Inhibitory Effects of Bisphenol-A on Neural Stem Cells Proliferation and Differentiation in the Rat Brain Are Dependent on Wnt/β-Catenin Pathway

Synthesis and biological evaluation of novel Trifluoromethylated Arylidene-hydrazinyl-thiazoles as neuroprotective agents

Neurodegenerative diseases, a substantial global health challenge affecting millions, underscore the pressing need for novel and effective pharmacotherapeutic drugs to address these disorders. In this concern, a library of novel trifluoromethylated arylidene-hydrazinyl-thiazoles has been synthesized and assessed for their anti-neurodegenerative potential. Multicomponent regioselective chemical transformation has been carried out utilizing thiosemicarbazide, trifluoromethylated 1,3-diketones and heteroaryl aldehydes in the presence of N-bromosuccinimide (NBS) in refluxing ethanol. The regioisomeric structure of the synthesized products was unambiguously characterized by employing heteronuclear 2D NMR spectroscopic studies. All the synthesized derivatives were evaluated for their anti-neurodegenerative properties on rat brain hippocampus-derived Neural Stem Cells (NSCs), examining their impact on survival, proliferation and neuronal differentiation in vitro. Among the tested thiazole derivatives, compounds 4a, 4b, 4c, 4f, 4 g, 4b' and 4i' demonstrated a remarkable increase in the number of neuronal cells as compared to the control group within the NSC culture and also exhibited the ability to promote NSC differentiation towards the neuronal lineage. Additionally, the selected compounds showed protection against amyloid beta (Aβ)-induced neurotoxicity in NSCs culture. Incorporating the trifluoromethyl group into the thiazole scaffold is a pivotal factor in augmenting biopotency, resulting in a marked increase in the count of neuronal cells compared to their non-fluorinated thiazole counterparts.

The association between urinary BPA concentrations and urinary incontinence in women

Urinary incontinence (UI) significantly impacts the quality of life and psychological well-being of female patients. Although emerging evidence suggests potential links between endocrine-disrupting chemicals and pelvic floor disorders, previous studies on the association between bisphenol A (BPA) exposure and UI in women have yielded inconsistent results. This study aimed to examine this potential association using data from the 2015-2016 National Health and Nutrition Examination Survey (NHANES) (n = 467). Through multiple logistic regression analysis with three adjustment models: Model 1 (crude), Model 2 (adjusted for socio-demographic factors: age, race/ethnicity, education, marital status, and poverty ratio), and Model 3 (further adjusted for BMI, hypertension, diabetes, alcohol/smoking status, and delivery history), we assessed BPA exposure categorized into quartiles. No significant associations were observed between BPA exposure and either stress urinary incontinence (SUI) or mixed urinary incontinence (MUI) across all models (P > 0.05). However, participants in the highest BPA quartile (> 7.6 ng/mg creatinine) exhibited a significantly increased risk of urge urinary incontinence (UUI) in Model 1 (OR = 2.01, 95% CI [1.12-3.63]), Model 2 (OR = 2.04, 95% CI [1.08-3.85]), and Model 3 (OR = 2.48, 95% CI [1.18-5.20]). This study has several limitations, including its cross-sectional design, reliance on self-reported UI outcomes, single measurement of urinary BPA, and potential residual confounding from unmeasured factors. While these findings suggest that environmental BPA exposure may contribute to UUI risk in women, future longitudinal studies with repeated biomarker measurements and objective UI assessments are needed to confirm these observations and explore potential mechanisms. If validated, reducing BPA exposure through public health interventions could emerge as a novel preventive strategy for UUI.

Bacopaside-I ameliorates motor dysfunction and neurodegeneration in rat model of Parkinson's disease

Chronic administration of Bacopa monnieri extract exerts neuroprotective potential in multiple animal models of neurodegenerative disorders such as Parkinson's disease (PD), Alzheimer's disease (AD), depression, and other cognitive impairments. However, the underlying mechanism of action remained unclear. Rotenone model of PD holds a great potential for investigating PD pathology and motor and nonmotor symptoms. Herein, we evaluated the neuroprotective effect of Bacopaside-I (BS-I), a major triterpenoid saponin of Bacopa monnieri extract, against rotenone-induced in vivo model of PD and explored the possible molecular mechanism. Rats were exposed to rotenone (2 mg/kg body weight) for a period of 4 consecutive weeks to induce PD-like behavior. BS-I (5, 15, and 45 mg/kg) was administered orally. Behavioral data (rotarod, foot printing, and grip strength test) suggest that BS-I plays a significant role in attenuating the motor function deficit. Exposure to rotenone reduces the dopamine level and increases oxidative stress, while BS-I treatment reversed these changes. Furthermore, chronic administration of BS-I increased the expression levels of dopamine transporter (DAT) and vesicular monoamine transporter (VMAT) genes and the numbers of tyrosine hydroxylase (TH)-positive neurons as compared to rotenone-exposed animals. Our study established the neuroprotective role of BS-I in PD model and laid the foundation for further evaluation of BS-I-based drug in future studies.

Prenatal exposure to Bisphenol A sex-specifically disrupts prepulse inhibition and decreases parvalbumin-positive neurons in the prefrontal cortex of adult rats

Early-life exposure to bisphenol A (BPA) has adverse effects on neuronal development and behavioral performance; however, many aspects of its effects remain unknown. Here, we aimed to investigate whether prenatal exposure to BPA can induce psychotic-like behaviors and impair certain schizophrenia-related GABAergic markers, including GAD67, NRG1, ERbB4, and parvalbumin (PV), in the prefrontal cortex (PFC) of adult offspring rats. Pregnant Sprague-Dawley rats were orally administered BPA (0.25 and 2.5 mg/kg/day), ethinyl estradiol as a reference estrogen, or a vehicle during the pregnancy period. On postnatal days (PNDs) 62-63, male and female offspring were tested for prepulse inhibition (PPI) and locomotor activity, followed by tissue collection on PND 64. Both doses of BPA significantly decreased PPI in female offspring compared to the control group, while no significant changes were observed in male offspring. Moreover, in female offspring, a marked reduction in the density of PV-positive neurons in the PFC was observed in both BPA groups compared to the control group. In the locomotor activity test, neither sex showed significant changes. Meanwhile, the PFC expression of GAD67, NRG1, and ERbB4 genes did not show significant alterations in either male or female rats. Overall, this study demonstrates that prenatal BPA exposure disrupts PPI and decreases PV-positive neurons in the PFC of adult female rats. In other words, early neurodevelopment can be sex-specifically impaired by BPA, which may consequently increase susceptibility to schizophrenia in adulthood. Therefore, the detrimental effects of BPA on embryonic and fetal brain development should be considered in health policies related to pregnancy.

The combined damage of bisphenol A and high fat diet to learning and memory in young male mice: the regulatory effect of BDNF/TrkB/PI3K/AKT pathway on autophagy

With the popularity of takeaway and processed food, combined exposure to Bisphenol A (BPA) and high fat diet (HFD) is becoming increasingly common. BPA or HFD intake in children could impair learning and memory ability, but the combined effect and mechanisms remain unclear. In this study, we fed young male mice with 0.1 μg/mL BPA (L-BPA), 0.2 μg/mL BPA (H-BPA), 60 %HFD (HFD), 0.1 BPA + HFD (L-BPA + HFD) and 0.2 BPA + HFD (H-BPA + HFD) for 8 weeks. The results showed that recognition memory and free exploration of mice were impaired in the BPA or HFD group, and the damage of exploration was more severe in the combined group. All treated groups showed morphological changes in hippocampal neurons. The levels of synaptic structural protein PSD-95 and SYN were reduced in BPA and HFD alone or in combination groups. BPA or HFD led to changes in autophagy levels in the hippocampus, manifested by decreased protein levels of mTOR and P62, increased level of LC3B, and more significant changes in the combined group. The BDNF/TrkB/PI3K/AKT pathway was inhibited in BPA or HFD groups, especially in the combined group. Our results suggested that combined BPA with HFD exposure could impair learning and memory ability, and the combined effect might be related to the BDNF/TrkB/PI3K/AKT pathway, which regulated mTOR mediated autophagy and finally caused hippocampal synaptic damage.

Embryonic BPF exposure induces neurodevelopmental and neurobehavioral toxicity by affecting neural stem cell proliferation in Drosophila

BPF is a ubiquitous environmental chemical that has been shown to affect neurodevelopmental toxicity from animals to humans. Whether BPF exposure affects neural stem cell proliferation and differentiation is unknown. Here, we utilized a method of permeabilization of Drosophila embryos to analyze the effects of exposure to 0.5 mM, 1 mM, and 2 mM BPF on the proliferation and differentiation of neural stem cells. Our results showed that BPF exposure reduced the number of neuroblasts and intermediate neural progenitors during the embryonic stage, which caused the neuron/glial cell ratio to be out of balance, with a decrease in the number of neurons and an increase in the number of glial cells. BPF exposure caused neurotoxicity by reducing the activities of the antioxidant enzymes CAT and SOD, the downregulation of the transcriptional levels of oxidative stress-related genes, which triggered oxidative damage. As a result, embryonic BPF exposure affected the development of the neuromuscular junctions (NMJs) by reducing the number of axon branches and synaptic buttons, decreasing the number of peristaltic contractions, and reducing larval locomotion. In conclusion, our results demonstrate that embryonic BPF exposure disrupts neural stem cell proliferation, causing neurodevelopmental toxicity and abnormal larval behavior.

Bisphenol S interrupted axonogenesis on a human embryonic stem cells derived neural differentiation model: Conserved axon guidance and WNT signaling pathway involved

Bisphenol S (BPS) is the main substitute for bisphenol A (BPA). However, the neurodevelopmental toxicity of BPS and the underlying mechanisms remain unraveled. In present study, the neuro-differentiating human embryonic stem cells, hESC, was exposed to BPS (0-375 µM) at different stages (the precursor stage, the precursor to maturation stage, and the whole differentiation stage) to assess the potential neurodevelopmental toxicity and its mechanisms. The results revealed that BPS exposure interrupted axonogenesis, manifesting a trend of initial stimulating followed by inhibition, and peaked at the intermediate dose (3.75 μM) significantly, then reached the nadir at the high dose (375 μM) significantly in the precursor to maturation stage and the whole differentiation stage. Transcriptomics analysis showed that the main interrupted pathway enriched in axonogenesis, myelination, and neurotransmitter secretion by the GO function analysis and immune-related pathway by the KEGG analysis, besides, conserved axon guidance (Slit-Robo, Netrin-DCC, Semaphorin-Plexin) and WNT signaling pathway was also enriched in KEGG pathway analysis, which previously proved to regulate axonogenesis by directly acting on growth cones and inhibit axon growth by neuroinflammatory responses. And we found that a higher neuroinflammatory response may be induced through whole-differentiation-stage exposure than the response of exposure through the precursor to maturation stage. Overall, our findings indicated the non-monotonic neurodevelopmental toxicity of BPS exposure, and the inhibition of axonogenesis was possibly mediated by conserved axon guidance and WNT signaling pathway, while neuro-immune related pathway should be further investigated.

Sex-specific effects of prenatal bisphenol A exposure on transcriptome-interactome profiles of autism candidate genes in neural stem cells from offspring hippocampus

Bisphenol A (BPA), an endocrine-disrupting chemical, is increasingly linked to the pathogenesis of autism spectrum disorder (ASD). This study investigates the effects of prenatal BPA exposure on neural stem cells (NSCs) from the hippocampi of rat offspring, a brain region critical for neurodevelopment and implicated in ASD. Pregnant rats were administered with BPA or vehicle control once daily via oral gavage from gestational day 1 until parturition. NSCs were isolated from the offspring's hippocampi on postnatal day 1, and RNA sequencing was performed to examine transcriptomic alterations. Differentially expressed genes (DEGs) were identified through RNA-seq and further analyzed using Ingenuity Pathway Analysis (IPA) to explore disrupted pathways. In addition, in vitro proliferation assays were conducted, utilizing immunofluorescence staining for Sox2, a stem cell marker, and BrdU to quantify proliferating NSCs. Our results revealed that prenatal BPA exposure induced sex-specific alterations in NSC gene expression, with ASD-related genes such as Atp1a3, Nefl, and Grin1 being particularly dysregulated in male offspring. Moreover, sex-specific changes in NSC proliferation were observed. The study underscores BPA's potential as an environmental risk factor for ASD, emphasizing the need for further research into its role in sex-specific neurodevelopmental effects.

Implication of Pyrethroid Neurotoxicity for Human Health: A Lesson from Animal Models

Pyrethroids, synthetic insecticides used in pest management, pose health risks, particularly neurotoxic effects, with studies linking exposure to a neurodegenerative disorder. This review examines the neurotoxic mechanisms of pyrethroids analyzing literature from animal model studies. It identifies critical targets for neurotoxicity, including ion channels, oxidative stress, inflammation, neuronal cell loss, and mitochondrial dysfunction. The review also discusses key therapeutic targets and signaling pathways relevant to Pyrethroids neurotoxicity management, including calcium, Wnt/β-catenin, mTOR, MAPK/Erk, PI3K/Akt, Nrf2, Nurr1, and PPARγ. Our findings demonstrate that pyrethroid exposure triggers multiple neurotoxic pathways that bear resemblance to the mechanisms underlying neurotoxicity. Oxidative stress and inflammation emerge as prominent factors that contribute to neuronal degeneration, alongside disrupted mitochondrial function. The investigation highlights the significance of ion channels as primary neurodegeneration targets while acknowledging the potential involvement of various other receptors and enzymes that may exacerbate neurological damage. Additionally, we elucidate how pyrethroids may interfere with therapeutic targets associated with neuronal dysfunction, potentially impairing treatment efficacy.Also, exposure to these chemicals can alter DNA methylation patterns and histone modifications, ultimately leading to changes in gene expression that may enhance susceptibility to neurological disorders. Pyrethroid neurotoxicity poses a significant public health risk, necessitating future research for protective strategies against pesticide-induced neurological disorders and understanding the interplay between neurodegenerative diseases, potentially leading to innovative therapeutic interventions.

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

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

Bisphenol-F and Bisphenol-S (BPF and BPS) Impair the Stemness of Neural Stem Cells and Neuronal Fate Decision in the Hippocampus Leading to Cognitive Dysfunctions

Neurogenesis occurs throughout life in the hippocampus of the brain, and many environmental toxicants inhibit neural stem cell (NSC) function and neuronal generation. Bisphenol-A (BPA), an endocrine disrupter used for surface coating of plastic products causes injury in the developing and adult brain; thus, many countries have banned its usage in plastic consumer products. BPA analogs/alternatives such as bisphenol-F (BPF) and bisphenol-S (BPS) may also cause neurotoxicity; however, their effects on neurogenesis are still not known. We studied the effects of BPF and BPS exposure from gestational day 6 to postnatal day 21 on neurogenesis. We found that exposure to non-cytotoxic concentrations of BPF and BPS significantly decreased the number/size of neurospheres, BrdU+ (proliferating NSC marker) and MAP-2+ (neuronal marker) cells and GFAP+ astrocytes in the hippocampus NSC culture, suggesting reduced NSC stemness and self-renewal and neuronal differentiation and increased gliogenesis. These analogs also reduced the number of BrdU/Sox-2+, BrdU/Dcx+, and BrdU/NeuN+ co-labeled cells in the hippocampus of the rat brain, suggesting decreased NSC proliferation and impaired maturation of newborn neurons. BPF and BPS treatment increases BrdU/cleaved caspase-3+ cells and Bax-2 and cleaved caspase protein levels, leading to increased apoptosis in hippocampal NSCs. Transmission electron microscopy studies suggest that BPF and BPS also caused degeneration of neuronal myelin sheath, altered mitochondrial morphology, and reduced number of synapses in the hippocampus leading to altered cognitive functions. These results suggest that BPF and BPS exposure decreased the NSC pool, inhibited neurogenesis, induced apoptosis of NSCs, caused myelin degeneration/synapse degeneration, and impaired learning and memory in rats.

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 (BPA) and neurological disorders: An overview

The human body is commonly exposed to bisphenol A (BPA), which is widely used in consumer and industrial products. BPA is an endocrine-disrupting chemical that has adverse effects on human health. In particular, many studies have shown that BPA can cause various neurological disorders by affecting brain development and neural function during prenatal, infancy, childhood, and adulthood exposure. In this review, we discussed the correlation between BPA and neurological disorders based on molecular cell biology, neurophysiology, and behavioral studies of the effects of BPA on brain development and function. Recent studies, both animal and epidemiological, strongly indicate that BPA significantly impacts brain development and function. It hinders neural processes, such as proliferation, migration, and differentiation during development, affecting synaptic formation and activity. As a result, BPA is implicated in neurodevelopmental and neuropsychiatric disorders like autism spectrum disorder (ASD), attention-deficit hyperactivity disorder (ADHD), and schizophrenia.

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.

Exploring novel insights into the molecular mechanisms underlying Bisphenol A-induced toxicity: A persistent threat to human health

Bisphenol A (BPA) is a ubiquitous industrial chemical used in the production of polycarbonate plastics and epoxy resins, found in numerous consumer products. Despite its widespread use, its potential adverse health effects have raised significant concerns. This review explores the molecular mechanisms and evidence-based literature underlying BPA-induced toxicities and its implications for human health. BPA is an endocrine-disrupting chemical (EDC) which exhibits carcinogenic properties by influencing various receptors, such as ER, AhR, PPARs, LXRs, and RARs. It induces oxidative stress and contributes to cellular dysfunction, inflammation, and DNA damage, ultimately leading to various toxicities including but not limited to reproductive, cardiotoxicity, neurotoxicity, and endocrine toxicity. Moreover, BPA can modify DNA methylation patterns, histone modifications, and non-coding RNA expression, leading to epigenetic changes and contribute to carcinogenesis. Overall, understanding molecular mechanisms of BPA-induced toxicity is crucial for developing effective strategies and policies to mitigate its adverse effects on human health.

Cyanidin improves spatial memory and cognition in bisphenol A-induced rat model of Alzheimer's-like neuropathology by restoring canonical Wnt signaling

INTRODUCTION

Research has unveiled the neurotoxicity of Bisphenol A (BPA) linked to neuropathological traits of Alzheimer's disease (AD) through varied mechanisms. This study aims to investigate the neuroprotective properties of cyanidin, an anthocyanin, in an in vivo model of BPA-induced Alzheimer's-like neuropathology.

METHODS

Three-week-old Sprague-Dawley rats were randomly assigned to four groups: vehicle control, negative control (BPA exposure), low-dose cyanidin treatment (BPA + cyanidin 5 mg/kg), and high-dose cyanidin treatment (BPA + cyanidin 10 mg/kg). Spatial memory was assessed through behavioral tests, including the Y-maze, novel object recognition, and Morris water maze. After behavioral tests, animals were euthanized, and brain regions were examined for acetylcholinesterase inhibition, p-tau, Wnt3, GSK3β, and β-catenin levels, antioxidant activities, and histopathological changes.

RESULTS

BPA-exposed groups displayed memory impairments, while cyanidin-treated groups showed significant memory improvement (p < 0.0001). Cyanidin down regulated p-tau and glycogen synthase kinase-3β (GSK3β) and restored Wnt3 and β-catenin levels (p < 0.0001). Moreover, cyanidin exhibited antioxidant properties, elevating catalase and superoxide dismutase levels. The intervention significantly reduced the concentrations of acetylcholinesterase in the cortex and hippocampus in comparison to the groups treated with BPA (p < 0.0001). Significant gender-based disparities were not observed.

CONCLUSION

Cyanidin demonstrated potent neuroprotection against BPA-induced Alzheimer's-like neuropathology by enhancing antioxidant defenses, modulating tau phosphorylation by restoring the Wnt/β-catenin pathway, and ameliorating spatial memory deficits. This study highlights the therapeutic potential of cyanidin in countering neurotoxicity linked to BPA exposure.

Cyanidin Ameliorates Bisphenol A-Induced Alzheimer's Disease Pathology by Restoring Wnt/β-Catenin Signaling Cascade: an In Vitro Study

Alzheimer's disease (AD) is a progressive neurodegenerative disorder causing memory loss and cognitive decline, linked to amyloid-beta (Aβ) plaques and hyperphosphorylated tau protein accumulation in the brain. Environmental pollutant bisphenol A (BPA) has been implicated in AD pathology due to its neurotoxic effects. This study aims to evaluate cyanidin from flower bracts of Musa acuminata Colla (red variety; AAA group) for its neuroprotective properties against BPA-induced AD pathology. The extraction of cyanidin was optimized using 70% ethanol in acidified water, showing promising anti-acetylcholinesterase activity. Cyanidin was effectively purified from the resultant extract and characterized using spectroscopic techniques. Two gradient doses of cyanidin (90 and 10 µg/ml) were determined based on cell viability assay. The role of cyanidin in promoting nerve growth and differentiation was assessed in PC12 cells for up to 72 h. A discernible and statistically significant difference was assessed in neurite extension at both doses at 72 h, followed by pre-treatment with cyanidin. BPA stimulation significantly increased the p-tau expression compared to the control (p < 0.0001). Pre-treatment with cyanidin reduced the tau expression; however, a significant difference was observed compared to control cells (p = 0.0003). Cyanidin significantly enhanced the mRNA expression of Wnt3a (p < 0.0001), β-catenin (p = 0.0004), and NeuroD1 (p = 0.0289), and decreased the expression of WIF1(p = 0.0040) and DKK1 (p < 0.0001), which are Wnt antagonist when compared to cells stimulated with BPA. Conclusively, our finding suggests that cyanidin could agonize nerve growth factor and promote neuronal differentiation, reduce tau-hyperphosphorylation by restoring the Wnt/β-catenin signaling cascade, and thereby render its neuroprotective potential against BPA-induced AD pathology.

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.

Ischemia-reperfusion injury: molecular mechanisms and therapeutic targets

Ischemia-reperfusion (I/R) injury paradoxically occurs during reperfusion following ischemia, exacerbating the initial tissue damage. The limited understanding of the intricate mechanisms underlying I/R injury hinders the development of effective therapeutic interventions. The Wnt signaling pathway exhibits extensive crosstalk with various other pathways, forming a network system of signaling pathways involved in I/R injury. This review article elucidates the underlying mechanisms involved in Wnt signaling, as well as the complex interplay between Wnt and other pathways, including Notch, phosphatidylinositol 3-kinase/protein kinase B, transforming growth factor-β, nuclear factor kappa, bone morphogenetic protein, N-methyl-D-aspartic acid receptor-Ca2+-Activin A, Hippo-Yes-associated protein, toll-like receptor 4/toll-interleukine-1 receptor domain-containing adapter-inducing interferon-β, and hepatocyte growth factor/mesenchymal-epithelial transition factor. In particular, we delve into their respective contributions to key pathological processes, including apoptosis, the inflammatory response, oxidative stress, extracellular matrix remodeling, angiogenesis, cell hypertrophy, fibrosis, ferroptosis, neurogenesis, and blood-brain barrier damage during I/R injury. Our comprehensive analysis of the mechanisms involved in Wnt signaling during I/R reveals that activation of the canonical Wnt pathway promotes organ recovery, while activation of the non-canonical Wnt pathways exacerbates injury. Moreover, we explore novel therapeutic approaches based on these mechanistic findings, incorporating evidence from animal experiments, current standards, and clinical trials. The objective of this review is to provide deeper insights into the roles of Wnt and its crosstalk signaling pathways in I/R-mediated processes and organ dysfunction, to facilitate the development of innovative therapeutic agents for I/R injury.

Modeling early human cortical development and evaluating neurotoxicity with a forebrain organoid system

The complexity and subtlety of brain development renders it challenging to examine effects of environmental toxicants on human fetal brain development. Advances in pluripotent cell-derived organoid systems open up novel avenues for human development, disease and toxicity modeling. Here, we have established a forebrain organoid system and recapitulated early human cortical development spatiotemporally including neuroepithelium induction, apical-basal axis formation, neural progenitor proliferation and maintenance, neuronal differentiation and layer/region patterning. To explore whether this forebrain organoid system is suitable for neurotoxicity modeling, we subjected the organoids to bisphenol A (BPA), a common environmental toxicant of global presence and high epidemic significance. BPA exposure caused substantial abnormalities in key cortical developmental events, inhibited progenitor cell proliferation and promoted precocious neuronal differentiation, leading premature progenitor cell depletion and aberrant cortical layer patterning and structural organization. Consistent with an antagonistic mechanism between thyroid hormone and BPA, T3 supplementation attenuated BPA-mediated cortical developmental abnormalities. Altogether, our in vitro recapitulation of cortical development with forebrain organoids provides a paradigm for efficient neural development and toxicity modeling and related remedy testing/screening.

Computational Construction of Toxicant Signaling Networks

Humans and animals are regularly exposed to compounds that may have adverse effects on health. The Toxicity Forecaster (ToxCast) program was developed to use high throughput screening assays to quickly screen chemicals by measuring their effects on many biological end points. Many of these assays test for effects on cellular receptors and transcription factors (TFs), under the assumption that a toxicant may perturb normal signaling pathways in the cell. We hypothesized that we could reconstruct the intermediate proteins in these pathways that may be directly or indirectly affected by the toxicant, potentially revealing important physiological processes not yet tested for many chemicals. We integrate data from ToxCast with a human protein interactome to build toxicant signaling networks that contain physical and signaling protein interactions that may be affected as a result of toxicant exposure. To build these networks, we developed the EdgeLinker algorithm, which efficiently finds short paths in the interactome that connect the receptors to TFs for each toxicant. We performed multiple evaluations and found evidence suggesting that these signaling networks capture biologically relevant effects of toxicants. To aid in dissemination and interpretation, interactive visualizations of these networks are available at http://graphspace.org.

Proteomics and disease network associations evaluation of environmentally relevant Bisphenol A concentrations in a human 3D neural stem cell model

Bisphenol A (BPA) exposure is associated with a plethora of neurodevelopmental abnormalities and brain disorders. Previous studies have demonstrated BPA-induced perturbations to critical neural stem cell (NSC) characteristics, such as proliferation and differentiation, although the underlying molecular mechanisms remain under debate. The present study evaluated the effects of a repeated-dose exposure of environmentally relevant BPA concentrations during the in vitro 3D neural induction of human induced pluripotent stem cells (hiPSCs), emulating a chronic exposure scenario. Firstly, we demonstrated that our model is suitable for NSC differentiation during the early stages of embryonic brain development. Our morphological image analysis showed that BPA exposure at 0.01, 0.1 and 1 µM decreased the average spheroid size by day 21 (D21) of the neural induction, while no effect on cell viability was detected. No alteration to the rate of the neural induction was observed based on the expression of key neural lineage and neuroectodermal transcripts. Quantitative proteomics at D21 revealed several differentially abundant proteins across all BPA-treated groups with important functions in NSC proliferation and maintenance (e.g., FABP7, GPC4, GAP43, Wnt-8B, TPPP3). Additionally, a network analysis demonstrated alterations to the glycolytic pathway, potentially implicating BPA-induced changes to glycolytic signalling in NSC proliferation impairments, as well as the pathophysiology of brain disorders including intellectual disability, autism spectrum disorders, and amyotrophic lateral sclerosis (ALS). This study enhances the current understanding of BPA-related NSC aberrations based mostly on acute, often high dose exposures of rodent in vivo and in vitro models and human GWAS data in a novel human 3D cell-based model with real-life scenario relevant prolonged and low-level exposures, offering further mechanistic insights into the ramifications of BPA exposure on the developing human brain and consequently, later life neurological disorders.

Antenatal Exposure to Plastic Pollutants: Study of the Bisphenols and Perfluoroalkyls Effects on Human Stem Cell Models

Endocrine disruptors (EDs), such as Bisphenols (BPs) and Perfluoroalkyls (PFs), are a class of plastic pollutants widely used in industrial applications. Human exposure to these molecules usually occurs through ingestion of contaminated food and water. Once entered the human body they can interfere with endogenous hormone signaling, leading to a wide spectrum of diseases. It has been reported that BPs and PFs can cross the placental barrier accumulating in the fetal serum, but the detrimental consequences for human development remain to be clarified. Here we analyze the effects of different doses of bisphenol A and S (BPA, BPS) perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) on proliferation and mitochondrial health on different types of stem cells: through an integrated approach that combines data from pluripotent stem cells (hiPSCs) with that from the “environment” in which the embryo develops (fetal annexes-derived perinatal stem cells) we verified the potential developmental toxicity of the in utero EDs exposure. Data obtained showed that overall, BPs, and PFs tended to increase the proliferation rate of perinatal stem cells; a similar response was observed in hiPSCs exposed to very low doses of BPs and PFs, while at higher concentrations these chemicals were toxic; in addition, both the BPs and the PFs exerted a mitotoxic effects hiPSCs at all the concentration studied. All these data suggest that antenatal exposure to BPs and PFs, also at very low concentrations, may modify the biological characteristics of stem cells present in both the developing fetus and the fetal annexes, thus perturbing normal human development.

Bisphenol-A Neurotoxic Effects on Basal Forebrain Cholinergic Neurons In Vitro and In Vivo

The widely used plasticizer bisphenol-A (BPA) is well-known for producing neurodegeneration and cognitive disorders, following acute and long-term exposure. Although some of the BPA actions involved in these effects have been unraveled, they are still incompletely known. Basal forebrain cholinergic neurons (BFCN) regulate memory and learning processes and their selective loss, as observed in Alzheimer's disease and other neurodegenerative diseases, leads to cognitive decline. In order to study the BPA neurotoxic effects on BFCN and the mechanisms through which they are induced, 60-day old Wistar rats were used, and a neuroblastoma cholinergic cell line from the basal forebrain (SN56) was used as a basal forebrain cholinergic neuron model. Acute treatment of rats with BPA (40 µg/kg) induced a more pronounced basal forebrain cholinergic neuronal loss. Exposure to BPA, following 1- or 14-days, produced postsynaptic-density-protein-95 (PSD95), synaptophysin, spinophilin, and N-methyl-D-aspartate-receptor-subunit-1 (NMDAR1) synaptic proteins downregulation, an increase in glutamate content through an increase in glutaminase activity, a downregulation in the vesicular-glutamate-transporter-2 (VGLUT2) and in the WNT/β-Catenin pathway, and cell death in SN56 cells. These toxic effects observed in SN56 cells were mediated by overexpression of histone-deacetylase-2 (HDAC2). These results may help to explain the synaptic plasticity, cognitive dysfunction, and neurodegeneration induced by the plasticizer BPA, which could contribute to their prevention.

Exposure to bisphenol A induces neurotoxicity associated with synaptic and cytoskeletal dysfunction in neuro-2a cells

Bisphenol A (BPA) has been reported to injure the developing and adult brain. However, the underlying mechanism still remains elusive. This study used neuro-2a cells as a cellular model to investigate the neurotoxic effects of BPA. Microtubule-associated protein 2 (MAP2) and tau protein maintain microtubule normal function and promote the normal development of the nervous system. Synaptophysin (SYP) and drebrin (Dbn) proteins are involved in regulating synaptic plasticity. Cells were exposed to the minimum essential medium (MEM), 0.01% (v/v) DMSO, and 150 μM BPA for 12, 24, or 36 h. Morphological analysis revealed that the cells in the BPA-treated groups shrank and collapsed compared with those in the control groups. CCK-8 and lactate dehydrogenase assay (LDH) assays showed that the mortality of neuro-2a cells increased as the BPA treatment time was prolonged. Ultrastructural analysis further revealed that cells demonstrated nucleolar swelling, dissolution of nuclear and mitochondrial membranes, and partial mitochondrial condensation following exposure to BPA. BPA also decreased the relative protein expression levels of MAP2, tau, and Dbn. Interestingly, the relative protein expression levels of SYP increased. These results indicated that BPA inhibited the proliferation and disrupted cytoskeleton and synaptic integrity of neuro-2a cells.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

Bisphenol-A (BPA) Impairs Hippocampal Neurogenesis via Inhibiting Regulation of the Ubiquitin Proteasomal System

The ubiquitin-proteasome system (UPS) controls protein homeostasis to maintain cell functionality and survival. Neurogenesis relies on proteasome function, and a defective proteasome system during brain development leads to neurological disorders. An endocrine-disrupting xenoestrogen bisphenol-A (BPA) used in plastic products adversely affects human health and causes neurotoxicity. Previously, we reported that BPA reduces neural stem cells (NSCs) proliferation and differentiation, impairs myelination and mitochondrial protein import, and causes excessive mitochondrial fragmentation leading to cognitive impairments in rats. Herein, we examined the effect(s) of prenatal BPA exposure on UPS functions during NSCs proliferation and differentiation in the hippocampus. Rats were orally treated with 40 µg/kg body weight BPA during day 6 gestation to day 21 postnatal. BPA significantly reduced proteasome activity in a cellular extract of NSCs. Immunocytochemistry exhibited a significant reduction of 20S proteasome/Nestin⁺ and PSMB5/Nestin⁺ cells in NSCs culture. BPA decreased 20S/Tuj1⁺ and PSMB5/Tuj1⁺ cells, indicating disrupted UPS during neuronal differentiation. BPA reduced the expression of UPS genes, 20S, and PSMB5 protein levels and proteasome activity in the hippocampus. It significantly reduced overall protein synthesis by the loss of Nissl substances in the hippocampus. Pharmacological activation of UPS by a bioactive triterpenoid 18α-glycyrrhetinic acid (18α GA) caused increased proteasome activities, significantly increased neurosphere size and number, and enhanced NSCs proliferation in BPA exposed culture, while proteasome inhibition by MG132 further aggravates BPA-mediated effects. In silico studies demonstrated that BPA strongly binds to catalytic sites of UPS genes (PSMB5, TRIM11, Parkin, and PSMD4) which may result in UPS inactivation. These results suggest that BPA significantly reduces NSCs proliferation by impairing UPS, and UPS activation by 18α GA could suppress BPA-mediated neurotoxicity and exerts neuroprotection.

Transient developmental exposure to low doses of bisphenol F negatively affects neurogliogenesis and olfactory behaviour in adult mice

Neural stem cells in the murine subventricular zone (SVZ) reactivate during postnatal development to generate neurons and glia throughout adulthood. We previously demonstrated that a postnatal thyroid hormone (TH) peak orchestrates this remodelling, rendering this process vulnerable to endocrine disruption. We exposed mice to 2 or 200 µg/kg bw/day of the bisphenol A-replacement and suspected TH-disruptor bisphenol F (BPF) in the drinking water, from embryonic day 15 to postnatal day 21 (P21). In parallel, one group was exposed to the TH-synthesis blocker propylthiouracil (0.15 % PTU). In contrast to PTU, BPF exposure did not affect serum TH levels at P15, P21 or P60. RNA-seq on dissected SVZs at P15 revealed dysregulated neurodevelopmental genes in all treatments, although few overlapped amongst the conditions. We then investigated the phenotype at P60 to analyse long-term consequences of transient developmental exposure. As opposed to hypothyroid conditions, and despite dysregulated oligodendrogenesis-promoting genes in the P15 SVZ exposed to the highest dose of BPF, immunostainings for myelin and OLIG2/CC1 showed no impact on global myelin content nor oligodendrocyte maturation in the P60 corpus callosum, apart from a reduced thickness. The highest dose did reduce numbers of newly generated SVZ-neuroblasts with 22 %. Related to this were behavioural alterations. P60 mice previously exposed to the highest BPF dose memorized an odour less well than control animals did, although they performed better than PTU-exposed animals. All mice could discriminate new odours, but all exposed groups showed less interest in social odours. Our data indicate that perinatal exposure to low doses of BPF disrupts postnatal murine SVZ remodelling, and lowers the adult neuron/oligodendroglia output, even after exposure had been absent for 40 days. These anomalies warrant further investigation on the potential harm of alternative bisphenol compounds for human foetal brain development.

Nattokinase attenuates bisphenol A or gamma irradiation-mediated hepatic and neural toxicity by activation of Nrf2 and suppression of inflammatory mediators in rats

Nattokinase (NK), a protease enzyme produced by Bacillus subtilis, has various biological effects such as lipid-lowering activity, antihypertensive, antiplatelet/anticoagulant, and neuroprotective effects. Exposure to environmental toxicants such as bisphenol A (BPA) or γ-radiation (IR) causes multi-organ toxicity through several mechanisms such as impairment of oxidative status, signaling pathways, and hepatic and neuronal functions as well as disruption of the inflammatory responses. Therefore, this study is designed to evaluate the ameliorative effect of NK against BPA- or IR-induced liver and brain damage in rats. Serum ammonia level and liver function tests were measured in addition to brain oxidative stress markers, amyloid-beta, tau protein, and neuroinflammatory mediators. Moreover, relative quantification of brain nuclear factor-erythroid 2-related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) genes, as well as apoptotic markers in brain tissue, was carried out in addition to histopathological examination. The results showed that NK improved liver functions, impaired oxidative status, the cholinergic deficits, and minified the misfolded proteins aggregates. Furthermore, NK alleviated the neuroinflammation via modulating NF-κB/Nrf2/HO-1 pathway and glial cell activation in addition to their antiapoptotic effect. Collectively, the current results revealed the protective effect of NK against hepatic and neurotoxicity derived from BPA or IR.

Bisphenol-A Mediated Impaired DRP1-GFER Axis and Cognition Restored by PGC-1α Upregulation Through Nicotinamide in the Rat Brain Hippocampus

The regulatory network of mitochondrial biogenesis and dynamics is vital for mitochondrial functions and cellular homeostasis. Any impairment in the mitochondrial network leads to neurodegenerative disorders. Our earlier studies suggest that environmental toxicant Bisphenol-A (BPA) exposure reduces neurogenesis by abnormal mitochondrial dynamics and mitochondrial biogenesis through impairment of mitochondrial fission factor dynamin-related protein (DRP1) and mitochondrial import protein GFER, which leads to demyelination, neurodegeneration, and cognitive deficits in the rats. In the present study, we found that chronic BPA exposure reduces PGC-1α levels (master regulator of mitochondrial biogenesis), alters mitochondrial localization of DRP1 and GFER, and reduces the number of PGC-1α/NeuN+ and PGC-1α/β-tubulin+ neurons in the rat hippocampus, suggesting reduced PGC-1α-mediated neurogenesis. Nicotinamide significantly increased PGC-1α protein levels, PGC-1α/NeuN+ co-labeled cells in BPA-treated rat hippocampus and PGC-1α/β-tubulin+ co-labeled cells in neuron culture derived from hippocampal neural stem cells. Interestingly, PGC-1α upregulation by nicotinamide also resulted in increased GFER levels and restored mitochondrial localization of GFER (increased GFER/TOMM20 co-labeled cells) in vitro and in vivo following BPA treatment. Nicotinamide also reduced DRP1 levels and prevented DRP1 mitochondrial localization in BPA-treated neuronal cultures and hippocampus, suggesting reduced mitochondrial fission. This resulted in reduced cytochrome c levels in neuronal culture and reduced hippocampal neurodegeneration (reduced caspase-3/NeuN+ co-labeled neurons) following nicotinamide treatment in BPA-treated group. Consequently, activation of PGC-1α by nicotinamide restored BPA-mediated cognitive deficits in rats. Results suggest that the treatment of nicotinamide has therapeutic potential and rescues BPA-mediated neuronal death and cognitive deficits by upregulating the PGC-1α and GFER-DRP1 link, thus balancing mitochondrial homeostasis.

Selective effects of perinatal estrogen on proliferation and new neurons in hippocampus and piriform cortex of rats at weaning

BACKGROUND

A recent report links heightened prenatal amniotic estrogen levels to an increased risk of autism spectrum disorder (ASD). In this study, we examined the developmental effects of perinatal estrogen treatment on stem cell activity in weaned rats.

METHODS

Sprague-Dawley rats received ethinyl estradiol (EE2, 10µg/kg/day) or vehicle orally from gestational day 6 until parturition. Offspring were then treated with the same daily dose from postnatal days (PNDs) 1-21. The effects of perinatal estrogen treatment on stem cell activities in the subgranular zone (SGZ) of the hippocampus and the piriform cortex were evaluated in male and female rat pups.

RESULTS

EE₂ treatment increased the total Ki67-immunoreactive (Ki67-ir) cell counts in the SGZ of males and females (p<0.05). However, no treatment or sex differences were detectable in the density of the doublecortin (DCX)-immunoreactive (DCX-ir) deposits in the hippocampus. In the piriform cortex, no treatment or sex differences were detected in Ki67-ir cell counts. However, the EE₂ treatment significantly reduced the DCX-ir cell count in male, but not female rats (male EE₂ group=29₂±22/mm², male vehicle group=402±19/mm², female EE² group=34₂±15/mm², female vehicle group=331±9/mm²).

CONCLUSIONS

Perinatal estrogen treatment increased hippocampal Ki67-ir cell counts in both sexes and selectively reduced DCX-ir cell counts in the piriform cortex of males. These data suggest that exposure to abnormally high levels of estrogens early in life may have an impact on neural cell development. Alterations in development so early in life may have long-term cognitive impact.

Pumpkin extract and fermented whey individually and in combination alleviated AFB1- and OTA-induced alterations on neuronal differentiation invitro

Food and feed are daily exposed to mycotoxin contamination which effects may be counteracted by functional compounds like carotenoids and fermented whey. Among mycotoxins, the most toxic and studied are aflatoxin B1 (AFB1) and ochratoxin A (OTA), which neurotoxicity is not well reported. Therefore, SH-SY5Y human neuroblastoma cells ongoing differentiation were exposed during 7 days to digested bread extracts contained pumpkin and fermented whey, individually and in combination, along with AFB1 and OTA and their combination, in order to evaluate their presumed effects on neuronal differentiation. The immunofluorescence analysis of βIII-tubulin and dopamine markers pointed to OTA as the most damaging treatment for cell differentiation. Cell cycle analysis reported the highest significant differences for OTA-contained bread compared to the control in phase G₀/G₁. Lastly, RNA extraction was performed and gene expression was analyzed by qPCR. The selected genes were related to neuronal differentiation and cell cycle. The addition of functional ingredients in breads not only enhancing the expression of neuronal markers, but also induced an overall improvement of gene expression compromised by mycotoxins activity. These data confirm that in vitro neuronal differentiation may be impaired by AFB1 and OTA-exposure, which could be modulated by bioactive compounds naturally found in diet.

Evaluation of BPA effects on autophagy in Neuro-2a cells

Bisphenol A (BPA), which is used for the industrial production of polycarbonate plastics and epoxy resins, is found in many commercially available products. Plasticizer BPA produces chemical substances worldwide, and knowledge of its effects on humans and animals is increasing. In the present work, the morphology of cells was observed by optical microscopy and phalloidin staining to evaluate the toxic effect of BPA on Neuro-2a cells. Autophagy has an important role in the regulation of cell metabolism. To study the effect of BPA on the autophagy in Neuro-2a cells, the expression distribution of LC3 was detected by immunofluorescence, and the expression levels of p62 and Beclin1 were determined using western blot and quantitative real-time PCR (qRT-PCR), respectively. Optical microscopy and phalloidin staining revealed that the cells became rounded and small and that the dendritic spine of the cells were reduced at high BPA doses. Immunofluorescence analysis demonstrated that the expression of LC3 fluorescence intensity was weak at increasing BPA concentrations. Western blot results showed that the relative expression of protein p62 increased significantly and that the relative expression levels of the Beclin1 and the LC3 proteins significantly decreased with increasing BPA concentration. qRT-PCR results showed that the relative expression level of autophagy-related p62 mRNA increased significantly and that the relative expression level of Beclin1 mRNA decreased significantly with increasing BPA concentration. The above results indicated that BPA treatment exerted dose-dependent toxic effects on Neuro-2a cells, and BPA inhibited the autophagy level of Neuro-2a cells, thereby providing a new perspective in studying the toxic effect of BPA on Neuro-2a cells.

Does Bisphenol A Confer Risk of Neurodevelopmental Disorders? What We Have Learned from Developmental Neurotoxicity Studies in Animal Models

Substantial evidence indicates that bisphenol A (BPA), a ubiquitous environmental chemical used in the synthesis of polycarbonate plastics and epoxy resins, can impair brain development. Clinical and epidemiological studies exploring potential connections between BPA and neurodevelopmental disorders in humans have repeatedly identified correlations between early BPA exposure and developmental disorders, such as attention deficit/hyperactivity disorder and autism spectrum disorder. Investigations using invertebrate and vertebrate animal models have revealed that developmental exposure to BPA can impair multiple aspects of neuronal development, including neural stem cell proliferation and differentiation, synapse formation, and synaptic plasticity-neuronal phenotypes that are thought to underpin the fundamental changes in behavior-associated neurodevelopmental disorders. Consistent with neuronal phenotypes caused by BPA, behavioral analyses of BPA-treated animals have shown significant impacts on behavioral endophenotypes related to neurodevelopmental disorders, including altered locomotor activity, learning and memory deficits, and anxiety-like behavior. To contextualize the correlations between BPA and neurodevelopmental disorders in humans, this review summarizes the current literature on the developmental neurotoxicity of BPA in laboratory animals with an emphasis on neuronal phenotypes, molecular mechanisms, and behavioral outcomes. The collective works described here predominantly support the notion that gestational exposure to BPA should be regarded as a risk factor for neurodevelopmental disorders.

Bisphenol a affects neurodevelopmental gene expression, cognitive function, and neuromuscular synaptic morphology in Drosophila melanogaster

Bisphenol A (BPA) is an environmentally prevalent endocrine disrupting chemical that can impact human health and may be an environmental risk factor for neurodevelopmental disorders. BPA has been associated with behavioral impairment in children and a variety of neurodevelopmental phenotypes in model organisms. We used Drosophila melanogaster to explore the consequences of developmental BPA exposure on gene expression, cognitive function, and synapse development. Our transcriptome analysis indicated neurodevelopmentally relevant genes were predominantly downregulated by BPA. Among the misregulated genes were those with roles in learning, memory, and synapse development, as well as orthologs of human genes associated with neurodevelopmental and neuropsychiatric disorders. To examine how gene expression data corresponded to behavioral and cellular phenotypes, we first used a predator-response behavioral paradigm and found that BPA disrupts visual perception. Further analysis using conditioned courtship suppression showed that BPA impairs associative learning. Finally, we examined synapse morphology within the larval neuromuscular junction and found that BPA significantly increased the number of axonal branches. Given that our findings align with studies of BPA in mammalian model organisms, this data indicates that BPA impairs neurodevelopmental pathways that are functionally conserved from invertebrates to mammals. Further, because Drosophila do not possess classic estrogen receptors or estrogen, this research suggests that BPA can impact neurodevelopment by molecular mechanisms distinct from its role as an estrogen mimic.

Role of Bisphenol A in Autophagy Modulation: Understanding the Molecular Concepts and Therapeutic Options

Abstract:

Bisphenol A (4,4′-isopropylidenediphenol) is an organic compound, commonly used in the plastic bottles, packaging containers, beverages and resin industry. The adverse effects of bisphenol A were studied in various systems of the body. Autophagy is a lysosomal degradation process meant for the regeneration of new cells. The role of bisphenol A on autophagy modulation in the pathogenesis of diseases is still debatable. Few research studies showed that bisphenol A-induced adverse effects were associated with autophagy dysregulation, while few showed the activation of autophagy by bisphenol A. Such contrasting views make the subject more interesting and debatable. In the present review, we discuss the different steps of autophagy, genes involved, and the effect of bisphenol A in autophagy modulation on different systems of the body. We also discuss the methods for monitoring autophagy and the roles of drugs such as chloroquine, verteporfin, and rapamycin in autophagy. Proper understanding of the role of bisphenol A in the modulation of autophagy may be important for future treatment and drug discovery.

Roles of ERRα and TGF-β signaling in stemness enhancement induced by 1 µM bisphenol A exposure via human neural stem cells

Bisphenol A (BPA) is a common industrial chemical widely used to produce various plastics and is known to impair neural stem cells (NSCs). However, the effects of low-dose BPA exposure on the stemness maintenance and differentiation fate of NSCs remain unclear in the infant brain. The present study demonstrated that 1 µM BPA promoted human NSC proliferation and stemness, without significantly increasing apoptosis. The Chip-seq experiments demonstrated that both the cell cycle and the TGF-β signaling pathway were accelerated after treatment with 1 µM BPA. Subsequently, estrogen-related receptor α (ERRα) gene knockout cell lines were constructed using CRISPR/Cas9. Further western blotting and chromatin immunoprecipitation-PCR experiments demonstrated that BPA maintained cell stemness by binding to an EERα receptor and activating the TGF-β1 signaling pathway, including the downstream factors Aurora kinases B and Id2. In conclusion, the stemness of NSCs could be maintained by BPA at 1 µM through the activation of the ERRα and TGF-β1 signaling pathways and could restrain the differentiation of NSCs into neurons. The present research further clarified the mechanism of BPA toxicity on NSCs from the novel perspective of ERRα and TGF-β1 signaling pathways regulated by BPA and provided insights into potential novel methods of prevention and therapy for neurogenic diseases.

Role of neurotoxicants in the pathogenesis of Alzheimer's disease: a mechanistic insight

Alzheimer's disease (AD) is the most conspicuous chronic neurodegenerative syndrome, which has become a significant challenge for the global healthcare system. Multiple studies have corroborated a clear association of neurotoxicants with AD pathogenicity, such as Amyloid beta (Aβ) proteins and neurofibrillary tangles (NFTs), signalling pathway modifications, cellular stress, cognitive dysfunctions, neuronal apoptosis, neuroinflammation, epigenetic modification, and so on. This review, therefore, aimed to address several essential mechanisms and signalling cascades, including Wnt (wingless and int.) signalling pathway, autophagy, mammalian target of rapamycin (mTOR), protein kinase C (PKC) signalling cascades, cellular redox status, energy metabolism, glutamatergic neurotransmissions, immune cell stimulations (e.g. microglia, astrocytes) as well as an amyloid precursor protein (APP), presenilin-1 (PSEN1), presenilin-2 (PSEN2) and other AD-related gene expressions that have been pretentious and modulated by the various neurotoxicants. This review concluded that neurotoxicants play a momentous role in developing AD through modulating various signalling cascades. Nevertheless, comprehension of this risk agent-induced neurotoxicity is far too little. More in-depth epidemiological and systematic investigations are needed to understand the potential mechanisms better to address these neurotoxicants and improve approaches to their risk exposure that aid in AD pathogenesis.Key messagesInevitable cascade mechanisms of how Alzheimer's Disease-related (AD-related) gene expressions are modulated by neurotoxicants have been discussed.Involvement of the neurotoxicants-induced pathways caused an extended risk of AD is explicited.Integration of cell culture, animals and population-based analysis on the clinical severity of AD is addressed.

Bisphenol a Induces Autophagy Defects and AIF-Dependent Apoptosis via HO-1 and AMPK to Degenerate N2a Neurons

Bisphenol A (BPA) is an environmental contaminant widely suspected to be a neurological toxicant. Epidemiological studies have demonstrated close links between BPA exposure, pathogenetic brain degeneration, and altered neurobehaviors, considering BPA a risk factor for cognitive dysfunction. However, the mechanisms of BPA resulting in neurodegeneration remain unclear. Herein, cultured N2a neurons were subjected to BPA treatment, and neurotoxicity was assessed using neuronal viability and differentiation assays. Signaling cascades related to cellular self-degradation were also evaluated. BPA decreased cell viability and axon outgrowth (e.g., by down-regulating MAP2 and GAP43), thus confirming its role as a neurotoxicant. BPA induced neurotoxicity by down-regulating Bcl-2 and initiating apoptosis and autophagy flux inhibition (featured by nuclear translocation of apoptosis-inducing factor (AIF), light chain 3B (LC3B) aggregation, and p62 accumulation). Both heme oxygenase (HO)-1 and AMP-activated protein kinase (AMPK) up-regulated/activated by BPA mediated the molecular signalings involved in apoptosis and autophagy. HO-1 inhibition or AIF silencing effectively reduced BPA-induced neuronal death. Although BPA elicited intracellular oxygen free radical production, ROS scavenger NAC exerted no effect against BPA insults. These results suggest that BPA induces N2a neurotoxicity characterized by AIF-dependent apoptosis and p62-related autophagy defects via HO-1 up-regulation and AMPK activation, thereby resulting in neuronal degeneration.

Acute Exposure to Bisphenol A Causes Oxidative Stress Induction with Mitochondrial Origin in Saccharomyces cerevisiae Cells

Bisphenol A (BPA) is a major component of the most commonly used plastic products, such as disposable plastics, Tetra Paks, cans, sport protective equipment, or medical devices. Due to the accumulation of excessive amounts of plastic waste and the subsequent release of BPA into the environment, BPA is classified as a pollutant that is undesirable in the environment. To date, the most interesting finding is the ability of BPA to act as an endocrine disrupting compound due to its binding to estrogen receptors (ERs), and adverse physiological effects on living organisms may result from this action. Since evidence of the potential pro-oxidizing effects of BPA has accumulated over the last years, herein, we focus on the detection of oxidative stress and its origin following BPA exposure using pulsed-field gel electrophoresis, flow cytometry, fluorescent microscopy, and Western blot analysis. Saccharomyces cerevisiae cells served as a model system, as these cells lack ERs allowing us to dissect the ER-dependent and -independent effects of BPA. Our data show that high concentrations of BPA affect cell survival and cause increased intracellular oxidation in yeast, which is primarily generated in the mitochondrion. However, an acute BPA exposure does not lead to significant oxidative damage to DNA or proteins.

Bisphenol-A inhibits mitochondrial biogenesis via impairment of GFER mediated mitochondrial protein import in the rat brain hippocampus

Mitochondrial biogenesis relies on different protein import machinery, as mitochondrial proteins are imported from the cytosol. The mitochondrial intermembrane space assembly (MIA) pathway consists of GFER/ALR and CHCHD4/Mia40, responsible for importing proteins and their oxidative folding inside the mitochondria. The MIA pathway plays an essential role in complex IV (COX IV) biogenesis via importing copper chaperone COX17, associated with the respiratory chain. BPA, an environmental toxicant, found in consumable plastics, causes neurotoxicity via impairment in mitochondrial dynamics, neurogenesis, and cognitive functions. We studied the levels of key regulatory proteins of mitochondrial import pathways and mitochondrial biogenesis after BPA exposure in the rat hippocampus. BPA caused a significant reduction in the levels of mitochondrial biogenesis proteins (PGC1α, and TFAM) and mitochondrial import protein (GFER). Immunohistochemical analysis showed reduced co-localization of NeuN with GFER, PGC-1α, and TFAM suggesting impaired mitochondrial biogenesis and protein import. BPA exposure resulted in damaged mitochondria with distorted cristae in neurons and caused a significant reduction in GFER localization inside IMS as depicted by immunogold electron microscopy. The reduced levels of GFER resulted in defective COX17 import. The translocation of cytochrome c into the cytosol and increased cleaved caspase-3 levels triggered apoptosis due to BPA toxicity. Overall, our study implicates GFER as a potential target for impaired mitochondrial protein machinery, biogenesis, and apoptosis against BPA neurotoxicity in the rat hippocampus.

Nanomedicine against Alzheimer's and Parkinson's Disease

Alzheimer's and Parkinson's are the two most rampant neurodegenerative disorders worldwide. Existing treatments have a limited effect on the pathophysiology but are unable to fully arrest the progression of the disease. This is due to the inability of these therapeutic molecules to efficiently cross the blood-brain barrier. We discuss how nanotechnology has enabled researchers to develop novel and efficient nano-therapeutics against these diseases. The development of nanotized drug delivery systems has permitted an efficient, site-targeted, and controlled release of drugs in the brain, thereby presenting a revolutionary therapeutic approach. Nanoparticles are also being thoroughly studied and exploited for their role in the efficient and precise diagnosis of neurodegenerative conditions. We summarize the role of different nano-carriers and RNAi-conjugated nanoparticle-based therapeutics for their efficacy in pre-clinical studies. We also discuss the challenges underlying the use of nanomedicine with a focus on their route of administration, concentration, metabolism, and any toxic effects for successful therapeutics in these diseases.

Maternal Bisphenol A (BPA) Exposure Alters Cerebral Cortical Morphogenesis and Synaptic Function in Mice

Early-life exposure to bisphenol A (BPA), synthetic compound used in polycarbonate plastic, is associated with altered cognitive and emotional behavior later in life. However, the brain mechanism underlying the behavioral deficits is unknown. Here, we show that maternal BPA exposure disrupted self-renewal and differentiation of neural progenitors during cortical development. The BPA exposure reduced the neuron number, whereas it increased glial cells in the cerebral cortex. Also, synaptic formation and transmission in the cerebral cortex were suppressed after maternal BPA exposure. These changes appeared to be associated with autophagy as a gene ontology analysis of RNA-seq identified an autophagy domain in the BPA condition. Mouse behavioral tests revealed that maternal BPA caused hyperactivity and social deficits in adult offspring. Together, these results suggest that maternal BPA exposure leads to abnormal cortical architecture and function likely by activating autophagy.

Protective effect of alpha-lipoic acid on bisphenol A-induced learning and memory impairment in developing mice: nNOS and keap1/Nrf2 pathway

The adverse effects of bisphenol A (BPA) on learning and memory may be related with oxidative stress, but the mechanisms are unclear. This study aimed to investigate the mechanism of damaged learning and memory caused by BPA through inducing oxidative stress, as well as to explore whether alpha-lipoic acid (ALA) show a protective action. Female mice were exposed to 0.1 μg/mL BPA, 0.2 μg/mL BPA, 0.6 mg/mL ALA, and 0.2 BPA + ALA through drinking water for 8 weeks. The results showed that ALA protected against the impairment of spatial, recognition, and avoidance memory caused by BPA. ALA replenished the reduce of hippocampus coefficient, serum estradiol (E2) level, and hippocampal neurotransmitters levels induced by BPA. ALA alleviated BPA-induced oxidative stress and hippocampal histological changes. BPA exposure reduced the levels of synaptic structural proteins and PKC/ERK/CREB pathway proteins, and ALA improved these reductions. ALA altered the protein levels of nNOS and keap1/Nrf2 pathway affected by BPA. Our results suggested that impairments of learning and memory caused by BPA was related to the damage of hippocampal synapses mediated by oxidative stress, and ALA protected learning and memory by reducing the oxidative stress induced by BPA through regulating the nNOS and keap1/Nrf2 pathway.

Bisphenol A and rotenone induce S-nitrosylation of protein disulfide isomerase (PDI) and inhibit neurite outgrowth of primary cultured cells of the rat hippocampus and PC12 cells

Bisphenol A (BPA) interferes the function and development of the central nervous system (CNS), resulting in behavioral abnormalities and memory loss. S-nitrosylation of protein disulfide isomerase (PDI) is increased in brains with sporadic Alzheimer's disease and Parkinson's disease. The aim of the present study was to clarify the role of nitric oxide (NO) in BPA-induced neurotoxicity. Since rotenone induces NO-mediated neurodegeneration through S-nitrosylation of PDI, it was used as a positive control. First, rats were treated with BPA and rotenone, and S-nitrosylation of PDI was detected in rat brain microsomes. BPA and rotenone decreased RNase oxidation activity of PDI concomitant with S-nitrosylation of PDI. Next, to clarify S-nitrosylation of PDI by BPA and rotenone in rat brains, we treated the rat pheochromocytoma cell line PC12 and primary cultured neuron cells from the rat hippocampus with BPA (5 and 10 μM) and rotenone (100 or 200 nM). BPA induced S-nitrosylation of PDI, while NG-monomethyl-L-arginine (L-NMMA), a NOS inhibitor, exerted the opposite effects. Finally, to evaluate the toxicity of BPA in the CNS, we investigated its effects on neurite outgrowth of PC12 and primary cultured neuron cells. BPA inhibited neurite outgrowth of these cells, while L-NMMA reversed this inhibition. The involvement of PDI activity in neurite outgrowth was also examined, and bacitracin, a PDI inhibitor, is shown to decrease neurite outgrowth. Furthermore, the overexpression of PDI, but not a catalytically inactive PDI mutant, enhanced neurite outgrowth. These results suggested that S-nitrosylation of PDI induced by excessive NO caused BPA-induced neurotoxicity.

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.

The Impact of Estrogen and Estrogen-Like Molecules in Neurogenesis and Neurodegeneration: Beneficial or Harmful?

Estrogens and estrogen-like molecules can modify the biology of several cell types. Estrogen receptors alpha (ERα) and beta (ERβ) belong to the so-called classical family of estrogen receptors, while the G protein-coupled estrogen receptor 1 (GPER-1) represents a non-classical estrogen receptor mainly located in the plasma membrane. As estrogen receptors are ubiquitously distributed, they can modulate cell proliferation, differentiation, and survival in several tissues and organs, including the central nervous system (CNS). Estrogens can exert neuroprotective roles by acting as anti-oxidants, promoting DNA repair, inducing the expression of growth factors, and modulating cerebral blood flow. Additionally, estrogen-dependent signaling pathways are involved in regulating the balance between proliferation and differentiation of neural stem/progenitor cells (NSPCs), thus influencing neurogenic processes. Since several estrogen-based therapies are used nowadays and estrogen-like molecules, including phytoestrogens and xenoestrogens, are omnipresent in our environment, estrogen-dependent changes in cell biology and tissue homeostasis have gained attention in human health and disease. This article provides a comprehensive literature review on the current knowledge of estrogen and estrogen-like molecules and their impact on cell survival and neurodegeneration, as well as their role in NSPCs proliferation/differentiation balance and neurogenesis.

Neural stem cell-based in vitro bioassay for the assessment of neurotoxic potential of water samples

Intensive agriculture activities, industrialization and growing numbers of wastewater treatment plants along river banks collectively contribute to the elevated levels of neurotoxic pollutants in natural water reservoirs across Europe. We established an in vitro bioassay based upon neural stem cells isolated from the subventricular zone of the postnatal mouse to evaluate the neurotoxic potential of raw wastewater, treated sewage effluent, groundwater and drinking water. The toxic potential of water samples was evaluated employing viability, proliferation, differentiation and migration assays. We found that raw wastewater could reduce the viability and proliferation of neural stem cells, and decreased the neuronal and astrocyte differentiation, neuronal neurite growth, astrocyte growth and cell migration. Treated sewage water also showed inhibitory effects on cell proliferation and migration. Our results indicated that relatively high concentrations of nitrogenous substances, pesticides, mercuric compounds, bisphenol-A, and phthalates, along with some other pollutants in raw wastewater and treated sewage water, might be the reason for the neuroinhibitory effects of these water samples. Our model successfully predicted the neurotoxicity of water samples collected from different sources and also revealed that the incomplete removal of contaminants from wastewater can be problematic for the developing nervous system. The presented data also provides strong evidence that more effective treatments should be used to minimize the contamination of water before release into major water bodies which may be considered as water reservoirs for human usage in the future.

Phosphofructokinase-1 Inhibition Promotes Neuronal Differentiation of Neural Stem Cells and Functional Recovery After Stroke

Ischemic stroke is a major cause of long-term disability. Neuronal differentiation of neural stem cells (NSCs) is crucial for brain repair after stroke. However, the underlying mechanisms remain unclear. Here, the role and potential mechanisms of phosphofructokinase-1 (PFK-1), the rate-limiting enzyme of glycolysis, was investigated in stroke using middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation models. We found that stroke increased the PFK-1 expression of NSCs. However, PFK-1 inhibition promoted neuronal differentiation of NSCs and facilitated the dendritic maturation of newborn neurons in vitro and in vivo. Moreover, PFK-1 inhibition also improved the spatial memory performance of MCAO rats. Additionally, we proved that the effect of PFK-1 inhibition above might be achieved by promoting β-catenin nuclear translocation and activating its downstream signaling, independent of Wnt signaling. Thus, these observations reveal a critical role of PFK-1 in stroke, which may provide a novel target for regenerative repair after stroke.