Environmental neurotoxic pollutants: review

Neurotoxic effects of chronic exposure to perfluorobutane sulfonate in adult zebrafish (Danio Rerio)

Per and polyfluoroalkyl substances (PFAS) are synthetic compounds extensively utilized in industrial applications and consumer products. Long-chain PFAS has been linked to negative health impacts, prompting the introduction of shorter-chain alternatives like perfluorobutane sulfonate (PFBS). While long-chain PFAS are known to induce oxidative stress, neuroinflammation, and neuronal apoptosis, the neurotoxic potential of short-chain PFAS like PFBS was not well studied. This study aims to evaluate the neurotoxic effect and bioaccumulation of PFBS on adult zebrafish. In this study, adult zebrafish were exposed to PFBS at concentrations of 0.14, 1.4, and 14 μM for 28 days. PFBS accumulation in zebrafish brain tissue was confirmed by specific mass spectrum peaks. Behavioral assays revealed significant anxiety-like behavior, with PFBS (14 μM) exposed zebrafish spending more time in the bottom zone of the novel tank diving test (179.33 ± 1.03 s) and in the light and dark preference results showed increased time spent in the dark zone (165.17 ± 10.89 s). Learning and memory deficits were evident in the T-maze test, where PFBS-exposed zebrafish spent less time in the favorable zone (0.67 ± 1.15 s). Biochemical analysis showed significant inhibition of acetylcholinesterase (AChE) activity in the male and female brains (0.06 μmol/min and 0.09 μmol/min). Antioxidant enzyme levels were reduced, with superoxide dismutase (SOD) 5.45 U/mg protein in the male brain and 4.06 U/mg protein in the female brain, leading to increased oxidative stress biomarkers like lipid peroxidation and nitric oxide levels in male (0.99 μmol/mg/ml and 8.85 μM) and female brain (1.83 μmol/mg/ml and 8.74 μM), respectively. Gene expression analysis demonstrated the downregulation of SOD, CAT, GSR, and GPx, indicating impaired antioxidant defense mechanisms. Histopathological analysis of PFBS exposure groups revealed vacuolation and increased pyknotic neurons in the optic tectum region of the brain. Our study suggests that PFBS exposure leads to bioaccumulation in the brain, causing histopathological changes and cognitive impairment. In conclusion, PFBS induces neurotoxicity which can be a potential risk as they are incorporated into a range of consumer products.

Lithium with environmentally relevant concentrations interferes with mitochondrial function, antioxidant response, and autophagy processes in Daphnia magna, leading to changes in life-history traits and behavior

With the increasing production and use of lithium-based products, concerns over lithium pollution in aquatic ecosystems are increasing, whereas research on its toxicity mechanisms in aquatic organisms remains limited. The main objective of the present study was to explore the effects of environmentally relevant concentrations of lithium exposure on the life-history strategy, behavior, antioxidant system, and autophagy process of Daphnia magna. Acute (24-96 h) and chronic (21 days) exposure experiments under three lithium treatments (low: 8.34 μg/L, medium: 83.44 μg/L, and high: 834.41 μg/L) were conducted. The results indicated that exposure to medium and high lithium concentrations led to eye and tail deformities in D. magna. Furthermore, developmental and reproductive parameters such as body length, total neonates per female, and average neonates per time were negatively influenced. Lithium also interfered with energy metabolism to cause the decreasing swimming speed and the reduction in the swimming range. In addition, lithium exposure affected the expression of gsk-3β, further disrupting the dynamic balance of mitochondrial fission, fusion, and regeneration, which caused ROS accumulation and induced oxidative stress. D. magna attenuated the stress by activating the FoxO/SESN and Nrf2/Keap1 pathways, synergistically enhancing downstream antioxidant enzymes expression. Concurrently, D. magna also mitigated oxidative stress and mitochondrial damage by promoting autophagy and inhibiting apoptosis. In summary, lithium harmed the physiological and biochemical functions of D. magna through multiple mechanisms, suggesting that environmental lithium pollution may pose a potential threat to aquatic organisms.

Chlorpyrifos-oxon results in autophagic flux dysfunction contributing to neuronal apoptosis via a ROS/AMPK/CHOP activation pathway

Chlorpyrifos (CPF) is a widely used organophosphate (OP) pesticide in agriculture and sanitation, known to elicit neurotoxic effects. Chlorpyrifos-oxon (CPO), a metabolite of CPF, is the primary neurotoxic agent, yet its mechanisms are less understood. In this study, we investigated the effects and underlying mechanisms of CPO-induced neurotoxicity. CPO exposure significantly induced cytotoxicity in Neuro-2a cells, alongside the activation of apoptosis, as evidenced by an increase in the apoptotic cell population, caspase-3 activity, and cleavage of caspaspe-3, -7, and PARP proteins. Furthermore, defective autophagy was observed in CPO-treated Neuro-2a cells, indicated by increased expression of Beclin-1, Atg5, LC3-II, and p62 proteins. 3-MA, an autophagy inhibitor, suppressed CPO-activated LC3-II and apoptotic marker proteins expression, but not p62. In contrast, chloroquine and bafilomycin A1, autophagic flux inhibitors, potentiated the CPO-induced elevation of LC3-II, p62, and cleaved caspase-3 and -7 protein levels. CPO exposure also upregulated CHOP protein expression. Transfection with CHOP-specific siRNA markedly reduced CHOP protein expression, autophagic flux dysfunction, and apoptosis. Additionally, CPO exposure significantly increased AMPKα phosphorylation and reactive oxygen species (ROS) generation. Antioxidant N-acetylcysteine (NAC), but not the AMPK inhibitor Compound C, effectively attenuated the CPO-induced ROS generation in neuronal cells, which was accompanied by the prevention of AMPKα activation, downstream CHOP expression, autophagic flux dysfunction, and apoptosis. Collectively, these findings suggest that CPO-induced neurotoxicity arises from autophagic flux dysfunction, contributing to apoptosis via the ROS-activated AMPK pathway, which regulates CHOP expression, ultimately leading to neuronal cell death. Targeting the ROS/AMPK/CHOP axis may offer a promising intervention to against CPO-induced neurotoxicity.

Low lipid levels caused by bisphenol S exposure trigger neuroinflammation and apoptosis in the brain of zebrafish

Bisphenol S (BPS), as an environmental pollutant, is known to reduce brain lipid levels and induce neurotoxicity. However, whether brain lipid imbalance can induce neurotoxicity has not yet been clarified. Here, wild-type zebrafish and apoEb mutant zebrafish were used to investigate the effect of BPS on the macrophages proliferation and microglia mobilization caused by the decrease of cerebral lipids and its potential neurotoxic effects. The zebrafish exposed to BPS (1, 10, or 100 μg/L) from 2 hours after fertilization (hpf) to 3 days after fertilization (dpf) displayed microglial aggregation, as well as a decrease in brain lipid content. Lipidomic analyses of the brains and plasma of 50 dpf zebrafish exposed to BPS were used to identify key lipids, including lysophosphatidylcholine and phosphatidylcholine in brain and phosphatidylcholine in plasma. The apoEb mutant zebrafish as a hyperlipidemia model was used to further demonstrate that BPS-induced lipid reduction increased the number of microglia in the brain. Our data provide new insight into the mechanism by which pollutants cause neurotoxicity.

Trimester-specific associations of exposure to epoxide alkanes, alkenals, and 1,3-butadiene with preschool children's intellectual development: A birth cohort study in Wuhan, China

The impact of prenatal exposure to contaminants with neurotoxicity like epoxide alkanes (ethylene oxide, propylene oxide), alkenals (acrolein, crotonaldehyde), and 1,3-butadiene on children's intellectual development remains underreported, and related sensitive window is of interest. In this cohort study, metabolites of these contaminants were measured in 3,081 urine samples from 1,027 pregnant women across three trimesters. Children's intelligence quotient was evaluated at 4-6 years old. Generalized estimating equation models showed that higher urinary concentrations of 2-hydroxypropyl mercapturic acid (a metabolite of propylene oxide), 3-hydroxypropyl mercapturic acid (HPMMA, a metabolite of crotonaldehyde), and the sum of acrolein metabolites in the first trimester were associated with lower visual spatial index (VSI), working memory index (WMI), or processing speed index scores. Quantile g-computation models revealed that co-exposure to these contaminants in the first trimester were associated with lower VSI (β = -0.98, 95 % CI: -1.94, -0.03) and WMI (β = -0.86, 95 % CI: -1.66, -0.06) scores, with HPMMA as the major contributor. These results suggested that early pregnancy could be a sensitive window during which exposure to propylene oxide, crotonaldehyde, and acrolein may impair offspring's intellectual development.

The role of pyroptosis in environmental pollutants-induced multisystem toxicities

The global ecosystem is adversely affected by environmental pollutants, which have numerous deleterious consequences on both the environment and human health. A multitude of human organs and systems, including the neurological, digestive, cardiovascular, reproductive, and respiratory systems, can be adversely affected by these pollutants. Pyroptosis is a form of programmed cell death, primarily involving the Caspase-1/Gasdermin D (GSDMD) classical inflammasome pathway, Caspase-4/5/11/GSDMD non-classical inflammasome pathway, Caspase-3/8 pathway, and other signaling pathways, which induce cell death and regulate the occurrence of inflammatory responses. Pyroptosis plays an important role in a range of diseases, including cancer, neurodegenerative diseases and cardiovascular disease. Evidence has emerged in recent years indicating that environmental pollutants exert various toxic effects by modulating pyroptosis. In this review, we examine hepatotoxicity, cardiovascular toxicity, nephrotoxicity, neurotoxicity, pulmonary toxicity, reproductive toxicity and the related mechanisms caused by environmental pollutants through the regulation of pyroptosis. We aim to provide theoretical references for future toxicity research on environmental pollutants.

Air Pollution-Induced Neurotoxicity: The Relationship Between Air Pollution, Epigenetic Changes, and Neurological Disorders

Air pollution is a major global health threat, responsible for over 8 million deaths in 2021, including 700,000 fatalities among children under the age of five. It is currently the second leading risk factor for mortality worldwide. Key pollutants, such as particulate matter (PM2.5, PM10), ozone, sulfur dioxide, nitrogen oxides, and carbon monoxide, have significant adverse effects on human health, contributing to respiratory and cardiovascular diseases, as well as neurodevelopmental and neurodegenerative disorders. Among these, particulate matter poses the most significant threat due to its highly complex mixture of organic and inorganic compounds with diverse sizes, compositions, and origins. Additionally, it can penetrate deeply into tissues and cross the blood-brain barrier, causing neurotoxicity which contributes to the development of neurodegenerative diseases. Although the link between air pollution and neurological disorders is well documented, the precise mechanisms and their sequence remain unclear. Beyond causing oxidative stress, inflammation, and excitotoxicity, studies suggest that air pollution induces epigenetic changes. These epigenetic alterations may affect the expression of genes involved in stress responses, neuroprotection, and synaptic plasticity. Understanding the relationship between neurological disorders and epigenetic changes induced by specific air pollutants could aid in the early detection and monitoring of central nervous system diseases.

Focusing on Keap1, IKKβ, and Bcl2 proteins: predicted targets of stigmasterol in neurodegeneration

Oxidative stress, driven by excess ROS, damages lipids, proteins, and DNA, leading to neuronal apoptosis and inflammation, a key factor in neurodegenerative diseases. This study explored stigmasterol, a bioactive phytosterol, with neuroprotective potential, revealing strong docking interactions, especially with Keap1 (binding energy of -11.62 Kcal/mol). Stigmasterol formed two hydrogen bonds with Ile258 and Val305 in Keap1, suggesting it could disrupt Keap1-Nrf2 interactions, potentially activating antioxidant responses by promoting Nrf2 translocation to the nucleus. In the Bcl2-stigmasterol complex, which exhibited a binding energy of -8.41 Kcal/mol, hydrophobic interactions with residues Ser50, Gln52, and Leu185 stabilized the complex, indicating stigmasterol's role in inhibiting apoptosis by strengthening of Bcl2 mediated inhibition of pro-apoptotic factors like Bax. Furthermore, the IKKβ-stigmasterol complex displayed a hydrogen bond between Asp385 residue and stigmasterol (2.83 Å), with a binding energy of -8.33 Kcal/mol, suggested that stigmasterol may regulate inflammation by stabilizing IKKβ, thereby preventing NF-κB translocation and reducing inflammation. Molecular dynamics simulations confirmed the stability of stigmasterol's interactions, especially with Keap1, which showed low RMSD values and consistent hydrogen bonding. RMSF and Rg analyses indicated that stigmasterol had stabilizing effects on Bcl2 and IKKβ. These results underscore stigmasterol's potential for neuroprotection through antioxidant and anti-inflammatory actions.

Immunological, neurological, and intestinal changes in red swamp crayfish (Procambarus clarkii) exposed to the combined toxicity of Pyrogallol and microplastics

This study investigates the combined effects of pyrogallol (PG) and microplastics (MPs) on the freshwater crayfish Procambarus clarkii, evaluating their impacts both individually and in combination. Over 15 days, crayfish were exposed to 100 mg/L MPs, 10 mg/L PG, and a mixture of 10 mg/L PG + 100 mg/L MPs. The activities of serum lysozyme (LYZ), phenoxide (Phx), and acid phosphatase (ACP), along with neurological markers such as acetylcholinesterase (AchE) and nitric oxide (NO), were measured. Histological alterations in the intestines were also assessed. Results indicated that both PG and MPs, separately or jointly, decreased immune parameters (LYZ, Phx, ACP) and neurotoxic indicators (AchE, NO). Histologically, crayfish exposed to PG and MPs showed significant intestinal damage, including epithelial disorganization, tissue tearing, and necrosis, with combined exposure exacerbating these effects. These findings suggest that PG and MPs interact synergistically, particularly regarding histopathological changes, highlighting the need for monitoring wastewater effluents in aquatic ecosystems.

Acclimation and recovery dynamics of behavioral and coloration responses of a common fish (Squalius cephalus) to paracetamol exposure

Freshwater ecosystems are increasingly exposed to pharmaceutical contamination, impacting non-target species. Concentrations can vary over time and location, allowing for potential acclimation or recovery effects. Additionally, parasites might interfere with the absorption and adverse outcomes pathways of pollutants. We examined the combined effects of paracetamol and parasite on the behavior and coloration of the European chub (Squalius cephalus), a ubiquitous fish species, from natural populations. Fish were exposed in mesocosms to acute doses of paracetamol (16 μg g-1 once a day over two days), followed by lower doses during a long-term exposure (1.6 μg g-1 once a week over three weeks), followed by a three-week recovery phase. Acute exposure induced marginal decreases in behavioral activity, and changes in dorsal brightness, hue and UV luminance. Interestingly, the long-term phase alone did not yield notable results on behavior and coloration. However, some effects of the acute exposure persisted during the long-term phase, highlighting that the expression of biological responses may be delayed in relation to past high exposure. Parasitism did not attenuate acute impacts, suggesting parasites may not help mitigate effects of paracetamol on behavior and coloration, but alone increased activity levels slightly. No effects of pollutant exposure, either of the acute or long-term phase, were observed after a recovery phase, indicating ability for recovery dynamics. Overall, our findings emphasize that pollutants effects can be highly transient, with rapid recovery when pollutant exposure ceased. Considering different exposure phases is crucial when assessing the ecological consequences of environmental contaminants.

Urban stressors: Interactive effects of noise, light regime and fluoxetine on zebrafish behavior

Chemical, noise and light pollution are pervasive anthropogenic stressors. These stressors have been investigated individually; however, to our knowledge no one has investigated interactions between the three or their impacts on fish. The current study investigated the effects of chronic exposure to a common environmental pollutant, fluoxetine (3 and 300 ng/L), light pollution (artificial light at night), and acute environmental noise (motorboat engine) on the behavioral responses of zebrafish (Danio rerio). The effects of these treatments on zebrafish boldness, anxiety, time to feed, habitat preference in the presence of a visual predation cue (bird), and shoaling behavior in the presence of a conspecific alarm chemical and a visual predation cue were measured. Fluoxetine alone decreased zebrafish boldness, although effects were dose-, sex-, and noise-order-dependent. Zebrafish exposed to artificial light at night showed higher activity levels and were bolder than fish that were raised in an environment with a normal 12 h light-12 h dark photoperiod. Noise exposure often resulted in increased activity. However, we also observed interactions between the three factors. In several experiments, fluoxetine suppressed the effects artificial light at night, suggesting an antagonistic interaction. Fluoxetine also reduced behavioral responses to sudden noise in several experiments. The visual predation cue caused significant reductions in activity, but all three factors affected responses to predation, leading to behaviors that may increase zebrafish vulnerability. The order in which fish were exposed to noise pollution was also important. Fish that were tested with noise first often reacted more strongly than those that were initially tested without noise, suggesting that noise increased the stress of adaption to a new environment. Environmental stressors often co-exist in the real world and the limited number of studies in this area underscores the need for more comprehensive research.

A review on sustainable management strategies for navigating the piling e-waste crisis and associated environmental threats

In today's fast-paced technological era, multifaceted technological advancements in our contemporary lifestyle are surging the use of electronic devices, which are significantly piling e-waste and posing environmental concerns. This stock of e-waste is expected to keep rising up to 50 mt year-1. Formal recycling of such humongous waste is a major challenge, especially in developing nations. Mishandling of e-waste poses serious threats to human health, soil, and water ecosystem, threatening ecological and environmental sustainability. Complex matrix of resourceful materials comprising valuable metals like gold, silver, and copper, and hazardous substances such as lead, mercury, cadmium, and brominated flame retardants make its judicious management even more crucial. Potential toxic elements such as Pb, Cd, Cr, As, and Hg, as well as plastic/microplastics, nanoparticles are prevalent in components like batteries, cathode ray tubes, circuit boards, glass and plastic components which are known to cause neurological, renal, and developmental damage in humans. Effective and sustainable management of these requires a comprehensive understanding of their sources, environmental behavior, and toxicological impacts. This review explores potential approached for sustainable e-waste recycling (recycling of glass, plastic, rare earth metals, and base metals), and resource recycling through pyrometallurgy, hydrometallurgy, biometallurgy, biohydrometallurgy, bioleaching and biodegradation plastic alongside challenges and prospects.

Mechanisms Underlying the Size-Dependent Neurotoxicity of Polystyrene Nanoplastics in Zebrafish

Nanoplastics (NPs) are ubiquitous in the environment, posing significant threats to biological systems, including nervous systems, across various trophic levels. Nevertheless, the molecular mechanisms behind the size-dependent neurotoxicity of NPs remain unclear. Here, we investigated the neurotoxicity of 20 and 100 nm polystyrene NPs (PS-NPs) to zebrafish. Utilizing molecular dynamics simulations and complementary methods, we discovered that PS-NPs initiated neurotoxicity by promoting dimerization of the toll-like receptor 4/myeloid differentiation-2 (TLR4/MD-2) complex. This process involves the binding of PS-NPs to the hydrophobic pocket of MD-2, which induced the flipping of Phe-126 toward the dimer interface and the bending of the C-terminal domain of TLR-4, bringing the two domains into close proximity. Thereafter, the astrocytes and microglia were activated, initiating a cascade of events that include neuroinflammation, central nervous system cell apoptosis, inhibition of motor neuron development, and ultimately alteration of the swimming behavior of zebrafish. Further, 20 nm PS-NPs elicited more severe neurotoxicity than 100 nm PS-NPs, attributed to their higher accumulation in the brain as determined through 14C-labeled PS-NPs and more effective interaction with the TLR4/MD-2 complex. Overall, our study uncovers the mechanisms underlying the size-dependent neurotoxicity of NPs, which merit attention during their risk assessment and regulation.

NeuTox 2.0: A hybrid deep learning architecture for screening potential neurotoxicity of chemicals based on multimodal feature fusion

Chemically induced neurotoxicity is a critical aspect of chemical safety assessment. Traditional and costly experimental methods call for the development of high-throughput virtual screening. However, the small datasets of neurotoxicity have limited the application of advanced deep learning techniques. The current study developed a hybrid deep learning architecture, NeuTox 2.0, through multimodal feature fusion for enhanced prediction accuracy and generalization ability. We incorporated transfer learning based on self-supervised learning, graph neural networks, and molecular fingerprints/descriptors. Four datasets were used to profile neurotoxicity; these were related to blood-brain barrier permeability, neuronal cytotoxicity, microelectrode array-based neural activity, and mammalian neurotoxicity. Comprehensive performance evaluations demonstrated that NeuTox 2.0 has relatively higher predictive capability across all statistical metrics. Specifically, NeuTox 2.0 exhibits remarkable performance in three of the four datasets. In the BBB dataset, although it does not outperform the PaDEL descriptor model, its performance closely approximates that of the top single-modal model. The ablation experiments indicated that NeuTox 2.0 can learn the deeper structural differences of molecules from various feature extractions and capture complex interactions and mapping relationships between various modalities, thereby improving performance for neurotoxicity prediction. Evaluations of anti-noise ability indicated that NeuTox 2.0 has excellent noise resistance relative to traditional machine learning. We applied the NeuTox 2.0 model to predict the neurotoxicity of 315,790 compounds in the REACH database. The results showed that 701 compounds exhibited potential neurotoxicity in the four neurotoxicity-related predictions. In conclusion, NeuTox 2.0 can be used as an efficient tool for early neurotoxicity screening of environmental chemicals.

Dietary interventions in mitigating the impact of environmental pollutants on Alzheimer's disease - A review

Numerous studies linking environmental pollutants to oxidative stress, inflammation, and neurotoxicity have assigned pollutants to several neurodegenerative disorders, including Alzheimer's disease (AD). Heavy metals, pesticides, air pollutants, and endocrine disruptor chemicals have been shown to play important roles in AD development, with some traditional functions in amyloid-β formation, tau kinase action, and neuronal degeneration. However, pharmacological management and supplementation have resulted in limited improvement. This raises the interesting possibility that activities usually considered preventive, including diet, exercise, or mental activity, might be more similar to treatment or therapy for AD. This review focuses on the effects of diet on the effects of environmental pollutants on AD. One of the primary issues addressed in this review is a group of specific diets, including the Mediterranean diet (MeDi), Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH intervention for Neurodegenerative Delay (MIND), which prevent exposure to these toxins. Such diets have been proven to decrease oxidative stress and inflammation, which are unfavorable for neuronal growth. Furthermore, they contribute to positive changes in the composition of the human gut microbiota and thus encourage interactions in the Gut-Brain Axis, reducing inflammation caused by pollutants. This review emphasizes a multi-professional approach with reference to nutritional activities that would lower the neurotoxic load in populations with a high level of exposure to pollutants. Future studies focusing on diet and environment association plans may help identify preventive measures aimed at enhancing current disease deceleration.

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.

Lead exposure leads to premature neural differentiation via inhibiting Wnt signaling

Heavy metals, such as Lead (Pb), are ubiquitous environmental pollutants that is a considerable problem worldwide. Increasing evidences suggest that Pb exposure negatively impact central nervous system. However, the exact toxic mechanism of Pb on early human brain development remain unclear due to the limitations of animal models and 2D cell models. In this study, we used human cortical organoids to reveal that Pb had specific early neurodevelopmental toxicity during the neural differentiation stage. We observed that short-term Pb exposure (10 days) is sufficient to induce premature neuronal differentiation. Mechanistically, Pb exposure downregulates the Wnt signaling in cortical organoids, and the activation of Wnt signaling reverses the neurodevelopmental phenotype. In support, Pb exposure during pregnancy lead to premature neuronal differentiation and reduced neurogenesis in mice. In conclusion, our study reveals the neuropathogenesis of Pb exposure and uncovers the potential intervention role of Wnt activation.

ATF5-mediated mitochondrial unfolded protein response protects against Pb-induced mitochondria damage in SH-SY5Y cell

Mitochondria is the primary target of lead (Pb) in neural cells, and Pb exposure can cause impairment to mitochondrial function and morphology. Recent studies have reported that a conserved cellular stress response, called mitochondrial unfolded protein response (mtUPR), is activated in response to mitochondrial dysfunction and protein misfolding and play protective roles in aging and neurodegeneration, but it's unknown whether mtUPR could protect against Pb-induced neurotoxicity. In this study, we found that sublethal level exposure of PbAc (2.5 μM) could cause mitochondria damage and then activate mtUPR by promoting the expression of mitochondrial proteases (LonP1 and ClpP), molecular chaperone (HSPA1A). ATF5 mediated mtUPR activation as knocking out ATF5 significantly inhibited Pb-induced LonP1 and ClpP expression. Moreover, ATF5 deficiency exacerbated Pb-induced mitochondrial morphological and oxidative phosphorylation (OXPHOS) functional damage, resulting in oxidative stress and ultimately promoting cell death. Conversely, overexpression of ATF5 confers protection against Pb-induced oxidative stress and cell death. Collectively, thess results highlight that mtUPR mediated by ATF5 safeguards against mitochondria damage caused by Pb exposure, providing insights into the development of new strategies for mitigating the Pb neurotoxicity.

Chlorpyrifos-oxon induced neuronal cell death via endoplasmic reticulum stress-triggered apoptosis pathways

Chlorpyrifos (CPF) is one of the organophosphorus pesticides widely used throughout the world. Epidemiological studies suggested a link between CPF exposure and neurologic disorders, while the molecular mechanisms remain inconclusive. In the present study, we investigated the impacts of chlorpyrifos-oxon (CPO), the major toxic CPF metabolite, on cell apoptosis, and explored possible mechanism associated with endoplasmic reticulum (ER) stress in SH-SY5Y cells. Results showed that CPO exposure induced dose-dependent apoptosis and expression of ER stress-related proteins in SH-SY5Y cells. Pretreatment with 4-PBA (an ER stress inhibitor) effectively inhibited the expression of GRP78, GRP94, p-IRE1α, and XBP1-s, and apoptotic events. Pretreatment with STF-083010 (an IRE1α inhibitor) partially attenuated CPO-induced apoptosis. In addition, CPO exposure significantly evoked the generation of reactive oxygen species (ROS) which could be eliminated by pretreatment of 4-PBA. Of note, buffering the ROS generation with antioxidant NAC had little impact on the expression of p-IRE1α, and only partially attenuated CPO-induced apoptosis. In contrast, co-pretreatment with NAC and STF-083010 effectively inhibited CPO-induced apoptotic events. Collectively, our results indicate that CPO exposure exerts neuronal cytotoxicity via ER stress downstream-regulated IRE1α/XBP1 signaling pathway and ROS generation-triggered apoptosis. These findings highlight the role of ER stress in CPF-induced neurotoxicity, and provide a promising target for the intervention of organophosphate-associated neurodegenerative diseases.

Coenzyme Q10 ameliorates cyclophosphamide-induced chemobrain by repressing neuronal apoptosis and preserving hippocampal neurogenesis: Mechanistic roles of Wnt/ β-catenin signaling pathway

Deterioration in the neurocognitive function of cancer patients referred to as "Chemobrain" is a devastating obstacle associated with cyclophosphamide (CYP). CYP is an alkylating agent, clinically utilized as an efficient anticancer and immunosuppressant. Coenzyme Q10 (CoQ10) is a worthwhile micronutrient with diverse biological activities embracing antioxidant, anti-apoptotic, and neuroprotective effects. The current experiment was designed for investigating the neuroprotective capability of CoQ10 versus CYP-elicited chemobrain in rats besides elucidating the causal molecular mechanisms. Male Sprague Dawley rats received CoQ10 (10 mg/kg, orally, once daily, for 10 days) and/or a single dose of CYP (200 mg/kg i.p. on day 7). CoQ10 counteracted CYP-induced cognitive and motor dysfunction as demonstrated by the findings of neurobehavioral tests (passive avoidance, Y maze, locomotion, and rotarod tests). Histopathological analysis further affirmed the neuroprotective abilities of CoQ10. CoQ10 effectually diminished CYP-provoked oxidative injury by restoring the antioxidant activity of catalase (CAT) enzyme while reducing malondialdehyde (MDA) levels. Besides, CoQ10 efficiently repressed CYP-induced neuronal apoptosis by downregulating the expression of Bax and caspase-3 while upregulating the Bcl-2 expression. Moreover, CoQ10 hampered CYP-provoked upregulation in acetylcholinesterase (AChE) activity. Furthermore, CoQ10 considerably augmented hippocampal neurogenesis by elevating the expressions of brain-derived neurotrophic factor (BDNF) and Ki-67. These promising neuroprotective effects can be credited to upregulating Wnt/β-catenin pathway as evidenced by the elevated expressions of Wnt-3a, β-catenin, and Phoshpo-glycogen synthase kinase-3 β (p-GSK-3β). Collectively, these findings proved the neuroprotective capabilities of CoQ10 against CYP-induced chemobrain through combating oxidative injury, repressing intrinsic apoptosis, boosting neurogenesis, and eventually upregulating the Wnt/β-catenin pathway.

Innovative mechanisms of micro- and nanoplastic-induced brain injury: Emphasis on the microbiota-gut-brain axis

Micro- and nanoplastics (MNPs), emerging environmental pollutants, infiltrate marine, terrestrial, and freshwater systems via diverse pathways, culminating in their accumulation in the human body through food chain transmission, posing potential health risks. Researches have demonstrated that MNPs disrupt gut microbiota equilibrium and compromise intestinal barrier integrity, as well as traverse the blood-brain barrier, leading to brain damage. Moreover, the complex interaction between the gut and the nervous system, facilitated by the "gut-brain axis," indicates an additional pathway for MNPs-induced brain damage. This has intensified scientific interest in the intercommunication between MNPs and the gut-brain axis. While existing studies have documented microbial imbalances and metabolic disruptions subsequent to MNPs exposure, the precise mechanisms by which the microbiota-gut-brain axis contributes to MNPs-induced central nervous system damage remain unclear. This review synthesizes current knowledge on the microbiota-gut-brain axis, elucidating the pathogenesis of MNPs-induced gut microbiota dysbiosis and its consequent brain injury. It emphasizes the complex interrelation between MNPs and the microbiota-gut-brain axis, advocating for the gut microbiota as a novel therapeutic target to alleviate MNP-induced brain harm.

Determining bad actors: A linear mixed effects model approach to elucidate behavioral toxicity of metal mixtures in drinking water

Mixtures of chemical contaminants can pose a significant health risk to humans and wildlife, even at levels considered safe for each individual chemical. There is a critical need to develop statistical methods to evaluate the drivers of toxic effects in chemical mixtures (i.e., bad actors) from exposure studies. Here, we develop a hierarchical modeling framework to disentangle the toxicity of complex metal mixtures from a screening study of 92 drinking well water samples containing multiple metal elements from Maine and New Hampshire, USA. In order to screen for neurodevelopmental impacts from exposure to these drinking water samples, we use a larval zebrafish (Danio rerio) behavioral assay. Zebrafish are an advantageous toxicological model organism due to combining the complexity of a vertebrate organism and higher-throughput exposure methods. We formulate a linear mixed modeling approach that captures intrinsic complexity in a common larval behavioral assay in order to improve its sensitivity and rigor and identify drivers of behavioral toxicity from the metal mixtures within the drinking water samples. Our analysis identifies lead (Pb), cadmium (Cd), nickel (Ni), copper (Cu), barium (Ba), and uranium (U) as metals that consistently impact larval locomotor activity, individually and across nine pairs of those metals. Our model also elucidates three distinct clusters of metal mixture components that drive behavioral effects: (Ba:Cu:U), (Ni:Pb:U), (Ba:Pb:U). Having identified a set of "bad-actor" metals from the water samples, we conduct exposure experiments for each individual metal (Pb, Cd, Ni, Cu, and Ba) at levels considered safe by the US Environmental Protection Agency drinking water regulatory limits and validate Pb, Ni, Cu, and Ba as behavioral toxicants at these concentrations. Collectively, our modeling approach estimates the impact of metal elements on a complex behavioral outcome in a statistically robust manner and establishes an approach to capture "bad actors" and key chemical interactions in a complex mixture.

Development of a TBXT-EGFP iPS cell model for screening the early developmental toxicity of typical environmental pollutants

In our daily lives, we are inevitably exposed to a variety of environmental pollutants in numerous ways. Fortunately, recent years have witnessed significant advancements in the field of stem cell toxicology, which have provided new opportunities for research in environmental toxicology. Applying stem cell technology to environmental toxicology, overcomes some of the limitations of traditional screening methods and we can more accurately predict the toxicity of environmental pollutants. However, there are still several aspects of stem cell toxicology models that require improvement, such as increasing the throughput of detection and simplifying detection methods. Consequently, we developed an environmental pollutant toxicity detection model based on TBXT-EGFP iPS cells and screened the developmental toxicity of 38 typical environmental pollutants. Our results indicate that TBBPA-BDBPE, TBBPA-BHEE, DG, and AO2246 may interfere with the expression of TBXT, a critical marker gene for early human embryo development, implying that these environmental pollutants could lead to developmental abnormalities.

Developing an Approach for Integrating Chemical Analysis and Transcriptional Changes to Assess Contaminants in Water, Sediment, and Fish

Pharmaceuticals in aquatic environments pose threats to aquatic organisms because of their continuous release and potential accumulation. Monitoring methods for these contaminants are inadequate, with targeted analyses falling short in assessing water quality's impact on biota. The present study advocates for integrated strategies combining suspect and targeted chemical analyses with molecular biomarker approaches to better understand the risks posed by complex chemical mixtures to nontarget organisms. The research aimed to integrate chemical analysis and transcriptome changes in fathead minnows to prioritize contaminants, assess their effects, and apply this strategy in Wascana Creek, Canada. Analysis revealed higher pharmaceutical concentrations downstream of a wastewater-treatment plant, with clozapine being the most abundant in fathead minnows, showing notable bioavailability from water and sediment sources. Considering the importance of bioaccumulation factor and biota-sediment accumulation factor in risk assessment, these coefficients were calculated based on field data collected during spring, summer, and fall seasons in 2021. Bioaccumulation was classified as very bioaccumulative with values >5000 L kg-1, suggesting the ability of pharmaceuticals to accumulate in aquatic organisms. The study highlighted the intricate relationship between nutrient availability, water quality, and key pathways affected by pharmaceuticals, personal care products, and rubber components. Prioritization of these chemicals was done through suspect analysis, supported by identifying perturbed pathways (specifically signaling and cellular processes) using transcriptomic analysis in exposed fish. This strategy not only aids in environmental risk assessment but also serves as a practical model for other watersheds, streamlining risk-assessment processes to identify environmental hazards and work toward reducing risks from contaminants of emerging concern. Environ Toxicol Chem 2024;43:2252-2273. © 2024 SETAC.

Exposure to Metals, Pesticides, and Air Pollutants: Focus on Resulting DNA Methylation Changes in Neurodegenerative Diseases

Individuals affected by neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), are dramatically increasing worldwide. Thus, several efforts are being made to develop strategies for stopping or slowing the spread of these illnesses. Although causative genetic variants linked to the onset of these diseases are known, they can explain only a small portion of cases. The etiopathology underlying the neurodegenerative process in most of the patients is likely due to the interplay between predisposing genetic variants and environmental factors. Epigenetic mechanisms, including DNA methylation, are central candidates in translating the effects of environmental factors in genome modulation, and they play a critical role in the etiology of AD, PD, and ALS. Among the main environmental exposures that have been linked to an increased risk for these diseases, accumulating evidence points to the role of heavy metals, pesticides, and air pollutants. These compounds could trigger neurodegeneration through different mechanisms, mainly neuroinflammation and the induction of oxidative stress. However, increasing evidence suggests that they are also capable of inducing epigenetic alterations in neurons. In this article, we review the available literature linking exposure to metals, pesticides, and air pollutants to DNA methylation changes relevant to neurodegeneration.

Analysis of the relationship between sleep-related disorders and cadmium in the US population

Background

Cadmium is a heavy metal that accumulates in the body due to environmental and occupational exposure. The neurotoxicity of cadmium received increasingly attention in recent years. Sleeping is regulated and coordinated by nervous system, however, little is known about the relationship between cadmium and sleep. This study aimed to examine the relationship between blood cadmium concentrations and sleep-related disorders in US adults.

Methods

This cross-sectional study used data on blood cadmium and sleep from the 2005-2008 and 2015-2020 National Health and Nutrition Examination Survey (NHANES). Weighted multiple regression, generalized weighted modeling, and weighted restricted cubic splines (RCS) were utilized to investigate the association between blood cadmium and sleep outcomes (sleep duration, trouble sleeping, symptoms of obstructive sleep apnea (OSA) and daytime sleepiness). Furthermore, subgroup analyses were conducted to investigate any differences in the associations between age, gender, ethnicity, education level, marital status, smoking status, alcohol consumption, diabetes mellitus (DM), cardiovascular disease (CVD) and hypertension groups.

Results

In 19,152 participants, the median blood cadmium concentration was 0.48 (IQR: 0.28, 0.82)μg/L. Compared with the lowest reference quartile, participants in the higher quartile had a significantly higher risk of insufficient sleeping (<7 h/night) in crude model (OR 1.53, 95% CI 1.33-1.74), Model 1 (OR 1.57, 95% CI 1.38-1.80) and Model 2 (OR 1.45, 95% CI 1.27-1.65). In the unadjusted model, individuals in the highest quartile of cadmium level had a significantly increased risk of OSA symptoms of 53% (OR = 1.53, 95% CI: 1.42, 1.65) compared with participants in the bottom quartile, and this risk increased by 35% (OR = 1.35, 95% CI: 1.23, 1.48) after adjusting for all covariates. Individuals in the highest quartile of cadmium level were 76% more likely to have a trouble sleeping than individuals in the lowest quartile in the unadjusted model (OR = 1.76, 95% CI: 1.31, 1.93), whereas in the fully adjusted model, this likelihood was 86% higher (OR = 1.86, 95% CI: 1.51, 1.96). A similar positive correlation was also observed for cadmium level and daytime sleepiness. However, no relationship was noted between cadmium and excessive sleep duration (≥9 h). A linear dose-response relationship was found between cadmium concentration and the risk of insufficient sleeping (P non-linearity = 0.321), OSA symptoms (P non-linearity = 0.176), trouble sleeping (P non-linearity = 0.682) and daytime sleepiness (P non-linearity = 0.565). Additionally, no significant interactions between cadmium concentrations and subgroup variables were identified (P for interaction>0.05).

Conclusion

Insufficient sleep, symptoms of OSA, trouble sleeping and daytime sleepiness were found to have a positive association with the blood cadmium concentration in US adults. However, further prospective studies are necessary to establish whether there is a causal relationship between these factors.

Development and child health in a world of synthetic chemicals

Chemical pollution is one of today's most significant threats to the developmental potential of children worldwide. Maternal exposure to toxicants can perturb sensitive windows of fetal development, indirectly through promoting antenatal disorders, abnormal placental adaptation, or directly through maternal-fetal transport. Current evidence clearly shows that persistent organic chemicals promote hypertensive disorders of pregnancy, placental abnormalities, and fetal growth restriction, whereas findings are less consistent for phthalates and bisphenols. Prospective birth cohorts strongly support a link between adverse neurodevelopmental outcomes and prenatal exposure to flame retardants and organophosphate pesticides. Emerging evidence reveals a potential association between in utero exposure to bisphenols and childhood behavioral disorders, while childhood metabolic health is more consistently associated with postnatal exposure to phthalates and bisphenols. IMPACT: Synthesizes emerging evidence linking modern forms of chemical pollution to antenatal disorders, fetal growth restriction and childhood disorders. Highlights potential developmental impacts of emerging pollutants of concern now ubiquitous in our environment but without regulatory restrictions.

Enviromental endocrine disruptor risks in the central nervous system: Neurotoxic effects of PFOS and glyphosate

Endocrine disruptors (EDs) pose significant risks to human and environmental health, with potential implications for neurotoxicity. This study investigates the synergistic neurotoxic effects of perfluorooctane sulfonate (PFOS) and glyphosate (GLY), two ubiquitous EDs, using SHSY5Y neuronal and C6 astrocytic cell lines. While individual exposures to PFOS and glyphosate at non-toxic concentrations did not induce significant changes, their combination resulted in a marked increase in oxidative stress and neuroinflammatory responses. Specifically, the co-exposure led to elevated levels of interleukin-6, tumor necrosis factor alpha, and interferon gamma, along with reduced interleukin-10 expression, indicative of heightened neuroinflammatory processes. These findings underscore the importance of considering the synergistic interactions of EDs in assessing neurotoxic risks and highlight the urgent need for further research to mitigate the adverse effects of these compounds on neurological health.

Neonicotinoid Pesticides Affect Developing Neurons in Experimental Mouse Models and in Human Induced Pluripotent Stem Cell (iPSC)-Derived Neural Cultures and Organoids

Neonicotinoids are synthetic, nicotine-derived insecticides used worldwide to protect crops and domestic animals from pest insects. The reported evidence shows that they are also able to interact with mammalian nicotine receptors (nAChRs), triggering detrimental responses in cultured neurons. Exposure to high neonicotinoid levels during the fetal period induces neurotoxicity in animal models. Considering the persistent exposure to these insecticides and the key role of nAChRs in brain development, their potential neurotoxicity on mammal central nervous system (CNS) needs further investigations. We studied here the neurodevelopmental effects of different generations of neonicotinoids on CNS cells in mouse fetal brain and primary cultures and in neuronal cells and organoids obtained from human induced pluripotent stem cells (iPSC). Neonicotinoids significantly affect neuron viability, with imidacloprid (IMI) inducing relevant alterations in synaptic protein expression, neurofilament structures, and microglia activation in vitro, and in the brain of prenatally exposed mouse fetuses. IMI induces neurotoxic effects also on developing human iPSC-derived neurons and cortical organoids. Collectively, the current findings show that neonicotinoids might induce impairment during neuro/immune-development in mouse and human CNS cells and provide new insights in the characterization of risk for the exposure to this class of pesticides.

Enhanced electrophysiological activity and neurotoxicity screening of environmental chemicals using 3D neurons from human neural precursor cells purified with PSA-NCAM

The assessment of neurotoxicity for environmental chemicals is of utmost importance in ensuring public health and environmental safety. Multielectrode array (MEA) technology has emerged as a powerful tool for assessing disturbances in the electrophysiological activity. Although human embryonic stem cell (hESC)-derived neurons have been used in MEA for neurotoxicity screening, obtaining a substantial and sufficiently active population of neurons from hESCs remains challenging. In this study, we successfully differentiated neurons from a large population of human neuronal precursor cells (hNPC) purified using a polysialylated neural cell adhesion molecule (PSA-NCAM), referred to as hNPCPSA-NCAM+. The functional characterization demonstrated that hNPCPSA-NCAM+-derived neurons improve functionality by enhancing electrophysiological activity compared to total hNPC-derived neurons. Furthermore, three-dimensional (3D) neurons derived from hNPCPSA-NCAM+ exhibited reduced maturation time and enhanced electrophysiological activity on MEA. We employed subdivided population analysis of active mean firing rate (MFR) based on electrophysiological intensity to characterize the electrophysiological properties of hNPCPSA-NCAM+-3D neurons. Based on electrophysiological activity including MFR and burst parameters, we evaluated the sensitivity of hNPCPSA-NCAM+-3D neurons on MEA to screen both inhibitory and excitatory neuroactive environmental chemicals. Intriguingly, electrophysiologically active hNPCPSA-NCAM+-3D neurons demonstrated good sensitivity to evaluate neuroactive chemicals, particularly in discriminating excitatory chemicals. Our findings highlight the effectiveness of MEA approaches using hNPCPSA-NCAM+-3D neurons in the assessment of neurotoxicity associated with environmental chemicals. Furthermore, we emphasize the importance of selecting appropriate signal intensity thresholds to enhance neurotoxicity prediction and screening of environmental chemicals.

Identification of neural-relevant toxcast high-throughput assay intended gene targets: Applicability to neurotoxicity and neurotoxicant putative molecular initiating events

The US EPA's Toxicity Forecaster (ToxCast) is a suite of high-throughput in vitro assays to screen environmental toxicants and predict potential toxicity of uncharacterized chemicals. This work examines the relevance of ToxCast assay intended gene targets to putative molecular initiating events (MIEs) of neurotoxicants. This effort is needed as there is growing interest in the regulatory and scientific communities about developing new approach methodologies (NAMs) to screen large numbers of chemicals for neurotoxicity and developmental neurotoxicity. Assay gene function (GeneCards, NCBI-PUBMED) was used to categorize gene target neural relevance (1 = neural, 2 = neural development, 3 = general cellular process, 3 A = cellular process critical during neural development, 4 = unlikely significance). Of 481 unique gene targets, 80 = category 1 (16.6 %); 16 = category 2 (3.3 %); 303 = category 3 (63.0 %); 97 = category 3 A (20.2 %); 82 = category 4 (17.0 %). A representative list of neurotoxicants (548) was researched (ex. PUBMED, PubChem) for neurotoxicity associated MIEs/Key Events (KEs). MIEs were identified for 375 compounds, whereas only KEs for 173. ToxCast gene targets associated with MIEs were primarily neurotransmitter (ex. dopaminergic, GABA)receptors and ion channels (calcium, sodium, potassium). Conversely, numerous MIEs associated with neurotoxicity were absent. Oxidative stress (OS) mechanisms were 79.1 % of KEs. In summary, 40 % of ToxCast assay gene targets are relevant to neurotoxicity mechanisms. Additional receptor and ion channel subtypes and increased OS pathway coverage are identified for potential future assay inclusion to provide more complete coverage of neural and developmental neural targets in assessing neurotoxicity.

Transcriptomic analysis reveals the effects of maternal exposure to bisphenol AF on hypothalamic development in male neonatal mice

Fragmented data suggest that bisphenol AF (BPAF), a chemical widely used in a variety of products, might have potential impacts on the hypothalamus. Here, we employed male neonatal mice following maternal exposure to explore the effects of low-dose BPAF on hypothalamic development by RNA-sequencing. We found that maternal exposure to approximately 50 µg/(kg·day) BPAF from postanal day (PND) 0 to PND 15 altered the hypothalamic transcriptome, primarily involving the pathways and genes associated with extracellular matrix (ECM) and intercellular adhesion, neuroendocrine regulation, and neurological processes. Further RNA analysis confirmed the changes in the expression levels of concerned genes. Importantly, we further revealed that low-dose BPAF posed a stimulatory impact on pro-opiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus and induced the browning of inguinal white adipose tissue. All findings indicate that developmental exposure to low-dose BPAF could interfere with hypothalamic development and thereby lead to alterations in the metabolism. Interestingly, 5000 µg/(kg·day) BPAF caused slighter, non-significant or even inverse alterations than the low dose of 50 µg/(kg·day), displaying a dose-independent effect. Further observations suggest that the the dose-independent effects of BPAF might be associated with oxidative stress and inflammatory responses caused by the high dose. Overall, our study highlights a risk of low-dose BPAF to human neuroendocrine regulation and metabolism.

The role of exosome-shuttled miRNAs in heavy metal-induced peripheral tissues and neuroinflammation in Alzheimer's disease

Heavy metal-induced neuroinflammation is a significant pathophysiologic mechanism in Alzheimer's disease (AD). Microglia-mediated neuroinflammation plays a crucial role in the pathogenesis of AD. Multiple miRNAs are differentially expressed in peripheral tissues after heavy metal exposure, and increasing evidence suggests that they are involved in AD progression by regulating microglial homeostasis. Exosomes, which are capable of loading miRNAs and crossing the bloodbrain barrier, serve as mediators of communication between peripheral tissues and the brain. In this review, we summarize the current evidence on the link between miRNAs in peripheral tissues and neuroinflammation in AD after heavy metal exposure and propose a role for miRNAs in the microglial neurodegenerative phenotype (MGnD) of AD. This study will help to elucidate the link between peripheral tissue damage and MGnD-mediated neuroinflammation in AD after heavy metal exposure. Additionally, we summarize the regulatory effects of natural compounds on peripheral tissue-derived miRNAs, which could be potential therapeutic targets for natural compounds to regulate peripheral tissue-derived exosomal miRNAs to ameliorate heavy metal-induced MGnD-mediated neuroinflammation in patients with AD after heavy metal exposure.

Relationship between the cGAS-STING and NF-κB pathways-role in neurotoxicity

Neurotoxicity can cause a range of symptoms and disorders in humans, including neurodegenerative diseases, neurodevelopmental disorders, nerve conduction abnormalities, neuroinflammation, autoimmune disorders, and cognitive deficits. The cyclic guanosine-adenosine synthase (cGAS)-stimulator of interferon genes (STING) pathway and NF-κB pathway are two important signaling pathways involved in the innate immune response. The cGAS-STING pathway is activated by the recognition of intracellular DNA, which triggers the production of type I interferons and pro-inflammatory cytokines, such as tumor necrosis factor, IL-1β, and IL-6. These cytokines play a role in oxidative stress and mitochondrial dysfunction in neurons. The NF-κB pathway is activated by various stimuli, such as bacterial lipopolysaccharide, viral particle components, and neurotoxins. NF-κB activation may lead to the production of pro-inflammatory cytokines, which promote neuroinflammation and cause neuronal damage. A potential interaction exists between the cGAS-STING and NF-κB pathways, and NF-κB activation blocks STING degradation by inhibiting microtubule-mediated STING transport. This review examines the progress of research on the roles of these pathways in neurotoxicity and their interrelationships. Understanding the mechanisms of these pathways will provide valuable therapeutic insights for preventing and controlling neurotoxicity.

Negative Association of Cognitive Performance With Blood Serum Neurotoxicity and Its Modulation by Human Herpes Virus 5 (HHV5) Seropositivity in Healthy Women

Identification of early influences on cognitive decline is of paramount importance in order to stem the impacts of decrements in cognitive functioning and to potentially intervene. Thus, here we focused on 132 healthy adult women (age range 26-98 years) to (a) determine whether factors circulating in serum may exert neurotoxic effects in vitro, (b) evaluate associations between serum neurotoxicity and cognitive performance, and (c) assess the influence of human herpes virus (HHV) seroprevalence and other factors on apoptosis and cognitive performance. The results documented that the addition of serum from healthy adult women to neural cell cultures resulted in apoptosis, indicating the presence of circulating neurotoxic factors in the serum. Furthermore, apoptosis increased with age, and was associated with decreased cognitive performance. Stepwise regression evaluating the influence of 6 HHVs on apoptosis and cognitive function revealed that only HHV5 (cytomegalovirus; CMV) seropositivity was significantly associated with apoptosis and cognitive decline, controlling for age. These findings document neurotoxic effects of serum from healthy women across the adult lifespan and suggest a unique detrimental influence associated with CMV seropositivity.

Environmental toxicants and nephrotoxicity: Implications on mechanisms and therapeutic strategies

Kidneys are one of the most important organs in the human body. In addition to filtering 200 liters of fluid every 24 hours, the kidney also regulates acid-base balance, maintains electrolyte balance, and removes waste and toxicants from the body. Nephrotoxicity is the term used to describe the deterioration of kidney function caused by the harmful effects of medications and various types of environmental toxicants. Exposure to environmental toxicants is an inevitable side effect in the world's increasing industrialization and even more prevalent in underdeveloped nations. Growing data over the past few years has illuminated the probable connection between environmental toxicants and nephrotoxicity. Phthalates, microplastics, acrylamide and bisphenol A are environmental toxicants of particular concern, which are known to have nephrotoxic effects. Such toxicants may accumulate in the kidneys of humans after being consumed, inhaled, or come into contact with the skin. They can enter cells through endocytosis and accumulate in the cytoplasm. Small-sized nephrotoxicants can cause a variety of ailments including inflammation with increased production of pro-inflammatory cytokines, oxidative stress, mitochondrial dysfunction, autophagy, and apoptosis. This study uncovers the potential for new insights concerning the relationship between various environmental toxicants and kidney health. The objectives of this review is to establish information gaps, assess and identify the toxicity mechanisms of different nephrotoxicants, identify innovative pharmacological therapies that demonstrate promising therapeutic benefits/ relevance, and discuss the predictions for the future based on the analysis of the literature.

Association between exposure to heavy metals in atmospheric particulate matter and sleep quality: A nationwide data linkage study

BACKGROUND

Recent studies have demonstrated that long-term exposure to particulate matter (PM) is associated with poor sleep quality. However, no studies have linked PM constituents, particularly heavy metals, to sleep quality.

OBJECTIVE

This study investigated the association between exposure to heavy metals in PM and sleep quality.

METHODS

We obtained nationwide data from the Korean Community Health Survey conducted in 2018 among adults aged 19-80 years. Sleep quality was evaluated using Pittsburgh Sleep Quality Index (PSQI). Poor sleep quality was defined as PSQI ≥5. One-year and three-month average concentrations of heavy metals (lead, manganese, cadmium, and aluminum) in PM with diameter ≤10 μm were obtained from nationwide air quality monitoring data and linked to the survey data based on individual district-level residential addresses. Logistic regression analyses were performed after adjusting for age, gender, education level, marital status, smoking status, alcohol consumption, history of hypertension, and history of diabetes mellitus.

RESULTS

Of 32,050 participants, 17,082 (53.3%) reported poor sleep quality. Increases in log-transformed one-year average lead (odds ratio, 1.14; 95% confidence interval, 1.08-1.20), manganese (1.31; 1.25-1.37), cadmium (1.03; 1.00-1.05), and aluminum concentrations (1.17; 1.10-1.25) were associated with poor sleep quality. Increases in log-transformed three-month average manganese (odds ratio, 1.13; 95% confidence interval, 1.09-1.17) and aluminum concentrations (1.28; 1.21-1.35) were associated with poor sleep quality.

CONCLUSION

We showed for the first time that exposure to airborne lead, manganese, cadmium, and aluminum were associated with poor sleep quality. This study may be limited by self-reported sleep quality and district-level exposure data.

What does scientometry tell us about mercury toxicology and its biological impairments?

Mercury is a toxic pollutant that poses risks to both human and environmental health, making it a pressing public health concern. This study aimed to summarize the knowledge on mercury toxicology and the biological impairments caused by exposure to mercury in experimental studies and/or diagnosis in humans. The research was conducted on the main collection of Web of Science, employing as a methodological tool a bibliometric analysis. The selected articles were analyzed, and extracted data such as publication year, journal, author, title, number of citations, corresponding author's country, keywords, and the knowledge mapping was performed about the type of study, chemical form of mercury, exposure period, origin of exposure, tissue/fluid of exposure measurement, mercury concentration, evaluation period (age), mercury effect, model experiments, dose, exposure pathway, and time of exposure. The selected articles were published between 1965 and 2021, with Clarkson TW being the most cited author who has also published the most articles. A total of 38% of the publications were from the USA. These studies assessed the prenatal and postnatal effects of mercury, emphasizing the impact of methylmercury on neurodevelopment, including motor and cognitive evaluations, the association between mercury and autism, and an evaluation of its protective effects against mercury toxicity. In observational studies, the blood, umbilical cord, and hair were the most frequently used for measuring mercury levels. Our data analysis reveals that mercury neurotoxicology has been extensively explored, but the association among the outcomes evaluated in experimental studies has yet to be strengthened. Providing metric evidence on what is unexplored allows for new studies that may help governmental and non-governmental organizations develop guidelines and policies.

A stronger association of mental disorders with smaller particulate matter and a modifying effect of air temperature

Mental disorders (MDs) can be triggered by adverse weather conditions and particulate matter (PM) such as PM2.5 and PM10 (aerodynamic diameter ≤2.5 μm and ≤10 μm). However, there is a dearth of evidence on the role of smaller PM (e.g. PM1, aerodynamic diameter ≤1 μm) and the potential modifying effects of weather conditions. We aimed to collect daily data on emergency department visits and hospitalisations for schizophrenia-, mood-, and stress-related disorders in a densely populated Chinese city (Hefei) between 2016 and 2019. A time-stratified case-crossover analysis was used to examine the short-term association of MDs with PM1, PM2.5, and PM10. The potential modifying effects of air temperature conditions (cold and warm days) were also explored. The three size-fractioned PMs were all associated with an increased risk of MDs; however, the association differed between emergency department visit and hospitalisation. Specifically, PM1 was primarily associated with an increased risk of emergency department visit, whereas PM2.5 was primarily associated with an increased risk of hospitalisation, and PM10 was associated with an increased risk of both emergency department visit and hospitalisation. The PM-MD association appeared to be greatest (although not significant) for PM1 (odds ratio range: 1.014-1.055), followed by PM2.5 (odds ratio range: 1.001-1.009) and PM10 (odds ratio range: 1.001-1.006). Furthermore, the PM-MD association was observed on cold days; notably, the association between PM and schizophrenia-related disorders was significant on both cold and warm days. Our results suggest that the smaller the PM, the greater the risk of MDs, and that the PM-MD association could be determined by air temperature conditions.

Effects and mechanisms of bisphenols exposure on neurodegenerative diseases risk: A systemic review

Environmental bisphenols (BPs) pose a global threat to human health because of their extensive use as additives in plastic products. BP residues are increasing in various environmental media (i.e., water, soil, and indoor dust) and biological and human samples (i.e., serum and brain). Both epidemiological and animal studies have determined an association between exposure to BPs and an increased risk of neurodegenerative diseases (e.g., Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis), including cognitive abnormalities and behavioral disturbances. Hence, understanding the biological responses to different BPs is essential for prevention, and treatment. This study provides an overview of the underlying pathogenic molecular mechanisms as a valuable basis for understanding neurodegenerative disease responses to BPs, including accumulation of misfolded proteins, reduction of tyrosine hydroxylase and dopamine, abnormal hormone signaling, neuronal death, oxidative stress, calcium homeostasis, and inflammation. These findings provide new insights into the neurotoxic potential of BPs and ultimately contribute to a comprehensive health risk evaluation.

Zebrafish neuromast sensory system: Is it an emerging target to assess environmental pollution impacts?

Environmental pollution poses risks to ecosystems. Among these risks, one finds neurotoxicity and damage to the lateral line structures of fish, such as the neuromast and its hair cells. Zebrafish (Danio rerio) is recommended as model species to be used in ecotoxicological studies and environmental biomonitoring programs aimed at assessing several biomarkers, such as ototoxicity. However, little is known about the history of and knowledge gaps on zebrafish ototoxicity. Thus, the aim of the current study is to review data available in the scientific literature about using zebrafish as animal model to assess neuromast toxicity. It must be done by analyzing the history and publication category, world production, experimental design, developmental stages, chemical classes, neuromasts and hair cell visualization methods, and zebrafish strains. Based on the results, number, survival and fluorescence intensity of neuromasts, and their hair cells, were the parameters oftentimes used to assess ototoxicity in zebrafish. The wild AB strain was the most used one, and it was followed by Tübingen and transgenic strains with GFP markers. DASPEI was the fluorescent dye most often applied as method to visualize neuromasts, and it was followed by Yo-Pro-1 and GFP transgenic lines. Antibiotics, antitumorals, metals, nanoparticles and plant extracts were the most frequent classes of chemicals used in the analyzed studies. Overall, pollutants can harm zebrafish's mechanosensory system, as well as affect their behavior and survival. Results have shown that zebrafish is a suitable model system to assess ototoxicity induced by environmental pollution.

Metabolomic modelling and neuroprotective effects of carvacrol against acrylamide toxicity in rat's brain and sciatic nerve

The study aimed to investigate the harmful effects of acrylamide (AA), which forms in carbohydrate-rich foods at temperatures above 120°C, on the central and peripheral nervous systems and to evaluate the potential neuroprotective effects of carvacrol (CRV). Male Wistar Albino rats were subjected to AA (40 mg/kg/bw/day) and CRV (50 mg/kg/bw/day) for 15 days. Following the last administration, evaluations revealed disrupted gait, heightened thermal sensitivity and altered paw withdrawal thresholds in AA-exposed rats. Notably, AA reduced glutathione (GSH) and raised malondialdehyde (MDA) levels in both brain and sciatic nerve tissues. AA raised nuclear factor erythroid 2-related factor 2 (Nrf2), caspase 3 and nuclear factor κB (NF-κB) gene expressions while decreasing NR4A2. CRV co-administration mitigated gait abnormalities, elevated GSH levels and lowered MDA levels in both tissues. CRV also modulated gene expression, reducing Nrf2 and NF-κB while increasing NR4A2. Histopathological signs of AA-induced neurodegeneration and elevated glial fibrillary acidic protein levels observed in brain and sciatic nerve tissues were rectified with simultaneous administration of CRV, thereby demonstrating neuroprotective efficacy in both regions. This study is pioneering in demonstrating CRV's neuroprotective potential against AA-induced neurotoxicity in both central and peripheral nervous systems, effectively addressing limitations in the literature. In conclusion, the study revealed AA-induced neurodegeneration in the brain and sciatic nerve, with CRV significantly mitigating this neurotoxicity. This novel research underscores CRV's promise as a neuroprotective agent against AA-induced adverse effects in both the central and peripheral nervous systems.

Agricultural activities and risk of Alzheimer's disease: the TRACTOR project, a nationwide retrospective cohort study

Data regarding Alzheimer's disease (AD) occurrence in farming populations is lacking. This study aimed to investigate whether, among the entire French farm manager (FM) workforce, certain agricultural activities are more strongly associated with AD than others, using nationwide data from the TRACTOR (Tracking and monitoring occupational risks in agriculture) project. Administrative health insurance data (digital electronic health/medical records and insurance claims) for the entire French agricultural workforce, over the period 2002-2016, on the entire mainland France were used to estimate the risk of AD for 26 agricultural activities with Cox proportional hazards model. For each analysis (one for each activity), the exposed group included all FMs that performed the activity of interest (e.g. crop farming), while the reference group included all FMs who did not carry out the activity of interest (e.g. FMs that never farmed crops between 2002 and 2016). There were 5067 cases among 1,036,069 FMs who worked at least one year between 2002 and 2016. Analyses showed higher risks of AD for crop farming (hazard ratio (HR) = 3.72 [3.47-3.98]), viticulture (HR = 1.29 [1.18-1.42]), and fruit arboriculture (HR = 1.36 [1.15-1.62]). By contrast, lower risks of AD were found for several animal farming types, in particular for poultry and rabbit farming (HR = 0.29 [0.20-0.44]), ovine and caprine farming (HR = 0.50 [0.41-0.61]), mixed dairy and cow farming (HR = 0.46 [0.37-0.57]), dairy farming (HR = 0.67 [0.61-0.73]), and pig farming (HR = 0.30 [0.18-0.52]). This study shed some light on the association between a wide range of agricultural activities and AD in the entire French FMs population.

Elimination of Acrolein by Disodium 5'-Guanylate or Disodium 5'-Inosinate at High Temperature and Its Application in Roasted Pork Patty

Acrolein (ACR) is a highly active, simple unsaturated aldehyde found in various high-temperature processed foods. Its long-term accumulation in the human body increases the risk of chronic diseases. Animal and plant foodstuffs are rich in disodium 5'-guanylate (GMP) and disodium 5'-inosinate (IMP), which are authorized flavor enhancers. Herein, we used liquid chromatography with tandem mass spectrometry to explore the reaction-active kinetics and pathway of the interaction between GMP/IMP and ACR and validated it in roasted pork patties. Our results suggested that GMP and IMP could efficiently eliminate ACR by forming ACR adducts (GMP-ACR, IMP-ACR). In addition, IMP exhibited a higher reaction rate, whereas GMP had a good trapping capacity at a later stage. As carriers of GMP and IMP, dried mushrooms and shrimp exhibited an effective ACR-trapping ability in the ACR model and roasted pork patty individually and in combination. Adding 10% of dried mushroom or shrimp alone or 5% of dried mushroom and shrimp in combination eliminated up to 53.9%, 55.8%, and 55.2% ACR in a roasted pork patty, respectively. This study proposed a novel strategy to eliminate the generation of ACR in roasted pork patties by adding foodstuffs rich in GMP and IMP.

Comparing Ocular Toxicity of Legacy and Alternative Per- and Polyfluoroalkyl Substances in Zebrafish Larvae

Studies comparing the ocular toxicity potential between legacy and alternative PFAS are lacking. To address this research gap, zebrafish larvae were exposed to both legacy PFAS (i.e., perfluorooctanesulfonic acid [PFOS] and perfluorooctanoic acid [PFOA]) and their corresponding alternatives (i.e., perfluorobutanesulfonic acid [PFBS] and perfluorobutanoic acid [PFBA]). Alterations in their visual behaviors, such as phototactic and optomotor responses (OMR), were assessed at sublethal concentrations. Gene expression variations in visual function-associated pathways were also measured. Visual behavioral assessment revealed that PFOS exposure resulted in concentration-dependent reductions in phototactic responses at 10-1000 μg/L, with PFOA exerting reduction effects only at 100 mg/L. However, their two alternatives had no effect at all tested concentrations. Following an improved contrast-OMR (C-OMR) assessment, PFOS decreased the OMR to a water flow stimulus at 10, 100, and 1000 μg/L. The gene expression analysis revealed that PFOS exposure markedly downregulated most genes involved in the opsins in the photoreceptor and phototransduction cascade, which explains the observed visual behavior changes well. Our findings indicate that PFOS is the most likely PFAS to cause visual toxicity, with PFOA present but less likely, and their substitutes, PFBS and PFBA, cannot be classified as visually toxic to zebrafish.

Neurotoxicity of Titanium Dioxide Nanoparticles: A Comprehensive Review

The increasing use of titanium dioxide nanoparticles (TiO2 NPs) across various fields has led to a growing concern regarding their environmental contamination and inevitable human exposure. Consequently, significant research efforts have been directed toward understanding the effects of TiO2 NPs on both humans and the environment. Notably, TiO2 NPs exposure has been associated with multiple impairments of the nervous system. This review aims to provide an overview of the documented neurotoxic effects of TiO2 NPs in different species and in vitro models. Following exposure, TiO2 NPs can reach the brain, although the specific mechanism and quantity of particles that cross the blood-brain barrier (BBB) remain unclear. Exposure to TiO2 NPs has been shown to induce oxidative stress, promote neuroinflammation, disrupt brain biochemistry, and ultimately impair neuronal function and structure. Subsequent neuronal damage may contribute to various behavioral disorders and play a significant role in the onset and progression of neurodevelopmental or neurodegenerative diseases. Moreover, the neurotoxic potential of TiO2 NPs can be influenced by various factors, including exposure characteristics and the physicochemical properties of the TiO2 NPs. However, a systematic comparison of the neurotoxic effects of TiO2 NPs with different characteristics under various exposure conditions is still lacking. Additionally, our understanding of the underlying neurotoxic mechanisms exerted by TiO2 NPs remains incomplete and fragmented. Given these knowledge gaps, it is imperative to further investigate the neurotoxic hazards and risks associated with exposure to TiO2 NPs.

Exposome and unhealthy aging: environmental drivers from air pollution to occupational exposures

The aging population worldwide is facing a significant increase in age-related non-communicable diseases, including cardiovascular and brain pathologies. This comprehensive review paper delves into the impact of the exposome, which encompasses the totality of environmental exposures, on unhealthy aging. It explores how environmental factors contribute to the acceleration of aging processes, increase biological age, and facilitate the development and progression of a wide range of age-associated diseases. The impact of environmental factors on cognitive health and the development of chronic age-related diseases affecting the cardiovascular system and central nervous system is discussed, with a specific focus on Alzheimer's disease, Parkinson's disease, stroke, small vessel disease, and vascular cognitive impairment (VCI). Aging is a major risk factor for these diseases. Their pathogenesis involves cellular and molecular mechanisms of aging such as increased oxidative stress, impaired mitochondrial function, DNA damage, and inflammation and is influenced by environmental factors. Environmental toxicants, including ambient particulate matter, pesticides, heavy metals, and organic solvents, have been identified as significant contributors to cardiovascular and brain aging disorders. These toxicants can inflict both macro- and microvascular damage and many of them can also cross the blood-brain barrier, inducing neurotoxic effects, neuroinflammation, and neuronal dysfunction. In conclusion, environmental factors play a critical role in modulating cardiovascular and brain aging. A deeper understanding of how environmental toxicants exacerbate aging processes and contribute to the pathogenesis of neurodegenerative diseases, VCI, and dementia is crucial for the development of preventive strategies and interventions to promote cardiovascular, cerebrovascular, and brain health. By mitigating exposure to harmful environmental factors and promoting healthy aging, we can strive to reduce the burden of age-related cardiovascular and brain pathologies in the aging population.

Metallothionein expression in the central nervous system in response to chronic heavy metal exposure: possible neuroprotective mechanism

It has been reported that volcanoes release several tonnes of mercury per year among other heavy metals through eruptions, fumaroles, or diffuse soil degassing. Since a high percentage of the world's population lives in the vicinity of an active volcano, the aim of this study is to evaluate the accumulation of these metals in the central nervous system and the presence of cellular mechanisms of heavy metal detoxification such as metallothioneins. To carry out this study, wild mice (Mus musculus) chronically exposed to an active volcanic environment were captured in Furnas village (Azores, Portugal) and compared with those trapped in a reference area (Rabo de Peixe, Azores, Portugal). On the one hand, the heavy metal load has been evaluated by analyzing brain and cerebellum using ICP-MS and a mercury analyzer and on the other hand, the presence of metallothionein 2A has been studied by immunofluorescence assays. Our results show a higher load of metals such as mercury, cadmium and lead in the central nervous system of exposed mice compared to non-exposed individuals and, in addition, a higher immunoreactivity for metallothionein 2A in different areas of the cerebrum and cerebellum indicating a possible neuroprotection process.

Screening of genes encoding proteins that interact with Nrf2: Probing a cDNA library from Mytilus coruscus using a yeast two-hybrid system

The Nuclear factor Erythroid 2-related factor 2 (Nrf2) is the most important endogenous antioxidant factor in organisms, and it has been demonstrated that it exerts extensive control over the immune response by interacting with crucial innate immunity components directly or indirectly. Although Nrf2 has been widely confirmed to be involved in stress resistance in mammals and some fish, its contribution to mollusks oxidative stress resistance has not frequently been documented. In this investigation, total RNA was taken from the digestive gland of M. coruscus, and a cDNA library was constructed and screened using the GATEWAY recombination technology. The Nrf2 cDNA sequence of M. coruscus was cloned into the pGBKT7 vector to prepare the bait plasmid. Using yeast two-hybrid system, after auxotrophic medium screening, sequencing, and bioinformatics analysis, 13 binding proteins that interacted with Nrf2 were finally identified. They were QM-like protein, 40S ribosomal protein S4 (RPS4), ribosomal protein S2 (RPS2), ribosomal protein L12 (RPL12), EF1-alpha mRNA for elongation factor 1 alpha (eEF1-alpha), ferritin, alpha-amylase, trypsin, vdg3, period clock protein, cyclophilin A isoform 1 (CYP A), serine protease CFSP2, histone variant H2A.Z (H2A.Z). For a better understanding the physiological function of Nrf2 in animals and as a potential target for future research on protein roles in Nrf2 interactions, it is crucial to clarify these protein interactions.

The amyotrophic lateral sclerosis exposome: recent advances and future directions

Amyotrophic lateral sclerosis (ALS) is a fatal disease of motor neuron degeneration with typical survival of only 2-5 years from diagnosis. The causes of ALS are multifactorial: known genetic mutations account for only around 70% of cases of familial ALS and 15% of sporadic cases, and heritability estimates range from 8% to 61%, indicating additional causes beyond genetics. Consequently, interest has grown in environmental contributions to ALS risk and progression. The gene-time-environment hypothesis posits that ALS onset occurs through an interaction of genes with environmental exposures during ageing. An alternative hypothesis, the multistep model of ALS, suggests that several hits, at least some of which could be environmental, are required to trigger disease onset, even in the presence of highly penetrant ALS-associated mutations. Studies have sought to characterize the ALS exposome - the lifetime accumulation of environmental exposures that increase disease risk and affect progression. Identifying the full scope of environmental toxicants that enhance ALS risk raises the prospect of preventing disease by eliminating or mitigating exposures. In this Review, we summarize the evidence for an ALS exposome, discussing the strengths and limitations of epidemiological studies that have identified contributions from various sources. We also consider potential mechanisms of exposure-mediated toxicity and suggest future directions for ALS exposome research.