Toxic effects of perinatal arsenic exposure on the brain of developing rats and the beneficial role of natural antioxidants

Ellagic acid ameliorates arsenic-induced neuronal ferroptosis and cognitive impairment via Nrf2/GPX4 signaling pathway

Arsenic, a neurotoxic metalloid, poses significant health risks. However, ellagic acid, renowned for its antioxidant properties, has shown potential in neuroprotection. This study aimed to investigate the neuroprotective effects of ellagic acid against arsenic-induced neuronal ferroptosis and cognitive impairment and elucidate the underlying mechanisms. Using an arsenic-exposed Wistar rat model and an arsenic-induced HT22 cells model, we assessed cognitive ability, measured serum and brain arsenic levels, and evaluated pathological damage through histological analysis and transmission electron microscopy. Additionally, we examined oxidative stress and iron ion levels using GSH, MDA, ROS and tissue iron biochemical kits, and analyzed the expression of ferroptosis-related markers using western blot and qRT-PCR. Our results revealed that arsenic exposure increased both serum and brain arsenic levels, resulting in hippocampal pathological damage and subsequent decline in learning and memory abilities. Arsenic-induced neuronal ferroptosis was mediated by the inhibition of the xCT/GSH/GPX4/Nrf2 signaling axis and disruption of iron metabolism. Notably, ellagic acid intervention effectively reduced serum and brain arsenic levels, ameliorated neuronal damage, and improved oxidative stress, ferroptosis, and cognitive impairment. These beneficial effects were associated with the activation of the Nrf2/Keap1 signaling pathway, upregulation of GPX4 expression, and enhanced iron ion excretion. In conclusion, ellagic acid demonstrates promising neuroprotective effects against arsenic-induced neurotoxicity by mitigating neuronal ferroptosis and cognitive impairment.

Developmental exposure to arsenic reduces anxiety levels and leads to a depressive-like behavior in female offspring rats: Molecular changes in the prefrontal cortex

Exposure to inorganic arsenic (iAs) detrimentally affects the structure and function of the central nervous system. In-utero and postnatal exposure to iAs has been connected to adverse effects on cognitive development. Therefore, this investigation explores neurobehavioral and neurochemical effects of 0.05 and 0.10 mg/L iAs exposure during gestation and lactation periods on 90-day-old female offspring rats. The assessment of anxiety- and depressive-like behaviors was conducted through the application of an elevated plus maze and a forced swim test. The neurochemical changes were evaluated in the prefrontal cortex (PFC) through the determination of enzyme activities and α1 GABAA subunit expression levels. Our findings revealed a notable impact of iAs exposure on anxiety and the induction of depressive-like behavior in 90-day-old female offspring. Furthermore, the antioxidant status within the PFC exhibited discernible alterations in exposed rats. Notably, the activities of acetylcholinesterase and glutamate pyruvate transaminase demonstrated an increase, while glutamate oxaloacetate transaminase activity displayed a decrease within the PFC due to the iAs treatment. Additionally, a distinct downregulation in the mRNA expression of the α1GABAA receptor was observed in this neuronal region. These findings strongly suggest that iAs exposure during early stages of rat development causes significant modifications in brain oxidative stress markers and perturbs the activity of enzymes associated with cholinergic and glutamatergic systems. In parallel, it elicits a discernible reduction in the level of GABA receptors within the PFC. These molecular alterations may play a role in the diminished anxiety levels and the depressive-like behavior outlined in the current investigation.

Mechanistic insights into phenanthrene-triggered oxidative stress-associated neurotoxicity, genotoxicity, and behavioral disturbances toward the brandling worm (Eisenia fetida) brain: The need for an ecotoxicological evaluation

In this study, earthworm (Eisenia fetida) brain was chosen as targeted receptors to probe the mechanisms of oxidative stress-related neurotoxicity, genotoxicity, and behavioral disturbances triggered by PHE. Results showed that PHE stress can initiate significant amounts of ROS, thus triggering oxidative stress in E. fetida brain. These effects were accompanied by a significant increase of damage to macromolecules DNA and lipids, resulting in severe oxidative effects. PHE exposure can induce AChE inhibition by ROS-induced injury and the accumulation of excess ACh at the nicotinic post-synaptic membrane, thus inducing aggravated neurological dysfunction and neurotoxicity of E. fetida through an oxidative stress pathway. Moreover, the burrowing behavior of earthworms was disturbed by oxidative stress-induced neurotoxicity after exposure to PHE. Furthermore, the abnormal mRNA expression profiles of oxidative stress- and neurotoxicity-related genes in worm brain were induced by PHE stress. The IBR results suggested that E. fetida brain was suffered more serious damage caused by PHE under higher doses and long-term exposure. Taken together, PHE exposure can trigger oxidative stress-mediated neurotoxicity and genotoxicity in worm brain and behavioral disorder through ROS-induced damage. This study is of great significance to evaluate the harmful effects of PHE and its mechanisms on soil ecological health.

Ecotoxicological evaluation of oxidative stress-mediated neurotoxic effects, genetic toxicity, behavioral disorders, and the corresponding mechanisms induced by fluorene-contaminated soil targeted to earthworm (Eisenia fetida) brain

Fluorene is a commonly identified PAH pollutant in soil and exhibits various worrisome hazardous effects to soil organisms. Currently, the toxicity profiles of fluorene on earthworm brain are rare, and the mechanisms and their corresponding pathways involved in fluorene-triggered neurotoxicity, genotoxicity, and behavior changes have not been reported hitherto. Herein, earthworm (Eisenia fetida) brain was chosen as targeted receptor to explore the neurotoxic effects, genetic toxicity, behavioral disorders, and related mechanisms caused by fluorene-induced oxidative stress pathways. The results showed excess fluorene initiated the release of excessive quantities of ROS in earthworm brain, which have caused oxidative stress and accompanied by serious oxidative effects, including LPO (lipid peroxidation) and DNA injury. To minimize the damage effects, the antioxidant defense mechanisms (antioxidant enzymes and non-enzymatic antioxidants) were activated, and entailed a decrease of the antioxidant capacity in E. fetida brain, which, in turn, causes further ROS-induced ROS release. Exposure of fluorene induced the abnormal mRNA expression of genes relevant to oxidative stress (e.g., GST, SOD, CAT, GPx, MT, and Hsp70) and neurotoxicity (e.g., H02, C04, D06, and E08) in E. fetida brain. Specifically, fluorene can bind directly to AChE, destroying the conformation of this protein, and even affecting its physiological functions. This occurrence caused the inhibition of AChE activity and excess ACh accumulation at the nicotinic post-synaptic membrane, finally triggering neurotoxicity by activation of pathways related to oxidative stress. Moreover, the avoidance responses and burrowing behavior were obviously disturbed by oxidative stress-induced neurotoxicity after exposure to fluorene. The results form IBR suggested more severe poisoning effects to E. fetida brain initiated by high-dose and long-term exposure of fluorene. Among, oxidative stress injury and genotoxic potential are more sensitive endpoint than others. Collectively, fluorene stress can provoke potential neurotoxicity, genotoxicity, and behavioral disturbances targeted to E. fetida brain through the ROS-mediated pathways involving oxidative stress. These findings are of great significance to estimate the detrimental effects of fluorene and the corresponding mechanisms on soil eco-safety.

Natural Dietary Compounds in the Treatment of Arsenic Toxicity

Chronic exposure to arsenic (As) compounds leads to its accumulation in the body, with skin lesions and cancer being the most typical outcomes. Treating As-induced diseases continues to be challenging as there is no specific, safe, and efficacious therapeutic management. Therapeutic and preventive measures available to combat As toxicity refer to chelation therapy, antioxidant therapy, and the intake of natural dietary compounds. Although chelation therapy is the most commonly used method for detoxifying As, it has several side effects resulting in various toxicities such as hepatotoxicity, neurotoxicity, and other adverse consequences. Drugs of plant origin and natural dietary compounds show efficient and progressive relief from As-mediated toxicity without any particular side effects. These natural compounds have also been found to aid the elimination of As from the body and, therefore, can be more effective than conventional therapeutic agents in ameliorating As toxicity. This review provides an overview of the recently updated knowledge on treating As poisoning through natural dietary compounds. This updated information may serve as a basis for defining novel prophylactic and therapeutic formulations.

Perinatal arsenic exposure-induced sustained microglial activation leads to impaired cognitive response in BALB/c mice

Arsenic is infamous for its adverse health effects worldwide. It is known to induce cognitive impairment in experimental model animals and children in the arsenic-affected area. Although the effect of arsenic on neuronal health is well studied, but the involvement of the brain immune component, microglia, has not been well explored. The present study is focused on examining the role of microglia in arsenic-induced cognitive impairment. We have used balb/c mice for the study. Pregnant dams were gavaged with sodium arsenite (0.38 mg/kg body weight) from gestational day 5 (GD5) till postnatal day 22 (PND22). Mice were sacrificed on PND 7, 14, 22 and isolated brains were used for various assays. The study reveals that perinatal arsenic exposure keeps the microglia activated and skews them towards the M1 phenotype. Increased microglial proliferation, ROS, NO, higher levels of proinflammatory cytokines and chemokines were observed in the arsenic exposed group. Enhanced phagocytosis and phagocytic receptor TREM2, along with decreased expression of SNAP25 and PSD95, were correlated for enhanced neuronal pruning leading to impaired learning and memory response. Taken together, the study reveals an association between arsenic exposure and altered cognitive response where enhanced neuronal pruning by arsenic-activated microglia plays an important role in developing mice.

Therapeutic effects of CoenzymeQ10, Biochanin A and Phloretin against arsenic and chromium induced oxidative stress in mouse (Mus musculus) brain

Arsenic and chromium are the most common environmental toxicants prevailing in nature. Hence, the present study endeavors to investigate the salutary effects of Coenzyme Q10 (CoQ10), Biochanin A (BCA), and Phloretin (PHL) on the combined neurotoxic impact of arsenic and chromium in the Swiss albino mice (Mus musculus). Sodium meta-arsenite (100 ppm) and potassium dichromate (75 ppm) were given orally in conjugation with CoQ10 (10 mg/kg), BCA & PHL (50 mg/kg each) in accordance with body weight per day for the 2 weeks experimental duration. Weight reduction was figured out in the exposed toxic group of arsenic and chromium in contrast with the comparison group (control), and with the selected anti-oxidants treatment, it rose significantly to the basal status (p < 0.05). The concentration of arsenic and chromium was reduced significantly (p < 0.001) amidst all the natural compounds co-medicated groups. Anti-oxidant indicators, viz. lipid peroxidation (LPO) and protein carbonyl content (PCC), were found elevated, with reduction observed in the levels of superoxide dismutase (SOD), reduced glutathione (GSH), glutathione s-transferase (GST), and total thiols (TT) in the arsenic and chromium, co-exposed mice. The alterations in redox homeostasis were well corroborated with the estimations of cholinesterase's enzymes (p < 0.05) along with DNA fragmentation assay and altered Nrf2 signaling. The administration of CoQ10, BCA, and PHL ameliorated the effects of arsenic and chromium induced oxidative stress in the exposed mice. Our research unfolds the remedial outcome of these natural compounds contrary to the combined arsenic and chromium associated-neurotoxicity in the experimental model.

Aquoeus Extracts of Daucus Carota (Linn) Protected the Postnatal Developing Cerebellum of Wistar Rats Against Arsenic-Induced Oxidative Stress

The neuroprotective effects of the aqueous extract of Daucus carota (Dc) tuber against arsenic-induced oxidative damage on the developing cerebellum of Wistar rats were studied. Twenty-five pregnant rats (110-200g) were divided into five groups (n=5) - control received distilled water; Arsenic (As); Dc (200mg/kg); Dc (200mg/kg) +As; Vitamin C (Vc) (100mg/kg) +As. The pregnant rats in all the groups were treated orally from the first day of pregnancy to postnatal day 21. The Dc extract and Vc were administered one hour before the administration of As. Body weight of the pups on days 1, 7, 14, 21 and 28 were recorded, while neurobehavioural (forelimb grip strength and negative geotaxis) tests were done on day 21 pups. The rats were sacrificed and cerebellar tissues were collected for oxidative stress, histological (H and E), and immunohistochemical studies. Decreased forelimb grip strength, increased lipid peroxidation and decreased glutathione, glutathione peroxidase, catalase and superoxide dismutase was observed in the As group compared with the control and other treated groups. Histologically, the cerebellar cortex of the As pups showed persistent external granular layer (EGL) on postnatal day 21, reduced thickness of the molecular layer (ML) on postnatal day 28, pyknotic and depleted Purkinje cells compared with the control and other treated rats. Immunohistochemical evaluations of the cerebellar cortex showed astroliosis in the As-treated group on day 21 pups compared with the control and other treated groups.  Aqueous extracts of Daucus carota and Vitamin C reversed the toxicity caused by arsenic. From the results of the study, arsenic-induced oxidative stress with morphological alterations in the perinatal developing rat cerebellum. Extracts of Daucus carota exhibited antioxidant activity as such may be a potential neuroprotective agent.

Protective Effect of Dictyophora Polysaccharides on Sodium Arsenite-Induced Hepatotoxicity: A Proteomics Study

The purpose of this study is to understand the mechanism of sodium arsenite (NaAsO₂)-induced apoptosis of L-02 human hepatic cells, and how Dictyophora polysaccharide (DIP) protects L-02 cells from arsenic-induced apoptosis. The results revealed that DIP pretreatment inhibited NaAsO₂ induced L-02 cells apoptosis by increasing anti-apoptotic Bcl-2 expression and decreasing pro-apoptotic Bax expression. Proteomic analysis showed that arsenic treatment disrupted the expression of metabolism and apoptosis associated proteins, including ribosomal proteins (RPs). After pretreatment with DIP, the expression levels of these proteins were reversed or restored. For the first time, it was observed that the significant decrease of cytoplasmic RPs and the increase of mitochondrial RPs were related to human normal cell apoptosis induced by arsenic. This is also the first report that the protective effect of DIP on cells was related to RPs. The results highlight the relationship between RPs and apoptosis, as well as the relationship between RPs and DIP attenuating arsenic-induced apoptosis.

Physicochemical Analysis of Yogurt Produced by Leuconostoc mesenteroides H40 and Its Effects on Oxidative Stress in Neuronal Cells

Leuconostoc mesenteroides H40 (H40) was isolated from kimchi, and its probiotic properties and neuroprotective effect was evaluated in oxidatively stressed SH-SY5Y cells. H40 was stable in artificial gastric conditions and can be attached in HT-29 cells. In addition, H40 did not produce β-glucuronidase and showed resistant to several antibiotics. The conditioned medium (CM) was made using HT-29 cells refined with heat-killed probiotics (Probiotics-CM) and heated yogurts (Y-CM) to investigate the neuroprotective effect. Treatment with H40-CM not only increased cell viability but also significantly improved brain derived neurotropic factor (BDNF) expression and reduced the Bax/Bcl-2 ratio in oxidatively stress-induced SH-SY5Y cells. Besides, probiotic Y-CM significantly increased BDNF mRNA expression and decreased Bax/Bcl-2 ratio. The physicochemical properties of probiotic yogurt with H40 was not significantly different from the control yogurt. The viable cell counts of lactic acid bacteria in control and probiotic yogurt with H40 was 8.66 Log CFU/mL and 8.96 Log CFU/mL, respectively. Therefore, these results indicate that H40 can be used as prophylactic functional dairy food having neuroprotective effects.

Protective effect of Catharanthus roseus plant extracts against endosulfan and its isomers induced impacts on non-targeted insect model, Drosophila melanogaster and live brain cell imaging

Endosulfan has been recognized as a highly controversial pesticide due to its acute toxicity, potential bioaccumulation, persistency, and long-range atmospheric transport. Several plant extracts act as antioxidant agents against wide-range of pesticide toxicity hazards through the free radicals scavenging properties. Plants' secondary metabolites are considered as efficient protective agents against various cellular toxic injuries. Understanding these properties of botanicals, several researchers currently focused on the detoxification and ameliorative potency of plant extracts against highly toxic chemicals. In our studies, we focused on the endosulfan total and its isomers (alpha and beta) induced changes on Drosophila melanogaster and their ameliorative effects by co-administrated with methanolic and aqueous extracts of Catharanthus roseus whole plant. We selected the 1/5th EC₅₀ concentration of alpha-endosulfan, beta-endosulfan, and endosulfan (total) and co-administrated with 1/50th EC₅₀ concentration of aqueous and methanolic extracts and evaluated their ameliorative effects, in terms of verifying the life stage activities, protein profiling and also by using live brain cells imaging. We finally concluded that, the methanolic and aqueous extracts inhibit the toxic impacts caused by endosulfan and its isomers and also increasing the survival rate of the test organism.

Influence of Iron on Cytotoxicity and Gene Expression Profiles Induced by Arsenic in HepG2 Cells

The toxicity of arsenic (As) could be influenced by many environmental factors and elements. Iron (Fe) is one of the elements that could be involved in As-induced toxicity. In this study, the interactive effects of Fe and As in HepG2 cells were analyzed based on cytotoxicity and transcriptomic analyses. The results showed that Fe could decrease cell viability and increase mitochondrial depolarization induced by As exposure. Oxidative stress and damage have been proven to be one of the main mechanisms of As toxicity. Our results showed that Fe increased the generation of reactive oxygen species (ROS) and lipid peroxidation product malondialdehyde (MDA) induced by As exposure. Microarray analysis further verified that Fe increased the alteration of gene expression and biological processes related to oxidative stress, cell proliferation, and the apoptotic signaling pathway caused by As exposure. Both results of cytotoxicity and transcriptomic analyses suggest that an increase of Fe in the human body could increase the As-induced toxicity, which should be considered during the health risk assessment of As.

Gestational Arsenic Trioxide Exposure Acts as a Developing Neuroendocrine-Disruptor by Downregulating Nrf2/PPARγ and Upregulating Caspase-3/NF-ĸB/Cox2/BAX/iNOS/ROS

The goal of this investigation was to evaluate the effects of gestational administrations of arsenic trioxide (ATO; As₂O₃) on fetal neuroendocrine development (the thyroid-cerebrum axis). Pregnant Wistar rats were orally administered ATO (5 or 10 mg/kg) from gestation day (GD) 1 to 20. Both doses of ATO diminished free thyroxine and free triiodothyronine levels and augmented thyrotropin level in both dams and fetuses at GD 20. Also, the maternofetal hypothyroidism in both groups caused a dose-dependent reduction in the fetal serum growth hormone, insulin growth factor-I (IGF-I), and IGF-II levels at embryonic day (ED) 20. These disorders perturbed the maternofetal body weight, fetal brain weight, and survival of pregnant and their fetuses. In addition, destructive degeneration, vacuolation, hyperplasia, and edema were observed in the fetal thyroid and cerebrum of both ATO groups at ED 20. These disruptions appear to depend on intensification in the values of lipid peroxidation, nitric oxide, and H₂O₂, suppression of messenger RNA (mRNA) expression of nuclear factor erythroid 2-related factor 2 and peroxisome proliferator-activated receptor gamma, and activation of mRNA expression of caspase-3, nuclear factor kappa-light-chain-enhancer of activated B cells, cyclooxygenase-2, Bcl-2–associated X protein, and inducible nitric oxide synthase in the fetal cerebrum. These data suggest that gestational ATO may disturb thyroid-cerebrum axis generating fetal neurodevelopmental toxicity.

Selenium and zinc protections against metal-(loids)-induced toxicity and disease manifestations: A review

Metals are ubiquitous in the environment due to huge industrial applications in the form of different chemicals and from extensive mining activities. The frequent exposures to metals and metalloids are crucial for the human health. Trace metals are beneficial for health whereas non-essential metals are dangerous for the health and some are proven etiological factors for diseases including cancers and neurological disorders. The interactions of essential trace metals such as selenium (Se) and zinc (Zn) with non-essential metals viz. lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in biological system are very critical and complex. A huge number of studies report the protective role of Se and Zn against metal toxicity, both in animal and cellular levels, and also explain the numerous mechanisms involved. However, it has been considered that a tiny dyshomeostasis in the metals/trace metals status in biological system could induce severe deleterious effects that can manifest to numerous diseases. Thus, in this particular review, we have demonstrated the critical protection mechanism/s of Se and Zn against Cd, Pb, As and Hg toxicity in a one by one manner to clarify the up-to-date findings and perspectives. Furthermore, biomolecular consequences are comprehensively presented in light of particular cellular/biomolecular events which are somehow linked to a subsequent disease. The analyzed reports support significant protection potential of Se and Zn, either alone or in combination with other agents, against each of the abovementioned non-essential metals. However, Se and Zn are still not being used as detoxifying agents due to some unexplained reasons. We hypothesized that Se could be a potential candidate for detoxifying As and Hg regardless of their chemical speciations, but requires intensive clinical trials. However, particularly Zn-Hg interaction warrants more investigations both in animal and cellular level.

Developmental Neurotoxicity of Arsenic: Involvement of Oxidative Stress and Mitochondrial Functions

Over the last decade, there has been an increased concern about the health risks from exposure to arsenic at low doses, because of their neurotoxic effects on the developing brain. The exact mechanism underlying arsenic-induced neurotoxicity during sensitive periods of brain development remains unclear, although enhanced oxidative stresses, leading to mitochondrial dysfunctions might be involved. Here, we highlight the generation of reactive oxygen species (ROS) and oxidative stress which leads to mitochondrial dysfunctions and apoptosis in arsenic-induced developmental neurotoxicity. Here, the administration of sodium arsenite at doses of 2 or 4 mg/kg body weight in female rats from gestational to lactational (GD6-PD21) resulted to increased ROS, led to oxidative stress, and increased the apoptosis in the frontal cortex, hippocampus, and corpus striatum of developing rats on PD22, compared to controls. Enhanced levels of ROS were associated with decreased mitochondrial membrane potential and the activity of mitochondrial complexes, and hampered antioxidant levels. Further, neuronal apoptosis, as measured by changes in the expression of pro-apoptotic (Bax, Caspase-3), anti-apoptotic (Bcl2), and stress marker proteins (p-p38, pJNK) in arsenic-exposed rats, was discussed. The severities of changes were found to more persist in the corpus striatum than in other brain regions of arsenic-exposed rats even after the withdrawal of exposure on PD45 as compared to controls. Therefore, our results indicate that perinatal arsenic exposure leads to abrupt changes in ROS, oxidative stress, and mitochondrial functions and that apoptotic factor in different brain regions of rats might contribute to this arsenic-induced developmental neurotoxicity.

Biomarkers of exposure and effect in a working population exposed to lead, manganese and arsenic

Lead (Pb), manganese (Mn) and arsenic (As) are among the major toxicants in mining environments. Miners are commonly and repeatedly exposed to this toxic mixture. Some adverse effects may appear at concentrations below environmental quality guidelines for individual mixture components. Further, Pb, Mn, and As induce common adverse outcomes, such as interferences in the cholinergic system and heme synthesis. It is thus vital to monitor miners through biomarkers (BM), such that subclinical effects may be identified at an early stage. The main objectives of this study were to evaluate the exposure of a mining population to these three metals and determine alterations in cholinergic and heme synthesis parameters. Blood and urine samples of workers (n = 60) were obtained from a Portuguese mining industry and compared with a control population (n = 80). The levels of the metals were determined in biological samples, as well as urinary heme precursor levels, delta aminolevulinic acid (ALA) and porphyrins, and blood acetylcholinesterase (AChE) activity. The miners exhibited significantly higher values of Pb and As in blood and urine compared to control. In the case of Mn near or slightly higher than limit values were found. Our data show that heme precursors may be used simultaneously with metal levels as BMs for multiple metal exposures on an individual basis, resulting in 94.3% and 95.7% accuracy, respectively, in blood and urine, for subjects correctly identified with respect to occupation. This study also revealed that biological monitoring of this working population regarding metal body burden and heme precursor accumulation is advisable.

WITHDRAWN: Toxic effects of gestational arsenic trioxide on the neuroendocrine axis of developing rats

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Arsenic-induced oxidative stress, cholinesterase activity in the brain of Swiss albino mice, and its amelioration by antioxidants Vitamin E and Coenzyme Q10

Arsenic toxicity becomes one of the major public health issues in several countries. Chronic and acute exposure to arsenic has been reported to be toxic to various systems of the human body and also observed in controlled experimental studies. The study was conducted to evaluate the neurotoxic effect of arsenic in Swiss albino mice and its amelioration by Vitamin E, Coenzyme Q10 and their combination. Swiss albino mice were treated with arsenic of 136 ppm for 15 days. The daily dose is 1/3 of LD 50 (acute) reported dose of arsenic. Thereafter, the animals were maintained either on drinking water or treated with Vitamin E (50 mg/kg bwt), Coenzyme Q10 (10 mg/kg bwt), and their combination by i.p.daily for 15 days. After the treatment, animals were sacrificed. The weight of the brain was marginally lower (ns), in arsenic-treated group as compared to control and antioxidant-protected groups. The LPO (lipid peroxidation) level was higher in arsenic-treated group, and this elevation was checked to some extent by the selected antioxidants which were statistically significant in combination of antioxidant-protected group. A significant reduction was found in GSH (reduced glutathione) level in the brain of arsenic-treated mice whereas GSH level was considerably higher in antioxidant-protected groups. Further, total thiol and total protein level were lower in arsenic-treated group. However, total thiol was significantly higher in antioxidant-protected groups. CAT (catalase) activity was significantly lower while SOD (superoxide dismutase) activity was marginally lowered in arsenic-treated group, and it was slightly higher in antioxidant-protected groups. Further, reduction in AChE (acetylcholinesterase) and BChE (butyrylcholinesterase) and motor coordination activity were also observed in arsenic-treated groups. Whereas, a higher AChE, BChE, and motor coordination activity was observed in antioxidant-protected group. These data indicate a positive role of selected antioxidant against the toxicity of arsenic in the brain of mice.

Effects of arsenic toxicity beyond epigenetic modifications

Worldwide chronic arsenic (As) poisoning by arsenic-contaminated groundwater is one of the most threatening public health problems. Chronic inorganic As (inAs) exposure has been associated with various forms of cancers and numerous other pathological effects in humans, collectively known as arsenicosis. Over the past decade, evidence indicated that As-induced epigenetic modifications have a role in the adverse effects on human health. The main objective of this article is to review the evidence on epigenetic modifications induced by arsenicals. The epigenetic components play a crucial role in the regulation of gene expression, at both transcriptional and posttranscriptional levels. We synthesized the large body of existing research on arsenic exposure and epigenetic mechanisms of health outcomes with an emphasis on recent publications. Changes in patterns of DNA methylation, histone posttranslational modifications, and microRNAs have been repeatedly observed after inAs exposure in laboratory studies and in studies of human populations. Such alterations have the potential to disturb cellular homeostasis, resulting in the modulation of key pathways in the As-induced carcinogenesis. The present article reviews recent data on As-induced epigenetic effects and concludes that it is time for heightened awareness of pathogenic arsenic exposure, particularly for pregnant women and children, given the potential for a long-lasting disturbed cellular homeostasis.

Cortex and hippocampus DNA epigenetic response to a long-term arsenic exposure via drinking water

The neurotoxicity of arsenic is a serious health problem, especially for children. DNA epigenetic change may be an important pathogenic mechanism, but the molecular pathway remains obscure. In this study, the weaned male Sprague-Dawly (SD) rats were treated with arsenic trioxide via drinking water for 6 months, simulating real developmental exposure situation of children. Arsenic exposure impaired the cognitive abilities, and altered the expression of neuronal activity-regulated genes. Total arsenic concentrations of cortex and hippocampus tissues were significantly increased in a dose-dependent manner. The reduction in 5-methylcytosine (5 mC) and 5-hydroxymethylcytosine (5hmC) levels as well as the down-regulation of DNA methyltransferases (DNMTs) and ten-eleven translocations (TETs) expression suggested that DNA methylation/demethylation processes were significantly suppressed in brain tissues. S-adenosylmethionine (SAM) level wasn't changed, but the expression of the important indicators of oxidative/anti-oxidative balance and tricarboxylic acid (TCA) cycle was significantly deregulated. Overall, arsenic can disrupt oxidative/anti-oxidative balance, further inhibit TETs expression through TCA cycle and alpha-ketoglutarate (α-KG) pathway, and consequently cause DNA methylation/demethylation disruption. The present study implies oxidative stress but not SAM depletion may lead to DNA epigenetic alteration and arsenic neurotoxicity.

Nutritional management can assist a significant role in alleviation of arsenicosis

Consumption of arsenic contaminated water causes serious skin disease and cancer in a significant number of exposed people. Chelating agents, consider an expensive therapy, are employed in the treatment of arsenic intoxication. There are reports which suggest that the poorest suffer the most from arsenicosis. This may be due to improper diet intake, consist of low protein and micronutrients which increase the vulnerability to arsenic-related disorders. Several human studies demonstrated the associations between malnourishment and the development of arsenic-caused skin lesions, skin cancer and cardiovascular effects. Thus, there is an urgent need of implementation of mitigation strategies for improving the health of exposed populations. Nutrition enhances the detoxification process so food rich in vitamins, protein, antioxidants help in its detoxification process. Methylation is the detoxification process which takes place via S-adenosylmethionine (SAM). It is a methyl group donor and it derived its methyl group from diet. Nutritional intervention thus may appear as a practical and inexpensive approach. Nutrition provides protection from toxic effect of arsenic by two ways (i) methylation of As (ii) antioxidants which provides protection against free radical species. The governments and NGOs may run awareness programmes in arsenic affected area regarding prevention and alternate therapy which can decrease the susceptibility of the exposed population. They could also help in distributing cheaper, high protein diets particularly to the masses who cannot afford such foods. Thus, to prevent arsenicosis alternate therapy and proper nutrition could be the important strategy for alleviating its toxic effects. This mini review provides an insight on the importance of nutrition in preventing adverse effect cause by arsenic to suffer population.

Medicinal plants and natural products in amelioration of arsenic toxicity: a short review

CONTEXT

Chronic arsenic toxicity (arsenicosis) is considered a serious public health menace worldwide, as there is no specific, safe, and efficacious therapeutic management of arsenicosis.

OBJECTIVES

To collate the studies on medicinal plants and natural products with arsenic toxicity ameliorative effect, active pre-clinically and/or clinically.

METHODS

Literature survey was carried out by using Google, Scholar Google and Pub-Med. Only the scientific journal articles found on the internet for last two decades were considered. Minerals and semi-synthetic or synthetic analogs of natural products were excluded.

RESULTS

Literature study revealed that 34 medicinal plants and 14 natural products exhibited significant protection from arsenic toxicity, mostly in preclinical trials and a few in clinical studies.

CONCLUSION

This research could lead to development of a potentially useful agent in clinical management of arsenicosis in humans.

Arsenic Metabolism and Toxicity Influenced by Ferric Iron in Simulated Gastrointestinal Tract and the Roles of Gut Microbiota

Iron (Fe) is a common trace element in drinking water. However, little is known about how environmental concentrations of Fe affect the metabolism and toxicity of arsenic (As) in drinking water. In this study, influence of Fe at drinking water-related concentrations (0.1, 0.3, and 3 mg Fe (total)/L) on As metabolism and toxicity, and the roles of gut microbiota during this process were investigated by using in vitro Simulator of the Human Intestinal Microbial Ecosystem (SHIME). Results showed that Fe had ability to decrease bioaccessible As by coflocculation in small intestine. 0.1 and 0.3 mg/L Fe significantly increased As methylation in simulated transverse and descending colon. Gut microbiota played an important role in alteration of As species, and Fe could affect As metabolism by changing the gut microbiota. Bacteroides, Clostridium, Alistipes, and Bilophila had As resistance and potential ability to methylate As. Cytotoxicity assays of effluents from simulated colons showed that the low levels of Fe decreased As toxicity on human hepatoma cell line HepG2, which might be due to the increase of methylated As. When assessing the health risk of As in drinking water, the residual Fe should be considered.

Influence of diet, vitamin, tea, trace elements and exogenous antioxidants on arsenic metabolism and toxicity

Health risk of arsenic (As) has received increasing attention. Acute and chronic exposure to As could cause several detrimental effects on human health. As toxicity is closely related to its bioaccessibility and metabolism. In real environment, many factors, such as diet and nutrition, can influence As bioaccessibility, metabolism and toxicity. This paper mainly reviews the influences of diets and elements on As bioaccessibility, metabolism and toxicity and their underlying mechanisms to provide suggestions for future investigations. Vitamins, jaggery, fruit, tea, glutathione, N-acetylcysteine and zinc could reduce the As-induced toxicity by increasing antioxidative enzymes to antagonize oxidative stress caused by As and/or increasing As methylation. However, bean and betel nut could increase risk of skin lesions caused by As. Interestingly, high-fat diet, selenium and iron have incompatible effects on As bioaccessibility, metabolism and toxicity in different experimental conditions. Based on current literatures, the As methylation and As-induced oxidative damage might be two main ways that the diets and elements influence As toxicity. Combined application of in vitro human cell lines and gastrointestinal models might be useful tools to simultaneously characterize the changes in As bioaccessibility and toxicity in the future research.

Ferulic acid reverses the cognitive dysfunction caused by amyloid β peptide 1-40 through anti-oxidant activity and cholinergic activation in rats

Cholinergic dysfunction and oxidation stress are the dominant mechanisms of memory deficit in Alzheimer's disease (AD). This study describes how ferulic acid (FA) ameliorates cognitive deficits induced by mecamylamine (MECA), scopolamine (SCOP), central acetylcholinergic neurotoxin ethylcholine mustard aziridinium ion (AF64A) and amyloid β peptide (Aβ1-40). This study also elucidates the role of anti-oxidant enzymes and cholinergic marker acetylcholinesterase (AChE) in the reversal of FA from Aβ1-40-induced cognitive deficits in rats. At 100 mg/kg, FA attenuated impairment induced by MECA and SCOP plus MECA; however, this improvement was not blocked by the peripheral muscarinic receptor antagonist scopolamine methylbromide (M-SCOP). At 100 and 300 mg/kg, FA also attenuated the impairment of inhibitory passive avoidance induced by AF64A. Further, FA attenuated the performance impairment and memory deficit induced by Aβ1-40 in rats, as did vitamin E/C. FA reversed the deterioration of superoxide dismutase (SOD) and AChE activities, and the glutathione disulfide (GSSG) and glutathione (GSH) levels in the cortex and hippocampus. Vitamin E/C only selectively reversed deterioration in the hippocampus. We suggest that FA reduced the progression of cognitive deficits by activating central muscarinic and nicotinic receptors and anti-oxidant enzymes.

Vitamin C in disease prevention and cure: an overview

The recognition of vitamin C is associated with a history of an unrelenting search for the cause of the ancient haemorrhagic disease scurvy. Isolated in 1928, vitamin C is essential for the development and maintenance of connective tissues. It plays an important role in bone formation, wound healing and the maintenance of healthy gums. Vitamin C plays an important role in a number of metabolic functions including the activation of the B vitamin, folic acid, the conversion of cholesterol to bile acids and the conversion of the amino acid, tryptophan, to the neurotransmitter, serotonin. It is an antioxidant that protects body from free radical damage. It is used as therapeutic agent in many diseases and disorders. Vitamin C protects the immune system, reduces the severity of allergic reactions and helps to fight off infections. However the significance and beneficial effect of vitamin C in respect to human disease such as cancer, atherosclerosis, diabetes, neurodegenerative disease and metal toxicity however remains equivocal. Thus further continuous uninterrupted efforts may open new vistas to understand its significance in disease management.