BPA-toxicity via superoxide anion overload and a deficit in β-catenin signaling in human bone mesenchymal stem cells

Health risks of Bisphenol-A exposure: From Wnt signaling perspective

Human beings are routinely exposed to chronic and low dose of Bisphenols (BPs) due to their widely pervasiveness in the environment. BPs hold similar chemical structures to 17β-estradiol (E2) and thyroid hormone, thus posing threats to human health by rendering the endocrine system dysfunctional. Among BPs, Bisphenol-A (BPA) is the best-known and extensively studied endocrine disrupting compound (EDC). BPA possesses multisystem toxicity, including reproductive toxicity, neurotoxicity, hepatoxicity and nephrotoxicity. Particularly, the central nervous system (CNS), especially the developing one, is vulnerable to BPA exposure. This review describes our current knowledge of BPA toxicity and the related molecular mechanisms, with an emphasis on the role of Wnt signaling in the related processes. We also discuss the role of oxidative stress, endocrine signaling and epigenetics in the regulation of Wnt signaling by BPA exposure. In summary, dysfunction of Wnt signaling plays a key role in BPA toxicity and thus can be a potential target to alleviate EDCs induced damage to organisms.

Edaravone counteracts redox and metabolic disruptions in an emerging zebrafish model of sporadic ALS

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which the death of motor neurons leads to loss of muscle function. Additionally, cognitive and circadian disruptions are common in ALS patients, contributing to disease progression and burden. Most ALS cases are sporadic, and environmental exposures contribute to their aetiology. However, animal models of these sporadic ALS cases are scarce. The small vertebrate zebrafish is a leading organism to model neurodegenerative diseases; previous studies have proposed bisphenol A (BPA) or β-methylamino-l-alanine (BMAA) exposure to model sporadic ALS in zebrafish, damaging motor neurons and altering motor responses. Here we characterise the face and predictive validity of sporadic ALS models, showing their potential for the mechanistic study of ALS drugs. We phenotypically characterise the BPA and BMAA-induced models, going beyond motor activity and motor axon morphology, to include circadian, redox, proteostasis, and metabolomic phenotypes, and assessing their predictive validity for ALS modelling. BPA or BMAA exposure induced concentration-dependent activity impairments. Also, exposure to BPA but not BMAA induced motor axonopathy and circadian alterations in zebrafish larvae. Our further study of the BPA model revealed loss of habituation to repetitive startles, increased oxidative damage, endoplasmic reticulum (ER) stress, and metabolome abnormalities. The BPA-induced model shows predictive validity, since the approved ALS drug edaravone counteracted BPA-induced motor phenotypes, ER stress, and metabolic disruptions. Overall, BPA exposure is a promising model of ALS-related redox and ER imbalances, contributing to fulfil an unmet need for validated sporadic ALS models.

Bisphenol-A Abrogates Proliferation and Differentiation of C2C12 Mouse Myoblasts via Downregulation of Phospho-P65 NF-κB Signaling Pathway

Previous studies showed that bisphenol-A (BPA), a monomer of polycarbonate plastic, is leached out and contaminated in foods and beverages. This study aimed to investigate the effects of BPA on the myogenesis of adult muscle stem cells. C2C12 myoblasts were treated with BPA in both proliferation and differentiation conditions. Cytotoxicity, cell proliferation and differentiation, antioxidant activity, apoptosis, myogenic regulatory factors (MRFs) gene expression, and mechanism of BPA on myogenesis were examined. C2C12 myoblasts exposed to 25-50 µM BPA showed abnormal morphology, expressing numerous and long cytoplasmic extensions. Cell proliferation was inhibited and was accumulated in subG1 and S phases of the cell cycle, subsequently leading to apoptosis confirmed by nuclear condensation and the expression of apoptosis markers, cleaved caspase-9 and caspase-3. In addition, the activity of antioxidant enzymes, catalase, superoxide dismutase, and glutathione peroxidase was significantly decreased. Meanwhile, BPA suppressed myoblast differentiation by decreasing the number and size of multinucleated myotubes via the modulation of MRF gene expression. Moreover, BPA significantly inhibited the phosphorylation of P65 NF-κB in both proliferation and differentiation conditions. Altogether, the results revealed the adverse effects of BPA on myogenesis leading to abnormal growth and development via the inhibition of phospho-P65 NF-κB.

Biochemical responses and antioxidant defense mechanisms in Channa Striatus exposed to Bisphenol S

Bisphenol S (BPS), a BPA analog and a safer alternative, is utilized in a diverse range of industrial applications, such as making polycarbonate plastics, epoxy resins, thermal receipt papers, and currency bills. Recently, the increased use of BPS in containers and packages for daily life has been interrogated due to its identical chemical structure and probable endocrine-disrupting actions as BPA has. The present study aimed to evaluate the alterations in biochemical indices and antioxidant enzymes as certain indicators of the endocrine-disrupting effect of BPS in Channa striatus, a freshwater fish. BPS-exposed fish species were subjected to three sub-lethal concentrations of BPS (1, 4, and 12 ppm) and observed after an interval of 7 and 21 days. Exposure to BPS caused a reduction in the level of protein in muscle, gonads and the liver due to an impairment of protein synthesis. Levels of cholesterol in the muscle, gonads, and liver of BPS-exposed fish were found to be decreased after treatment, indicating either an inhibition of cholesterol biosynthesis in the liver or reduced absorption of dietary cholesterol. The levels of antioxidant enzymes such as superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase showed remarkable increases, while the activity of glutathione S-transferase decreased considerably, indicating the antioxidant defense mechanism to counteract the oxidative stress induced by BPS. Moreover, a significant increase was noted in the level of lipid peroxidation products, like malondialdehyde and conjugate diene, which represent biomarkers of oxidative stress. The histoarchitecture changes were also observed in the liver, muscle and gonads of BPS-treated fish species. The present study showed that sub-lethal exposure to BPS significantly influenced the activities of these enzymes and peroxidation byproducts. From this study, it is concluded that BPS-caused toxic effects in fish species lead to an imbalance in the antioxidant defense system. It is clearly indicated that BPS toxicity could lead to susceptible oxidative stress in various tissues and could damage vital organs.

Low-dose bisphenols exposure sex-specifically induces neurodevelopmental toxicity in juvenile rats and the antagonism of EGCG

Bisphenols (BPs) can negatively affect neurobehaviors in rats, whereas the mechanism remains unclear. Here, the mechanism of BPs-induced neurodevelopmental toxicity and its effective detoxification measures were investigated in vitro and in vivo. In in vitro experiments, primary hippocampal neurons from neonatal rats of different genders were treated with bisphenol A (BPA), bisphenol S (BPS) and bisphenol B (BPB) at 1 nM-100 μM, epigallocatechin gallate (EGCG) and G15, an antagonist of G protein-coupled estrogen receptor (GPER) for 7 d. Results indicated that BPs affected neuronal morphogenesis, impaired GABA synthesis and Glu/GABA homeostasis. Neuronal morphogenetic damage induced by low-doses BPA may be mediated by GPER. Neurotoxicity of BPS is weaker than BPA and BPB. In in vivo studies, exposure to BPA (0.5 μg/kg·bw/day) on PND 10-40 caused oxidative stress and inflammation in rat hippocampus, disrupted neuronal morphogenesis and neurotransmitter homeostasis, ultimately impaired spatial memory of rats. Males are more sensitive to BPA exposure than females. Both in vivo and in vitro studies indicated that EGCG, a phytoestrogen, can alleviate BPA-induced neurotoxicity. Taken together, low-doses BPA exposure sex-specifically disrupted neurodevelopment and further impaired learning and memory ability in rats, which may be mediated by GPER. Promisingly, EGCG effectively mitigated the BPA-induced neurodevelopmental toxicity.

Current Evidence on Bisphenol A Exposure and the Molecular Mechanism Involved in Related Pathological Conditions

Bisphenol A (BPA) is one of the so-called endocrine disrupting chemicals (EDCs) and is thought to be involved in the pathogenesis of different morbid conditions: immune-mediated disorders, type-2 diabetes mellitus, cardiovascular diseases, and cancer. The purpose of this review is to analyze the mechanism of action of bisphenol A, with a special focus on mesenchymal stromal/stem cells (MSCs) and adipogenesis. Its uses will be assessed in various fields: dental, orthopedic, and industrial. The different pathological or physiological conditions altered by BPA and the related molecular pathways will be taken into consideration.

Morphological, immunohistochemical, and biochemical study on the ameliorative effect of gallic acid against bisphenol A-induced nephrotoxicity in male albino rats

This study aimed to determine the effect of gallic acid (GA) on ameliorating bisphenol A (BPA) nephrotoxicity in male rat kidneys. Forty rats were assigned randomly into two groups: control (ten animals) and BPA (40 mg/kg bwt) (thirty animals), the second group was divided into three subgroups: BPA alone, BPA + G50 (50 mg/kg bwt), and BPA + G200 (200 mg/kg bwt). The biochemical analysis included measurements of the contents of nitric oxide, lipid peroxidation, reactive oxygen species, and cytokines (interleukin-1α and interleukin-6) in the kidney. The antioxidant enzymes catalase and superoxide dismutase were also measured in the kidney. Kidney function was assessed by determining uric acid, urea, and creatinine levels. The morphological investigations included hematoxylin and eosin staining for assessing the general histology and determining the glomerular and corpuscular areas, the tubular cell degeneration mean area, and the mean leukocyte infiltration area. Also, collagen fiber intensity and polysaccharide content were analyzed. Furthermore, immunohistochemical, morphometric, and ultrastructural studies were carried out. The results revealed morphological, immunohistochemical, and biochemical alterations in the kidney. Most of these changes showed a satisfactory improvement of kidney damage when BPA-administered rats were treated with GA at both doses. In conclusion, GA exhibited a strong protective effect against BPA-induced nephrotoxicity.

Evaluation of toxicological effects of bisphenol S with an in vitro human bone marrow mesenchymal stem cell: Implications for bone health

As the use of bisphenol A (BPA) has been restricted in consumer products, bisphenol S (BPS) is one major alternative to BPA for various materials, leading to growing concerns about its health risks in human beings. However, little is known about the toxic effects of BPS on bone health. We employed human bone marrow mesenchymal stem cells (hBMSCs) for the in vitro assessment of BPS on cell proliferation, differentiation, and self-renewal. Our study revealed that BPS at concentrations of 10^-10-10^-7 M increased cell viability but induced the morphological changes of hBMSCs. Moreover, BPS decreased ROS generation and increased Nrf2 expression. Furthermore, BPS not only activated ERα/β expression but also increased β-catenin expression and induced the replicative senescence of hBMSCs. Furthermore, we found that the upregulation of β-catenin induced by BPS was mediated, in part, by ER signaling. Overall, our results suggested BPS exposure caused the homeostatic imbalance of hBMSCs.

Protective role of resveratrol and apigenin against toxic effects of bisphenol a in rat salivary gland

OBJECTIVES

The aim of this study was to investigate the cellular changes caused by Bisphenol A (BPA) exposure in salivary gland cells and to examine the protective role of resveratrol (RSV) and apigenin (APG) molecules against the negative effects of BPA.

MATERIALS AND METHODS

Forty-two rats were randomly divided into 6 groups as; (i) control, (ii) BPA (130 mg/kg), (iii) BPA + RSV100 (100 mg/kg), (iv) BPA + RSV200 (200 mg/kg), (v) BPA + APG100 (100 mg/kg), and (vi) BPA + APG200 (200 mg/kg). In all experimental groups, the chemicals were given by gavage every day for a total of 28 days.

RESULTS

The BPA administration caused a significant increase in tissue oxidative stress parameters as opposed to a significant decrease in tissue antioxidant levels (p < 0.05). On the other hand, it was observed that RSV and APG treatment reversed this situation (p < 0.05). The BPA administration did not cause a significant change in tissue prostaglandin E₂ (PGE₂) and nitric oxide levels, whereas low-dose RSV significantly reduced the tissue PGE₂ levels compared to BPA (p < 0.05). BPA caused cytopathological changes and apoptosis in salivary gland cells. In the BPA group, edema, nuclear pleomorphism, and pyknotic nuclei were observed. Moreover, both RSV and APG were found to provide protection against BPA-induced cellular damage, while RSV provided better cellular protection than APG. The control group had a normal histological structure.

CONCLUSION

BPA caused cytopathological changes and apoptosis in salivary gland cells. As a result, it was observed that these phytochemicals probably have cytoprotective effects in BPA intoxication.

Impact of Bisphenol A on Structure and Function of Mitochondria: A Critical Review

Bisphenol A (BPA) is an industrial chemical used extensively to manufacture polycarbonate plastics and epoxy resins. Because of its estrogen-mimicking properties, BPA acts as an endocrine-disrupting chemical. It has gained attention due to its high chances of daily and constant human exposure, bioaccumulation, and the ability to cause cellular toxicities and diseases at extremely low doses. Several elegant studies have shown that BPA can exert cellular toxicities by interfering with the structure and function of mitochondria, leading to mitochondrial dysfunction. Exposure to BPA results in oxidative stress and alterations in mitochondrial DNA (mtDNA), mitochondrial biogenesis, bioenergetics, mitochondrial membrane potential (MMP) decline, mitophagy, and apoptosis. Accumulation of reactive oxygen species (ROS) in conjunction with oxidative damage may be responsible for causing BPA-mediated cellular toxicity. Thus, several reports have suggested using antioxidant treatment to mitigate the toxicological effects of BPA. The present literature review emphasizes the adverse effects of BPA on mitochondria, with a comprehensive note on the molecular aspects of the structural and functional alterations in mitochondria in response to BPA exposure. The review also confers the possible approaches to alleviate BPA-mediated oxidative damage and the existing knowledge gaps in this emerging area of research.

Genotoxic potential of bisphenol A: A review

Bisphenol A (BPA), as a major component of some plastic products, is abundant environmental pollutant. Due to its ability to bind to several types of estrogen receptors, it can trigger multiple cellular responses, which can contribute to various manifestations at the organism level. The most studied effect of BPA is endocrine disruption, but recently its prooxidative potential has been confirmed. BPA ability to induce oxidative stress through increased ROS production, altered activity of antioxidant enzymes, or accumulation of oxidation products of biomacromolecules is observed in a wide range of organisms - estrogen receptor-positive and -negative. Subsequently, increased intracellular oxidation can lead to DNA damage induction, represented by oxidative damage, single- and double-strand DNA breaks. Importantly, BPA shows several mechanisms of action and can trigger adverse effects on all organisms inhabiting a wide variety of ecosystem types. Therefore, the main aim of this review is to summarize the genotoxic effects of BPA on organisms across all taxa.

The possible effect of lactoferrin on the epigenetic characteristics of early mammalian embryos exposed to bisphenol A

BACKGROUND

The main objective of this review was to state a hypothetical mechanism of the antitoxic effect of lactoferrin (Lf) on embryos exposed to bisphenol A (BPA). On this basis, it is possible to suggest Lf as a potential protective health component before conception upon toxic effects and viral infections.

METHODS

The narrative review was performed using systematic review methods to identify relevant literature. The resources required for this study were obtained by searching the electronic database PubMed (MEDLINE). Articles were searched using the keywords "BPA," "lactoferrin," "DNA-methylation," "epigenetic," "mammals," "human," and "mouse." The inclusion criteria were as follows: (a) primary or original research; (b) study of epigenetic modification; and (c) study focuses on early mammalian development.

RESULTS

Presented data demonstrate that Lf can modulate epigenetical characteristic, such as DNA methylation and reactive oxygen species (ROS), and, thereby, may serve as a potential readily available pharmaceutical product.

CONCLUSION

Suggested hypothesis is based on the important interrelated role of changes in epigenetic modifications and oxidative stress in early embryogenesis under the influence of BPA and virus infection as a cause of the development of pathologies in the adult organism.

Bisphenol A induces pyroptotic cell death via ROS/NLRP3/Caspase-1 pathway in osteocytes MLO-Y4

Bisphenol A (BPA), a ubiquitous endocrine-disrupting chemical, is commonly used as a plasticizer to manufacture various food packaging materials. Evidence has demonstrated that BPA disturbed bone health. However, few studies focused on the effect of BPA on osteocytes, making up over 95% of all the bone cells. Here, we reported that BPA inhibited the cell viability of MLO-Y4 cells, and increased apoptosis in a dose-dependent manner. Furthermore, BPA up-regulated protein expressions of speck-like protein containing CARD (ASC), NLRP3, cleaved caspase-1 (Casp-1 p20) and cleaved gasdermin D (GSDMD-N), and increased the ratios of interleukin (IL)-1β/pro-IL-1β and IL-18/pro-IL-18 in MLO-Y4 cells. BPA enhanced levels of lactate dehydrogenase (LDH), IL-1β and IL-18 in culture supernatants. This pyroptotic death and the NLPR3 inflammasome activation were reversed by the caspase-1 inhibitor VX765 or the NLRP3 inflammasome inhibitor MCC950. Furthermore, BPA stimulated the production of intracellular reactive oxygen species (ROS), mitochondrial ROS (mtROS), elevated malondialdehyde (MDA) level and decreased superoxide dismutase (SOD) activity, which led to oxidative damage in MLO-Y4 cells. The ROS scavenger N-acetylcysteine (NAC) or the mitochondrial antioxidant Mito-TEMPO inhibited the NLPR3 inflammasome activation and pyroptotic death induced by BPA. Collectively, our data suggest that BPA causes pyroptotic death of osteocytes via ROS/NLRP3/Caspase-1 pathway.

Alterations of Kiss 1 receptor, GnRH receptor and nuclear receptors of the hypothalamo-pituitary-ovarian axis following low dose bisphenol-A exposure in Wistar rats

Bisphenol A is a chemical used primarily as a monomer in the production of polycarbonate plastics and epoxy resins. It is a synthetic chemical compound that is produced in billions of pounds annually, and tagged as an endocrine disruptor. Bisphenol A is a high production synthetic chemical compound that is used in the production of many consumables and equipments of daily consumption and use by man. Growing interest in possible health threats posed by endocrine disrupting chemicals (bisphenol-A inclusive), as these substances are in our environment, food, and many consumer products. Therefore, this study aims to determine bisphenol-A effects on the hypothalamo-pituitary-ovarian axis, and role of melatonin in this regard. Forty-two Wistar rats were bred, grouped into 7, with each group consisting of 6 rats. Experimental groups were administered low and high doses of bisphenol-A and melatonin, starting from day 19, and was continued for 7 weeks orally. They were left to develop into full adults and were sacrificed on day 120±4 days. Blood samples, hypothalamus, pituitary and ovarian tissues were excised for biochemical and tissue antioxidants assays as well as genetic studies. Results show elevated gonadotropin and androgen levels. There was disruption of reactive oxygen species in the ovarian tissues, as well as alterations in the expression of genes that regulate reproduction at the hypothalamus and pituitary levels. Conclusion of early exposure to bisphenol-A is associated with prolonged duration of disruption of reproductive functions in female Wistar rats, which persist long after cessation of the exposure. Melatonin antioxidant effects give some promising outturns against bisphenol-A induced toxicities.

Bisphenol A induced toxicity in blood cells of freshwater fish Channa punctatus after acute exposure

The widespread use of bisphenol A (BPA) has led to its ubiquity in the natural environment. It is extensively incorporated into different industrial products and is associated with deleterious health effects on both public and wildlife. The current trial was conducted to determine the toxic potential of bisphenol A using various parameters viz haematological, biochemical, and cytological in freshwater fish Channa punctatus. For this purpose, fish were exposed to 1.81 mg/l (1/4 of LC₅₀) and 3.81 mg/l (1/2 of LC₅₀) of BPA along with positive (acetone) and negative controls (water) for 96 h. The blood samples were collected at 24, 48, 72, and 96 h post-exposure. Compared to the control group, fish after acute exposure to BPA showed a significant decrease in HB content, number of red blood cells, PCV values whereas a significant increase in WBCs count was recorded with an increase in the exposure period. Besides, oxidative stress (determined as malondialdehyde content) increased as BPA concentration increased. Further, the activity of different antioxidant enzymes like catalase, and superoxide dismutase decreased significantly after treatment. Results also showed significantly increased frequency of morphological alterations, nuclear changes, and increased DNA damage potential of BPA in red blood cells. Further structural analysis of erythrocytes in maximally damaged group using Scanning Electron Microscopy was performed. The study concludes that BPA exhibits genotoxic activity and oxidative stress could be one of the mechanisms leading to genetic toxicity.

Evaluation of Oxidative stress, antioxidant enzymes and genotoxic potential of bisphenol A in fresh water bighead carp (Aristichthys nobils) fish at low concentrations

Bisphenol A (BPA) is one of the emerging contaminants associated with deleterious health effects on both public and wildlife and is extensively incorporated into different industrial products. Therefore, the current trial was conducted to determine the oxidative stress, status of different antioxidant enzymes and genotoxic potential of bisphenol A in fresh water fish at low concentrations. For this purpose, a total of 80 fresh water bighead carp (Aristicthys nobilis) received from commercial fish center were randomly divided and kept in four groups (A-D). Fish in groups (B-D) were exposed to different levels of BPA for a period of 60 days while fish of group A served as control group. Treated fish exhibited different physical and behavioral ailments in a time and treatment manners. Results showed significantly (p < 0.05) increased quantity of different oxidative stress biomarkers such as thiobarbituric acid reactive substance (TBARS), reduced glutathione (GSH) and the contents of reactive oxygen species (ROS) in gills, liver, kidneys and brain of exposed fish. Concentration of different antioxidant enzymes like catalase, superoxide dismutase, peroxidase and total proteins was significantly (p < 0.05) decreased in gills, liver, kidneys and brain of exposed fish. Results showed significantly (p < 0.05) increased frequency of morphological alterations, nuclear changes in red blood cells and increased DNA damage potential of bisphenol A in gills, liver, kidneys and brain tissues. The current trial concludes that even at very low concentrations bisphenol A causes toxic effects via turbulences in physiological and biochemical parameters in multiple tissues of fish.

Quercetin abrogates bisphenol A induced altered neurobehavioral response and oxidative stress in zebrafish by modulating brain antioxidant defence system

Bisphenol A (BPA), a well-recognized anthropogenic xenoestrogen, has been identified as a causative agent responsible for inducing carcinogenicity, cognitive impairment, neurotoxicity, oxidative stress, etc. However, BPA-induced neurotoxicity and its possible amelioration through natural compound intervention remain elusive. The current study was performed to elucidate the neurotoxic potential of BPA in zebrafish (Danio rerio) by waterborne exposure and its possible amelioration by quercetin co-supplementation. Protective effect of quercetin against BPA-induced altered neurobehavioral response, oxidative stress and neuromorphological changes were evaluated in zebrafish brain. The present findings reveal that BPA-induced altered neurobehavioral response was ameliorated by quercetin. Biochemical studies advocate the potential therapeutic efficacy of quercetin against BPA-induced oxidative stress in zebrafish brain. Quercetin also shows neuroprotection against BPA-induced augmented neuronal pyknosis in periventricular grey zone (PGZ) of zebrafish brain. These basic findings indicate that quercetin may act as an effective intervention against BPA-induced neurotoxicity in zebrafish through down-regulation of oxidative stress.

ROS signaling cascades: dual regulations for osteoclast and osteoblast

Accumulating evidence indicates that intracellular reactive oxygen species (ROS) production is highly involved in bone homeostasis by intervening osteoclast or osteoblast differentiation. Interestingly, ROS that are known as oxidizing agents exert dose-dependent biphasic properties in bone remodeling, including preventing osteoblast activity but accelerating osteoclast resorption. ROS mainly composed of superoxide anion radical, hydroxyl radical, nitric oxide, and two-electron reduction product hydrogen peroxide, which are important components to regulate bone cell metabolism and function in mammal skeleton. These free radicals can be partly produced in bone and boosted in an inflammation state. Although numerous researches have emphasized the impacts of ROS on bone cell biology and verified the mechanism of ROS signaling cascades, the recapitulatory commentary is necessary. In this review article, we particularly focus on the regulation of the intracellular ROS and its potential mechanism impacting on cell-signaling transduction in osteoclast and osteoblast differentiation for preferable understanding the pathogenesis and searching for novel therapeutic protocols for human bone diseases.

Luteolin-Supplemented diets ameliorates Bisphenol A-Induced toxicity in Drosophila melanogaster

Bisphenol A (BPA) is an industrial chemical used in the production of various plastic materials. It is associated with reproductive, immunological and neurological disorders. Luteolin, a flavonoid found in fruits and vegetables, possesses anti-oxidative, anti-inflammatory and free radical scavenging properties. Here, we carried out studies to ascertain if Luteolin would ameliorate BPA-induced toxicity in Drosophila melanogaster. Firstly, flies were treated separately with Luteolin (0, 50, 100, 150 and 300 mg/kg diet) and BPA (0, 0.01, 0.05 and 0.1 mM) for 28 days survival assessments. Consequently, Luteolin (150 and 300 mg/kg diet) and/or BPA (0.05 mM) were exposed to D. melanogaster for 7 days for the evaluation of nitric oxide level, eclosion rate, viability assay, histology of fat body, antioxidant (Glutathione-S-transferase, catalase and total thiol), oxidative stress (hydrogen peroxide) and behavioural (negative geotaxis and acetylcholinesterase) markers. The results showed that BPA induced antioxidant-oxidative stress imbalance and behavioural deficit in flies. Luteolin increased survival rate and augmented antioxidant markers in flies. Importantly, Luteolin ameliorated BPA-induced degeneration in the fat body around the rostral, thorax and abdominal regions, oxidative stress, behavioural deficit, reduction in cell viability and eclosion rate of D. melanogaster (p < 0.05). Overall, this study offered further insights on the antioxidative and chemopreventive properties of Luteolin against BPA-induced toxicity.

Molecular and cellular mechanisms linking air pollution and bone damage

Air pollution is the second most important risk factor associated with noncommunicable diseases after smoking. The effects of pollution on health are commonly attributable to particulate matter (PM), a complex mixture of particles suspended in the air. PM can penetrate the lower respiratory tract and has harmful direct and indirect effects on different organs and tissues. Direct effects are caused by the ability of PM components to cross the respiratory membrane and enter the bloodstream; indirect effects are systemic consequences of the local airway response. Recent work suggests that PM is an independent risk factor for low bone mineral density and osteoporosis-related fractures. Osteoporosis is a common age-related disease closely linked to bone fractures, with severe clinical consequences affecting quality of life, morbidity, and mortality. In this review, we discuss potential mechanisms behind the association between outdoor air pollution, especially PM, and bone damage. The discussion features four main mechanisms: 1) several different atmospheric pollutants can induce low-grade systemic inflammation, which affects bone metabolism through a specific effect of cytokines such as TNFα, IL-1β, IL-6, and IL-17 on osteoblast and osteoclast differentiation and function; 2) some pollutants, particularly certain gas and metal compounds, can cause oxidative damage in the airway and bone cells; 3) different groups of pollutants can act as endocrine disruptors when binding to the receptors in bone cells, changing their functioning; and 4) air pollution can directly and indirectly cause vitamin D deficiency. Characterizing these mechanisms will better define the physiopathology of bone damage, and recognizing air pollution as a modifiable risk factor for osteoporosis will inform environmental policies. Such knowledge will also guide the prevention of fractures due to fragility and help reduce health-related costs.

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

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

The effects of different bisphenol derivatives on oxidative stress, DNA damage and DNA repair in RWPE-1 cells: A comparative study

Bisphenol A (BPA) is a well-known endocrine disruptor and it is widely used mainly in the plastics industry. Due to recent reports on its possible impact on health (particularly on the male reproductive system), bisphenol F (BPF) and bisphenol S (BPS) are now being used as alternatives. In this study, RWPE-1 cells were used as a model to compare cytotoxicity, oxidative stress-causing potential and genotoxicity of these chemicals. In addition, the effects of the bisphenol derivatives were assessed on DNA repair proteins. RWPE-1 cells were incubated with BPA, BPF, and BPS at concentrations of 0-600 μM for 24 h. The inhibitory concentration 20 (IC₂₀ , concentration that causes 20% of cell viability loss) values for BPA, BPF, and BPS were 45, 65, and 108 μM, respectively. These results indicated that cytotoxicity potentials were ranked as BPA > BPF > BPS. We also found alterations in superoxide dismutase, glutathione peroxidase and glutathione reductase activities, and glutathione and total antioxidant capacity in all bisphenol-exposed groups. In the standard and modified Comet assay, BPS produced significantly higher levels of DNA damage vs the control. DNA repair proteins (OGG1, Ape-1, and MyH) involved in the base excision repair pathway, as well as p53 protein levels were down-regulated in all of the bisphenol-exposed groups. We found that the BPA alternatives were also cytotoxic and genotoxic, and changed the expressions of DNA repair enzymes. Therefore, further studies are needed to assess whether they can be used safely as alternatives to BPA or not.

Effects of environmental stressors on stem cells

Environmental toxicants are ubiquitous, and many are known to cause harmful health effects. However, much of what we know or think we know concerning the targets and long-term effects of exposure to environmental stressors is sadly lacking. Toxicant exposure may have health effects that are currently mischaracterized or at least mechanistically incompletely understood. While much of the recent excitement about stem cells (SCs) focuses on their potential as therapeutic agents, they also offer a valuable resource to give us insight into the mechanisms and risks of toxicant effects. Not only as a response to the increasing ethical pressure to reduce animal testing, SC studies allow us valuable insight into the true effects of human exposure to environmental stressors under controlled conditions. We present a review of the history of publications on the effects of environmental stressors on SCs, followed by a consolidation of the literature over the past five years on a subset of key environmental stressors of importance to human health and their effects on both embryonic and tissue SCs. The review will make constructive suggestions as to areas of toxicant research where further studies are needed, as well as making indications of the potential utility for advancing knowledge and directing research on environmental toxicology.

Melatonin Improves Oocyte Maturation and Mitochondrial Functions by Reducing Bisphenol A-Derived Superoxide in Porcine Oocytes In Vitro

Bisphenol A (BPA) is synthetic organic compound that exhibits estrogen-like properties and it induces mitochondrial superoxide production. Melatonin (Mela) protects against BPA-mediated cell damage and apoptosis. However, the antioxidative effects of Mela against BPA-induced superoxide production in porcine oocytes are still not known. In this study, we investigated the antioxidative effects of Mela against BPA-derived superoxide on oocyte maturation in pigs. To investigate the effects of the superoxide specific scavenger, Mito-TEMPO, on porcine oocyte maturation in response to BPA exposure apoptosis proteins, we treated the oocytes with Mito-TEMPO (0.1 µM) after pre-treating them with BPA (75 µM) for 22 h. As expected, the reduction in meiotic maturation and cumulus cell expansion of cumulus-oocyte-complexes (COCs) in the BPA (75 µM) treated group was recovered (p < 0.01) by treatment with Mito-TEMPO (0.1 µM). An increase in the levels of mitochondrial apoptotic proteins (AIF, cleaved Cas 3 and cleaved Parp1) in response to BPA-induced damage was also reduced by Mito-TEMPO treatment in porcine COCs. Interestingly, we confirmed the positive effects of Mela with respect to superoxide production upon BPA exposure during oocyte maturation and also confirmed the reduction in mitochondrial apoptosis in Mela (0.1 µM)-treated porcine COCs. These results provide evidence for the first time that antioxidative effects of Mela on BPA-derived superoxide improve porcine oocyte maturation.

Bisphenol A affects cell viability involved in autophagy and apoptosis in goat testis sertoli cell

Bisphenol A (BPA) is shown to be the endocrine disruptor that induces reproductive dysfunction in male animals. In this study, we aim to probe the effects of BPA exposure on induction of autophagy in goat Sertoli Cells (gSCs), as well as the relationship between autophagy and apoptosis. Results indicated that exposure to BPA (100, 200, 300, 400, 500 and 600μM) decreased the cell viability in a concentration-dependent manner. Exposure of gSCs to 500μM BPA for 12h resulted in in vitro triggered loss of mitochondrial membrane potential (ΔΨm) and increased reactive oxygen species (ROS) production. Apoptosis with an increase in Bax:Bcl-2 ratio and higher rates of autophagy, such as autophagosome formation and increased expression of autophagy-related markers were also induced in gSCs exposed to 500μM BPA. Furthermore, treatment with 350nM Rapamycin (Rap, autophagy activator) alleviated a decrease in cell viability, intracellular ROS production, and reduction of ΔΨm, as well as decreasing apoptosis. Collectively, our results indicated that gSCs viability was disrupted after BPA treatment through affecting ROS production, mitochondrial membrane potential and inducing autophagy/apoptosis.

Induction of oxidative stress by bisphenol A and its pleiotropic effects

Bisphenol A (BPA) has become a target of intense public scrutiny since concerns about its association with human diseases such as obesity, diabetes, reproductive disorders, and cancer have emerged. BPA is a highly prevalent chemical in consumer products, and human exposure is thought to be ubiquitous. Numerous studies have demonstrated its endocrine disrupting properties and attributed exposure with cytotoxic, genotoxic, and carcinogenic effects; however, the results of these studies are still highly debated and a consensus about BPA's safety and its role in human disease has not been reached. One of the contributing factors is a lack of molecular mechanisms or modes of action that explain the diverse and pleiotropic effects observed after BPA exposure. The increase in BPA research seen over the last ten years has resulted in more studies that examine molecular mechanisms and revealed links between BPA-induced oxidative stress and human disease. Here, a review of the current literature examining BPA exposure and the induction of reactive oxygen species (ROS) or oxidative stress will be provided to examine the landscape of the current BPA literature and provide a framework for understanding how induction of oxidative stress by BPA may contribute to the pleiotropic effects observed after exposure. Environ. Mol. Mutagen. 58:60-71, 2017. © 2017 Wiley Periodicals, Inc.

Bisphenol-A and metabolic diseases: epigenetic, developmental and transgenerational basis

Exposure to environmental toxicants is now accepted as a factor contributing to the increasing incidence of obesity and metabolic diseases around the world. Such environmental compounds are known as 'obesogens'. Among them, bisphenol-A (BPA) is the most widespread and ubiquitous compound affecting humans and animals. Laboratory animal work has provided conclusive evidence that early-life exposure to BPA is particularly effective in predisposing individuals to weight gain. Embryonic exposure to BPA is reported to generate metabolic disturbances later in life, such as obesity and diabetes. When BPA administration is combined with a high-fat diet, there is an exacerbation in the development of metabolic disorders. Remarkably, upon BPA exposure of gestating females, metabolic disturbances have been found both in the offspring and later in life in the mothers themselves. When considering the metabolic effects generated by an early developmental exposure to BPA, one of the questions that arises is the role of precursor cells in the etiology of metabolic disorders. Current evidence shows that BPA and other endocrine disruptors have the ability to alter fat tissue development and growth by affecting the capacity to generate functional adipocytes, as well as their rate of differentiation to specific cell types. Epigenetic mechanisms seem to be involved in the BPA-induced effects related to obesity, as they have been described in both in vitro and in vivo models. Moreover, recent reports also show that developmental exposure to BPA generates abnormalities that can be transmitted to future generations, in a process called as transgenerational epigenetic inheritance.