, extracellular signal-regulated kinase (ERK), p-ERK, p38 mitogen-activated protein kinase (p38MAPK), p-p38MAPK, p-Tau (Ser199), p-Tau (Ser202), p-Tau (Ser396), synaptophysin (SYP) and postsynaptic scaffold postsynaptic density-95 (PSD-95) were detected by Western blot analysis.

KEY FINDINGS

Our results showed that H₂ O₂ treatment enhanced intracellular ROS production in N2a cells. SPI prevented H₂ O₂ -induced oxidative damage via inhibiting Aβ_1-42 production, decreasing Tau phosphorylation and improving synaptic structural plasticity. Notably, H₂ O₂ -increased p38MAPK activation was attenuated by SPI administration, and p38MAPK inhibitor BIRB796 markedly reduced H₂ O₂ -induced oxidative damage in N2a cells.

CONCLUSIONS

Our findings suggest that SPI protects N2a cells from H₂ O₂ -induced oxidative damage through inactivation of p38MAPK.

Bisphenol A and Male Fertility: Myths and Realities

Bisphenol A (BPA) represents the main chemical monomer of epoxy resins and polycarbonate plastics. The environmental presence of BPA is widespread, and it can easily be absorbed by the human body through dietary and transdermal routes, so that more than 90% of the population in western countries display detectable BPA levels in the urine. As BPA is qualified as an endocrine disruptor, growing concern is rising for possible harmful effects on human health. This review critically discusses the available literature dealing with the possible impact of BPA on male fertility. In rodent models, the in vivo exposure to BPA negatively interfered with the regulation of spermatogenesis throughout the hypothalamic-pituitary-gonadal axis. Furthermore, in in vitro studies, BPA promoted mitochondrial dysfunction and oxidative/apoptotic damages in spermatozoa from different species, including humans. To date, the claimed clinical adverse effects on male fertility are largely based on the results from studies assessing the relationship between urinary BPA concentration and conventional semen parameters. These studies, however, produced controversial evidence due to heterogeneity in the extent of BPA exposure, type of population, and enrollment setting. Moreover, the cause-effect relationship cannot be established due to the cross-sectional design of the studies as well as the large spontaneous between- and within-subject variability of semen parameters. The best evidence of an adverse effect of BPA on male fertility would be provided by prospective studies on clinically relevant endpoints, including natural or medically assisted pregnancies among men either with different exposure degrees (occupational/environmental) or with different clinical conditions (fertile/subfertile).

Prenatal bisphenol A exposure contributes to Tau pathology: Potential roles of CDK5/GSK3β/PP2A axis in BPA-induced neurotoxicity

Bisphenol A (BPA) is a well-known endocrine disruptor used to manufacture polycarbonate plastics and epoxy resins. BPA exposure especially occupational perinatal exposure to has been linked to numerous adverse effects for the offspring. Available data have shown that perinatal exposure to BPA contributes to neurodegenerative pathological changes; however, the potential mechanisms remain unclear. This study attempted to investigate the long-term consequences of perinatal exposure to BPA on the offspring mouse brain. The pregnant mice were given either a vehicle control or BPA (2, 10, 100 μg/kg/d) from day 6 of gestation until weaning (P6-PND21, foetal and neonatal exposure). At 3, 6 and 9 months of age, the neurotoxic effects in the offspring in each group were investigated. We found that the spine density but not the dendritic branches in the hippocampus were noticeably reduced at 6 and 9 months of age. Meanwhile, p-Tau, the characteristic protein for tauopathy, was dramatically increased in both the hippocampus and cortex at 3-9 months of age. Mechanically, the balance of kinase and protein phosphatase, which plays critical roles in p-Tau regulation, was disturbed. It indicated that GSK3β and CDK5, two critical kinases, were activated in most of the BPA perinatal exposure group, while protein phosphatase 2A (PP2A), one of the important phosphatases, regulated p-Tau expression through its demethylation, methylation and phosphorylation. Taken together, the present study may be translatable to the human occupational BPA exposure due to a similar exposure level. BPA perinatal exposure causes long-term adverse effects on the mouse brain and may be a risk factor for tauopathies, and the CDK5/GSK3β/PP2A axis might be a promising therapeutic target for BPA-induced neurodegenerative pathological changes.

Bisphenol A and its substitutes regulate human B cell survival via Nrf2 expression

B cells contribute to produce inflammatory cytokines and antibodies, to present autoantigens, and to interact with T cells, which lead to body defense and disease control. Nuclear factor (erythroid-derived 2)-like 2(Nrf2) is responsible for gene expression of antioxidant enzymes to protect cells from oxidative stress by reactive oxygen species(ROS) production. Bisphenol A(BPA) may not be safe due to the effect on body's physiological functions. The chemicals that substitute for BPA may still have similar effects in the body. Tritan™ copolyester is a novel plastic form using BPA substitutes, 1,4-cyclohexanedimethanol(CHDM), dimethyl terephthalate(DMT), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol(TMCD). Isosorbide(ISO) was also used as a substitute for TMCD and DMT. Here, we investigated whether B cell viability is influenced by BPA and its substitutes via Nrf2 induction using WiL2-NS human B lymphoblast cells. When cytotoxicity was measured by using assays with MTT, CellTiter-Glo, trypan blue and propidium iodide, cytotoxicity by BPA was higher than that by substitutes. BPA and its substitutes showed significant cytotoxicity and ROS production, which were attenuated by the treatment with N-acetylcysteine(NAC), a ROS scavenger. In addition, BPA treatment enhanced gene expression of antioxidant enzymes, heme oxygenase(HO)-1, catalase, superoxide dismutase(SOD) 1 and 2. As H₂O₂ treatment induced cell death and Nrf2 amount in WiL2-NS cells, BPA treatment increased Nrf2. Cell death by H₂O₂ was increased in doxycycline-inducible Nrf2-knockdown(KD) cells. In Cytotoxicity by the treatment with BPA or its substitutes was also enhanced in Nrf2-KD cells but that was reduced by Nrf2 overexpression compared to control cells. Taken together, these results implicate that B cell cytotoxicity by substitutes should be lower than BPA and Nrf2 can prevent B cells from BPA- or BPA substitutes-induced cytotoxicity via ROS production. Data suggest that the comprehensive studies or evaluation could be necessary to replace BPA in manufacture by other substitutes.

Evaluation of the Influence of Halogenation on the Binding of Bisphenol A to the Estrogen-Related Receptor γ

Halogenation of organic compounds is one the most important transformations in chemical synthesis and is used for the production of various industrial products. A variety of halogenated bisphenol analogs have recently been developed and are used as alternatives to bisphenol A (BPA), which is a raw material of polycarbonate that has adverse effects in animals. However, limited information is available on the potential toxicity of the halogenated BPA analogs. In the present study, to assess the latent toxicity of halogenated BPA analogs, we evaluated the binding and transcriptional activities of halogenated BPA analogs to the estrogen-related receptor γ (ERRγ), a nuclear receptor that contributes to the growth of nerves and sexual glands. Fluorinated BPA analogs demonstrated strong ERRγ binding potency, and inverse antagonistic activity, similar to BPA. X-ray crystallography and fragment molecular orbital (FMO) calculation revealed that a fluorine-substituted BPA analog could interact with several amino acid residues of ERRγ-LBD, strengthening the binding affinity of the analogs. The ERRγ binding affinity and transcriptional activity of the halogenated BPAs decreased with the increase in the size and number of halogen atom(s). The IC₅₀ values, determined by the competitive binding assay, correlated well with the binding energy obtained from the docking calculation, suggesting that the docking calculation could correctly estimate the ERRγ binding potency of the BPA analogs. These results confirmed that ERRγ has a ligand binding pocket that fits very well to BPA. Furthermore, this study showed that the binding affinity of the BPA analogs can be predicted by the docking calculation, indicating the importance of the calculation method in the risk assessment of halogenated compounds.

Polyozellin alleviates atopic dermatitis-like inflammatory and pruritic responses in activated keratinocytes and mast cells

Polyozellus multiplex is an edible mushroom that offers beneficial pharmacological effects against intestinal inflammation and cancer. Previous studies have demonstrated that polyozellin, a major component of P. multiplex, has therapeutic activities against inflammation, cancer, and oxidative stress-related disorders. This study aimed to determine the pharmacological effects of polyozellin on inflammatory and pruritic responses, the major symptoms of atopic dermatitis (AD), and to define its underlying mechanism of action. Our results showed that polyozellin inhibited the expression of inflammatory cytokines and chemokines through blockade of signal transducer and activator of transcription 1 and nuclear factor-κB in activated keratinocytes, the major cells involved in AD progression. Based on the histological and immunological analyses, oral treatment with polyozellin attenuated the Dermatophagoides farinae extract (DFE)/2,4-dinitrochlorobenzene (DNCB)-induced atopic inflammatory symptoms in the skin. Pruritus is an unpleasant sensation for AD patients that causes scratching behavior and ultimately exacerbates the severity of AD. To find a possible explanation for the anti-pruritic effects of polyozellin, we investigated its effects on mast cells and mast cell-derived histamines. Oral treatment with polyozellin reduced the DFE/DNCB-induced tissue infiltration of mast cells, the serum histamine levels, and the histaminergic scratching behaviors. Additionally, polyozellin decreased the immunoglobulin E-stimulated degranulation of mast cells. Taken together, the findings of this study provide us with novel insights into the potential pharmacological targets of polyozellin for treating AD by inhibiting the inflammatory and pruritic responses.

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.

Bisphenol F-Induced Neurotoxicity toward Zebrafish Embryos

In this study, the influence of bisphenol F (BPF) toward central nervous system (CNS) was assessed using zebrafish embryos. We found that BPF could induce significant neurotoxicity toward zebrafish embryos, including inhibited locomotion, reduced moving distance, and CNS cell apoptosis at an effective concentration of 0.0005 mg/L. Immunofluorescence assay showed that both microglia and astrocyte in zebrafish brain were significantly activated by BPF, indicating the existence of neuroinflammatory response. Peripheral motor neuron development was significantly inhibited by BPF at 72 hpf. RNA-seq data indicated that neuronal developmental processes and cell apoptosis pathways were significantly affected by BPF exposure, which was consistent with the phenotypic results. Chip-seq assay implied that the transcriptional changes were not mediated by ERα. Additionally, no significant change was found in neurotransmitter levels (5-hydroxytryptamine, dopamine, and acetylcholine) or acetylcholinesterase (Ache) enzyme activity after BPF exposure, indicating that BPF may not affect neurotransmission. In conclusion, BPF could lead to abnormal neural outcomes during zebrafish early life stage through inducing neuroinflammation and CNS cell apoptosis even at environmentally relevant concentration.

Immunotoxic Potential of Bisphenol F Mediated through Lipid Signaling Pathways on Macrophages

As a bisphenol A (BPA) alternative, bisphenol F (BPF) has been detected in various products, such as paper products, personal care products, and food. More importantly, the toxicity of BPF remains underexplored. We reported an integrated method to study the immunotoxic potentials and the underlying mechanisms of BPF on cell apoptosis, macrophage polarization, reactive oxygen species generation, expression and secretion of immune-related cytokines, and reprogramming of lipid signaling. More serious to BPA, BPF induced apoptosis in macrophages. The apoptosis was induced by activating both sphingomyelin-ceramide signaling pathway and oxidative stress, which included intrinsic (bax and caspase-9) and extrinsic apoptotic pathways (tumor necrosis factor receptor 1, caspase-8, and caspase-3). BPF exposure also induced the proinflammatory phenotype of the macrophage. This alternation was shown to be closely correlated with the modulation of biosynthesis and degradation of glycerophospholipids. This study demonstrated novel evidence that BPF as a substituent of BPA induced immunotoxic effects at environmentally relevant concentrations. We also showed that the reprogramming of lipidome plays a key role in the regulation of macrophage polarization and the induction of immunotoxicity of the BPA analogue.

Bisphenol-A induces neurodegeneration through disturbance of intracellular calcium homeostasis in human embryonic stem cells-derived cortical neurons

Bisphenol-A (BPA) is a representative exogenous endocrine disruptor, which is extensively composed in plastic products. Due to the capability of passing through the blood-brain barrier, evidence has linked BPA exposure with multiple neuropsychological dysfunctions, neurobehavioral disorders and neurodegenerative diseases. However, the underlying mechanism by which BPA induces neurodegeneration still remains unclear. Our study used human embryonic stem cells-derived human cortical neurons (hCNs) as a cellular model to investigate the adverse neurotoxic effects of BPA. hCNs were treated with 0, 0.1, 1 and 10 μM BPA for 14 days. Impacts of BPA exposure on cell morphology, cell viability and neural marker (MAP2) were measured for evaluating the neurodegeneration. The intracellular calcium homeostasis, reactive oxygen species (ROS) generation and organelle functions were also taken into consideration. Results revealed that chronic exposure of BPA damaged the neural morphology, induced neuronal apoptosis and decreased MAP2 expression at the level of both transcription and translation. The intracellular calcium levels were elevated in hCNs after BPA exposure through NMDARs-nNOS-PSD-95 mediating. Meanwhile, BPA led to oxidative stress by raising the ROS generation and attenuating the antioxidant defense in hCNs. Furthermore, BPA triggered ER stress and increased cytochrome c release by impairing the mitochondrial function. Ultimately, BPA triggered the cell apoptosis by regulating Bcl-2 family and caspase-dependent signaling pathway. Taken together, BPA exerted neurotoxic effects on hCNs by eliciting apoptosis, which might due to the intracellular calcium homeostasis perturbation and cell organellar dysfunction.

Neurotoxicity of BPA, BPS, and BPB for the hippocampal cell line (HT-22): An implication for the replacement of BPA in plastics

Bisphenol A (BPA), a plastic additive, is ubiquitous in the environment and has endocrine disrupting effects. As many countries have prohibited the manufacture and sale of plastic products with BPA, BPA analogs have been used to replace BPA during production, including bisphenol S (BPS) and bisphenol B (BPB). To investigate the toxicities of BPA and its analogs on neurons, reactive oxygen species (ROS) assay, Annexin V-FITC (fluorescein) apoptosis detection assay, lactate dehydrogenase (LDH) cytotoxicity assay, and Cell Counting Kit-8 assay were conducted to comprehensively assess the influence of different concentrations of BPA, BPB, and BPS on ROS, apoptosis, damage, and proliferation for hippocampal HT-22 cells, respectively. Results showed that 6 h of exposure to bisphenols (BPs) could increase the ROS levels, 24 h and 48 h of exposure could induce higher apoptosis and LDH leakage rates for HT-22 cells, and 7 d of exposure could inhibit the cell proliferations. In addition, non-monotonic dose-response relationships were observed between the concentrations of bisphenols and the toxic effects mentioned above. The neurotoxic effects of BPA, BPB and BPS on HT-22 cells were in the increasing order of BPS, BPA, and BPB. In conclusion, these results showed that exposure to BPA and its analogs may result in adverse effects on hippocampal neuronal cell lines. BPS is a surrogate with lower neurotoxicity to replace BPA in production of plastic utensils.

Bisphenol A Activates Calcium Influx in Immortalized GnRH Neurons

Bisphenol A (BPA) is one of the most widely used chemicals worldwide, e.g., as a component of plastic containers for food and water. It is considered to exert an estrogenic effect, by mimicking estradiol (E2) action. Because of this widespread presence, it has attracted the interest and concern of researchers and regulators. Despite the vast amount of related literature, the potential adverse effects of environmentally significant doses of BPA are still object of controversy, and the mechanisms by which it can perturb endocrine functions, and particularly the neuroendocrine axis, are not adequately understood. One of the ways by which endocrine disruptors (EDCs) can exert their effects is the perturbation of calcium signaling mechanisms. In this study, we addressed the issue of the impact of BPA on the neuroendocrine system with an in vitro approach, using a consolidated model of immortalized Gonadotropin-Releasing Hormone (GnRH) expressing neurons, the GT1–7 cell line, focusing on the calcium signals activated by the endocrine disruptor. The investigation was limited to biologically relevant doses (nM–µM range). We found that BPA induced moderate increases in intracellular calcium concentration, comparable with those induced by nanomolar doses of E2, without affecting cell survival and with only a minor effect on proliferation.

Metabolic perturbation, proliferation and reactive oxygen species jointly contribute to cytotoxicity of human breast cancer cell induced by tetrabromo and tetrachloro bisphenol A

Halogenated bisphenol A analogues (X-BPA) have been widely used in industrial production, such as flame retardant. Although BPA exposure was found to result in cytotoxicity, toxicity of X-BPA and molecular mechanism remain under-explored. In this study, we employed human breast cancer cell as a model to investigate the concentration-dependent toxicity and underlying mechanisms of tetrabromo bisphenol A (TBBPA) and tetrachloro bisphenol A (TCBPA). An integrated method involving molecular toxicology and mass spectrometry (MS)-based global metabolomics was applied to evaluate the toxicity of TCBPA and TBBPA on cell viability, reactive oxygen species (ROS), and metabolic alterations. The results demonstrated that low micromolar levels (0-10 μM) of TCBPA/TBBPA exposure induced cell proliferation and activated the energy metabolism of both glycolysis and amino acid. On the other hand, high micromolar levels (10-50 μM) of TCBPA/TBBPA exposure perturbed the balance between ROS and antioxidative defense process by promoting the ROS generation via the down-regulation of glutathione biosynthesis and up-regulation of nucleotide metabolism. This study, for the first time, provides evidence and mechanism for better understanding the cytotoxicity of TCBPA and TBBPA by regulating the specific metabolic pathways.