Beneficial effect of N-acetylcysteine against organophosphate toxicity in mice

Cellular responses following ex vivo lung exposure to the nerve agent VX - Potential for additional treatment targets?

Following inhalation exposure to organophosphorus nerve agents, symptoms rapidly develop and severe respiratory symptoms, such as bronchorrhea and bronchoconstriction are the leading causes of lethality. Nerve agent-induced lung injury is little investigated and the standard treatment for symptomatic relief targets the enzyme acetylcholinesterase and muscarinic acetylcholine and GABAergic receptors. In the present study, cellular responses in lung tissue during the acute (40 min) and extended phase (24 h) following severe exposure to the nerve agent VX have been investigated using an ex vivo rat precision-cut lung slice model including electrostimulation to induce a cholinergic response. Changes in protein amount, cell viability, together with, inflammatory and oxidative stress markers have been determined in both the lung tissue and incubation medium. During the acute phase, VX caused significantly increased airway contraction and decreased airway relaxation. Five micromolar of VX did not affect the sample protein levels and cell viability in lung tissue. Among seven markers of cellular responses investigated in the lung tissue, increased levels of heme oxygenase-1 and matrix metalloproteinase-9 together with decreased levels of glutathione in the incubation medium were observed in the acute phase following VX-exposure compared to electrostimulation only. No difference in cellular response was observed following VX-exposure for 24 h compared to the air control. In comparison, LPS-exposure resulted in time-dependent changes in all markers of inflammation and oxidative response. In conclusion, the present study demonstrated VX-specific patterns of oxidative responses in the lung, as well as, signs of inflammatory response and remodelling of extracellular matrix. These potential mechanisms of tissue injury should be further investigated for their potential as additional therapeutic targets during the acute phase of intoxication.

Comparative Analysis of Outcomes in Acute Organophosphate Poisoning With and Without N-acetyl Cysteine Intervention

INTRODUCTION

Organophosphorus poisoning (OPP) stands as a significant health concern in numerous regions, especially in developing nations. Despite the rising complexities and case fatalities associated with exposure, the treatment approach has remained unchanged for many years. Based on clinical insights, certain pharmacologic agents have demonstrated utility in enhancing outcomes and reducing complications arising from this type of exposure.

OBJECTIVES

The objective of this study is to compare the outcome of N-acetyl cysteine in the treatment of acute organophosphate poisoning cases. In terms of a) its impact on the requirement of atropine, b) Length of hospital stay, and mortality.

METHODS

The study was conducted in the intensive care unit (ICU) of the General Hospital Lahore. Thirty patients with a history and clinical presentation indicative of acute organophosphorus poisoning were randomly divided into two groups in a 1:1 ratio. The treatment group received parenteral administration of atropine, pralidoxime, and N-acetylcysteine (NAC) as an adjuvant, and the control group received standard treatment for acute organophosphate (OP) toxicity.

RESULT

Throughout the study duration, 30 patients suffering acute organophosphate (OP) toxicity (14 men, 16 women) were examined, with an age mean of (25.83±11.59) years. In the interventional group, only four patients required ICU admission, but in the control group, eight patients were admitted to ICU. The correlation result between the dose of atropine and length of hospital stays was not statistically significant between both study groups (<0.005). Plasma Cholinesterase (PChE) level (KU L-1) and total dose of Pralidoxime (g) were statistically significant in the length of hospital stay. The data was not normally distributed, so the non-parametric tests were applied. The Wilcoxon ranked test showed significant improvement in both the controlled and interventional groups because the p-value was (<0.005). Intergroup comparison analyzed by using the Mann-Whitney U test showed a significant reduction in the severity and other associated symptoms in the interventional group because the p-value was (0.001).

CONCLUSION

The outcome demonstrated that the NAC group had a decreased demand for atropine rather than Pralidoxime. In the NAC group, the length of hospital stay and mortality was decreased. The administration of NAC to the present study procedure for acute organophosphate (OP) poisoning is suggested.

The role of a combination of N-acetylcysteine and magnesium sulfate as adjuvants to standard therapy in acute organophosphate poisoning: A randomized controlled trial

Background

Mortality in acute organophosphate (OP) poisoning remains high despite current standard therapy with atropine and oximes. Due to dose-limiting side effects of atropine, novel therapies are targeting other putative mechanisms of injury, including oxidative damage, to reduce atropine dosage.

Objectives

N-acetylcysteine (NAC) and magnesium sulfate (MgSO₄) have different mechanisms of actions and should act synergistically in OP poisoning. In this study, we wanted to evaluate whether this novel combination, used as an adjuvant to standard care, could improve clinical outcomes.

Methods

The study was conducted in the Emergency Department and ICU of AIIMS Bhubaneswar (a tertiary care center and government teaching institute) between July 2019 and July 2021. Eighty-eight adult patients with history and clinical features of acute OP poisoning were randomly allocated (1:1) into two groups. The Study group received 600 mg NAC via nasogastric tube thrice daily for 3 days plus a single dose of 4 g Inj. MgSO₄ IV on first day and the Control group received suitably matched placebo (double-blinding) - in addition to standard care in both the groups. The primary outcome measure was to compare the total dose of Inj. Atropine required (cumulative over the entire treatment duration) between the control group and the study group receiving NAC and MgSO₄. The secondary outcome measures were lengths of ICU and hospital stays, need and duration of mechanical ventilation, the differences in BuChE activity, oxidative stress biomarkers - MDA and GSH levels, the incidences of adverse effects including delayed sequalae like intermediate syndrome and OPIDN, and comparison of mortality between the two groups.

Results

Data from 43 patients in Control and 42 patients in Study group was finally analyzed. The baseline parameters were comparable. Total atropine requirements were lower in the Study group [175.33 ± 81.25 mg (150.01-200.65)] compared to the Control [210.63 ± 102.29 mg (179.15-242.11)] [Mean ± SD (95% CI)], but was not statistically significant. No significant differences in any of the other clinical or biochemical parameters were noted.

Conclusion

The N-acetylcysteine and MgSO₄ combination as adjuvants failed to significantly reduce atropine requirements, ICU/hospital stay, mechanical ventilatory requirements, mortality and did not offer protection against oxidative damage.

Cumulative Effects of Paraoxon and Leptin on Oxidative Damages in Rat Tissues: Prophylactic and Therapeutic Roles of N-Acetylcysteine

Exposure to paraoxon (POX) and leptin (LP) could cause an imbalance between oxidants and antioxidants in an organism, which can be prevented by introduction of exogenous antioxidants such as N-acetylcysteine (NAC). The aim of this study was to evaluate synergic or additive effects of administration of exogenous LP plus POX on the antioxidant status, as well as the prophylactic and therapeutic roles of NAC in various rat tissues. Fifty-four male Wistar rats were divided into nine groups treated with different compounds: Control (no treatment), POX (0.7 mg/kg), NAC (160 mg/kg), LP (1 mg/kg), POX+LP, NAC-POX, POX-NAC, NAC-POX+LP, and POX+LP-NAC. In the last five groups, only the order of administered compounds differed. After 24 h, plasma and tissues were sampled and examined. The results showed that administration of POX plus LP significantly increased biochemical indices in plasma and antioxidant enzymes activities and decreased glutathione content in the liver, erythrocytes, brain, kidney, and heart. In addition, cholinesterase and paraoxonase 1 activities in the POX+LP-treated group were decreased and malondialdehyde level was increased in the liver, erythrocytes, and brain. However, administration of NAC rectified induced changes although not to the same extent. Our study suggests that POX or LP administration engage the oxidative stress system per se; however, their combination did not produce significantly greater effects. Moreover, both prophylactic and therapeutic treatments of rats with NAC supported the antioxidant defense against oxidative damage in tissues, most probably through both its free radical scavenging ability and maintaining intracellular GSH levels. It can therefore be suggested that NAC has particularly protective effects against POX or/and LP toxicity.

Succinate prodrugs in combination with atropine and pralidoxime protect cerebral mitochondrial function in a rodent model of acute organophosphate poisoning

Pesticides account for hundreds of millions of cases of acute poisoning worldwide each year, with organophosphates (OPs) being responsible for the majority of all pesticide-related deaths. OPs inhibit the enzyme acetylcholinesterase (AChE), which leads to impairment of the central- and peripheral nervous system. Current standard of care (SOC) alleviates acute neurologic-, cardiovascular- and respiratory symptoms and reduces short term mortality. However, survivors often demonstrate significant neurologic sequelae. This highlights the critical need for further development of adjunctive therapies with novel targets. While the inhibition of AChE is thought to be the main mechanism of injury, mitochondrial dysfunction and resulting metabolic crisis may contribute to the overall toxicity of these agents. We hypothesized that the mitochondrially targeted succinate prodrug NV354 would support mitochondrial function and reduce brain injury during acute intoxication with the OP diisopropylfluorophosphate (DFP). To this end, we developed a rat model of acute DFP intoxication and evaluated the efficacy of NV354 as adjunctive therapy to SOC treatment with atropine and pralidoxime. We demonstrate that NV354, in combination with atropine and pralidoxime therapy, significantly improved cerebral mitochondrial complex IV-linked respiration and reduced signs of brain injury in a rodent model of acute DFP exposure.

Protective effects of antioxidants on striatal dopamine release induced by organophosphorus pesticides

Although the toxic effects of organophosphorus (OP) pesticides have been classically attributed to inhibition of the acetylcholinesterase, other neurotoxic mechanisms, as oxidative stress can also occur. Here we evaluated if antioxidants prevent the excessive dopamine release induced by OP pesticides in conscious and freely moving rats, using cerebral microdialysis technique. Intrastriatal infusion of paraoxon (5 mM), glufosinate (10 mM) or glyphosate (5 mM) significantly increased the dopamine release (1006 ± 106%, 991 ± 142%, and 1164 ± 128%, relative to baseline, respectively). To evaluate if these increased dopamine release could be related to oxidative stress, we pretreated animals with antioxidants glutathione (GSH, 400 or 800 μM), dithiothreitol (DTT, 5 or 10 μM), trolox (1 or 3 mM), and α-lipoic acid (ALA, 400 or 800 μM) before administration of OP pesticides. Intrastriatal administration of the antioxidants GSH, DTT, trolox, and ALA was highly effective in preventing the glyphosate and glufosinate-induced dopamine overflow. However, only GSH (800 μM) significantly decreased the effect of paraoxon on dopamine levels. The high toxicity of this pesticide and the low concentrations used could explain this lack of effect in our experimental conditions. The fact that ROS scavengers prevent the excessive dopamine release induced by OP pesticides, further supports the view that dopamine overflow can cause neuronal damage mediated, at least in part, by oxidative stress.

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.

N-Acetylcysteine Reverses Monocrotophos Exposure-Induced Hepatic Oxidative Damage via Mitigating Apoptosis, Inflammation and Structural Changes in Rats

Oxidative stress-mediated tissue damage is primarily involved in hepatic injuries and dysfunctioning. Natural antioxidants have been shown to exert hepatoprotective, anti-inflammatory and antiapoptotic properties. The present study evaluated the effect of N-acetylcysteine (NAC) against monocrotophos (MCP) exposure-induced toxicity in the rat liver. Albino Wistar rats were divided into four groups: (1) control, (2) NAC-treated, (3) MCP-exposure, (4) NAC and MCP-coexposure group. The dose of MCP (0.9 mg/kg b.wt) and NAC (200 mg/kg b.wt) were administered orally for 28 days. Exposure to MCP caused a significant increase in lipid peroxidation, protein oxidation and decreased glutathione content along with the depletion of antioxidant enzyme activities. Further MCP exposure increased pro-inflammatory cytokines levels and upregulated Bax and Caspase-3 expressions. MCP exposure also caused an array of structural alternations in liver tissue, as depicted by the histological and electron microscopic analysis. Thepretreatment of NAC improved glutathione content, restored antioxidant enzyme activities, prevented oxidation of lipids and proteins, decreased pro-inflammatory cytokines levels and normalized apoptotic protein expression. Treatment of NAC also prevented histological and ultrastructural alternations. Thus, the study represents the therapeutic efficacy and antioxidant potential of NAC against MCP exposure in the rat liver.

Organophosphate pesticides and new-onset diabetes mellitus: From molecular mechanisms to a possible therapeutic perspective

Organophosphate is a commonly used pesticide in the agricultural sector. The main action of organophosphate focuses on acetylcholinesterase inhibition, and it therefore contributes to acute cholinergic crisis, intermediate syndrome and delayed neurotoxicity. From sporadic case series to epidemiologic studies, organophosphate has been linked to hyperglycemia and the occurrence of new-onset diabetes mellitus. Organophosphate-mediated direct damage to pancreatic beta cells, insulin resistance related to systemic inflammation and excessive hepatic gluconeogenesis and polymorphisms of the enzyme governing organophosphate elimination are all possible contributors to the development of new-onset diabetes mellitus. To date, a preventive strategy for organophosphate-mediated new-onset diabetes mellitus is still lacking. However, lowering reactive oxygen species levels may be a practical method to reduce the risk of developing hyperglycemia.

Effect of N-acetylcysteine on attenuation of chlropyrifos and its methyl analogue toxicity in male rats

The attenuating effect of 150 mg/kg of N-acetylcysteine (NAC) against the oral administration of 7.88 and 202.07 mg/kg/day for 14 days of either chlropyrifos-ethyl (CPE-E) or chlropyrifos-methyl (CPF-M), respectively, in male rat was investigated using biochemical and genetic markers. Biomarkers such as acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), paraoxonase (PON), adenosine 5'-triphosphatase (ATP-ase), glutathione-S-transferase (GST), catalase (CAT), glutathione reduced (GSH) in serum showed a significant decline in their levels, while calcium (Ca⁺²), cytochrome C reduction (CYC-R), lipid peroxidation (LPO), nitric oxide (NO) levels showed a significant increase in serum of treated rats. Regarding the genotoxic parameters, when rats are treated either with CPE-E or CPF-M, liver DNA, chromosomal aberration (CA), and micronucleated polychromatic erythrocytes (MnPCE) significantly increased, while the mitotic index (MI) and polychromatic erythrocytes (PCE)/ normochromatic erythrocytes (NCE) ratio were significantly decreased. However, the administration of NAC following the intoxication of CPF-E or CPF-M attenuated the tested biochemical and genotoxic markers. It can be concluded that NAC can be used to ameliorate the toxicity of certain organophosphorus compounds such as CPF-E and CPF-M.

The Effect of Organophosphate Exposure on Neuronal Cell Coenzyme Q10 Status

Organophosphate (OP) compounds are widely used as pesticides and herbicides and exposure to these compounds has been associated with both chronic and acute forms of neurological dysfunction including cognitive impairment, neurophysiological problems and cerebral ataxia with evidence of mitochondrial impairment being associated with this toxicity. In view of the potential mitochondrial impairment, the present study aimed to investigate the effect of exposure to commonly used OPs, dichlorvos, methyl-parathion (parathion) and chloropyrifos (CPF) on the cellular level of the mitochondrial electron transport chain (ETC) electron carrier, coenzyme Q10 (CoQ10) in human neuroblastoma SH-SY5Y cells. The effect of a perturbation in CoQ10 status was also evaluated on mitochondrial function and cell viability. A significant decreased (P < 0.0001) in neuronal cell viability was observed following treatment with all three OPs (100 µM), with dichlorvos appearing to be the most toxic to cells and causing an 80% loss of viability. OP treatment also resulted in a significant diminution in cellular CoQ10 status, with levels of this isoprenoid being decreased by 72% (P < 0.0001), 62% (P < 0.0005) and 43% (P < 0.005) of control levels following treatment with dichlorvos, parathion and CPF (50 µM), respectively. OP exposure was also found to affect the activities of the mitochondrial enzymes, citrate synthase (CS) and mitochondrial electron transport chain (ETC) complex II+III. Dichlorvos and CPF (50 µM) treatment significantly decreased CS activity by 38% (P < 0.0001) and 35% (P < 0.0005), respectively compared to control levels in addition to causing a 54% and 57% (P < 0.0001) reduction in complex II+III activity, respectively. Interestingly, although CoQ10 supplementation (5 μM) was able to restore cellular CoQ10 status and CS activity to control levels following OP treatment, complex II+III activity was only restored to control levels in neuronal cells exposed to dichlorvos (50 µM). However, post supplementation with CoQ10, complex II+III activity significantly increased by 33% (P < 0.0005), 25% (P < 0.005) and 35% (P < 0.0001) in dichlorvos, parathion and CPF (100 µM) treated cells respectively compared to non-CoQ10 supplemented cells. In conclusion, the results of this study have indicated evidence of neuronal cell CoQ10 deficiency with associated mitochondrial dysfunction following OP exposure. Although CoQ10 supplementation was able to ameliorate OP induced deficiencies in CS activity, ETC complex II+III activity appeared partially refractory to this treatment. Accordingly, these results indicate the therapeutic potential of CoQ10 supplementation in the treatment of OP poisoning. However, higher doses may be required to engender therapeutic efficacy.

Predominant role of antioxidants in ameliorating the oxidative stress induced by pesticides

Oxidative stress has been reported as one of the adverse effects caused due to pesticides, which is the main mechanism of the toxicity in humans and animals and is a useful parameter in monitoring studies. It involves an imbalance in the equilibrium state of ROS and antioxidant defenses leading to alterations in various antioxidant enzyme levels and lipid peroxidation. The objective of the current paper is to present a review of the potential role and protective mechanism action of the antioxidant micronutrient supplementation to ameliorate the oxidative stress induced by pesticides. Studies in animal models and human were retrieved through the relevant search of the literature and categorized. Various animal studies were categorized according to the type of supplementation. Animal studies provide evidence to conclude the potential protective role of antioxidants in ameliorating the adverse effects of pesticides. Similar studies in humans are meager suggesting for further comprehensive research.

Does oxidative stress contribute to toxicity in acute organophosphorus poisoning? - a systematic review of the evidence

Introduction: Organophosphorus (OP) insecticide self-poisoning is a global problem, killing tens of thousands of people every year. Oxidative stress has been proposed to play a pathological role in OP poisoning, but whether it plays a direct toxic role is currently unclear.Objectives: To determine whether there is consistent evidence of oxidative stress in patients with acute OP insecticide self-poisoning, and whether there are animal or human trial data that indicate that treatment of oxidative stress provides clinical benefit, which would suggest a direct toxic effect of oxidative stress.Methods: We conducted a systematic review using the PubMed, EMBASE and MEDLINE databases, and the Cochrane Database of Systematic reviews, based upon the following search terms and keywords: "organophosphate poisoning", "oxidative stress" and "antioxidant". All articles relevant to the aims of the study were included. Articles related to chronic OP poisoning, to use of medicines without antioxidant benefits, or to subjects other than oxidative stress were excluded. The search returned 256 results of which 17 studies were considered relevant and grouped under the following categories: observational human studies (n = 11) and intervention studies in animals (n = 4) and humans (n = 2).Oxidative stress markers in human studies: Oxidative damage to lipids and proteins was reported in all eleven human studies. Eight of nine studies reported variable increases in a weak marker of lipid peroxidation, malondialdehyde. In two case-control studies, erythrocyte membrane malondialdehyde concentrations were 380% and 160% higher in cases than controls, while plasma malondialdehyde concentrations were ∼63% higher in cases than controls in three case-control studies. In a prospective study, plasma malondialdehyde did not increase significantly from baseline in moderate or severely poisoned patients. Five case-control studies measured thiol residues as markers of protein oxidative damage and found variable changes after poisoning. No evidence of oxidative DNA damage was found in the one study that investigated it.Antioxidant intervention studies in animals: After treatment with an antioxidant, all four studies showed an improvement in either markers of oxidative damage or antioxidant activity. One mouse study with a relatively low risk of bias showed that administration of acetylcysteine 200 mg/kg reduced malondialdehyde by 35% and increased survival by more than 60%.Antioxidant intervention studies in humans: We found two small randomised controlled trials reporting the use of acetylcysteine as an adjunct to standard treatment in acute OP poisoning. The trials found that acetylcysteine reduced atropine requirements by 77% and 55%, but did not affect clinically relevant outcomes.Conclusions: Several studies showed evidence of OP insecticide-induced oxidative damage and antioxidant activity, suggesting that endogenous antioxidant defences are triggered in acute OP poisoning. However, the markers of lipid peroxidation used were weak, there was high inter-individual variability between studies in results and quality, and marked variation between the OP insecticides involved. Animal data provide some evidence that antioxidants alleviate adverse effects of acute poisoning, suggesting that oxidative stress may directly cause clinical harm. Acetylcysteine appeared beneficial in animal studies, but this could be mediated via increased synthesis of the endogenous detoxifying agent, glutathione, rather than through a direct antioxidant effect. The two human clinical studies were too small to provide any clear evidence to support the use of acetylcysteine in OP poisoning. Further research into the mechanisms of oxidative stress in acute OP poisoning, combined with large unambiguous clinical trials of antioxidants, are required before they can be used routinely in treatment.

Rapid degradation of the organophosphate pesticide - Chlorpyrifos by a novel strain of Pseudomonas nitroreducens AR-3

The indiscriminate use of pesticides leads to serious food safety and toxicity issues and threatens the environment and biodiversity. Pseudomonas nitroreducens AR-3 isolated from pesticide contaminated agricultural soil removed 97% of chlorpyrifos (CP) in just 8 h, in a mineral salt medium (MSM) containing glucose (1.0 g/L) and yeast extract (0.5 g/L) at 30 °C and 2% (v/v) inoculum when challenged with 100 mg/L CP. 3, 5, 6-trichloro 2-pyridinol (TCP), the degradation product of CP was detected only in low levels, indicating its further degradation. Organophosphate hydrolase (OPH), the enzyme considered responsible for CP degradation, had an intracellular localization. Crude OPH (1 mg/ml) removed 42% of 100 mg/L chlorpyrifos in just 2 h, indicating a rapid rate of degradation. Ultra-fast degradation of chlorpyrifos with an inducible OPH marks the potential of P. nitroreducens AR-3 for bioremediation of organophosphates. The strain AR-3 has the fastest rate of organophosphate degradation reported till date among Pseudomonads.

Oxidative and histopathological alterations after sub-acute exposure of diisopropyl phosphorofluoridate in mice: Beneficial effect of N‑acetylcysteine

AIMS

Protective efficacy of N‑acetylcysteine (NAC) was assessed against sub-acute diisopropyl phosphorofluoridate (DFP) poisoning in mice.

MAIN METHODS

Mice were allocated into nine groups of six each: vehicle control; DFP (0.125 LD₅₀ ≈ 0.483 mg/kg bwt, s.c.); DFP + Atropine (ATR, 10 mg/kg bwt, i.p., 0 min); DFP + Pralidoxime (2-PAM, 30 mg/kg bwt, i.m., 0 min); DFP + NAC (150 mg/kg bwt, i.p., -60 min); DFP + ATR + NAC; DFP + 2-PAM + NAC; DFP + ATR + 2-PAM; and DFP + ATR + 2-PAM + NAC. Animals received various treatments for 21 d daily. Plasma butyrylcholinesterase (BChE) was measured after 7, 14 and 21 d of exposure. Brain acetylcholinesterase (AChE) and reduced glutathione (GSH), malondialdehyde (MDA), glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), and superoxide dismutase (SOD) were measured (brain, liver and kidney) after 21 d of exposure. Histopathology, immunohistochemistry, and Western blot for inducible nitric oxide synthase (iNOS) and c-fos were also performed.

KEY FINDINGS

DFP significantly reduced BChE and AChE levels. Diminished GSH, CAT, SOD (brain and liver), GPx, GR, and elevated MDA (Brain) levels were also observed. DFP caused notable histopathology (brain, liver and kidney) and over expression of iNOS, and c-fos proteins (brain). NAC enhanced the protective efficacy of ATR and 2-PAM in most parameters, without any appreciable protection in iNOS and c-fos expression.

SIGNIFICANCE

NAC as an adjunct with ATR and 2-PAM, exhibited marked beneficial effects against sub-acute DFP poisoning, indicating its possible implications in the management of OP poisoning.

Antioxidant and cytoprotective effects of N-acetylcysteine against subchronic oral glyphosate-based herbicide-induced oxidative stress in rats

It is claimed that oxidative stress has a prominent role in the mechanism of toxic effects formed by glyphosate-based herbicide (GBH) in living systems. A strong thiol compound, N-acetylcysteine (NAC), has antioxidative and cytoprotective properties. The objective in this subchronic toxicity study was to identify the prophylactic effect of NAC over histopathological changes and oxidative stress induced by GBH in blood, renal, liver, cardiac, and brain tissues. A sum of 28 male Wistar rats were divided into four equal groups, each containing 7 rats. During the study, group I (control group) was supplied with normal rodent bait and tap water ad libitum. The applied agents were 160 mg/kg NAC to group II, 375 mg/kg as equivalent to 1/10 of lethal dose 50% (LD50) of GBH to group III, and 160 mg/kg of NAC and 375 mg/kg of GBH together once per day as oral gavage to group IV for 8 weeks. While GBH decreased the levels of GSH in blood, liver, kidney, and brain tissues, it considerably increased malondialdehyde levels. On the contrary, these parameters happened to improve in the group supplied with NAC. Besides, it was seen that NAC was observed to improve the histopathologic changes in rat tissues induced by GBH. It was concluded that NAC protects oxidative stress and tissue damage induced by GBH in blood and tissue and this prophylactic effect could be attributed to its antioxidant and free radical sweeper character.

Inducible nitric oxide synthase inhibitor, 1400W, mitigates DFP-induced long-term neurotoxicity in the rat model

Chemical nerve agents (CNA) are increasingly becoming a threat to both civilians and military personnel. CNA-induced acute effects on the nervous system have been known for some time and the long-term consequences are beginning to emerge. In this study, we used diisopropylfluorophosphate (DFP), a seizurogenic CNA to investigate the long-term impact of its acute exposure on the brain and its mitigation by an inducible nitric oxide synthase (iNOS) inhibitor, 1400W as a neuroprotectant in the rat model. Several experimental studies have demonstrated that DFP-induced seizures and/or status epilepticus (SE) causes permanent brain injury, even after the countermeasure medication (atropine, oxime, and diazepam). In the present study, DFP-induced SE caused a significant increase in iNOS and 3-nitrotyrosine (3-NT) at 24 h, 48 h, 7d, and persisted for a long-term (12 weeks post-exposure), which led to the hypothesis that iNOS is a potential therapeutic target in DFP-induced brain injury. To test the hypothesis, we administered 1400W (20 mg/kg, i.m.) or the vehicle twice daily for the first three days of post-exposure. 1400W significantly reduced DFP-induced iNOS and 3-NT upregulation in the hippocampus and piriform cortex, and the serum nitrite levels at 24 h post-exposure. 1400W also prevented DFP-induced mortality in <24 h. The brain immunohistochemistry (IHC) at 7d post-exposure revealed a significant reduction in gliosis and neurodegeneration (NeuN+ FJB positive cells) in the 1400W-treated group. 1400W, in contrast to the vehicle, caused a significant reduction in the epileptiform spiking and spontaneous recurrent seizures (SRS) during 12 weeks of continuous video-EEG study. IHC of brain sections from the same animals revealed a significant reduction in reactive gliosis (both microgliosis and astrogliosis) and neurodegeneration across various brain regions in the 1400W-treated group when compared to the vehicle-treated group. A multiplex assay from hippocampal lysates at 6 weeks post-exposure showed a significant increase in several key pro-inflammatory cytokines/chemokines such as IL-1α, TNFα, IL-1β, IL-2, IL-6, IL-12, IL-17a, MCP-1, LIX, and Eotaxin, and a growth factor, VEGF in the vehicle-treated animals. 1400W significantly suppressed IL-1α, TNFα, IL-2, IL-12, and MCP-1 levels. It also suppressed DFP-induced serum nitrite levels at 6 weeks post-exposure. In the Morris water maze, the vehicle-treated animals spent significantly less time in the target quadrant in a probe trial at 9d post-exposure compared to their time spent in the same quadrant 11 days previously (i.e., 2 days prior to DFP exposure). Such a difference was not observed in the 1400W and control groups. However, learning and short-term memory were unaffected when tested at 10-16d and 28-34d post-exposure. Accelerated rotarod, horizontal bar test, and the forced swim test revealed no significant changes between groups. Overall, the findings from this study suggest that 1400W may be considered as a potential therapeutic agent as a follow-on therapy for CNA exposure, after controlling the acute symptoms, to prevent mortality and some of the long-term neurotoxicity parameters such as epileptiform spiking, SRS, neurodegeneration, reactive gliosis in some brain regions, and certain key proinflammatory cytokines and chemokine.

Novel Clinical Toxicology and Pharmacology of Organophosphorus Insecticide Self-Poisoning

Organophosphorus insecticide self-poisoning is a major global health problem, killing over 100,000 people annually. It is a complex multi-organ condition, involving the inhibition of cholinesterases, and perhaps other enzymes, and the effects of large doses of ingested solvents. Variability between organophosphorus insecticides—in lipophilicity, speed of activation, speed and potency of acetylcholinesterase inhibition, and in the chemical groups attached to the phosphorus—results in variable speed of poisoning onset, severity, clinical toxidrome, and case fatality. Current treatment is modestly effective, aiming only to reactivate acetylcholinesterase and counter the effects of excess acetylcholine at muscarinic receptors. Rapid titration of atropine during resuscitation is lifesaving and can be performed in the absence of oxygen. The role of oximes in therapy remains unclear. Novel antidotes have been tested in small trials, but the great variability in poisoning makes interpretation of such trials difficult. More effort is required to test treatments in adequately powered studies.

A Raman, SERS and UV-circular dichroism spectroscopic study of N-acetyl-l-cysteine in aqueous solutions

The aim of this work is to evaluate the vibrational and structural properties of N-acetyl-l-cysteine (NAC), and its molecular structure and electronic properties in relation to the action of thiol and amine groups at different pH.

Occupational and environmental exposure to pesticides and cytokine pathways in chronic diseases (Review)

Pesticides can exert numerous effects on human health as a consequence of both environmental and occupational exposures. The available knowledge base suggests that exposure to pesticides may result in detrimental reproductive changes, neurological dysfunction and several chronic disorders, which are defined by slow evolution and long-term duration. Moreover, an ever increasing amount of data have identified an association between exposure to pesticides and the harmful effects on the immune system. The real impact of alterations in humoral cytokine levels on human health, in particular in the case of chronic diseases, is still unclear. To date, studies have suggested that although exposure to pesticides can affect the immune system functionally, the development of immune disorders depends on the dose and duration of exposure to pesticides. However, many of the respective studies exhibit limitations, such as a lack of information on exposure levels, differences in the pesticide administration procedures, difficulty in characterizing a prognostic significance to the weak modifications often observed and the interpretation of obtained results. The main challenge is not just to understand the role of individual pesticides and their combinations, but also to determine the manner and the duration of exposure, as the toxic effects on the immune system cannot be separated from these considerations. There is a clear need for more well-designed and standardized epidemiological and experimental studies to recognize the exact association between exposure levels and toxic effects and to identify useful biomarkers of exposure. This review focuses on and critically discusses the immunotoxicity of pesticides and the impact of cytokine levels on health, focusing on the development of several chronic diseases.

A comparative study on toxicity induced by carbosulfan and malathion in Wistar rat liver and spleen

Organophosphorus (OP) and carbamate (CM) pesticides are widely used in agriculture. These pesticides are highly toxic to humans and their residues in food pose potential threat to human health. In this comparative study, we investigated the effect of subchronic exposure of OPs (malathion, MAL) and CM (Carbosulfan, CB) on rat liver and spleen. Biochemical analysis showed that levels of hepatic enzymes (ALT, ALP, LDH and PAL) changed after exposure to the pesticides. In the liver extracts, lipid peroxidation index increased after the treatment by pesticides. Our results indicated that exposure to MAL and CB leads to alteration of liver redox status. Both pesticides induced focal inflammation and fibrosis in the liver. After subchronic administration of MAL (200 mg/kg) and CB (25 mg/kg), systemic inflammation, as depicted by the increase in IFN-δ activity in liver, was observed in both malathion and carbosulfan treated animals. In addition, the results showed that MAL significantly increased TCD4+ and TCD8+ lymphocyte number. It also decreased INF-δ and IL-4 production. However, CB induced a reduction of TCD8+ number and cytokine production in spleen cells. In conclusion, malathion and carbosulfan had significant immunomodulatory properties in the spleen with inflammation and oxidative stress induction in the liver.

Efficacy of N-Acetylcysteine, Glutathione, and Ascorbic Acid in Acute Toxicity of Paraoxon to Wistar Rats: Survival Study

There are a great number of reports with assertions that oxidative stress is produced by organophosphorus compound (OPC) poisoning and is a cofactor of mortality and morbidity in OPC toxicity. In addition, antioxidants have been suggested as adjuncts to standard therapy. However, there is no substantial evidence for the benefit of the use of antioxidants in survival after acute intoxication of OPCs. The present study was conducted to assess the effectiveness of three non-enzymatic antioxidants (NEAOs), N-acetylcysteine (NAC), glutathione (GSH), and ascorbic acid (AA), in acute intoxication of adult male Wister rats with paraoxon. The efficacy of the antioxidants was estimated as both a pretreatment and a concurrent application along with the standard oxime, pralidoxime (2-PAM). Relative risk of death after 48 hours of application was estimated by Cox regression analysis. The results revealed no benefit of either tested NEAO to the improvement in survival of experimental rats. The application of these antioxidants was found to be deleterious when administered along with pralidoxime compared to the treatment with pralidoxime alone. It has been concluded that the tested non-enzymatic antioxidants are not useful in acute toxicity for improving survival rates. However, the individual toxic dynamics of diversified OPCs should not be overlooked and further studies with different OPCs are suggested.

A targeted metabolomics approach toward understanding metabolic variations in rice under pesticide stress

Diazinon insecticide is widely applied throughout rice (Oryza sativa L.) fields in Iran. However, concerns are now being raised about its potential adverse impacts on rice fields. In this study, a time-course metabolic change in rice plants was investigated after diazinon treatment using gas chromatography-mass spectrometry (GC-MS), and subsequently the statistical strategy of random forest (RF) was performed in order to find the stress-associated effects. According to the results, a wide range of metabolites were dynamically varied as a result of the plant response to diazinon such as biosynthesis and metabolism of sugars, amino acids, organic acids, and phenylpropanoids, all correlating with the exposure time. Plant response was involved in multiple metabolic pathways, most of which were correlated with the exposure time. In this study, RF was explored as a potential multivariate method for GC-MS analysis of metabolomics data of rice (O. sativa L.) plants under diazinon stress; more than 31 metabolites were quantitatively determined, and time-course metabolic response of the plant during different days after treatment was measured. Results demonstrated RF as a potential multivariate method for GC-MS analysis of changes in plant metabolome under insecticide stress.

Impact of N-acetylcysteine and sesame oil on lipid metabolism and hypothalamic-pituitary-adrenal axis homeostasis in middle-aged hypercholesterolemic mice

Hyperlipidemia and stress are important factors affecting cardiovascular health in middle-aged individuals. We investigated the effects of N-acetylcysteine (NAC) and sesame oil on the lipidemic status, liver architecture and the hypothalamic-pituitary-adrenal (HPA) axis of middle-aged mice fed a cholesterol-enriched diet. We randomized 36 middle-aged C57bl/6 mice into 6 groups: a control group, a cholesterol/cholic acid diet group, a cholesterol/cholic acid diet group with NAC supplementation, a cholesterol/cholic acid diet enriched with 10% sesame oil and two groups receiving a control diet enriched with NAC or sesame oil. NAC administration prevented the onset of the disturbed lipid profile, exhibiting decreased lipid peroxidation and alkaline phosphatase (ALP) levels, restored nitric oxide bioavailability and reduced hepatic damage, compared to non-supplemented groups. High-cholesterol feeding resulted in increased hypothalamic glucocorticoid receptors (GR) levels, while NAC supplementation prevented this effect. NAC supplementation presented significant antioxidant capacity by means of preventing serum lipid status alterations, hepatic damage, and HPA axis disturbance due to high-cholesterol feeding in middle-aged mice. These findings suggest a beneficial preventive action of plant-derived antioxidants, such as NAC, on lipid metabolism and on the HPA axis.

Association of inflammatory response and oxidative injury in the pathogenesis of liver steatosis and insulin resistance following subchronic exposure to malathion in rats

Insulin resistance and risk of type 2 diabetes are the most important complications following exposure to organophosphorous (OPs) pesticides. Regarding the importance of liver on metabolic pathways regulation, in particular blood glucose homeostasis, we focused on liver inflammation and oxidative damages in a subchronic model of toxicity by malathion. Adult male Wistar rats of body weight 200-250g were used for the study. Malathion (200mg/kg b.w./day) was administered to rats by oral intubation for 28 days. Glycemic and insulin resistance indices, markers of liver injury, markers of inflammation and oxidative stress were assessed. Malathion-treated rats showed increased glycemia, insulinemia and glycated hemoglobin level, HOMA-IR and HOMA-β indices, plasma activities of hepatocellular enzymes, lipid peroxidation index, CD3(+)/CD4(+) and CD3(+)/CD4(+) and pro-inflammatory cytokines when decreased antioxidant status in liver was noted. Most of our study indicates that malathion promotes insulin resistance, inflammation and Hepatosteatosis in subchronic model of exposure. On the basis of biochemical and molecular findings, it is concluded that insulin resistance induced by malathion occurs through oxidative stress and related pro-inflammatory markers in a way to result in a reduced function of insulin in liver cells.

Antioxidant and anti-inflammatory effects of N-acetylcysteine against malathion-induced liver damages and immunotoxicity in rats

AIMS

Occupational exposure to organophosphate pesticides is becoming a common and increasingly alarming world-wide phenomenon. The present study is designed to investigate the preventive effect of N-acetylcysteine on malathion-induced hepatic injury and inflammation in rats.

MAIN METHODS

Adult male Wistar rats of body weight 200-230 g were used for the study. Malathion (200mg/kg b.w./day) was administered to rats by oral intubation and N-acetylcysteine (2g/l) in drinking water for 28 days. Rats were sacrificed on the 28th day, 2h after the last administration. Markers of liver injury (aspartate transaminase, alanine transaminase, alkaline phosphatase and lactate desyhdogenase), inflammation (leukocyte counts, myeloperoxidase, immunophenotyping of CD4(+) and CD8(+), interleukin-1β, interleukin-6 and interferon-γ expression) and oxidative stress (lipid peroxidation, reduced glutathione and antioxidant status) were assessed.

KEY FINDINGS

Malathion induced an increase in activities of hepatocellular enzymes in plasma, lipid peroxidation index, CD3(+)/CD4(+) and CD3(+)/CD4(+) percent and pro-inflammatory cytokines, when decreased antioxidant status in liver was noted. When malathion-treated rats were compared to NAC supplemented rats, leukocytosis, T cell count and IL-1β, IL-6, INF-γ expression were reduced. Furthermore, NAC restored liver enzyme activities and oxidative stress markers.

SIGNIFICANCE

Malathion induces hepatotoxicity, oxidative stress and liver inflammation. N-acetylcysteine showed therapeutic effects against malathion toxicity.

Acetylcholinesterase inhibitors: pharmacology and toxicology

Acetylcholinesterase is involved in the termination of impulse transmission by rapid hydrolysis of the neurotransmitter acetylcholine in numerous cholinergic pathways in the central and peripheral nervous systems. The enzyme inactivation, induced by various inhibitors, leads to acetylcholine accumulation, hyperstimulation of nicotinic and muscarinic receptors, and disrupted neurotransmission. Hence, acetylcholinesterase inhibitors, interacting with the enzyme as their primary target, are applied as relevant drugs and toxins. This review presents an overview of toxicology and pharmacology of reversible and irreversible acetylcholinesterase inactivating compounds. In the case of reversible inhibitors being commonly applied in neurodegenerative disorders treatment, special attention is paid to currently approved drugs (donepezil, rivastigmine and galantamine) in the pharmacotherapy of Alzheimer's disease, and toxic carbamates used as pesticides. Subsequently, mechanism of irreversible acetylcholinesterase inhibition induced by organophosphorus compounds (insecticides and nerve agents), and their specific and nonspecific toxic effects are described, as well as irreversible inhibitors having pharmacological implementation. In addition, the pharmacological treatment of intoxication caused by organophosphates is presented, with emphasis on oxime reactivators of the inhibited enzyme activity administering as causal drugs after the poisoning. Besides, organophosphorus and carbamate insecticides can be detoxified in mammals through enzymatic hydrolysis before they reach targets in the nervous system. Carboxylesterases most effectively decompose carbamates, whereas the most successful route of organophosphates detoxification is their degradation by corresponding phosphotriesterases.

Involvement of oxidative stress in liver injury after subchronic intoxication with low doses of chlorpyrifos — study on rats

Organophosphate compounds are nowadays the most frequently used pesticides. For these insecticides, the primary target is acetylcholinesterase and for this reason the main clinical effect of acute intoxication with organophosphate insecticides involves an irreversible inhibition of the activity of this enzyme. However, in the chronic or subchronic exposition oxidative stress has been reported as the main mechanism of its toxicity. The present study investigated the effect of three low doses (0.2, 2, 5 mg/kg bw) of chlorpyrifos for 14 or 28 days on serum liver enzymes and on oxidative stress parameters in the liver of rats. Chlorpyrifos treatment resulted in aminotransferases and alkaline phosphatase increase after 14 days (higher doses) and 28 days (all doses) treatment together with changes of antioxidative enzymes activities and reduced glutathione and malonyldialdehyde level in the liver. The enhancement of lipid peroxidation is temporary, reaching a peak after 14 days and decreasing after 28 days of treatment. Based on the experimental findings of this study the temporary liver injury caused by oxidative stress has been shown. The disturbances in the liver antioxidative status and increased liver membrane permeability may appear in case of doses near to the accepted human daily intake.

Increased oxidative stress is associated with the development of organophosphate-induced delayed neuropathy

Organophosphate-induced delayed neuropathy (OPIDN) is a progressive neuropathic disorder that manifests in days to weeks following exposure to an acute dose of organophosphates. The precise mechanism involved in the development of OPIDN is not clear as it develops after many days of the cessation of cholinergic crisis. The present study has been designed to understand the role of oxidative stress in the development of OPIDN, wherein neuropathy was developed by the administration of acute dose of monocrotophos (MCP) or dichlorvos (2,2-dichlorovinyl dimethyl phosphate (DDVP)) to rats. Significant motor deficits in terms of reduced spontaneous locomotor activity and performance on narrow beam test were observed after 14 days of exposure to MCP or DDVP, which persisted even on day 28, suggesting the development of OPIDN. Rats with OPIDN also exhibited an increase in malondialdehyde levels along with a decrease in thiol content in cerebral cortex, cerebellum and brain stem. Concomitantly, the activities of antioxidant enzymes, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase were reduced in the three brain regions. The biochemical and functional changes were associated with histological alterations in the brain regions studied. The results clearly indicate that the development of OPIDN is mediated in part through an increased oxidative stress and suggest that the strategies aimed at restoration of antioxidant capacity may be beneficial for the individuals with OPIDN-like symptoms.

Monocrotophos induced oxidative damage associates with severe acetylcholinesterase inhibition in rat brain

BACKGROUND

Neurotoxicity of organophosphate pesticide poisoning, a lead cause of death in South Asia, has not been clearly elucidated. Organophosphates inhibit acetylcholinesterase and neurotoxicity is primarily a result of acetylcholine induced hyperactivation in different regions of the brain. Neurotoxicity also results from oxidative stress induced by acetylcholinesterase inhibition in the brain. Determining the severity of acetylcholinesterase inhibition that induces oxidative damage may help in developing strategies that protect the brain from organophosphate induced toxicity.

AIM

To determine the level of acetylcholinesterase inhibition that induces oxidative stress in the brain following organophosphate pesticide poisoning.

METHODS

Brains of rats subject to acute monocrotophos poisoning (0.8 LD(50) by gavage) were assessed for acetylcholinesterase activity, antioxidant response and oxidative damage 2.5 and 8h after poisoning and on recovery from poisoning 24h later after poisoning. Assessments were made in the cortex, striatum and hippocampus, cholinergic rich regions and cerebellum, targets of organophosphate pesticide poisoning. Analysis was in comparison to non poisoned controls.

RESULTS

High acetylcholinesterase activities were noted in striatum followed by hippocampus, cerebellum and cortex. Acute severe monocrotophos poisoning inhibited acetylcholinesterase 87% in striatum, 67% in hippocampus, 58% in cerebellum, 53% in cortex and increased glutathione levels significantly in all brain regions 2.5h after poisoning. Significant lipid peroxidation and antioxidant enzymes were induced 8h after poisoning, directly correlated to high acetylcholinesterase inhibition (>67%). Recovery from monocrotophos poisoning was associated with absence of lipid peroxidation in the brain although acetylcholinesterase inhibition persisted.

CONCLUSIONS

Neurotoxicity of monocrotophos poisoning is characterized by oxidative damage in regions of the brain that exhibit high acetylcholinesterase activity and severe acetylcholinesterase inhibition. Recovery from poisoning is associated with prolonged induction of antioxidants that protect against oxidative damage.

Repeated malathion exposure induces behavioral impairment and AChE activity inhibition in brains of rat pups

The present study evaluated if repeated malathion administration would cause behavioral impairment in rat pups. Na+K+ ATPase and acetylcholinesterase (AChE) activities were investigated in brains of rat pups. Malathion was administered (100 or 200 mg/kg) orally (p.o.), once a day for four consecutive days. Rat pups were submitted to behavioral tests on the 5th day, 24 h after the last malathion administration. Malathion at the dose of 200 mg/kg caused a significant increase in the negative geotaxis latency and a decrease in the rotarod latency of rat pups. Rat pups exposed to malathion at both doses showed a significant decrease in the forelimb support latency and an inhibition of brain AChE activity. Repeated exposure of rat pups to malathion caused a decrease in motor coordination, vestibular function and muscular strength/coordination. The brain activity of AChE is involved in the behavioral alterations caused by malathion in rat pups.

Dimethoate-induced oxidative damage in erythrocytes of female adult rats

Pesticide hazards have been accentuated by the sharp rise in their agricultural, industrial and domestic use. Acute exposure to pesticides can cause oxidative damage. Our study investigated the potential ability of selenium (Se) and/or vitamin E, used as nutritional supplements, to alleviate erythrocyte oxidative damage induced by dimethoate (DM), an organophosphate pesticide. Female Wistar rats were exposed to DM (0.2g/L−1 of drinking water), DM + Se (0.5 mg/kg of diet), DM + vitamin E (100 mg/kg of diet), or DM + Se + vitamin E. Rats exposed to DM for 30 days showed an increase in malondialdehyde levels, superoxide dismutase and glutathione peroxidase activities in their erythocytes, while Na+,K+-ATPase and catalase activities, glutathione, non-protein thiol, vitamin E and vitamin C levels decreased. We also noted an increase in lactate dehydrogenase activity, marker of haemolysis and a decrease in acetylcholinesterase, the principal mode of organophosphorus action. Co-administration of Se or vitamin E to the diet of DM-treated rats ameliorated the biochemical parameters cited above. But the combined effect of Se and vitamin E was more powerful in antagonizing DM-induced oxidative stress. Therefore, our investigation revealed that both Se and vitamin E were useful elements in preventing DM-induced erythrocytes damage.

The antioxidant effect of wheat germ oil on subchronic coumaphos exposure in mice

Forty-eight male Balb/C mice, allocated to 4 equal groups, constituted the material of the study. The first group was maintained as the control group and was administered solely with a vehicle, which was used to dissolve coumaphos in the third and fourth groups. The second group was administered with 1.5 ml/kg.bw/day (∼1400 mg/kg.bw/day) of wheat germ oil. The third group received 5.5mg/kg.bw/day (1/10 LD50(oral)) of coumaphos. Finally, the fourth group was given both coumaphos and wheat germ oil at the doses indicated above. In all groups, the compounds were given directly into the stomach using a gastric tube, and treatment was continued for a period of 45 days. At the end of the 45th day, the liver, lungs, kidneys, brain, heart and spleen were extirpated in all of the animals. Tissue homogenates prepared from the tissue specimens were analysed for malondialdehyde (MDA) levels and catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. In conclusion, it was determined that coumaphos led to adverse alterations in the majority of the oxidative stress markers investigated. The administration of wheat germ oil alleviated the coumpahos-induced adverse effects detected in the tissues examined.

Ameliorating effect of N-acetylcysteine and curcumin on pesticide-induced oxidative DNA damage in human peripheral blood mononuclear cells

Endosulfan, malathion, and phosphamidon are widely used pesticides. Subchronic exposure to these contaminants commonly affects the central nervous system, immune, gastrointestinal, renal, and reproductive system. There effects have been attributed to increased oxidative stress. This study was conducted to examine the role of oxidative stress in genotoxicity following pesticide exposure using peripheral blood mononuclear cells (PBMC) in vitro. Further possible attenuation of genotoxicity was studied using N-acetylcysteine (NAC) and curcumin as known modulators of oxidative stress. Cultured mononuclear cells was isolated from peripheral blood of healthy volunteers, and exposed to varying concentrations of different pesticides: endosulfan, malathion, and phosphamidon for 6, 12, and 24 h. Lipid peroxidation was assessed by cellular malondialdehyde (MDA) level and DNA damage was quantified by measuring 8-hydroxy-2'-deoxyguanosine (8-OH-dG) using ELISA. Both MDA and 8-OH-dG were significantly increased in a dose-dependent manner following treatment with these pesticides. There was a significant decrease in MDA and 8-OH-dG levels in PBMC when co-treated with NAC or/and curcumin as compared to pesticide alone. These results indicate that pesticide-induced oxidative stress is probably responsible for the DNA damage, and NAC or curcumin attenuate this effect by counteracting the oxidative stress.

Protective effect of reduced glutathione on the liver injury induced by acute omethoate poisoning

Omethoate is an organophosphate insecticide with high toxicity. The aim of this study was to investigate the protective effect of exogenous reduced glutathione (GSH) on omethoate-induced liver injury. Sprague-Dawley rats were randomly divided into three groups: control, OM (omethoate poisoning), and OM+GSH (omethoate poisoning treated with GSH). The activities of acetylcholinesterase (AChE), aspartate aminotransferase (AST), alanine aminotransferase (ALT) in plasma, free organophosphate (FOP) in the liver were determined, and the histopathological changes in the liver were observed. Furthermore, TNF-α and NO in liver homogenate were assayed. The results showed that AChE activity was significantly inhibited by omethoate, but was not altered by GSH treatment. GSH was able to prevent hepatocellular edema and fatty degeneration, decrease liver FOP, attenuate the increased AST and ALT activity, and decline the increase of TNF-α and NO induced by omethoate. These results indicate GSH can attenuate liver injury, and suggest that GSH may be administered to protect the organ from injury in patients with acute organophosphate poisoning.

Oxidative stress in liver and red blood cells in acute lindane toxicity in rats

The aim of our study was to determine the role and dynamics of oxidative and nitrosative stress, as well as superoxide dismutase (SOD) and catalase activity in the hepatocytes and erythrocytes in early phase of acute lindane intoxication. Male Wistar rats were divided into groups: control, dimethylsulfoxide and lindane-treated groups (L, 8 mg/kg, intraperitoneally). Animals were sacrificed 0.5 and 4 hours after treatment (L(0.5) and L(4) groups, respectively). Oxidative and nitrosative stress parameters and antioxidant enzymes were determined spectrophotometrically. Liver and plasma thiobarbituric acid reactive substances (TBARS) concentration were significantly increased 0.5 after lindane administration (p < .01), with subsequent additional rise within 4 hours (p < .01), while plasma nitrite + nitrate level was significantly higher only 4 hours after lindane treatment. Total liver SOD activity was significantly increased in L(4) group in comparison with control group (p < .01). In conclusion, oxidative and nitrosative stress play an important role in early phase of acute lindane hepatotoxicity. Antioxidant capacity of hepatocytes is partly increased, due to an adaptive increase in SOD activity.

Tissue trace and major element levels in organophosphate insecticide fenthion (Lebaycid) toxicity in rats: prophylactic and therapeutic effect of exogenous melatonin

Organophosphate compounds are very toxic chemicals and used in widespread applications. The present study was designed to examine the role of exogenous melatonin against organophosphate toxicity in tissues (brain, heart, jejunum, kidney, liver, lung, muscle and pancreas) trace and major element levels of rats. Trace and major element concentrations in the tissues were measured in the sham group, the control group, prophylaxis with the melatonin group and therapy with the melatonin group (TM) by inductively coupled plasma-optical emission spectroscopy. Statistically significant differences among the experimental groups were detected for some tissue trace and major element concentrations. In the brain tissue, the Al, Mn and Se concentrations in the sham group were significantly higher than those in the control group (p<0.05). In the heart tissue, the Cu, Mn and Se concentrations in the sham group were significantly increased than those in the control group (p<0.05). In the kidney tissue, trace and major element concentrations in the TM group were significantly lower than those in the sham group (Fe and Mn; p<0.05, Cu, Mo, Ni, Ti, V and Zn; p<0.01). In the liver, Mg, Al, Zn and Ca concentrations in the TM group were significantly higher than those in the fenthion-treated control group (p<0.01). In the muscle tissue, element concentrations in the TM group were significantly lower when compared with the sham groups (Ca and Si; p<0.01). The Al, Cr, Mo, Ni, Si and Zn element concentrations were markedly decreased in the control group as compared with the TM group in the pancreas tissue (p<0.01). In conclusion, according to the results of the present study the major findings are that the fenthion-treated rat's tissue element levels were effected and the melatonin may normalize the altered levels of some trace and major elements of the tissues in organophosphate toxicity.

Changes in antioxidative parameters in the kidney of rats subchronically intoxicated with chlorfenvinphos — an organophosphate insecticide

Chlorfenvinphos is an organophosphate insecticide, posing a risk to those who are professionally involved in its production and use in agriculture, as well as to the general population. Organophosphates (OPs) are the class of insecticides, whose primary target is acetylcholinesterase (AChE) that hydrolyzes acetylcholine, a major neurotransmitter at the central and peripheral neuronal synapses. Moreover, many authors postulate that these compounds, both in acute and chronic intoxication, change the activities of antioxidative enzymes, thus leading to the enhancement of lipid peroxidation in many tissues. In the current study, animals received once a day, intragastrically with a stomach tube, 0.1ml/100g of olive oil (control groups) and oil solution of chlorfenvinphos at a dose of 0.02LD50 (0.3 mg/kg b. w.) — the experimental groups. The animals were sacrificed on day 14 or on day 28 of exposure. In the kidneys of rats, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) as well as reduced glutathione level (GSH) were determined. Chlorfenvinphos administration resulted in increased activities of antioxidative enzymes in the kidney of rats. Renal activities of SOD, GPx and GR were more pronounced on day 28 of chlorfenvinphos exposure than on day 14. The kidney reduced glutathione level (GSH) did not change in comparison to the control level. The current experimental findings indicate that subchronic administration of chlorfenvinphos leads to an adaptive response in the kidney of rats and this response is mostly due to reduced glutathione level and glutathione metabolism.