Carbofuran-induced oxidative stress in slow and fast skeletal muscles: prevention by memantine and atropine

Medicinal herbs and multiple sclerosis: Overview on the hard balance between new therapeutic strategy and occupational health risk

Multiple sclerosis (MS) is an autoimmune disease characterized by demyelination and axonal loss of the central nervous system (CNS). Despite its spread throughout the world, the mechanisms that determine its onset are still to be defined. Immunological, genetic, viral, and environmental factors and exposure to chemicals may trigger MS. Many studies have highlighted the anti-inflammatory and anti-oxidant effects of medicinal herbs, which make them a natural and complementary treatment for neurodegenerative diseases. A severe reduction of several MS symptoms occurs with herbal therapy. Thus, the request for medicinal plants with potential beneficial effects, for MS patients, is constantly increasing. Consequently, a production increase needs. Unfortunately, many medicinal herbs were untested and their action mechanism, possible adverse effects, contraindications, or interactions with other drugs, are poorly or not investigated. Keeping in mind the pathological mechanisms of MS and the oxidative damages and mitochondrial dysfunctions induced by pesticides, it is important to understand if pesticides used to increase agricultural productivity and their residues in medicinal plants, may increase the risk of developing MS in both workers and consumers. Studies providing some indication about the relationship between environmental exposure to pesticides and MS disease incidence are few, fragmentary, and discordant. The aim of this article is to provide a glance at the therapeutic potential of medicinal plants and at the risk for MS onset of pesticides used by medicinal plant growers and present in medicinal herbs.

Antioxidant mediated protective effect of Bridelia tomentosa leaf extract against carbofuran induced oxidative hepatic toxicity

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Bridelia tomentosa is a traditional medicinal plant that is used against colitis, traumatic injury, diarrhea, and diabetes.

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Gallic acid, Tannic acid, salicylic acid, and naringin were isolated from the leaf of B. tomentosa for the first time.

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B. tomentosa extract amended serum biochemical markers, MDA levels, and improved the levels of hepatic antioxidant enzymes.

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Phenolic and flavonoid compounds of the B. tomentosa can be used as nutraceuticals for treating oxidative hepatic ailments.

Bridelia tomentosa (B. tomentosa) is a traditional medicinal plant for treating diverse ailments. Hence, we designed our study to scrutinize the protective effect of the methanol extract of B. tomentosa leaf (BTL) against carbofuran-induced oxidative stress-mediated hepato-toxicity in Sprague-Dawley rats for the first time, along with the identification and quantification of phenolic acids and flavonoids by high-performance liquid chromatography (HPLC) and evaluation of antioxidant and antiradical activities of this extract. HPLC analysis confirmed the existence of tannic acid, gallic acid, salicylic acid, and naringin in B. tomentosa leaf extract which showed in-vitro antioxidant potentialities with DPPH, nitric oxide, hydrogen peroxide, and hydroxyl radical scavenging properties. Co-administration of B. tomentosa leaf extract with carbofuran showed dose-dependent significant protective effects of hepatic toxicity on serum markers such as alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, γ-glutamyl-transferase, lactate dehydrogenase, total bilirubin, total protein, albumin, globulin, lipid profile, urea, uric acid, and creatinine. Carbofuran intoxication also revealed an upsurge in malondialdehyde (MDA) and a decline in cellular endogenous antioxidant enzyme levels in rats compared with the control group. However, B. tomentosa leaf extract co-treatment increased the levels of hepatic antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase, and amended the MDA level. Similarly, histopathological evaluation further assured that BTL could keep the hepatocyte from carbofuran-induced damage. Therefore, all of our findings may conclude that the phenolic acids and flavonoids of B. tomentosa leaf extract are responsible to neutralize the toxic free radical-mediated oxidative hepatic damages.

Tamoxifen promotes white matter recovery and cognitive functions in male mice after chronic hypoperfusion

Cerebral white matter lesions (WMLs) induced by chronic cerebral hypoperfusion are one of the major components of stroke pathology and closely associated with cognitive impairment. However, the repair and related pathophysiology of white matter after brain injury remains relatively elusive and underexplored. Successful neuroregeneration is a method for the potential treatment of central nervous system (CNS) disorders. A non-steroidal estrogen receptor modulator, Tamoxifen, is an effective inhibitor of cell-swelling-activated anion channels and can mimic neuroprotective effects of estrogen in experimental ischemic stroke. However, its remains unclear whether Tamoxifen has beneficial effects in the pathological process after WMLs. In the present study, we investigated the efficacy of Tamoxifen on multiple elements of oligovascular niche of the male C57BL/6 mice brain after bilateral carotid artery stenosis (BCAS) - induced WMLs. Tamoxifen was injected intraperitoneally once daily from 1 day after BCAS until 1 day before sacrificed. Following chronic hypoperfusion, BCAS mice presented white matter demyelination, loss of axon-glia integrity, activated inflammatory response, and cognitive impairments. Tamoxifen treatment significantly facilitated functional restoration of working memory impairment in mice after white matter injury, thus indicating a translational potential for this estrogen receptor modulator given its clinical safety and applicability for WMLs, which lack of currently available treatments. Furthermore, Tamoxifen treatment reduced microglia activation and inflammatory response, favored microglial polarization toward to the M2 phenotype, enhanced oligodendrocyte precursor cells proliferation and differentiation, and promoted remyelination after chronic hypoperfusion. Together, our data indicate that Tamoxifen could alleviate white matter injury and play multiple targets protective effects following chronic hypoperfusion, which is a promising candidate for the therapeutic target for ischemic WMLs and other demyelination diseases associated cognitive impairment.

Exposure to carbamate and neurodevelopment in children: Evidence from the SMBCS cohort in China

BACKGROUND

Carbamate pesticides exposure have been linked with adverse health effects during developmental period. Based on 377 mother-child pairs from Sheyang Mini Birth Cohort Study, the present study aimed to assess carbofuranphenol exposure of three-year-old children and explore the associations between prenatal or postnatal carbofuranphenol exposures and neurodevelopmental indicators.

METHODS

Urinary carbofuranphenol concentrations were measured by gas chromatography-tandem mass spectrometry. Neural developmental quotient (DQ) of children was evaluated using Gesell Developmental Schedules. Generalized linear models were used to examine the associations between carbofuranphenol concentrations and neurodevelopment.

RESULTS

Geometric mean, geometric standard deviation, median, inter quartile range of postnatal urinary carbofuranphenol concentrations were 0.653 μg/L, 9.345 μg/L, 0.413 μg/L, 0.150-1.675 μg/L, respectively. Postnatal carbofuranphenol level showed negatively significant trend in language DQ [beta (β) = -0.121; 95% confidence interval (95% CI): 0.212, -0.031; p value (p) = 0.008] and total average DQ (β = -0.059, 95% CI: 0.115, -0.003; p = 0.035). Prenatal carbofuranphenol level showed negative correlations with children's adaptive DQ (β = -0.755; 95% CI: 1.257, -0.254; p = 0.003), social DQ (β = -0.341; 95% CI: 0.656, -0.027; p = 0.032) and total average DQ (β = -0.349; 95% CI: 0.693, -0.005; p = 0.047).

CONCLUSION

The results of the present study supposed children in agricultural region of China are widely exposed to carbamate pesticides, and both prenatal and postnatal exposure to carbamate pesticides may lead to neurodevelopmental effect.

The Concentration of Memantine in the Cerebrospinal Fluid of Alzheimer's Disease Patients and Its Consequence to Oxidative Stress Biomarkers

Memantine is a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist utilized as a palliative cure for Alzheimer’s disease. This is the second study examining the memantine concentrations in cerebrospinal fluid. The previously published study enrolled six patients, and three of them were theoretically in a steady state. In our study, we enrolled 22 patients who regularly used a standard therapeutic dose of memantine (20 mg/day, oral administration) before the sample collection. Patients were divided into four groups, according to the time of plasma and cerebrospinal fluid collection: 6, 12, 18, and 24 h after memantine administration. The cerebrospinal fluid samples were also assessed for selected oxidative stress parameters (malondialdehyde, 3-nitrotyrosine, glutathione, non-protein thiols, and non-protein disulfides). The plasma/cerebrospinal fluid (CSF) ratio for all time intervals were within the range of 45.89% (6 h) to 55.60% (18 h), which corresponds with previously published findings in most patients. The other aim of our study was to deduce whether the achieved “real” memantine concentration in the central compartment was sufficient to block NMDA receptors. The IC₅₀ value of memantine as an NMDA antagonist is in micromolar range; the lowest limit is 112 ng/ml (GluN2C), and this value was achieved only in three cases. The memantine cerebrospinal fluid concentration did not reach one quarter of the IC₅₀ value in five cases (one patient was excluded for noncompliance); therefore, the potency of memantine as a therapeutic effect in patients may be questionable. However, it appears that memantine therapy positively affected the levels of some oxidative stress parameters, especially non-protein thiols and 3-nitrotyrosine.

Inhibition of the transforming growth factor-β/SMAD cascade mitigates the anti-neurogenic effects of the carbamate pesticide carbofuran

The widely used carbamate pesticide carbofuran causes neurophysiological and neurobehavioral deficits in rodents and humans and therefore poses serious health hazards around the world. Previously, we reported that gestational carbofuran exposure has detrimental effects on hippocampal neurogenesis, the generation of new neurons from neural stem cells (NSC), in offspring. However, the underlying cellular and molecular mechanisms for carbofuran-impaired neurogenesis remain unknown. Herein, we observed that chronic carbofuran exposure from gestational day 7 to postnatal day 21 altered expression of genes and transcription factors and levels of proteins involved in neurogenesis and the TGF-β pathway (i.e. TGF-β; SMAD-2, -3, and -7; and SMURF-2) in the rat hippocampus. We found that carbofuran increases TGF-β signaling (i.e. increased phosphorylated SMAD-2/3 and reduced SMAD-7 expression) in the hippocampus, which reduced NSC proliferation because of increased p21 levels and reduced cyclin D1 levels. Moreover, the carbofuran-altered TGF-β signaling impaired neuronal differentiation (BrdU/DCX⁺ and BrdU/NeuN⁺ cells) and increased apoptosis and neurodegeneration in the hippocampus. Blockade of the TGF-β pathway with the specific inhibitor SB431542 and via SMAD-3 siRNA prevented carbofuran-mediated inhibition of neurogenesis in both hippocampal NSC cultures and the hippocampus, suggesting the specific involvement of this pathway. Of note, both in vitro and in vivo studies indicated that TGF-β pathway attenuation reverses carbofuran's inhibitory effects on neurogenesis and associated learning and memory deficits. These results suggest that carbofuran inhibits NSC proliferation and neuronal differentiation by altering TGF-β signaling. Therefore, we conclude that TGF-β may represent a potential therapeutic target against carbofuran-mediated neurotoxicity and neurogenesis disruption.

Vitamin C acts as a hepatoprotectant in carbofuran treated rat liver slices in vitro

The observations of liver slices when treated with different concentrations of carbofuran were as follows:-

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increased LPO

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decreased SOD, CAT, & protein content in all the treatments

The observations of liver slices when treated with different concentrations of carbofuran along with vitamin C were as follows:-

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the levels of LPO, SOD, CAT & total protein content reinstated towards normal level only in liver slices treated with low concentration

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at higher concentration of carbofuran treatment Vitamin C does not ameliorate the hepatic toxicity induced by carbofuran

The in vitro liver slice culture may prove to be a useful model for hepatotoxicological studies and Vitamin C, as a hepatoprotectant in mammalian system.

Carbamates, most commonly used pesticides in agricultural practices, have been reported to produce free radicals causing deleterious effects in animals. The present study was designed to assess the carbofuran induced oxidative stress in rat liver slices in vitro and also to evaluate protective role of vitamin C by incubating them in Krebs-Ringer HEPES Buffer (KRHB) containing incubation media (Williams medium E (WME) supplemented with glucose and antibiotics) with different concentrations of carbofuran. The results demonstrated that carbofuran caused significant increase in lipid peroxidation and inhibition in the activity of hepatic superoxide dismutase (SOD) in concentration dependent manner. The data with incubation medium reflected that carbofuran at lowest concentration caused an increase in SOD activity followed by its inhibition at higher concentration. Carbofuran treatment caused inhibition in the activity of catalase in liver slices and WME incubation medium. Pre-incubation of liver slices and the WME media with vitamin C restored the values of biochemical indices tested. The results indicated that carbofuran might induce oxidative stress in hepatocytes. The pretreatment with vitamin C may offer hepatoprotection from toxicity of pesticide at low concentration only.

Cholinesterase-inhibiting and genotoxic effects of acute carbofuran intoxication in man: a case report

Carbofuran belongs to the group of N-methylcarbamate insecticides used for the control of soil-dwelling and foliar-feeding insects in various crops; its consumption totals approximately 20,000 tonnes per year. Although the neurological effects on human beings have been well documented, little is known on its impact on the genome. A 38-year-old, healthy male worker employed in a carbofuran production facility accidentally inhaled the dust of the active ingredient carbofuran. Thirty minutes later, he experienced weakness, fatigue, perspiration, breathing difficulties, cephalalgia, disorientation, abdominal pain and vomiting. Blood samples were taken to measure cholinesterase activity, and to perform the alkaline comet assay and micronucleus assay combined with pancentromeric probes. Analyses were repeated 72 hr after intoxication and compared with the results obtained from regular monitoring conducted 10 days prior to the accident. Cholinesterase activity showed the highest correlation with the number of apoptotic cells, comet assay tail length, and number of long-tailed nuclei, suggesting that these are the genomic end-points primarily affected by carbofuran intake. Only a weak correlation was detected for the total number of micronuclei, centromere-containing micronuclei and nuclear buds. Since those end-points increased significantly 72 hr after the accident, they could be considered as late biomarkers of the effects of carbofuran intoxication. The results of this report suggest that, in the interests of higher standards in risk assessment and health hazard protection, periodical medical examination of carbamate-exposed populations should include genotoxicity testing in addition to the assessment of cholinesterase activity.

The role of oxidative stress in organophosphate and nerve agent toxicity

Organophosphate (OP) nerve agents exert their toxicity through inhibition of acetylcholinesterase. The excessive stimulation of cholinergic receptors rapidly causes neuronal damage, seizures, death, and long-term neurological impairment in those that survive. Owing to the lethality of organophosphorus agents and the growing risk they pose, medical interventions that prevent OP toxicity and the delayed injury response are much needed. Studies have shown that oxidative stress occurs in models of subacute, acute, and chronic exposure to OP agents. Key findings of these studies include alterations in mitochondrial function and increased free radical-mediated injury, such as lipid peroxidation. This review focuses on the role of reactive oxygen species in OP neurotoxicity and its dependence on seizure activity. Understanding the sources, mechanisms, and pathological consequences of OP-induced oxidative stress can lead to the development of rational therapies for treating toxic exposures.

Subacute and subchronic toxicity of Avalon(®) mixture (bentazone+dicamba) to rats

Subacute and subchronic toxicity of the herbicide Avalon(®), a mixture of bentazone and dicamba, were tested on rats. Avalon(®) was administered at dose levels of 250, 500 and 1000mg/kg body weight/day for 28 and 90 days. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities were monitored together with biochemistry parameters. The results showed that the mixture caused increases in the activities of ALT, AST and ALP, elevated concentrations of sodium, albumin and albumin/globulin ratio in males. In females, ALT activity, cholesterol and phosphate levels were increased. The changes generally were dose related and, in most cases, females exhibited lower susceptibility than males. The effects of a mixture are, in the most cases, different from the effects of the individual substances. The effects of bentazone were not prevalent which would be expected taking the composition of the mixture into account.

A transposable element insertion confers xenobiotic resistance in Drosophila

The increase in availability of whole genome sequences makes it possible to search for evidence of adaptation at an unprecedented scale. Despite recent progress, our understanding of the adaptive process is still very limited due to the difficulties in linking adaptive mutations to their phenotypic effects. In this study, we integrated different levels of biological information to pinpoint the ecologically relevant fitness effects and the underlying molecular and biochemical mechanisms of a putatively adaptive TE insertion in Drosophila melanogaster: the pogo transposon FBti0019627. We showed that other than being incorporated into Kmn1 transcript, FBti0019627 insertion also affects the polyadenylation signal choice of CG11699 gene. Consequently, only the short 3'UTR transcript of CG11699 gene is produced and the expression level of this gene is higher in flies with the insertion. Our results indicated that increased CG11699 expression leads to xenobiotic stress resistance through increased ALDH-III activity: flies with FBti0019627 insertion showed increased survival rate in response to benzaldehyde, a natural xenobiotic, and to carbofuran, a synthetic insecticide. Although differences in survival rate between flies with and without the insertion were not always significant, when they were, they were consistent with FBti0019627 mediating resistance to xenobiotics. Taken together, our results provide a plausible explanation for the increase in frequency of FBti0019627 in natural populations of D. melanogaster and add to the limited number of examples in which a natural genetic mutation has been linked to its ecologically relevant phenotype. Furthermore, the widespread distribution of TEs across the tree of life and conservation of stress response pathways across organisms make our results relevant not only for Drosophila, but for other organisms as well.

Carbofuran Induced Oxidative Stress in Rat Heart: Ameliorative Effect of Vitamin C

The aim of this study was to evaluate the effect of carbofuran on the levels of certain biomarkers in heart of rat exposed to sublethal concentrations of pesticide for 30 days after each interval of 24 h. The ameliorative effect of vitamin C by pretreatment of rats was also monitored. The results indicated that the activities of acetylcholinesterase and lactate dehydrogenase (LDH) decreased significantly in rat heart tissues, the extent of inhibition being concentration dependent. In contrast, the level of LDH increased in serum. The levels of malondialdehyde, total thiols, and glutathione were significantly elevated whereas the activities of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione-S-transferase were remarkably decreased in rat heart tissues. The serum concentrations of cholesterol increased by 47 and 77% and high density lipids decreased by 35 and 64%, respectively, due to exposure to 5 and 10% LD50 of carbofuran. The prior treatment of rats with vitamin C (100 mg kg−1 body weight) exerted significant ameliorative effect. The recovery was higher at low carbofuran concentration (5%) tested. The results indicated that carbofuran induced oxidative stress and caused damage to cardiac tissues, which could be recovered by prior application of vitamin C.

Gas chromatography-mass spectrometry based metabolomic approach for optimization and toxicity evaluation of earthworm sub-lethal responses to carbofuran

Despite recent advances in understanding mechanism of toxicity, the development of biomarkers (biochemicals that vary significantly with exposure to chemicals) for pesticides and environmental contaminants exposure is still a challenging task. Carbofuran is one of the most commonly used pesticides in agriculture and said to be most toxic carbamate pesticide. It is necessary to identify the biochemicals that can vary significantly after carbofuran exposure on earthworms which will help to assess the soil ecotoxicity. Initially, we have optimized the extraction conditions which are suitable for high-throughput gas chromatography mass spectrometry (GC-MS) based metabolomics for the tissue of earthworm, Metaphire posthuma. Upon evaluation of five different extraction solvent systems, 80% methanol was found to have good extraction efficiency based on the yields of metabolites, multivariate analysis, total number of peaks and reproducibility of metabolites. Later the toxicity evaluation was performed to characterize the tissue specific metabolomic perturbation of earthworm, Metaphire posthuma after exposure to carbofuran at three different concentration levels (0.15, 0.3 and 0.6 mg/kg of soil). Seventeen metabolites, contributing to the best classification performance of highest dose dependent carbofuran exposed earthworms from healthy controls were identified. This study suggests that GC-MS based metabolomic approach was precise and sensitive to measure the earthworm responses to carbofuran exposure in soil, and can be used as a promising tool for environmental eco-toxicological studies.

Solar photo-Fenton treatment of carbofuran: analysis of mineralization, toxicity, and organic by-products

The degradation of the pesticide carbofuran (CBF) using solar photo-Fenton treatment, at both the laboratory and the pilot scale, was evaluated. At the laboratory scale, in a suntest reactor, the Fe(2+) concentration and H(2)O(2) concentration were evaluated and optimized using the surface response methodology and the Pareto diagram. Under optimal conditions experiments were performed to evaluate the evolution of the substrate removal, oxidation, subsequent mineralization, toxicity and the formation of chloride ions during the treatment. The analysis and evolution of five CBF by-products as well as several control and reactivity tests at the density functional theory level were used to depict a general scheme of the main degradation pathway of CBF via the photo-Fenton system. Finally, at the pilot scale, a sample of the commercial CBF product Furadan was eliminated after 420 min by the photo-Fenton system using direct sunlight. Under these conditions, after 900 min 89% of toxicity (1/E(50) on Vibrio fischeri bacteria), 97% of chemical oxygen demand, and 90% of dissolved organic carbon were removed.

Effect of Roundup® (glyphosate formulation) in the energy metabolism and reproductive traits of Hyalella castroi (Crustacea, Amphipoda, Dogielinotidae)

Roundup(®) (glyphosate formulation) is a nonselective and posts emergent herbicide used for controlling aquatic weeds and different concentrations are used in cultures around the world. The objective of this investigation was to examine the effects of Roundup(®) (glyphosate formulation) on the biochemical composition, levels of lipoperoxidation, Na(+)/K(+)ATPase activity and reproductive traits in the Hyalella castroi. Amphipods were collected in summer 2009, in the southern Brazilian highlands. In the laboratory, the animals were kept in aquariums under controlled conditions for 7 days, and after this period they were exposed to 0.36, 0.52, 1.08 and 2.16 mg/l of glyphosate for 7 days. After the period of exposure, the animals were immediately frozen for determination of glycogen, proteins, lipids, triglycerides, cholesterol, levels of lipoperoxidation, and Na(+)/K(+)ATPase activity. During each day of the cultivation reproductive traits (number of reproductive pairs, ovigerous females and eggs in the marsupium) were observed. All concentrations of Roundup(®) induced significant decreases in all biochemical parameters and Na(+)/K(+)ATPase activity, and significant increase in lipoperoxidation levels. Showing this form a potentially toxic effect at very low concentrations, this pattern of results can lead to significant changes in trophic structure of limnic environments because these amphipods are important links in food chain in these habitats.

Protection of DFP-induced oxidative damage and neurodegeneration by antioxidants and NMDA receptor antagonist

Prophylactic agents acutely administered in response to anticholinesterases intoxication can prevent toxic symptoms, including fasciculations, seizures, convulsions and death. However, anticholinesterases also have long-term unknown pathophysiological effects, making rational prophylaxis/treatment problematic. Increasing evidence suggests that in addition to excessive cholinergic stimulation, organophosphate compounds such as diisopropylphosphorofluoridate (DFP) induce activation of glutamatergic neurons, generation of reactive oxygen (ROS) and nitrogen species (RNS), leading to neurodegeneration. The present study investigated multiple affectors of DFP exposure critical to cerebral oxidative damage and whether antioxidants and NMDA receptor antagonist memantine provide neuroprotection by preventing DFP-induced biochemical and morphometric changes in rat brain. Rats treated acutely with DFP (1.25 mg/kg, s.c.) developed onset of toxicity signs within 7-15 min that progressed to maximal severity of seizures and fasciculations within 60 min. At this time point, DFP caused significant (p<0.01) increases in biomarkers of ROS (F2-isoprostanes, F2-IsoPs; and F4-neuroprostanes, F4-NeuroPs), RNS (citrulline), and declines in high-energy phosphates (HEP) in rat cerebrum. At the same time, quantitative morphometric analysis of pyramidal neurons of the hippocampal CA1 region revealed significant (p<0.01) reductions in dendritic lengths and spine density. When rats were pretreated with the antioxidants N-tert-butyl-alpha-phenylnitrone (PBN, 200 mg/kg, i.p.), or vitamin E (100 mg/kg, i.p./day for 3 days), or memantine (18 mg/kg, i.p.), significant attenuations in DFP-induced increases in F2-IsoPs, F4-NeuroPs, citrulline, and depletion of HEP were noted. Furthermore, attenuation in oxidative damage following antioxidants or memantine pretreatment was accompanied by rescue from dendritic degeneration of pyramidal neurons in the CA1 hippocampal area. These findings closely associated DFP-induced lipid peroxidation with dendritic degeneration of pyramidal neurons in the CA1 hippocampal area and point to possible interventions to limit oxidative injury and dendritic degeneration induced by anticholinesterase neurotoxicity.

Biochemical composition, lipoperoxidation, Na(+)/K(+)ATPase activity and reproduction of Hyalella castroi (amphipoda, dogielinotidae) fed with different diets

This study compared the effect of different diets on the biochemical composition (lipids, cholesterol, proteins and glycogen) and the levels of lipoperoxidation and activity of Na(+)/K(+)ATPase of Hyalella castroi. We also investigated some patterns of the life cycle including survival, precopulatory mating pairs and number of ovigerous females after 21 days of culture with different diets. These crustaceans live in limnetic environments of the plateau (1,200 m a.s.l.) of the state of Rio Grande do Sul, in southern Brazil. Adult animals were collected in the autumn of 2006 in São José dos Ausentes. In the laboratory, the animals were kept submerged in aquariums, separated by sex, under controlled conditions. They were fed ad libitum for 21 days with different diets, and then some were used for biochemical determinations and others for observations of reproductive aspects. Statistical analysis revealed significant differences in the responses to glycogen, total proteins, lipoperoxidation levels and Na(+)/K(+)ATPase activity in both sexes of these amphipods and total lipids and total cholesterol levels only in females. These diets changed the biochemical patterns of the animals taken from the natural environment, and allowed a high survival rate but did not improve reproduction.

Carbofuran-induced alterations in the energy metabolism and reproductive behaviors of Hyalella castroi (Crustacea, Amphipoda)

Continuous or pulse exposure to pesticides may have negative effects on non-target organisms, resulting in a number of pathological and disturbed biochemical processes, including changes in energy budgets. The objective of this investigation was to examine the potential effects of carbofuran on the biochemical composition (glycogen, proteins, total lipids, triglycerides and cholesterol), levels of lipoperoxidation, Na+/K+ATPase activity, and reproductive behaviors (number of reproductive pairs, ovigerous females, and number of eggs) in the amphipod Hyalella castroi. The amphipods were collected in spring 2007, in the southern Brazilian highlands. In the laboratory, the animals were kept in aquariums under controlled conditions for 7 days, and after this period were exposed to 1 or 10 microg/L of carbofuran for 7 days. After the period of exposure, the animals were immediately frozen for determination of glycogen, proteins, lipids, triglycerides, total cholesterol, levels of lipoperoxidation, and Na+/K+ATPase activity. During each day of culture, reproductive behaviors were observed. Carbofuran induced significant decreases in biochemical reserves (glycogen, proteins, lipids, triglycerides and cholesterol), a significant increase in lipoperoxidation levels, and a decrease in Na+/K+ATPase activity in both males and females. Studies of all the biochemical parameters seem to be quite promising, in order to assess and predict the effects of toxicants on non-target organisms. The results showed that reproductive behaviors may provide sensitive criteria for assessing ecotoxicological effects. H. castroi lives among rooted aquatic macrophytes, and we suggest that it is a sensitive species that could be used in monitoring studies.

Carbofuran in water: Subchronic toxicity to rats

Carbofuran toxicity on rats was studied during subchronic exposure. Female and male rats were administered carbofuran in drinking water in concentrations of 25, 100 and 400ppm for a period of 90 days. Clinical symptoms, water consumption, body weight gain, organ weight, pathological and histopathological changes in the liver and kidneys were observed and biochemical and haematological examinations were carried out. The results obtained show that carbofuran administered to rats caused a significant decrease in water consumption as well as in brain, serum and erythrocyte cholinesterase activities. Statistically significant increases in relation to the control were found in the serum enzyme activities. The haematological data showed that carbofuran had no significant effect on Hb concentration and total RBC, but total WBC showed a significant statistical decrease. The histopathological changes in liver and kidneys were observed. However, cell regeneration in the liver and kidneys was found in all test groups.

Carbofuran-induced alterations in biochemical composition, lipoperoxidation, and Na+/K+ATPase activity of Hyalella pleoacuta and Hyalella curvispina in bioassays

The present study investigated the effects of carbofuran on the energy metabolism (levels of glycogen, total proteins, total lipids, triglycerides, and lipoperoxidation), Na+/K+ATPase activity, and reproductive parameters (formation of couples, ovigerous females, and mean number of eggs) in the freshwater amphipods Hyalella pleoacuta and Hyalella curvispina. These crustaceans live in limnetic environments of the plateau (H. pleoacuta) and coastal plain (H. curvispina) of the state of Rio Grande do Sul in southern Brazil. The animals were collected in the winter of 2006 in the Vale das Trutas (28 degrees 47'00''S-49 degrees 50'53''W) in the Municipality of São José dos Ausentes, and in Gentil Lagoon (29 degrees 56'30''S, 50 degrees 07'50''W) in the Municipality of Tramandaí. In the laboratory, the amphipods were kept submerged in aquariums under controlled conditions of photoperiod (12 h light: 12 h dark), temperature (23 degrees C+/-1), and constant oxygenation. Animals were exposed to carbofuran at a dose of 5 or 50 microg/L for a period of 7 days. At the end of this period, the animals were immediately frozen for determination of the biochemical parameters, lipoperoxidation levels (TBARS), and enzyme Na+/K+ATPase activity. During each day of culture, several reproductive parameters were observed. Statistical analysis (ANOVA) revealed that carbofuran induces significant decreases in glycogen, proteins, lipids, triglycerides, and Na+/K+ATPase, as well as a significant increase in lipoperoxidation levels. Studies of all the biochemical parameters seem to be quite promising, in order to assess and predict the effects of toxicants on non-target organisms. The results also suggest that the reproductive parameters (formation of couples, ovigerous females and mean number of eggs) may provide sensitive criteria for assessing ecotoxicological effects. Furthermore, H. pleoacuta and H. curvispina are suitable organisms for use in toxicity tests, and we suggest that they are sensitive species that could be used in monitoring studies.

Comparative evaluation of acetylcholinesterase status and genome damage in blood cells of industrial workers exposed to carbofuran

Literature data on carbofuran genotoxicity in vitro and in vivo are very scarce. There are few papers indicating that occupational exposure to this AChE inhibiting insecticide might be connected to increased risk of developing non-Hodgkin's lymphoma and lung cancer. Other authors showed its genotoxicity in vitro. We used comet and CBMN micronucleus assay combined with centromere probes to evaluate genome damage in lymphocytes of workers employed in carbofuran production. Also, the level of AChE activity in blood and plasma was measured. Only few workers exhibited AChE activity below 85%. Comet assay parameters were slightly but significantly elevated compared to control subjects, especially the long-tailed nuclei ratio. We found poor correlation between AChE activity and comet assay parameters, but significant effect of smoking and alcohol intake on the latest. In binucleated lymphocytes of workers significantly increased number of micronuclei, nuclear buds, and nucleoplasmic bridges was detected. Proportion of micronuclei with centromere, DAPI signal positive micronuclei was also elevated. Micronucleus assay parameters also appeared to be significantly influenced by duration of exposure to carbofuran. Together with published data on carbofuran's effect on health our results might indicate the need for further evaluations of its genotoxicity using a range of different cytogenetic techniques.

Human gastric cells resistant to (−)-epigallocatechin gallate show cross-resistance to several environmental pollutants

After a long-term culture in (-)-epigallocatechin gallate (EGCG, 20 microM), a major constituent of green tea, human gastric AGS cells developed 2.2-fold resistance to EGCG. The resistant AGS (AGS-R) cells were cross-resistant to several N-methylcarbamate insecticides, which are among the major control agents for pest insects in Taiwan. The AGS-R cells also showed protective effects against both the cytotoxicity and DNA damage induced by one of the mutagenic derivatives of N-methylcarbamate insecticide, N-nitroso methomyl, which is known to target the mammalian gastric tract. Therefore, acquisition of resistance by AGS cells through chronic exposure to EGCG implies that the tea-drinking habit of the Taiwanese is probably beneficial for the health of the gastric tract. In addition, AGS-R cells were cross-resistant to sodium arsenite and hydrogen peroxide, indicating that tolerance to oxidative stress might play a role in the development of resistance described in this investigation.

Carbofuran-Induced Oxidative Stress in Mammalian Brain

Chronic exposure to carbofuran, a carbamate pesticide, via oral administration has been reported to generate reactive oxygen species (ROS) in rat brain. However, information regarding the effect of short-term intraperitoneal (i.p.) carbofuran intoxication on oxidative stress is lacking. In the present study, the effect of carbofuran on oxidative indices in brain of Wistar rats has been determined by exposing the animals to three subacute concentrations (0.2, 0.4 and 0.8 mg/kg body weight) equivalent to 10, 20, and 40%, respectively, of its LD50 (i.p.) for 24 h. Rat liver has been used as a positive control. The results demonstrated that carbofuran treatment at the 3 concentrations tested caused significant increase in lipid peroxidation (LPO) by 12.50, 34.38, and 59.38%, respectively. The increased oxidative stress at same pesticide concentrations significantly induced activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase in rat brain; the impact on catalase being more marked only at high-pesticide doses (0.4 and 0.8 mg/kg body weight). Carbofuran also caused reduction in protein content of rat tissues tested. Rat brain was more severely affected by carbofuran than liver. The results clearly demonstrated that i.p. administration of carbofuran accelerated oxidative stress in rat brain in a dose-dependent manner.

Neurotoxic Potential of Depleted Uranium—Effects in Primary Cortical Neuron Cultures and in Caenorhabditis elegans

Depleted uranium (DU) is an extremely dense metal that is used in radiation shielding, counterbalances, armor, and ammunition. In light of the public concerns about exposure to DU and its potential role in Gulf War Syndrome (GWS), this study evaluated the neurotoxic potential of DU using focused studies on primary rat cortical neurons and the nematode Caenorhabditis elegans. We examined cell viability, cellular energy metabolism, thiol metabolite oxidation, and lipid peroxidation following exposure of cultured neurons to DU, in the form of uranyl acetate. We concurrently evaluated the neurotoxicity of uranyl acetate in C. elegans using various neuronal-green fluourescent protein reporter strains to visualize neurodegeneration. Our studies indicate that uranyl acetate has low cytotoxic potential, and uranium exposure does not result in significant changes in cellular energy metabolism, thiol metabolite oxidation, or lipid peroxidation. Furthermore, our C. elegans studies do not show any significant neurodegeneration following uranyl acetate exposure. Together, these studies suggest that DU, in the form of uranyl acetate, has low neurotoxic potential. These findings should alleviate the some of public concerns regarding DU as an etiologic agent of neurodegenerative conditions associated with GWS.

Neuronal oxidative injury and dendritic damage induced by carbofuran: protection by memantine

Carbamate insecticides mediate their neurotoxicity by acetylcholinesterase (AChE) inactivation. Male Sprague-Dawley rats acutely intoxicated with the carbamate insecticide carbofuran (1.5 mg/kg, sc) developed hypercholinergic signs within 5-7 min of exposure, with maximal severity characterized by seizures within 30-60 min, lasting for about 2 h. At the time of peak severity, compared with controls, AChE was maximally inhibited (by 82-90%), radical oxygen species (ROS) markers (F(2)-isoprostanes, F(2)-IsoPs; and F(4)-neuroprostanes, F(4)-NeuroPs) were elevated 2- to 3-fold, and the radical nitrogen species (RNS) marker citrulline was elevated 4- to 8-fold in discrete brain regions (cortex, amygdala, and hippocampus). In addition, levels of high-energy phosphates (HEPs) were significantly reduced (ATP, by 43-56%; and phosphocreatine, by 37-48%). Values of total adenine nucleotides and total creatine compounds declined markedly (by 41-56% and 35-45%, respectively), while energy charge potential remained unchanged. Quantitative morphometric analysis of pyramidal neurons of the hippocampal CA1 region revealed significant decreases in dendritic lengths (by 64%) and spine density (by 60%). Pretreatment with the N-methyl-D-aspartate (NMDA) receptor antagonist memantine (18 mg/kg, sc), in combination with atropine sulfate (16 mg/kg, sc), significantly attenuated carbofuran-induced changes in AChE activity and levels of F(2)-IsoPs and F(4)-NeuroPs, declines in HEPs, as well as the alterations in morphology of hippocampal neurons. MEM and ATS pretreatment also protected rats from carbofuran-induced hypercholinergic behavioral activity, including seizures. These findings support the involvement of ROS and RNS in seizure-induced neuronal injury and suggest that memantine by preventing carbofuran-induced neuronal hyperactivity blocks pathways associated with oxidative damage in neurons.

Comparative effects of acute and chronic carbofuran exposure on oxidative stress and drug-metabolizing enzymes in liver

The current study has been designed to examine the comparative effects of acute and chronic carbofuran exposure on lipid peroxidation, glutathione levels, and drug-metabolizing enzymes in rat liver. Activity of acetylcholinesterase, a bona fide marker of carbofuran exposure, was markedly inhibited after acute carbofuran exposure, whereas the extent of inhibition was much less after chronic exposure. Lipid peroxidation was accentuated after chronic carbofuran exposure. However, acute exposure resulted in relatively less increase in lipid peroxidation levels than with chronic exposure. Glutathione levels were significantly increased in liver of animals chronically exposed to carbofuran; on the contrary, there was a drastic reduction in glutathione levels after acute exposure. Cytochrome P450 was significantly induced in liver of animals treated with acute as well as chronic carbofuran. The activity of glutathione-S-transferase was induced after both acute and chronic carbofuran exposure; the increase was much higher in chronically exposed animals as compared with animals exposed acutely. Based on the results, it is clear that acute and chronic carbofuran exposure have differential effects on oxidative stress and drug-metabolizing enzymes in liver.

N-acetylcysteine ameliorates carbofuran-induced alterations in lipid composition and activity of membrane bound enzymes

The present work investigates the protective effects of N-acetylcysteine (NAC) on carbofuran-induced alterations in lipid composition and activity of membrane bound enzymes (Na+-K+-ATPase and Ca2+-ATPase) in the rat brain. Animals were exposed to carbofuran at a dose of 1 mg/kg body weight, orally, for a period of 28 days. A significant increase in lipid peroxidation in terms of TBARS was observed in brain after carbofuran exposure. NAC administration (200 mg/kg body weight) on the other hand lowered the carbofuran-induced lipid peroxidation to near normal. The increased lipid peroxidation following carbofuran exposure was accompanied by a significant decrease in the levels of total lipids, which is attributed to the reduction in phospholipid levels. Furthermore, NAC administration had a beneficial effect on carbofuran-induced alterations in lipid composition. The ratio of cholesterol to phospholipid, a major determinant of membrane fluidity, was increased in response to carbofuran exposure. This was associated with decreased activity of Na+-K+-ATPase and Ca2+-ATPase. NAC was observed to offer protection by restoring the cholesterol to phospholipid ratio along with the activity of Na+-K+-ATPase and Ca2+-ATPase. The results clearly suggest that carbofuran exerts its neurotoxic effects by increasing lipid peroxidation, altering lipid composition and activity of membrane bound enzymes. NAC administration ameliorated the effects of carbofuran suggesting its potential therapeutic effects in carbofuran neurotoxicity.

Cartap-induced cytotoxicity in mouse C2C12 myoblast cell line and the roles of calcium ion and oxidative stress on the toxic effects

Our previous study has demonstrated that instead of neuromuscular blockage cartap, an organonitrogen insecticide, could cause a marked irreversible Ca2+-dependent contracture in both isolated mouse and rabbit phrenic nerve-diaphragms. We further examined the potential of direct myocytotoxicity of cartap and the possible roles of calcium ion and oxidative stress on cartap-induced muscle cell injury using the mouse myoblast cell line, C2C12. Cartap exerted a dose- and time-dependent cytotoxic effect in C2C12 cells measured by MTT colorimetric assay and trypan blue dye exclusion. The extracellular activities of both creatine kinase (CK) and lactate dehydrogenase (LDH) were elevated in the cartap-treated groups at or greater than 100 microM. The isoenzymatic profiles showed that the elevations were mainly due to CK-3, LDH-3, and LDH-4. Following the addition of 0.5-2.5mM EGTA, a Ca2+ chelator, or 30-100 microM verapamil, an L-type Ca2+ channel blocker, the cartap-induced reduction in MTT metabolic rate of C2C12 cells was significantly restored in a dose-dependent manner in both EGTA and verapamil-treated cells. Furthermore, EGTA could significantly reduce the cartap-induced elevation in the levels of total extracellular CK and LDH activities. Additionally, cartap significantly increased the level of endogenous reactive oxygen species (ROS) in C2C12 cells in a dose- and time-dependent manner. The cartap-induced ROS generation could be significantly inhibited by antioxidants, including Vitamins C and E, catalase, and superoxide dismutase, with catalase the most effective. EGTA could significantly inhibit cartap-induced ROS generation in a dose-dependent manner. The results suggested that cartap could induce ROS generation in C2C12 cells via a Ca2+-dependent mechanism resulting in subsequent cytotoxicity, at least partially, to C2C12 cells. It is speculated that both Ca2+ and Ca2+-induced ROS may also play the central role on the myogenic contracture and myofiber injury of the diaphragm leading to respiratory failure and subsequent death in rabbits exposed ocularly to cartap.

Carbofuran-induced neurochemical and neurobehavioral alterations in rats: attenuation by N-acetylcysteine

Carbofuran, a widely used carbamate pesticide, has been reported to cause neurotoxicity. However, the underlying mechanisms involved in carbofuran neurotoxicity are not well understood. The present study was envisaged to investigate the possible role of oxidative stress in carbofuran neurotoxicity and to evaluate the protective effects of N-acetylcysteine (NAC). Acetylcholinesterase activity was significantly inhibited in all the regions of brain after carbofuran exposure (1 mg/kg body weight, orally, for 28 days). NAC, on the other hand, was found to partially restore the activity of acetylcholinesterase in carbofuran treated animals. Carbofuran exposure resulted in increased lipid peroxidation (LPO) in brain regions accompanied by decreased levels of glutathione. NAC administration to the carbofuran exposed animals lowered LPO along with partial repletion in glutathione levels. Concomitantly, the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase were significantly decreased after carbofuran exposure, while no significant change in the activity of glutathione-S-transferase was observed. NAC treatment to carbofuran treated rats resulted in protective effect on the activities of these enzymes. Marked impairment in the motor function was seen following carbofuran exposure, which is evident by significant decrease in the retention time of the rats on rotating rods. Cognitive deficits were also seen after carbofuran exposure as indicated by the significant decrease in active avoidance response. NAC treatment significantly improved the carbofuran-induced neurobehavioral deficits. The results clearly demonstrate that carbofuran exerts its neurotoxic effects by accentuating oxidative stress and suggest neuroprotective role of NAC in carbofuran neurotoxicity.