The pesticide deltamethrin increases free radical production and promotes nuclear translocation of the stress response transcription factor Nrf2 in rat brain

Assessment of deltamethrin-induced DNA damage, neurotoxic and neuroimmune effects in the brain tissue of brown trout (Salmo trutta fario)

This study investigated the impact of deltamethrin (DM) toxicity on brown trout (Salmo trutta fario), examining its effects on the immune system, including the white blood cell (WBC), lymphocyte (Lym), total immunoglobulin (T. Ig), and lysozyme levels, as well as its neurotoxic consequences on the brain tissue. The neurotoxic effects encompassed oxidative stress, the activity of the antioxidant enzymes, such as the superoxide dismutase (SOD) and catalase (CAT), acetylcholinesterase (AChE) activity, and DNA damage using 8-hydroxy-2-deoxyguanosine (8-OHdG). The DM exposure led to elevated levels of malondialdehyde (MDA), and 8-OHdG, while concurrently causing a reduction in the AChE activity, protein and lipid content, WBC count, Lym, lysozyme activity, T. Ig levels, as well as the SOD and CAT levels in the brain tissues of groups 2 and 3 when compared to those in group 1. In summary, the findings of this study strongly indicate that DM induces DNA damage, immunotoxicity, and neurotoxicity in the brain tissue of brown trout, primarily due to the excessive production of reactive oxygen species (ROS). Moreover, the observed dose-dependent responses of DM to the environmental concentrations on all the investigated parameters suggest its potential utility in aquaculture risk assessment.

Redox mechanisms of environmental toxicants on male reproductive function

Humans and wildlife, including domesticated animals, are exposed to a myriad of environmental contaminants that are derived from various human activities, including agricultural, household, cosmetic, pharmaceutical, and industrial products. Excessive exposure to pesticides, heavy metals, and phthalates consequently causes the overproduction of reactive oxygen species. The equilibrium between reactive oxygen species and the antioxidant system is preserved to maintain cellular redox homeostasis. Mitochondria play a key role in cellular function and cell survival. Mitochondria are vulnerable to damage that can be provoked by environmental exposures. Once the mitochondrial metabolism is damaged, it interferes with energy metabolism and eventually causes the overproduction of free radicals. Furthermore, it also perceives inflammation signals to generate an inflammatory response, which is involved in pathophysiological mechanisms. A depleted antioxidant system provokes oxidative stress that triggers inflammation and regulates epigenetic function and apoptotic events. Apart from that, these chemicals influence steroidogenesis, deteriorate sperm quality, and damage male reproductive organs. It is strongly believed that redox signaling molecules are the key regulators that mediate reproductive toxicity. This review article aims to spotlight the redox toxicology of environmental chemicals on male reproduction function and its fertility prognosis. Furthermore, we shed light on the influence of redox signaling and metabolism in modulating the response of environmental toxins to reproductive function. Additionally, we emphasize the supporting evidence from diverse cellular and animal studies.

The Gut-Brain Axis as a Therapeutic Target in Multiple Sclerosis

The CNS is very susceptible to oxidative stress; the gut microbiota plays an important role as a trigger of oxidative damage that promotes mitochondrial dysfunction, neuroinflammation, and neurodegeneration. In the current review, we discuss recent findings on oxidative-stress-related inflammation mediated by the gut-brain axis in multiple sclerosis (MS). Growing evidence suggests targeting gut microbiota can be a promising strategy for MS management. Intricate interaction between multiple factors leads to increased intra- and inter-individual heterogeneity, frequently painting a different picture in vivo from that obtained under controlled conditions. Following an evidence-based approach, all proposed interventions should be validated in clinical trials with cohorts large enough to reach significance. Our review summarizes existing clinical trials focused on identifying suitable interventions, the suitable combinations, and appropriate timings to target microbiota-related oxidative stress. Most studies assessed relapsing-remitting MS (RRMS); only a few studies with very limited cohorts were carried out in other MS stages (e.g., secondary progressive MS-SPMS). Future trials must consider an extended time frame, perhaps starting with the perinatal period and lasting until the young adult period, aiming to capture as many complex intersystem interactions as possible.

Effects of pyrethroids on the cerebellum and related mechanisms: a narrative review

Pyrethroids (PYRs) are a group of synthetic organic chemicals that mimic natural pyrethrins. Due to their low toxicity and persistence in mammals, they are widely used today. PYRs exhibit higher lipophilicity than other insecticides, which allows them to easily penetrate the blood-brain barrier and directly induce toxic effects on the central nervous system. Several studies have shown that the cerebellum appears to be one of the regions with the largest changes in biomarkers. The cerebellum, which is extremely responsive to PYRs, functions as a crucial region for storing motor learning memories. Exposure to low doses of various types of PYRs during rat development resulted in diverse long-term effects on motor activity and coordination functions. Reduced motor activity may result from developmental exposure to PYRs in rats, as indicated by delayed cerebellar morphogenesis and maturation. PYRs also caused adverse histopathological and biochemical changes in the cerebellum of mothers and their offspring. By some studies, PYRs may affect granule cells and Purkinje cells, causing damage to cerebellar structures. Destruction of cerebellar structures and morphological defects in Purkinje cells are known to be directly related to functional impairment of motor coordination. Although numerous data support that PYRs cause damage to cerebellar structures, function and development, the mechanisms are not completely understood and require further in-depth studies. This paper reviews the available evidence on the relationship between the use of PYRs and cerebellar damage and discusses the mechanisms of PYRs.

Molecular Characterization of Spodoptera frugiperda Heme Oxygenase and Its Involvement in Susceptibility to Chlorantraniliprole

The mammalian heme oxygenase (HO) plays an important role in cytoprotection against oxidative-stress-induced cell damage; however, functional characterization of insect HO is still limited. In this study, cDNA encoding a HO, named SfHO, was cloned from Spodoptera frugiperda. Analysis of the transcription level and enzymatic activity showed that exposure of the LC₃₀ concentration of chlorantraniliprole to the third instar larvae significantly upregulated both the mRNA level and enzymatic activity of SfHO at 24 h after treatment. Further injection of the HO activator, hemin, into the third instar larvae led to the upregulation of SfHO as well as decreased susceptibility of S. frugiperda to chlorantraniliprole. Consistently, overexpression of SfHO increased the Sf9 cell viability under chlorantraniliprole treatment. Strikingly, both RNAi and the dual-luciferase reporter assay in Sf9 cells revealed that, unlike mammalian HO that is regulated by the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), SfHO was not subject to the regulation by cap 'n' collar isoform C (CncC), the Nrf2 homologue in insects. These data provide insights into the function and regulatory mechanism of insect HOs and had applied implications for the control of S. frugiperda.

Dimethyl Fumarate Attenuates Di-(2-Ethylhexyl) Phthalate-Induced Nephrotoxicity Through the Nrf2/HO-1 and NF-κB Signaling Pathways

This study aimed to clarify the nephroprotective effect of dimethyl fumarate (DMF) against Di (2-ethylhexyl) phthalate (DEHP)-induced nephrotoxicity in both in vitro and in vivo models. The HEK-293 cells were exposed to different concentrations of DMF plus IC50 concentration of monoethylhexyl phthalate (MEHP) (the main metabolite of DEHP). Then, some of the oxidative stress parameters including ROS, MDA, and GSH, and cytotoxicity (MTT assay) were determined in treated cells. For in vivo evaluation, rats were divided into 7 groups (n = 6 per group). Corn oil group (gavage), DEHP group (200 mg/kg dissolved in corn oil, gavage), DMF (15, 30, and 60 mg/kg, gavage) plus DEHP (200 mg/kg) groups, DMF (60 mg/kg, gavage) alone, and vitamin E (20 mg/kg, intraperitoneal (IP)) plus DEHP (200 mg/kg) group. This treatment continued for 45 days. Then, BUN and creatinine were evaluated by a commercial kit based on the urease enzymatic method and the Jaffe method, respectively. Mitochondrial oxidative stress and mitochondrial dysfunction parameters were evaluated using appropriate reagents, and gene expression of the p65 nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (TNFα), nuclear factor E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) were evaluated by real-time PCR method. High concentrations of DMF significantly increased cell viability, and GSH content and significantly decreased ROS and MDA levels compared with the MEHP group in HEK-293 cells. DMF (60 mg/kg) significantly decreased BUN and creatinine levels compared with the DEHP group. Mitochondrial function and mitochondrial swelling were significantly improved in DMF group (60 mg/kg) compared with the DEHP group. DMF (30 and 60 mg/kg) significantly improved MMP collapse compared with the DEHP group. DMF (30 and 60 mg/kg) significantly decreased ROS levels compared with the DEHP group in isolated kidney mitochondria. DMF (60 mg/kg) significantly decreased MDA levels and significantly increased GSH content compared with DEHP group in isolated kidney mitochondria. The mRNA expression levels of Nrf2 and HO-1 were significantly reduced in the DEHP group compared to the control group and were significantly increased in the DMF group compared to the DEHP group. p65NF-κB and TNFα mRNA expression levels were significantly increased in the DEHP group compared to the control group. However, DMF significantly decreased p65NF-κB and TNFα mRNA expression compared to the DEHP group. DMF can act as a nephroprotective agent against DEHP partly through modulation of oxidative stress, mitochondrial function, and inflammation.

A Common Feature of Pesticides: Oxidative Stress-The Role of Oxidative Stress in Pesticide-Induced Toxicity

Pesticides are important chemicals or biological agents that deter or kill pests. The use of pesticides has continued to increase as it is still considered the most effective method to reduce pests and increase crop growth. However, pesticides have other consequences, including potential toxicity to humans and wildlife. Pesticides have been associated with increased risk of cardiovascular disease, cancer, and birth defects. Labels on pesticides also suggest limiting exposure to these hazardous chemicals. Based on experimental evidence, various types of pesticides all seem to have a common effect, the induction of oxidative stress in different cell types and animal models. Pesticide-induced oxidative stress is caused by both reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are associated with several diseases including cancer, inflammation, and cardiovascular and neurodegenerative diseases. ROS and RNS can activate at least five independent signaling pathways including mitochondrial-induced apoptosis. Limited in vitro studies also suggest that exogenous antioxidants can reduce or prevent the deleterious effects of pesticides.

Protective Effect of Nigella sativa and Onion Extract against 5-Fluorouracil-Induced Hepatic Toxicity

Aim: The present study intended to compare the antioxidant, anti-lipid peroxidation, and anti-inflammatory potentials of Nigella Sativa (NS) and onion extract on 5-FU-induced liver damage in rats. Material and methods: 48 rats were divided into control, control group of the onion extract, control group of the NS extract, 5-FU-treated, concomitant NS-treated, and concomitant onion extract-treated. Liver sections were processed for histological analysis (light and electron microscopic examination). Liver enzymes (ALT, AST, and ALP), inflammatory markers (TNF-α and IL-1), antioxidant markers (SOD, GSH, and GSH/GSSG ratio), 4-HNE, NF-κB, and Nrf2 were evaluated. Results: The 5-FU-treated group exhibited inflammation, congested hepatic sinusoid, and steatosis. Improvement with few pathological residues was seen in the concomitant extract-treated groups. The 5-FU-treated group showed higher liver enzymes. The enzymes decreased in the concomitantly treated groups. 5-FU induced liver damage through oxidative stress, inflammation, and lipid peroxidation. Concomitantly using NS and onion extracts resulted in a reduction in oxidative stress, lipid peroxidation, and inflammation. Conclusion: NS and onion extracts attenuated 5-FU-induced liver damage via antioxidative, anti-lipid peroxidative, and anti-inflammatory mechanisms. NS's role was exceptional when compared with onion extract.

Epigenetics in neurodegenerative disorders induced by pesticides

Neurodegenerative diseases are becoming major socio-economic burdens. However, most of them still have no effective treatment. Growing evidence indicates excess exposure to pesticides are involved in the development of various forms of neurodegenerative and neurological diseases through trigger epigenetic changes and inducing disruption of the epigenome. This review summaries studies on epigenetics alterations in nervous systems in relation to different kinds of pesticides, highlighting potential mechanism in the etiology, precision prevention and target therapy of various neurodegenerative diseases. In addition, the current gaps in research and future areas for study were also discussed.

Mechanistic insight into toxicity of phthalates, the involved receptors, and the role of Nrf2, NF-κB, and PI3K/AKT signaling pathways

The wide use of phthalates, as phthalates are used in the manufacturing of not only plastics but also many others goods, has become a main concern in the current century because of their potency to induce deleterious effects on organism health. The toxic effects of phthalates such as reproductive toxicity, cardiotoxicity, hepatotoxicity, nephrotoxicity, teratogenicity, and tumor development have been widely indicated by previous experimental studies. Some of the important mechanisms of toxicity by phthalates are the induction and promotion of inflammation, oxidative stress, and apoptosis. Awareness of the involved molecular pathways of these mechanisms will permit the detection of exact molecular targets of phthalates to protect or treat their toxicity. Up to now, various transcription factors and signaling pathways have been associated with phthalate-induced toxicity which by influencing on nuclear surface and the expression of different genes can alter cell hemostasis. In different studies, the role of nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor-κB (NF-κB), and phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathways in processes of oxidative stress, inflammation, apoptosis, and cancer has been shown following exposure to phthalates. In the present review, we aim to survey experimental studies (in vitro and in vivo) in order to show firstly the most involved receptors and also the importance and the role of the mentioned signaling pathways in phthalate-induced toxicity, and with considering this point, the future studies can focus on these molecular targets as a strategic method to reduce environmental chemicals-induced toxicity especially phthalates toxic effects.

Nerve Growth Factor Protects Against Pyrethroid-Induced Endoplasmic Reticulum (ER) Stress in Primary Hippocampal Neurons

Neurotrophins are a family of growth factors crucial for growth and survival of neurons in the developing and adult brain. Reduction in neurotrophin levels is associated with reduced neurogenesis and cognitive deficits in rodents. Recently, we demonstrated that long-term exposure to low levels of the pyrethroid pesticide deltamethrin causes hippocampal endoplasmic reticulum (ER) stress and learning deficits in mice. Here, we found that nerve growth factor (NGF) mRNA and protein were selectively reduced in the hippocampus of deltamethrin-treated mice. To explore potential mechanisms responsible for this observation, we employed mouse primary hippocampal neurons. Exposure of neurons to deltamethrin (1-5 μM) caused ER stress as indicated by increased levels of C/EBP-homologous protein (CHOP) and glucose-regulated protein 78 (GRP78). These changes were accompanied by increased levels of caspase-12, activated caspase-3, and decreased levels of NGF. Inhibition of ER stress with the eukaryotic initiation factor 2 alpha (eIF2α) inhibitor salubrinal abolished deltamethrin-induced activation of caspase-12 and caspase-3, and restored NGF levels. Furthermore, deltamethrin decreased Akt (protein kinase B) phosphorylation, which was significantly prevented by co-treatment with NGF or SC-79 in cells. Collectively, these results demonstrate that the loss of NGF following ER stress may contribute to deltamethrin-induced apoptosis in the hippocampus through the Akt signaling pathway, and that this may provide a plausible mechanism for impaired learning and memory observed following exposure of mice to deltamethrin.

Resveratrol Regulates Nrf2-Mediated Expression of Antioxidant and Xenobiotic Metabolizing Enzymes in Pesticides-Induced Parkinsonism

BACKGROUND

Combined maneb (MB) and paraquat (PQ), two widely used pesticides, increases oxidative stress leading to Parkinsonism. Xenobiotic metabolizing enzymes, cytochrome P450 (CYP) 2D6 and its mouse ortholog Cyp2d22 protect against Parkinsonism. Resveratrol, an antioxidant, restores antioxidant defense system through the activation of nuclear factor erythroid 2- related factor 2 (Nrf2). However, a crosstalk between Cyp2d22/CYP2D6-mediated protection and resveratrol-induced Nrf2 activation leading to neuroprotection is not yet elucidated.

OBJECTIVE

The study aimed to decipher the effect of resveratrol on Nrf2 activation and expression of its downstream mediators, nicotinamide adenine dinucleotide phosphate quinone oxidoreductase 1 (NQO1) and thioredoxin 1 (Trx1) along with Cyp2d22/CYP2D6 activity in combined MB and PQ mouse model of Parkinsonism and differentiated neuroblastoma cells.

RESULTS

MB and PQ reduced the dopamine content (mouse) and Cyp2d22/CYP2D6 activity (mouse/neuroblastoma cells) and increased the nuclear translocation of Nrf2 and expression of NQO1 and Trx1 (both). Resveratrol ameliorated pesticides-induced changes in dopamine content and Cyp2d22/CYP2D6 activity. It was found to promote nuclear translocation of Nrf2 and expression of NQO1 and Trx1 proteins. Since Cyp2d22/CYP2D6 inhibitor (ketoconazole/quinidine) per se reduced Cyp2d22/CYP2D6 activity and dopamine content, it was found to substantially increase the pesticides-induced reduction in Cyp2d22/CYP2D6 activity and dopamine content. Inhibitors normalized the pesticides induced changes in Nrf2 translocation and NQO1 and Trx1 levels in pesticides treated groups.

CONCLUSION

The results suggest that resveratrol promotes the catalytic activity of xenobiotic metabolizing enzyme, Cyp2d22/CYP2D6, which partially contributes to Nrf2 activation in pesticides- induced Parkinsonism.

Organophosphate-pesticides induced survival mechanisms and APE1-mediated Nrf2 regulation in non-small-cell lung cancer cells

Epidemiological and molecular studies have indicated that environmental exposure to organophosphate pesticides (OPPs) is associated with increased cancer risk; however, the underlying molecular mechanisms still need to be explained. Increasing cancer incidence is linked to OPPs-induced oxidative stress (OS). Our study evaluates monocrotophos (MCP) and chlorpyrifos (CP)-induced OS responses and apurinic/apyrimidinic endonuclease 1 (APE1) role in human non-small-cell lung cancer (NSCLC) cells. Our prior study has implicated OPPs-induced base excision repair (BER)-pathway dysregulation and APE1-mediated regulation of transcription factor (TF) c-jun in A549 cells. We further investigated the effects of MCP and CP on apoptosis, proliferation, and APE1's redox-regulation of nuclear factor-like 2 (Nrf2). Data demonstrates that MCP and CP at subtoxic concentrations induced reactive oxygen species generation and oxidative DNA base damage 8-oxo-dG lesions in NCI-H1299 cells. CP moderately upregulated the apoptosis-inducing factor (AIF) in A549 cells, however, it did not trigger other pro-apoptotic factors viz. caspase-9 and caspase-3, suggesting early caspase-independent apoptosis. However, dose-dependent AIF-downregulation was observed for MCP treatment. Furthermore, CP and MCP treatments upregulated proliferating cell nuclear antigen levels. Immunofluorescent confocal imaging showed the colocalization of APE1 with Nrf2 in 10 µM CP- and MCP-treated NCI-H1299 cells. Immunoprecipitation confirmed that APE1 and Nrf2 physically interacted, indicating the role of APE1-mediated Nrf2 activation following OPPs treatment. This study suggests that low concentration MCP and CP exposure generates OS along with DNA damage, and modulates apoptosis, and APE1-mediated Nrf2 activation, which might be considered as the possible mechanism promoting lung cancer cell survival, suggesting that APE1 may have the potential to become a therapeutic target for the treatment of NSCLC.

Ran participates in deltamethrin stress through regulating the nuclear import of Nrf2

The small GTPase Ran has a variety of biological functions, one of the most prominent of which is to regulate nucleocytoplasmic transport. In our previous study, it was suggested that Ran is involved in the deltamethrin (DM) stress. In addition, Keap1-Nrf2-ARE pathway was also confirmed to be associated with DM stress. We report here that under DM stress, interfering Ran or nuclear transport factor Ntf2 by RNAi could suppress the nuclear import of nuclear transcription factor Nrf2 which then down-regulates the expressions of detoxification enzyme genes (Cyp4d20, Cyp4ae1, GstD5, Sod3, etc.), ultimately resulting in a significant apoptosis of Drosophila Kc cells. In contrast, after overexpressing Ran in Kc cells, Nrf2 has a higher concentration in the nucleus, and the expressions of detoxification enzyme genes are up-regulated, while the DM-induced apoptosis is significantly lower than that of the control group. Additionally, we preliminary found silencing Ntf2 or Ran could prevent the nuclear import of transcription factor Dif under DM stress, subsequently decreased expressions of antimicrobial peptide genes (Drsl1). In summary, our data mainly indicates that Ran may participate in DM stress through regulating the nuclear import of Nrf2, which could help to study the mechanism of deltamethrin resistance.

Redox toxicology of environmental chemicals causing oxidative stress

Living organisms are surrounded with heavy metals such as methylmercury, manganese, cobalt, cadmium, arsenic, as well as pesticides such as deltamethrin and paraquat, or atmospheric pollutants such as quinone. Extensive studies have demonstrated a strong link between environmental pollutants and human health. Redox toxicity is proposed as one of the main mechanisms of chemical-induced pathology in humans. Acting as both a sensor of oxidative stress and a positive regulator of antioxidants, the nuclear factor erythroid 2-related factor 2 (NRF2) has attracted recent attention. However, the role NRF2 plays in environmental pollutant-induced toxicity has not been systematically addressed. Here, we characterize NRF2 function in response to various pollutants, such as metals, pesticides and atmospheric quinones. NRF2 related signaling pathways and epigenetic regulations are also reviewed.

Nano-curcumin versus curcumin in amelioration of deltamethrin-induced hippocampal damage

We aimed to prove that oxidative stress is the main mechanism responsible for hippocampal neurotoxicity induced by deltamethrin (DLM). The protective role of curcumin (CMN) and nano-curcumin (NCMN) over this toxicity was studied. The rats were categorized into four groups: control, DLM, CMN and NCMN. The study continued for 30 days. Hippocampus was processed for histological, biochemical and immunohistochemical studies. Caspase-3, glial fibrillar acidic protein (GFAP), acetylcholinesterase (AChE), malondialdehyde (MDA), glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) were measured for DLM-induced oxidative stress (increased MDA by 354%/decreased GSH by 61%, SOD by 61%, CAT 57%). Oxidative stress induced apoptosis of hippocampal neurons through increasing Nrf2, gamma-glutamyl cysteine synthetase heavy subunit (GCS-HS) and light subunit (GCS-LS) and decreasing AChE. It increases the activity of astrocytes through increasing GFAP. Finally, oxidative stress has a bad impaction on cognitive function. Improvement of oxidative stress was observed with use of CMN and NCMN (decrease of MDA/increase of GSH, SOD, CAT). The level of Nrf2, GCS-HS and GCS-LS decreased, while AChE, GFAP increased. Improvement of cognitive function was observed in both groups. In conclusion, oxidative stress is the common mechanism responsible for DLM-induced hippocampal neurotoxicity. It exerts apoptosis of hippocampal neurons through increasing Nrf2, HS-GCS, LS-GCS and decreasing AChE. In addition, it activates astrocytes through increasing expression of GFAP. The protective role of CMN and CMMN is related to their potent antioxidant effect. Much improvement has been detected with NCMN as compared to CMN.

Saliva and urine metabolic profiling reveals altered amino acid and energy metabolism in male farmers exposed to pesticides in Madhya Pradesh State, India

Globally, the human population is exposed to low doses of pesticides due to its extensive use in agriculture. The chronic exposure to pesticides can lead to cancer, depression, anxiety, Parkinson's and Alzheimer's diseases etc. Here, we have made an attempt to use mass spectrometry based metabolomics to investigate the metabolic perturbations induced by the pesticides in the urine and saliva samples of farmers from the Madhya Pradesh State of India. The study was aimed to establish non-invasive matrices like urine and saliva as alternative diagnostic matrices to the occupational exposure studies. Saliva and urine samples were collected from 51 pesticides applicators and acquired metabolic profiles of urine and saliva samples using gas chromatography-mass spectrometry (GC-MS). Multivariate pattern recognition and pathway analysis were used to analyze and interpret the data. Investigation of endogenous metabolic profiles revealed remarkable discrimination in both saliva and urine samples of the exposed population strongly suggesting the changes in metabolic composition within the identified metabolites (for urine samples: accuracy 0.9766, R² = 0.9130, Q² = 0.8703; for saliva samples, an accuracy of 0.9961, R² = 0.9698, Q² = 0.9637). Thirteen metabolites of urine samples and sixteen metabolites of saliva samples were identified as differential metabolites specific to pesticide exposure. Pathway analysis of differential metabolites revealed that amino acid metabolism, energy metabolism (glycolysis and TCA cycle) and glutathione metabolism (oxidative stress) were found to affect in pesticide exposed population. The present study suggested that GC-MS based metabolomics can help to reveal the metabolic perturbations in human population after pesticides exposure.

Pyrethroid exposure and neurotoxicity: a mechanistic approach

Pyrethroids are a class of synthetic insecticides that are used widely in and around households to control the pest. Concerns about exposure to this group of pesticides are now mainly related to their neurotoxicity and nigrostriatal dopaminergic neurodegeneration seen in Parkinson’s disease. The main neurotoxic mechanisms include oxidative stress, inflammation, neuronal cell loss, and mitochondrial dysfunction. The main neurodegeneration targets are ion channels. However, other receptors, enzymes, and several signalling pathways can also participate in disorders induced by pyrethroids. The aim of this review is to elucidate the main mechanisms involved in neurotoxicity caused by pyrethroids deltamethrin, permethrin, and cypermethrin. We also review common targets and pathways of Parkinson’s disease therapy, including Nrf2, Nurr1, and PPARγ, and how they are affected by exposure to pyrethroids. We conclude with possibilities to be addressed by future research of novel methods of protection against neurological disorders caused by pesticides that may also find their use in the management/treatment of Parkinson’s disease.

Deltamethrin toxicity: A review of oxidative stress and metabolism

Deltamethrin is widely used worldwide due to its valuable insecticidal activity against pests and parasites. Increasing evidence has shown that deltamethrin causes varying degrees of toxicity. Moreover, oxidative stress and metabolism are highly correlated with toxicity. For the first time, this review systematically summarizes the deltamethrin toxicity mechanism from the perspective of oxidative stress, including deltamethrin-mediated oxidative damage, antioxidant status, oxidative signaling pathways and modulatory effects of antagonists, synergists and placebos on oxidative stress. Further, deltamethrin metabolism, including metabolites, metabolic enzymes and pathways and deltamethrin metabolite toxicity are discussed. This review will shed new light on deltamethrin toxicity mechanisms and provide effective strategies to ensure pest control and prevention of human and animal poisoning.

Identification of Compounds That Inhibit Estrogen-Related Receptor Alpha Signaling Using High-Throughput Screening Assays

The nuclear receptor, estrogen-related receptor alpha (ERRα; NR3B1), plays a pivotal role in energy homeostasis. Its expression fluctuates with the demands of energy production in various tissues. When paired with the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), the PGC/ERR pathway regulates a host of genes that participate in metabolic signaling networks and in mitochondrial oxidative respiration. Unregulated overexpression of ERRα is found in many cancer cells, implicating a role in cancer progression and other metabolism-related diseases. Using high throughput screening assays, we screened the Tox21 10K compound library in stably transfected HEK293 cells containing either the ERRα-reporter or the reporter plus PGC-1α expression plasmid. We identified two groups of antagonists that were potent inhibitors of ERRα activity and/or the PGC/ERR pathway: nine antineoplastic agents and thirteen pesticides. Results were confirmed using gene expression studies. These findings suggest a novel mechanism of action on bioenergetics for five of the nine antineoplastic drugs. Nine of the thirteen pesticides, which have not been investigated previously for ERRα disrupting activity, were classified as such. In conclusion, we demonstrated that high-throughput screening assays can be used to reveal new biological properties of therapeutic and environmental chemicals, broadening our understanding of their modes of action.

Evaluation of Nrf2 with Exposure to Nanoparticles

Transcription factor Nrf2, nuclear factor (erythroid-derived 2)-like 2, is considered a master regulator of redox homeostasis and plays a central role in antioxidant and anti-inflammatory defence. It has been largely reported that oxidative stress is implicated in nanoparticle-induced toxicity with the involvement of Nrf2. Several basic methods for Nrf2 evaluation with exposure to nanoparticles are described in this chapter including real-time reverse transcription-polymerase chain reaction (RT-PCR), western blotting, immunofluorescence staining, electrophoretic mobility shift assay, DNase I footprinting, dimethylsulfate footprinting, protein pulse-chase analysis, and tert-butylhydroquinone treatment.

Pyrethroid bifenthrin induces oxidative stress, neuroinflammation, and neuronal damage, associated with cognitive and memory impairment in murine hippocampus

Exposure to synthetic pyrethroid (SPs) pesticides such as bifenthrin (BF) has been associated with adverse neurodevelopmental outcomes and cognitive impairments, but the underlying neurobiological mechanism is poorly understood so far. The present study has been designed to evaluate changes in behavior and in biomarkers of oxidative stress and neuroinflammation in the hippocampus of rats subchronically treated with BF. Rats exposed daily to BF at doses of 0.6 and 2.1 mg/kg b. w. for 60 days exhibited spatial and cognitive impairments as well as memory dysfunction after 60 days. This repeated BF treatment also significantly increased mRNA expression of pro-inflammatory cytokines tumor necrosis factor (TNF-α), interleukin (IL-1β), (IL-6), nuclear factor erythroid-2 (Nrf2), cyclooxygenase-2 (COX-2), nuclear factor-kappaB pathway (NF-kappaB), and prostaglandin E₂ (PGE₂) in the hippocampus. It further resulted in a significant increase in protein levels of Nrf2, COX-2, microsomal prostaglandin synthase-1 (mPGES-1) and NF-kappaB. This was accompanied by oxidative/nitrosative stress in the hippocampus of treated rats, as shown by increased levels of malondialdehyde (MDA), protein carbonyls (PCO), and nitric oxide (NO), and reduced levels of enzymatic (catalase, superoxide dismutase, and glutathione peroxidase) and non-enzymatic (reduced glutathione) antioxidants. The data are in line with those obtained in organotypic hippocampal slice cultures (OHSCs) isolated from mouse brain and exposed to BF for 72 h, showing neuronal death only at the high dose of 20 μM when compared to controls. These findings suggest that exposure to BF induces neuronal damage, alters redox state, and causes neuroinflammation in the hippocampus, which might lead to cognitive and memory impairment.

Metabolome disruption of pregnant rats and their offspring resulting from repeated exposure to a pesticide mixture representative of environmental contamination in Brittany

The use of pesticides exposes humans to numerous harmful molecules. Exposure in early-life may be responsible for adverse effects in later life. This study aimed to assess the metabolic modifications induced in pregnant rats and their offspring by a pesticide mixture representative of human exposure. Ten pregnant rats were exposed to a mixture of eight pesticides: acetochlor (246 μg/kg bw/d) + bromoxynil (12 μg/kg bw/d) + carbofuran (22.5 μg/kg bw/d) + chlormequat (35 μg/kg bw/d) + ethephon (22.5 μg/kg bw/d) + fenpropimorph (15.5 μg/kg bw/d) + glyphosate (12 μg/kg bw/d) + imidacloprid (12.5 μg/kg bw/d) representing the main environmental pesticide exposure in Brittany (France) in 2004. Another group of 10 pregnant rats served as controls. Females were fed ad libitum from early pregnancy, which is from gestational day (GD) 4 to GD 21. Urine samples were collected at GD 15. At the end of the exposure, mothers and pups were euthanized and blood, liver, and brain samples collected. 1H NMR-based metabolomics and GC-FID analyses were performed and PCA and PLS-DA used to discriminate between control and exposed groups. Metabolites for which the levels were significantly modified were then identified using the Kruskal-Wallis test, and p-values were adjusted for multiple testing correction using the False Discovery Rate. The metabolomics analysis revealed many differences between dams of the two groups, especially in the plasma, liver and brain. The modified metabolites are involved in TCA cycle, energy production and storage, lipid and carbohydrate metabolism, and amino-acid metabolism. These modifications suggest that the pesticide mixture may induce oxidative stress associated with mitochondrial dysfunction and the impairment of glucose and lipid metabolism. These observations may reflect liver dysfunction with increased relative liver weight and total lipid content. Similar findings were observed for glucose and energy metabolism in the liver of the offspring, and oxidative stress was also suggested in the brains of male offspring.

Inflammatory and cytotoxic effects of bifenthrin in primary microglia and organotypic hippocampal slice cultures

BACKGROUND

Pyrethroids, such as bifenthrin (BF), are among the most widely used class of insecticides that pose serious risks to human and wildlife health. Pyrethroids are proposed to affect astrocytic functions and to cause neuron injury in the central nervous system (CNS). Microglia are key cells involved in innate immune responses in the CNS, and microglia activation has been linked to inflammation and neurotoxicity. However, little information is known about the effects of BF-induced toxicity in primary microglial cells as well as in organotypic hippocampal slice cultures (OHSCs).

METHODS

Oxidative stress and inflammatory responses induced by BF were evaluated in primary microglial cells and OHSCs incubated with different concentrations of BF (1-20 μM) for 4 and 24 h. mRNA and protein synthesis of cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), nuclear erythroid-2 like factor-2 (Nrf-2), and microsomal prostaglandin synthase-1 (mPGES-1) was also studied by qPCR and Western blot. Cell viability was analyzed by MTT-tetrazolio (MTT) and lactate dehydrogenase (LDH) assays. Neurotoxicity in OHSCs was analyzed by propidium iodide (PI) staining and confocal microscopy.

RESULTS

Exposure of microglial cells to BF for 24 h resulted in a dose-dependent reduction in the number of viable cells. At sub-cytotoxic concentrations, BF increased reactive oxygen species (ROS), TNF-alpha synthesis, and prostaglandin E2 (PGE2) production, at both 4- and 24-h time points, respectively. Furthermore, BF incubation decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities and increased lipid peroxidation, protein oxidation, and H2O2 formation. In addition, BF significantly induced protein synthesis and mRNA expression of oxidative and inflammatory mediators after 4 and 24 h, including Nrf-2, COX-2, mPGES-1, and nuclear factor kappaB (NF-kappaB). A 24-h exposure of OHSCs to BF also increased neuronal death compared to untreated controls. Furthermore, depletion of microglia from OHSCs potently enhanced neuronal death induced by BF.

CONCLUSIONS

Overall, BF exhibited cytotoxic effects in primary microglial cells, accompanied by the induction of various inflammatory and oxidative stress markers including the Nrf-2/COX-2/mPGES-1/NF-kappaB pathways. Moreover, the study provided evidence that BF induced neuronal death in OHSCs and suggests that microglia exert a protective function against BF toxicity.

Paraquat and MPTP induce neurodegeneration and alteration in the expression profile of microRNAs: the role of transcription factor Nrf2

Both transcription factors (TFs) and microRNAs (miRNAs) can exert a widespread impact on gene expression. In the present study, we investigated the role of Nrf2 in paraquat-induced intracorporeal neurodegeneration and miRNA expression by exposing Nrf2 wild-type and knockout mice to paraquat (PQ) or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Exposure to 10 mg/kg PQ or 30 mg/kg MPTP caused damage to nerve cells in the substantia nigra (SN) in both Nrf2 (+/+) and Nrf2 (−/−) ICR mice, which included cell morphological changes, detectable apoptosis and a significant reduction in the number of dopaminergic (DA) neurons. When mice were exposed to the same PQ dose of 10 mg/kg, significant fewer tyrosine hydroxylase (TH)-positive DA neurons were observed in the Nrf2 (−/−) mice than that in the Nrf2 (+/+) mice. Both Nrf2 deficiency and PQ or MPTP exposure could alter miRNA expression profile in the SN, suggesting the potential involvement of Nrf2 in the PQ-induced or MPTP-induced miRNA expression alteration. The expression of miR-380-3p was altered by the Nrf2-MPTP interaction effect. miR-380-3p/Sp3-mRNA pathway is likely part of the mechanism of MPTP-induced neurodegeneration. Collectively, our results corroborated the protective role of Nrf2 and also demonstrated the essential interaction of Nrf2 with miRNAs in intracorporal neurodegeneration induced by neurotoxicants.

The gene expression regulators Nrf2 and small regulatory RNA molecule miR-380-3p protect nerve cells from damage caused by neurotoxins. Huangyuan Li, at Fujian Medical University, China, and colleagues examined the effects of paraquat and MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine), two chemicals known to induce parkinsonism, in mice lacking Nrf2, a key mediator of antioxidant and anti-inflammatory responses. They found that after MPTP or paraquat exposure, the extent of neuronal loss in the substantia nigra was greater in mice lacking Nrf2 than in wild-type controls. Moreover, Nrf2 deficiency prevented an upregulation of miR-380-3p following MPTP exposure. These findings implicate miR-380-3p in the mechanism through which Nrf2 protects the brain from Parkinson’s disease-related cell death and opens new avenues of investigation for developing more effective neuroprotective therapies.

Protective effects of l-glutamine against toxicity of deltamethrin in the cerebral tissue

BACKGROUND

Deltamethrin (DLM) is a broad-spectrum synthetic dibromo-pyrethroid pesticide that is widely used for agricultural and veterinary purposes. However, human exposure to the pesticide leads to neurotoxicity. Glutamine is one of the principal, free intracellular amino acids and may also be an antioxidant. This study was undertaken in order to examine the neuroprotective and antioxidant potential of l-glutamine against DLM toxicity in female Wistar albino rats.

MATERIALS AND METHODS

The rats were divided into the following groups (n=10): Group I: control (distilled water; 10 mL/kg, po one dose), Group II: l-glutamine (1.5 g/kg, po one dose), Group III: DLM (35 mg/kg, po one dose), and Group IV: DLM (35 mg/kg, po one dose) and l-glutamine (1.5 g/kg, po one dose after 4 hours). Total oxidant status (TOS), total antioxidant status (TAS), tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 levels and apoptosis were evaluated in brain tissue.

RESULTS

DLM-treated animals had a significant increase in brain biochemical parameters, as well as TOS and TAS. Furthermore, the histopathological examination showed neuronal cell degeneration in the cerebral tissue. l-Glutamine treatment decreased the elevated brain levels of TOS and neuronal cell degeneration. There was no difference in tumor necrosis factor-α, IL-1β, and IL-6 levels between the groups.

CONCLUSION

l-Glutamine may reduce the toxic effects of DLM in the cerebral tissue through antioxidant properties.

Influence of green tea extract on oxidative damage and apoptosis induced by deltamethrin in rat brain

In the present study, we investigated the protective effect of an aqueous extract of green tea leaves (GTE) against neurotoxicity and oxidative damage induced by deltamethrin (DM) in male rats. Four different groups of rats were used: the 1st group was the vehicle treated control group, the 2nd group received DM (0.6 mg/kg BW), the 3rd group received DM plus GTE, and the 4th received GTE alone (25 mg/kg BW). The brain tissues were collected at the end of the experimental regimen for subsequent investigation. Rats that were given DM had a highly significant elevation in MDA content, nitric oxide concentration, DNA fragmentation and expression level of apoptotic genes, TP53 and COX2. Additionally, a significant reduction in the total antioxidant capacity in the second group was detected. The findings for the 3rd group highlight the efficacy of GTE as a neuro-protectant in DM-induced neurotoxicity through improving the oxidative status and DNA fragmentation as well as suppressing the expression of the TP53 and COX2 genes. In conclusion, GTE, at a concentration of 25mg/kg/day, protected against DM-induced neurotoxicity through its antioxidant and antiapoptotic influence; therefore, it can be used as a protective natural product against DM-induced neurotoxicity.

Vitamin E attenuates neurotoxicity induced by deltamethrin in rats

Background

The safety of Deltamethrin (DM) has been raised as a point of concern. The current investigation was envisaged to explore the responsiveness of oxidative stress parameters, DNA fragmentation and expression levels of TP53, cycloxygenase 2 (COX2) and cytochrome p4502E1 (CYP2E1) as toxicological endpoint in rats treated with DM. as well as attention was provided to the neuroprotective effect of vitamin E (VE).

Methods

Four different groups of rats were used in this study, group I served as control, group II received DM (0.6 mg/kg BW), group III received both DM plus VE and finally group IV received VE only (200 mg/kg BW). The treatment regimen was extending for one month for all groups and the brain tissues were collected for further analysis.

Results

The obtained results showed a highly statistically significant increase in lipid peroxidation (LPO) content, nitric oxide concentration, and DNA fragmentation percentage and expression level of CYP2E1, TP53 and COX2 genes, in addition statistical significant reduction in total antioxidant capacity in DM treated group as compared to control were detected. Oral administration of VE attenuated the neurotoxic effects of DM through improvement of oxidative status, DNA fragmentation percentage and suppressing the expression level of CYP2E1, TP53 and COX2 genes.

Conclusion

From this study we concluded that VE supplementation has beneficial impacts on DM neurotoxicity in rats through its antioxidant and antiapoptotic properties.

Placental oxidative status in rural residents environmentally exposed to organophosphates

The impact of environmental organophosphate pesticide exposure on the placenta oxidative status was assessed. Placental samples were collected from women residing in an agricultural area during pesticide pulverization period, non-pulverization period and from control group. Carboxylesterase activity was significantly decreased in pulverization period group. Enzymatic and non-enzymatic defense system, the oxidative stress biomarkers and the nuclear factor erythroid 2-related factor levels showed no differences among groups. However, in the pulverization period group, an inverse association between catalase activity and placental index, a useful metric for estimating placental inefficiency, was found. This result suggests that catalase may serve as a potential placental biomarker of susceptibility to pesticides. Further studies designed from a gene-environment perspective are needed.

Protective role of Spirulina platensis against acute deltamethrin-induced toxicity in rats

Deltamethrin is a broad-spectrum synthetic pyrethroid insecticide and acaricide widely used for agricultural and veterinary purposes. However, its human and animal exposure leads to hepatonephrotoxicity. Therefore, the present study was undertaken to examine the hepatonephroprotective and antioxidant potential of Spirulina platensis against deltamethrin toxicity in male Wistar albino rats. Deltamethrin treated animals revealed a significant increase in serum biochemical parameters as well as hepatic and renal lipid peroxidation but caused an inhibition in antioxidant biomarkers. Spirulina normalized the elevated serum levels of AST, ALT, APL, uric acid, urea and creatinine. Furthermore, it reduced deltamethrin-induced lipid peroxidation and oxidative stress in a dose dependent manner. Therefore, it could be concluded that spirulina administration able to minimize the toxic effects of deltamethrin by its free radical-scavenging and potent antioxidant activity.

Metabolomics tools for describing complex pesticide exposure in pregnant women in Brittany (France)

BACKGROUND

The use of pesticides and the related environmental contaminations can lead to human exposure to various molecules. In early-life, such exposures could be responsible for adverse developmental effects. However, human health risks associated with exposure to complex mixtures are currently under-explored.

OBJECTIVE

THIS PROJECT AIMS AT ANSWERING THE FOLLOWING QUESTIONS: What is the influence of exposures to multiple pesticides on the metabolome? What mechanistic pathways could be involved in the metabolic changes observed?

METHODS

Based on the PELAGIE cohort (Brittany, France), 83 pregnant women who provided a urine sample in early pregnancy, were classified in 3 groups according to the surface of land dedicated to agricultural cereal activities in their town of residence. Nuclear magnetic resonance-based metabolomics analyses were performed on urine samples. Partial Least Squares Regression-Discriminant Analysis (PLS-DA) and polytomous regressions were used to separate the urinary metabolic profiles from the 3 exposure groups after adjusting for potential confounders.

RESULTS

The 3 groups of exposure were correctly separated with a PLS-DA model after implementing an orthogonal signal correction with pareto standardizations (R2 = 90.7% and Q2 = 0.53). After adjusting for maternal age, parity, body mass index and smoking habits, the most statistically significant changes were observed for glycine, threonine, lactate and glycerophosphocholine (upward trend), and for citrate (downward trend).

CONCLUSION

This work suggests that an exposure to complex pesticide mixtures induces modifications of metabolic fingerprints. It can be hypothesized from identified discriminating metabolites that the pesticide mixtures could increase oxidative stress and disturb energy metabolism.

Organic extract contaminants from drinking water activate Nrf2-mediated antioxidant response in a human cell line

Traditional risk assessment methods face challenges in estimating risks from drinking waters that contain low-levels of large numbers of contaminants. Here, we evaluate the toxicity of organic contaminant (OC) extracts from drinking water by examining activation of nuclear factor E2-related factor 2 (Nrf2)-mediated antioxidant response. In HepG2 cells, the Nrf2-mediated antioxidant response-measured as Nrf2 protein accumulation, expression of antioxidant response element (ARE)-regulated genes and ARE-luciferase reporter gene assays were activated by OC extracts from drinking water sources that detected 25 compounds in 9 classification groups. Individual OCs induced oxidative stress at concentrations much higher than their environmental levels; however, mixtures of contaminants induced oxidative stress response at only 8 times the environmental levels. Additionally, a synthetic OC mixture prepared based on the contamination profiling of drinking water induced ARE activity to the same extent as the real-world mixture, reinforcing our conclusion that these mixture exposures produce responses relevant for human exposure situations. Our study tested the possibility of assessing toxicity of OCs of drinking water using a specific ARE-pathway measurement. This approach should be broadly useful in assisting risk assessment of mixed environmental exposure.

Cytotoxicity induced by deltamethrin and its metabolites in SH-SY5Y cells can be differentially prevented by selected antioxidants

Deltamethrin, an α-cyano pyrethroid insecticide, is a relatively potent neurotoxicant. The main deltamethrin metabolism mechanisms are ester cleavage and oxidation at the 2' and 4' position of the terminal aromatic ring. Although some aspects of the toxicity properties of deltamethrin have been reported, limited information is available about the metabolites cytotoxic actions. The aims of this study are to examine in vitro neurotoxicity of deltamethrin and its metabolites 3-phenoxybenzoic acid (3-PBA), 2'-OH-deltamethrin, and 4'-OH-deltamethrin and to evaluate melatonin (0.1, 1μM), trolox (0.3, 1μM) and N-acetylcysteine (500, 1000μM) protective role in SH-SY5Y cells. MTT and neutral red uptake (NRU) assays were carried out to assess the cytotoxicity of deltamethrin and its metabolites. Of the three metabolites tested, while 3-PBA (0.01-1000μM) did not show neurotoxicity, 2'-OH- and 4'-OH-deltamethrin (10-1000μM) were more toxic than deltamethrin (10-1000μM). Levels of both nitric oxide (NO) and lipid peroxides measured as malondialdehyde were significantly increased in deltamethrin and 4'-OH-deltamethrin-treated cells. Compared to other antioxidants, 1μM MEL treatment effectively protected against deltamethrin and 4'-OH-deltamethrin-induced lipid peroxidation and ameliorated the NO adverse effect that might have been caused. These results suggest that oxidative stress observed is one of the major mechanisms of deltamethrin-induced neurotoxicity and it may be attributed in part to deltamethrin disposition and metabolism.