Paraquat-induced oxidative stress and dysfunction of the glutathione redox cycle in pulmonary microvascular endothelial cells

Protective role of vitamin E against acrylamide-induced testicular toxicity from pregnancy to adulthood: insights into oxidative stress and aromatase regulation

Acrylamide (ACR) is a toxic chemical frequently encountered in daily life, posing health risks. This study aimed to elucidate the molecular-level mechanism of ACR's toxic effects on testicles and investigate whether Vitamin E can mitigate these effects. A total of 40 adult pregnant rats were utilized, divided into four groups: Control, ACR, Vitamin E, and ACR + Vitamin E. ACR and Vitamin E were administered to the mother rats during pregnancy and lactation, and to the male offspring until the 8th week post-birth. Serum hormone levels, oxidant-antioxidant parameters, histopathological examination of testicular tissue, and mRNA and protein levels of the testicular and liver aromatase gene were analyzed. Spermiogram analysis was conducted on the collected sperm samples from the male offspring. The results revealed that ACR exposure adversely affected hormone levels, oxidant-antioxidant parameters, histological findings, as well as aromatase gene and protein expressions. However, Vitamin E administration effectively prevented the toxic effects of ACR. These findings demonstrate that ACR application significantly impairs the reproductive performance of male offspring rats by increasing liver aromatase activity.

Ocimum basilicum Essential Oil Modulates Hematotoxicity, Oxidative Stress, DNA Damage, and Cell Cycle Arrest Induced by β-cyfluthrin in Rat Liver

Pesticides are used in large quantities infrequently, resulting in environmental damage and health issues. The goal of the current study was to explore the ameliorating effect of Ocimum basilicum (Basil) leaves essential oil versus the harmful effects of β-cyfluthrin in rat liver. Male Wistar rats were classified at random into four groups; negative control (corn oil), basil leaves essential oil (BEO, 3 ml/kg), β-cyfluthrin (positive control) (β-Cyf; 15 mg/kg BW, 1/25 LD50), and BEO plus β-Cyf, respectively. The rats were given their doses orally every day for a month. Results revealed that BEO yielded 6.32 mg/g with 33 identified components, representing 97% of the total oil. BEO implicated a considerable level of total phenolic contents, DPPH radical scavenging capacity, ABTS activity, and FRAP. The treatment of β-Cyf dramatically elevated lipid peroxidation (TBARS and H2O2) (LPO), protein oxidation (PC, AOPP, and HYP), and considerably reduced enzymatic (SOD, CAT, GPx, GR, and GST) and non-enzymatic (GSH) antioxidants. After β-Cyf treatment, hematological parameters, body and liver weights, enzyme activity (AST, ALT, ALP, and LDH), as well as protein, albumin, globulin, and total bilirubin levels were all considerably affected. Furthermore, β-Cyf increased the expression of pro-inflammatory genes (TNF-α, IL-6) as well as DNA damage and cell cycle arrest in the G0/G1 phase and decreased the number of cells in S and G2/M phase of liver cells. Moreover, rats given BEO then intoxicated with β-Cyf showed substantial changes in the majority of the parameters tested. Finally, BEO was shown to have high antioxidant efficacy in combating β-Cyf toxicity because of its high phenolic content.

Anthrahydroquinone-2-6-disulfonate is a novel, powerful antidote for paraquat poisoning

Paraquat (PQ) is a widely used fast-acting pyridine herbicide. Accidental ingestion or self-administration via various routes can cause severe organ damage. Currently, no effective antidote is available commercially, and the mortality rate of poisoned patients is exceptionally high. Here, the efficacy of anthrahydroquinone-2-6-disulfonate (AH₂QDS) was observed in treating PQ poisoning by constructing in vivo and ex vivo models. We then explored the detoxification mechanism of AH₂QDS. We demonstrated that, in a rat model, the PQ concentration in the PQ + AH₂QDS group significantly decreased compared to the PQ only group. Additionally, AH₂QDS protected the mitochondria of rats and A549 cells and decreased oxidative stress damage, thus improving animal survival and cell viability. Finally, the differentially expressed genes were analysed in the PQ + AH₂QDS group and the PQ group by NextGen sequencing, and we verified that Nrf2's expression in the PQ + AH₂QDS group was significantly higher than that in the PQ group. Our work identified that AH₂QDS can detoxify PQ by reducing PQ uptake and protecting mitochondria while enhancing the body's antioxidant activity.

Mechanisms of deleterious effects of some pesticide exposure on pigs

The increase in the size of the global population increases the food and energy demand, making the use of pesticides in agricultural and livestock industries unavoidable. Exposure to pesticides can be toxic to the non-target species, such as humans, wildlife, and livestock, in addition to the target organisms. Various chemicals are used in the livestock industry to control harmful organisms, such as insects, weeds, and parasites. Pigs are one of the most important food sources for humans. In addition, pigs can be used as promising models for assessing the risk of absorption of environmental pollutants through the skin and oral exposure since they are physiologically similar to humans. Exposure to numerous environmental pollutants, such as mycotoxins, persistent organic pollutants, and heavy metals, has been reported to adversely affect growth, fertility, and endocrine homeostasis in pigs. Various pesticides have been observed in porcine tissues, blood, urine, and processed foods; however, there is a lack of comprehensive understanding of their effects on porcine health. This review provides a comprehensive description of the characteristics of pesticides that pigs can be exposed to and how their exposure affects porcine reproductive function, intestinal health, and endocrine homeostasis in vivo and in vitro.

Exploring the possible neuroprotective and antioxidant potency of lycopene against acrylamide-induced neurotoxicity in rats' brain

Acrylamide (Ac) is a carbonyl compound extracted from hydrated acrylonitrile with a significantly high chemical activity. It is widely existed and used in food processing, industrial manufacturing and laboratory personnel work. However, lycopene (Ly) is a most potent natural antioxidant among various common carotenoids extracted from red plants. Nevertheless, little is known about the relationship of Ac-induced neurotoxicity and the ameliorative role of Ly in the regulation of oxidative and antioxidant capacity during Ac exposure. Therefore, this work sought to investigate the neurotoxicity induced by Ac exposure and the potential modulatory role of Ly by reversing the brain dysfunctions during Ac exposure. For this purpose, forty male albino rats were assigned into four equal groups. Control group received distilled water, Ly group was given with a daily dose of 10 mg/kg bw, Ac group was given with a daily dose of 25 mg/kg bw, and Ac-Ly group was gavaged Ac plus Ly at the same doses as the former groups. All treatments were given orally for 21 consecutive days. The concentrations of antioxidants (reduced glutathione and glutathione peroxidase) and oxidative stress (malondialdehyde, nitric oxide and protein carbonyl) biomarkers, as well as neurotransmitters (serotonin and dopamine) and acetylcholinesterase (AChE) were measured in the brain homogenates. An immunohistochemical staining was applied with anti-GFPA antibody to determine the severity of astrocytosis. The in vivo study with rat model demonstrated that Ac exposure significantly decline the hematological parameters, brain neurotransmitters concentrations and AChE activity, as well as levels of antioxidant biomarkers but markedly elevate the levels of oxidative stress biomarkers. Moreover, marked histological alterations and astrocytosis were observed through the increased number of GFAP immunopositively cells in cerebral, cerebellar and hippocampal tissues compared with the other groups. Interestingly, almost all of the previously mentioned parameters were retrieved in Ac-Ly group compared to Ac group. These findings conclusively indicate that Ly oral administration provides adequate protection against the neurotoxic effects of Ac on rat brain tissue function and structure through modulations of oxidative and antioxidant activities.

Epalrestat suppresses cadmium-induced cytotoxicity through Nrf2 in endothelial cells

Cadmium (Cd) is an industrial and environmental pollutant that targets the vascular endothelium. The vascular system is critically affected by Cd toxicity. Recent studies have indicated an association between Cd and vascular diseases, although the mechanisms of Cd implications in vascular diseases are not clear. The purpose of the present study was to determine whether epalrestat (EPS), which is used for the treatment of diabetic neuropathy, protects against Cd-induced cytotoxicity in bovine aortic endothelial cells (BAECs). In the present study, the effects of EPS at near-plasma concentration were examined on Cd-induced cytotoxicity in BAECs. Cd-induced cytotoxicity was suppressed by pretreatment with EPS. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that serves a role in regulating the expression of glutamate cysteine ligase, the rate-limiting enzyme in glutathione (GSH) synthesis. In a previous study, EPS was demonstrated to increase GSH levels in BAECs in association with the Nrf2 pathway. In the present study, EPS increased GSH levels in BAECs exposed to Cd. The protective ability of EPS against the Cd-induced cytotoxicity disappeared following Nrf2 small interfering RNA transfection. In addition, EPS affected the intracellular levels of Cd, Cd transporter ZIP8 and metallothionein. To the best of our knowledge, the current study demonstrated, for the first time, that EPS suppresses Cd-induced cytotoxicity in BAECs. The upregulation of GSH may be associated with the suppression of Cd-induced cytotoxicity by EPS. From these findings, it may be proposed that the regulation of GSH, ZIP8 and metallothionein by EPS is a promising therapeutic approach to prevent Cd-induced toxicity.

Occupational exposure to organophosphorus and carbamates in farmers in La Cienega, Jalisco, Mexico: oxidative stress and membrane fluidity markers

Background

The region of La Cienega in Jalisco Mexico, is an important agricultural reference for the production of corn, sorghum and wheat, among other grains, so the use of pesticides for pest control is high. However, in this rural area there are no toxicological studies that assess the occupational risk of pesticide use. Therefore, this study is the first to determine the oxidative stress levels markers (GSH, GSSG, carbonyl groups, nitric oxide metabolites and lipid peroxides) as well as alteration of the mitochondrial membrane fluidity caused by occupational exposure to organophosphorus and carbamates in farmers of this region. This occupational risk can increase cellular oxidation, which explains the high prevalence of neurodegenerative diseases and cancer in Cienega settlers to be analyzed in future studies.

Methods

Comparative cross-sectional study was performed using two groups: one not exposed group (n = 93) and another one with occupational exposure (n = 113). The latter group was sub-divided into 4 groups based on duration of use/exposure to pesticides. Oxidative stress levels and membrane fluidity were assessed using spectrophotometric methods. Statistical analyses were performed using SPSS software ver. 19.0 for windows.

Results

The most commonly used pesticides were organophosphorus, carbamates, herbicide-type glyphosate and paraquat, with an average occupational exposure time of 35.3 years. There were statistically significant differences in markers of oxidative stress between exposed farmers and not exposed group (p = 0.000). However, in most cases, no significant differences were found in markers of oxidative stress among the 4 exposure sub-groups (p > 0.05).

Conclusion

In the Cienega region, despite the indiscriminate use of organophosphorus and carbamates, there are no previous studies of levels oxidative stress. The results show increased levels of oxidative stress in occupationally exposed farmers, particularly membrane fluidity levels increased three times in contrast to not exposed group.

Osteonecrosis of Femoral Head, An Overlooked Long-Term Complication after Paraquat Intoxication: A Retrospective Cohort Study

With increasing numbers of patients surviving acute intoxication phase, long-term complication after paraquat intoxication is a topic worth exploring, such as osteonecrosis (ON) of femoral head. We reviewed 86 paraquat-intoxicated survivors between 2000 and 2012 in Chang Gung Memorial Hospital, a 3700-bed tertiary hospital in Taiwan. With all the patients underwent same detoxification protocol in the acute stage, 17.4% of paraquat poisoning survivors developed ON of femoral head requiring surgery during follow up. Most of ON episodes occurred within 2 to 4 years after paraquat intoxication and then plateau after 6 years. ON patients exhibited higher SOFA scores than non-ON patients (2.80 ± 2.14 vs. 1.76 ± 1.52, p = 0.028). Furthermore, AKIN scores are also higher in the ON patients than non-ON patients (0.87 ± 1.13 vs. 0.38 ± 0.74, p = 0.040). Multivariate logistic regression showed higher AKIN score and higher partial pressure of carbon dioxide in the blood 48 hours after admission significantly predicted ON of femoral head after paraquat intoxication (p = 0.002 and p = 0.006 respectively). Larger studies with longer follow-up durations are warranted to confirm our finding.

Autophagy activation is required for homocysteine-induced apoptosis in bovine aorta endothelial cells

An elevated level of homocysteine (Hcy) in plasma is an independent risk factor for cardiovascular disease and central nervous system disease. Endothelial dysfunction as a result of apoptosis in endothelial cells is involved in the development and progression of these diseases. In this study, we aimed to investigate the effect of autophagy activation by amino acid starvation on Hcy-induced cytotoxicity in bovine aorta endothelial cells (BAECs). Hcy-induced lactate dehydrogenase (LDH) release was promoted by amino acid starvation. In addition, Hcy increased cleaved caspase-3 level, an indicator of apoptosis, by amino acid starvation. We revealed that oxidative stress is not involved in the Hcy-induced cytotoxicity promoted by amino acid starvation. Salazosulfapyridine (SASP), an SLC7A11 inhibitor, protected against the Hcy-induced LDH release promoted by amino acid starvation. SASP decreased the Hcy-induced cleaved caspase-3 level by amino acid starvation. We demonstrate for the first time that autophagy activation by amino acid starvation promotes Hcy-induced apoptosis in BAECs. Moreover, SLC7A11 inhibitor SASP, which is an amino acid transporter, protects against Hcy-induced apoptosis due to autophagy.

Lipoic acid antagonizes paraquat-induced vascular endothelial dysfunction by suppressing mitochondrial reactive oxidative stress

Paraquat (PQ) is a widely used herbicide in the agricultural field. The lack of an effective antidote is the significant cause of high mortality in PQ poisoning. Here, we investigate the antagonistic effects of alpha lipoic acid (α-LA), a naturally existing antioxidant, on PQ toxicity in human microvascular endothelial cells (HMEC-1). All the doses of 250, 500 and 1000 μM α-LA significantly inhibited 1000 μM PQ-induced cytotoxicity in HMEC-1 cells. α-LA pretreatment remarkably diminished the damage to cell migration ability, recovered the declined levels of the vasodilator factor nitric oxide (NO), elevated the expression level of endothelial nitric oxide synthases (eNOS), and inhibited the upregulated expression of vasoconstrictor factor endothelin-1 (ET-1). Moreover, α-LA pretreatment inhibited reactive oxygen species (ROS) generation, suppressed the damage to the mitochondrial membrane potential (ΔΨ _m) and mitigated the inhibition of adenosine triphosphate (ATP) production in HMEC-1 cells. These results suggested that α-LA could alleviate PQ-induced endothelial dysfunction by suppressing oxidative stress. In summary, our present study provides novel insight into the protective effects and pharmacological potential of α-LA against PQ toxicity in microvascular endothelial cells.

Peroxiredoxin6 in Endothelial Signaling

Peroxiredoxins (Prdx) are a ubiquitous family of highly conserved antioxidant enzymes with a cysteine residue that participate in the reduction of peroxides. This family comprises members Prdx1–6, of which Peroxiredoxin 6 (Prdx6) is unique in that it is multifunctional with the ability to neutralize peroxides (peroxidase activity) and to produce reactive oxygen species (ROS) via its phospholipase (PLA₂) activity that drives assembly of NADPH oxidase (NOX2). From the crystal structure, a C47 residue is responsible for peroxidase activity while a catalytic triad (S32, H26, and D140) has been identified as the active site for its PLA₂ activity. This paradox of being an antioxidant as well as an oxidant generator implies that Prdx6 is a regulator of cellular redox equilibrium (graphical abstract). It also indicates that a fine-tuned regulation of Prdx6 expression and activity is crucial to cellular homeostasis. This is specifically important in the endothelium, where ROS production and signaling are critical players in inflammation, injury, and repair, that collectively signal the onset of vascular diseases. Here we review the role of Prdx6 as a regulator of redox signaling, specifically in the endothelium and in mediating various pathologies.

Low concentrations of clarithromycin upregulate cellular antioxidant enzymes and phosphorylation of extracellular signal-regulated kinase in human small airway epithelial cells

BACKGROUND

It is well known that low-dose, long-term macrolide therapy is effective against chronic inflammatory airway diseases. Oxidative stress is considered to be a key pathogenesis factor in those diseases. However, the mechanism of action of low-dose, long-term macrolide therapy remains unclear. We have reported that clarithromycin (CAM), which is a representative macrolide antibiotic, could inhibit hydrogen peroxide (H2O2)-induced reduction of the glutathione (GSH)/glutathione disulfide (GSSG) ratio in human small airway epithelial cells (SAECs), via the maintenance of GSH levels through an effect on γ-glutamylcysteine synthetase (γ-GCS) expression. In this study, we examined the influence of CAM against H2O2-induced activities of cellular antioxidant enzymes and phosphorylated extracellular signal regulatory kinase (p-ERK) using SAECs, the main cells involved in chronic airway inflammatory diseases.

METHODS

SAECs were pretreated with CAM (1, 5, and 10 μM) for 72 h, and subsequently exposed to H2O2 (100 μM) for 0.5-2 h. Levels of GSH and GSSG, and activities of glutathione peroxidase (GPx)-1, glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), heme oxygenase (HO)-1 and p-ERK were assayed. mRNA expressions of GPx-1 and HO-1 were measured using the real-time reverse transcription polymerase chain reaction (RT-PCR). Tukey's multiple comparison test was used for analysis of statistical significance.

RESULTS

Pretreatment with low-dose (1 and 5 μM) CAM for 72 h inhibited H2O2-induced reductions of GPx-1, GR, SOD, CAT and HO-1 activities, and mRNA expressions of GPx-1 and HO-1, and improved the GSH/GSSG ratio. However, these alterations were not observed after pretreatment with high-dose (10 μM) CAM, which suppressed phosphorylation of cell proliferation-associated ERK to cause a significant (p < 0.01) decrease in cell viability.

CONCLUSIONS

CAM is efficacious against deterioration of cellular antioxidant enzyme activity caused by oxidative stress under low-dose, long-term treatment conditions. On the other hand, pretreatment with high-dose CAM suppressed phosphorylation of cell proliferation-associated ERK and decreased cell viability. The present study may provide additional evidence as to why low-dose, long-term administration of macrolides is effective for treating chronic inflammatory airway diseases.

2,3,5,4'‑Tetrahydroxystilbene‑2‑O‑β‑D‑glucoside inhibits septic serum‑induced inflammatory injury via interfering with the ROS‑MAPK‑NF‑κB signaling pathway in pulmonary aortic endothelial cells

Sepsis is characterized by injury to the microvasculature and the microvascular endothelial cells, leading to barrier dysfunction. However, the specific role of injury in septic endothelial barrier dysfunction remains to be elucidated. In the present study, it was hypothesized that endothelial cell inflammatory injury is likely required for barrier dysfunction under septic conditions in vitro. 2,3,5,4'‑Tetrahydroxystilbene‑2‑O‑β‑D‑glucoside (TSG), a compound extracted from Chinese herbs, is able to inhibit the inflammatory injury of septic‑serum in endothelial cells. In the present study, cell viability was assayed by CCK‑8 method; mRNA and protein expression was identified by RT‑qPCR, western blot or Elisa, respectively and the production of reactive oxygen species was observed by a fluorescence microscope. The present study indicated that septic serum significantly decreased the cell viability of pulmonary aortic endothelial cells (PAECs) following co‑cultivation for 6 h, which occurred in a time‑dependent manner. TSG notably increased the viability of PAECs in a time‑ and concentration‑dependent manner. Further investigations revealed that septic serum increased the secretion of interleukin (IL)‑1β, IL‑6 and C‑reactive protein in PAECs, whereas pretreatment with TSG significantly decreased the secretion of these inflammatory factors. These data indicated that septic serum increased inflammatory injury to the PAECs, and TSG decreased this injury via the reactive oxygen species‑mitogen‑activated protein kinase‑nuclear factor‑κB signaling pathway.

Redox Signaling Mediated by Thioredoxin and Glutathione Systems in the Central Nervous System

SIGNIFICANCE

The thioredoxin (Trx) and glutathione (GSH) systems play important roles in maintaining the redox balance in the brain, a tissue that is prone to oxidative stress due to its high-energy demand. These two disulfide reductase systems are active in various areas of the brain and are considered to be critical antioxidant systems in the central nervous system (CNS). Various neuronal disorders have been characterized to have imbalanced redox homeostasis. Recent Advances: In addition to their detrimental effects, recent studies have highlighted that reactive oxygen species/reactive nitrogen species (ROS/RNS) act as critical signaling molecules by modifying thiols in proteins. The Trx and GSH systems, which reversibly regulate thiol modifications, regulate redox signaling involved in various biological events in the CNS.

CRITICAL ISSUES

In this review, we focus on the following: (i) how ROS/RNS are produced and mediate signaling in CNS; (ii) how Trx and GSH systems regulate redox signaling by catalyzing reversible thiol modifications; (iii) how dysfunction of the Trx and GSH systems causes alterations of cellular redox signaling in human neuronal diseases; and (iv) the effects of certain small molecules that target thiol-based signaling pathways in the CNS.

FUTURE DIRECTIONS

Further study on the roles of thiol-dependent redox systems in the CNS will improve our understanding of the pathogenesis of many human neuronal disorders and also help to develop novel protective and therapeutic strategies against neuronal diseases. Antioxid. Redox Signal. 27, 989-1010.

Evaluation of Oxidative Stress and Antioxidant Status in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common respiratory condition involving the airways and characterized by airflow limitation. Gaseous and noxious particles play an important role in this process. Antioxidants are the substances that may protect cells from the damage caused by unstable molecules known as free radicals. The increased oxidative stress in patients with COPD is the result of an increased burden of inhaled oxidants, as well as increased amounts of reactive oxygen species (ROS) generated by various inflammatory, immune and epithelial cells of the airways. A total of 150 subjects with COPD and 100 healthy controls subjects were enrolled in this study from the period October 2015 to January 2016. The investigation included measurements of plasma superoxide dismutase activity (SOD), catalase activity (CAT), glutathione content (GSH) reduced form, (GPx) glutathione peroxidase, glutathione reductase (GR) and lipid peroxidation (LPO). Absorbance was measured by UV spectrophotometer. The estimated values of SOD, catalase, GPx, GSH and GR were found to be significantly (P = 0.0001) lower among the cases compared with controls. But, the levels of MDA were higher (P = 0.0001) in cases as compared to control group and there was significant difference in the oxidative stress parameters among the various stages of COPD. The post hoc analysis revealed that SOD was significantly (P < 0.01) lower among the mild, moderate and severe patients compared with very severe patients. The catalase was also observed to be significantly (P = 0.01) lower among mild, moderate and severe patients than very severe patients. The GPx was found to be significantly (P = 0.002) lower among the mild, moderate and severe patients compared with very severe patients. MDA was observed to be significantly higher in mild, moderate and severe patients compared with very severe (P = 0.001). GR was significantly (P = 0.003) lower among mild, moderate and severe patients than very severe patients. However, there was no significant difference in GSH among severity of COPD patients. This study suggests that oxidant and antioxidant imbalance plays an important role in various stages of severity of COPD. These results revealed the presence of an oxidative stress in subjects with COPD, and it is proportionate to the severity of disease.

Paraquat disrupts the anti-inflammatory action of cortisol in human macrophages in vitro: therapeutic implications for paraquat intoxications

The herbicide paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride) has been banned in Europe since 2007 due to its high toxicity in humans. However, it is still widely used in Middle/South America and in Asia where it is annually associated with a high incidence of unintentional and intentional poisoning. Human macrophage-like cell lines were used to shed more light on the inflammatory response elicited by paraquat. Paraquat (3-1000 μM) reduced cell viability in a dose- and time-dependent manner. Exposure to 50 or 200 μM paraquat for 24 h elevated the release of interleukin 8 and gene expression of tumor necrosis factor-α. Expression of the 11β-hydroxysteroid dehydrogenase 1 gene tended to increase, while cellular glutathione concentrations decreased. The anti-inflammatory effect of cortisol was significantly disrupted. The paraquat-induced cortisol resistance could not be prevented by N-acetyl-l-cysteine. However, a polyphenolic extract of grape seeds consisting of monomeric and oligomeric flavan-3-ols (MOF) reduced paraquat-induced inflammation in the presence of cortisol to baseline. In conclusion, the results suggest that an impaired cortisol response may contribute to paraquat-mediated inflammation. Agents with pleiotropic cellular and subcellular effects on redox regulation and inflammation, such as plant-derived polyphenols, may be an effective add-on to the therapy of paraquat intoxications with glucocorticoids.

Pinocembrin Provides Mitochondrial Protection by the Activation of the Erk1/2-Nrf2 Signaling Pathway in SH-SY5Y Neuroblastoma Cells Exposed to Paraquat

Pinocembrin (PB; 5,7-dihydroxyflavanone; C₁₅H₁₂O₄) is a flavonoid found in propolis and exerts antioxidant, anti-inflammatory, and antimicrobial effects. Furthermore, PB has been studied as a neuroprotective agent. However, it remains to be understood whether and how PB would induce mitochondrial protection in mammalian cells. Therefore, we investigated here the mechanism involved in the protective effects elicited by PB in paraquat (PQ; 100 μM)-treated SH-SY5Y neuroblastoma cells. PB (25 μM) pretreatment (for 4 h) downregulated the levels of Bcl-2-associated X protein (Bax), blocked the release of cytochrome c to the cytosol, and inhibited the PQ-induced activation of caspase-9 and caspase-3. Besides, PB prevented mitochondrial dysfunction by suppressing the PQ-elicited inhibition of complexes I and V. Moreover, PB abrogated the loss of mitochondrial membrane potential (MMP) and the decline in ATP levels in the cells exposed to PQ. PB exerted antioxidant effects on mitochondria by decreasing the levels of redox impairment markers in mitochondrial membranes. Importantly, PB enhanced the levels of mitochondrial reduced glutathione (GSH). Upregulation of enzymes involved in the synthesis of GSH was seen in the cells exposed to PB. PB afforded mitochondrial protection by activating the extracellular signal-regulated kinase/nuclear factor erythroid 2-related factor 2 (Erk1/2-Nrf2) axis, since inhibition of Erk1/2 or silencing of Nrf2 abrogated these effects. Therefore, PB exerted mitochondrial and cellular protection by an Erk1/2-Nrf2-dependent mechanism.

Salvianolic acid B protects against paraquat-induced pulmonary injury by mediating Nrf2/Nox4 redox balance and TGF-β1/Smad3 signaling

The present study was aimed at exploring the protective effects of Salvianolic acid B (SalB) against paraquat (PQ)-induced lung injury in mice. Lung fibrotic injuries were induced in mice by a single intragastrical administration of 300mg/kg PQ, then the mice were administrated with 200mg/kg, 400mg/kg SalB, 100mg/kg vitamin C (Vit C) and dexamethasone (DXM) for 14days. PQ-triggered structure distortion, collagen overproduction, excessive inflammatory infiltration, pro-inflammatory cytokine release, and oxidative stress damages in lung tissues and mortality of mice were attenuated by SalB in a dose-dependent manner. Furthermore, SalB was noted to enhance the expression and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and reduce expression of the reactive oxygen species-generating enzyme Nox4 [NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase-4]. SalB also inhibited the increasing expression of transforming growth factor (TGF)-β1 and the phosphorylation of its downstream target Smad3 which were enhanced by PQ. These results suggest that SalB may exert protective effects against PQ-induced lung injury and pulmonary fibrosis. Its mechanisms involve the mediation of Nrf2/Nox4 redox balance and TGF-β1/Smad3 signaling.

Immunotoxicological, biochemical, and histopathological studies on Roundup and Stomp herbicides in Nile catfish (Clarias gariepinus)

AIM

The current study was directed to investigate the immunotoxic and oxidative stress effects of Roundup and Stomp herbicides and their combination on Nile catfish (Clarias gariepinus).

MATERIALS AND METHODS

The experiment was carried out on 120 fish that randomly divided into four equal groups with three replicates: The first group kept as control, the second group exposed to 1/2 96 h lethal concentration 50 (LC50) of Roundup, the third group exposed to 1/2 96 h LC50 of Stomp, and the fourth one exposed to a combination of Roundup and Stomp at previously-mentioned doses. The experiment was terminated after 15 days; blood samples were obtained at 1(st), 8(th), and 15(th) days of treatment where the sera were separated for estimation of antioxidant enzymes. Meanwhile, at 15(th) day of exposure part of blood was collected from all groups with an anticoagulant for evaluation of phagocytic activity, then the fish were sacrificed, and specimens from the liver of all groups were obtained for histopathological examination.

RESULTS

Our results indicated that both herbicides either individually or in combination elucidated significant decrease in phagocytic activity that was highly marked in group exposed to both herbicides. Furthermore, our data elicited an obvious elevation in the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Meanwhile, the data depicted reduction in levels of reduced glutathione (GSH) and glutathione-S-transferase (GST). Histopathological investigation of liver proved the aforementioned results.

CONCLUSION

It could be concluded that either Roundup or Stomp alone cause significant deleterious effects on aquatic vertebrates. However, the use of their combination enhanced their toxic effects. Toxicity can end up in humans through the food chain.

Methyl viologen induces neural differentiation on murine P19 cells

Methyl viologen is a highly effective contact herbicide, a neurotoxic compound and an inducer of reactive oxygen species, which generate oxidative stress in cells. Reactive oxygen species has been known to function as an important messenger in cell differentiation. In this study, we investigated the effect of methyl viologen on neural cell differentiation using pluripotent mouse embryonal carcinoma P19 cells, which reportedly differentiate into neural cells upon exposure to retinoic acid. Methyl viologen, an inducer of intracellular reactive oxygen species, induced the differentiation of P19 cells into neural cells in the presence of neurofilament. Reduced glutathione, an eliminator of reactive oxygen species, also induced neural differentiation in P19 cells. These results suggest that P19 cells differentiate into neural cells, conceivably independent of intracellular reactive oxygen species.

Oxidative stress modulation by Rosmarinus officinalis in creosote-induced hepatotoxicity

Coal tar is a significant product generated from coal pyrolysis. Coal tar can be utilized as raw materials for various industries. It is also a type of raw material from which phenols, naphthalenes, and anthracene can be extracted. The present study was designed to investigate the possibility of coal tar creosote to induce oxidative stress and biochemical perturbations in rat liver and the role of rosemary (Rosmarinus officinalis) in ameliorating its toxic effects. Male Wister Albino rats were randomly divided into four groups of seven each, group I served as control; group II treated with rosemary (10 mL of water extract/kg BW for 21 days), group III received coal tar creosote (200 mg/4 mL olive oil/kg BW for 3 days), and group IV treated with both rosemary and coal tar creosote. The administration of coal tar creosote significantly caused elevation in lipid peroxidation (LPO) and reduction in the activities of glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST). A significant decrease in reduced glutathione (GSH) content was also observed. Liver aminotransferases aspartate transaminase (AST) and alanine transaminase (ALT)] and alkaline phosphatase (AlP) were significantly decreased while lactate dehydrogenase (LDH) was increased. Rosemary pretreatment to coal tar creosote-treated rats decreased LPO level and normalized GPx, GR, SOD, CAT, and GST activities, while GSH content was increased. Also, liver AST, ALT, AlP, and LDH were maintained near normal level due to rosemary treatment. In conclusion, rosemary has beneficial effects and could be able to antagonize coal tar creosote toxicity.

Protective effect of carnosic acid against paraquat-induced redox impairment and mitochondrial dysfunction in SH-SY5Y cells: Role for PI3K/Akt/Nrf2 pathway

Carnosic acid (CA) is a phenolic diterpene isolated from Rosmarinus officinalis and exerts anti-inflammatory, antioxidant, and anticarcinogenic activities in different cell types. It has been reported that CA is able to cause protective effects on experimental models of neurodegeneration. However, the exact mechanism by which CA prevents neuronal degeneration remains to be better studied. We investigated here whether there is a role for CA as a neuroprotective agent in a paraquat (PQ) model of Parkinson's disease (PD) regarding cellular and mitochondrial-related redox parameters. SH-SY5Y cells were treated with CA for 12h and were exposed to 100 μM PQ for 24h. It was found that CA at different concentrations prevented the effects of PQ on cell viability and redox parameters. CA alleviated reactive oxygen and nitrogen species production elicited by PQ, as well as decreased the toxic effect on mitochondrial function. Inhibition of Pi3K/Akt pathway with LY294002 or silencing of Nrf2 expression partially blocked the reversal of redox impairment induced by CA. Therefore, CA activated Nrf2 through modulation of PI3K/Akt pathway resulting in increased levels of antioxidant enzymes and consequent neuroprotection. Thus, CA may be viewed as a potential neuroprotective agent to be used in cases of Parkinson's disease (PD).

Nrf2/ARE Pathway Involved in Oxidative Stress Induced by Paraquat in Human Neural Progenitor Cells

Compelling evidences have shown that diverse environmental insults arising during early life can either directly lead to a reduction in the number of dopaminergic neurons or cause an increased susceptibility to neurons degeneration with subsequent environmental insults or with aging alone. Oxidative stress is considered the main effect of neurotoxins exposure. In this study, we investigated the oxidative stress effect of Paraquat (PQ) on immortalized human embryonic neural progenitor cells by treating them with various concentrations of PQ. We show that PQ can decrease the activity of SOD and CAT but increase MDA and LDH level. Furthermore, the activities of Cyc and caspase-9 were found increased significantly at 10 μM of PQ treatment. The cytoplasmic Nrf2 protein expressions were upregulated at 10 μM but fell back at 100 μM. The nuclear Nrf2 protein expressions were upregulated as well as the downstream mRNA expressions of HO-1 and NQO1 in a dose-dependent manner. In addition, the proteins expression of PKC and CKII was also increased significantly even at 1 μM. The results suggested that Nrf2/ARE pathway is involved in mild to moderate PQ-induced oxidative stress which is evident from dampened Nrf2 activity and low expression of antioxidant genes in PQ induced oxidative damage.

Artificial sweetener neohesperidin dihydrochalcone showed antioxidative, anti-inflammatory and anti-apoptosis effects against paraquat-induced liver injury in mice

The present study evaluated the protective effect of artificial sweetener neohesperidin dihydrochalcone (NHDC) against paraquat (PQ)-induced acute liver injury in mice. A single dose of PQ (75mg/kg body weight, i.p.) induced acute liver toxicity with the evidences of increased liver damage biomarkers, aspartate transaminase (AST) and alanine transaminase (ALT) activities in serum. Consistently, PQ decreased the antioxidant capacity by reducing glutathione peroxidase (GP-X), glutathione-S-transferase (GST) and catalase (CAT) activities, glutathione (GSH) level and total antioxidant capacity (T-AOC), as well as increasing reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS) levels. Histopathological examination revealed that PQ induced numerous changes in the liver tissues. Immunochemical staining assay indicated the upregulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions. However, NHDC ameliorates PQ-induced hepatic toxicity in mice by reversing these parameters. Additionally, NHDC significantly inhibited PQ-induced nuclear factor-kappa B (NF-κB) expression and mitochondrial-driven apoptotic signaling. TUNEL assay confirmed that PQ-induced apoptosis was relieved by NHDC. In conclusion, these findings suggested that NHDC showed potent antioxidant, anti-inflammatory and anti-apoptotic effects against PQ-induced acute liver damage.

Fluorescence labeling of carbonylated lipids and proteins in cells using coumarin-hydrazide

Carbonylation is a generic term which refers to reactive carbonyl groups present in biomolecules due to oxidative reactions induced by reactive oxygen species. Carbonylated proteins, lipids and nucleic acids have been intensively studied and often associated with onset or progression of oxidative stress related disorders. In order to reveal underlying carbonylation pathways and biological relevance, it is crucial to study their intracellular formation and spatial distribution. Carbonylated species are usually identified and quantified in cell lysates and body fluids after derivatization using specific chemical probes. However, spatial cellular and tissue distribution have been less often investigated. Here, we report coumarin-hydrazide, a fluorescent chemical probe for time- and cost-efficient labeling of cellular carbonyls followed by fluorescence microscopy to evaluate their intracellular formation both in time and space. The specificity of coumarin-hydrazide was confirmed in time- and dose-dependent experiments using human primary fibroblasts stressed with paraquat and compared with conventional DNPH-based immunocytochemistry. Both techniques stained carbonylated species accumulated in cytoplasm with strong perinuclear clustering. Using a complimentary array of analytical methods specificity of coumarin-hydrazide probe towards both protein- and lipid-bound carbonyls has been shown. Additionally, co-distribution of carbonylated species and oxidized phospholipids was demonstrated.

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Coumarin-hydrazide (CHH) chemical probe was used to label cellular carbonyls.

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CHH fluorescence microscopy allowed to monitor protein and lipid carbonyl distribution.

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CHH specificity towards protein- and lipid-bound carbonyls was demonstrated.

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CHH labeling and DNPH immunocytochemistry for microscopy imaging were compared.

Natural antioxidant betanin protects rats from paraquat-induced acute lung injury interstitial pneumonia

The effect of betanin on a rat paraquat-induced acute lung injury (ALI) model was investigated. Paraquat was injected intraperitoneally at a single dose of 20 mg/kg body weight, and betanin (25 and 100 mg/kg/d) was orally administered 3 days before and 2 days after paraquat administration. Rats were sacrificed 24 hours after the last betanin dosage, and lung tissue and bronchoalveolar lavage fluid (BALF) were collected. In rats treated only with paraquat, extensive lung injury characteristic of ALI was observed, including histological changes, elevation of lung : body weight ratio, increased lung permeability, increased lung neutrophilia infiltration, increased malondialdehyde (MDA) and myeloperoxidase (MPO) activity, reduced superoxide dismutase (SOD) activity, reduced claudin-4 and zonula occluden-1 protein levels, increased BALF interleukin (IL-1) and tumor necrosis factor (TNF)-α levels, reduced BALF IL-10 levels, and increased lung nuclear factor kappa (NF-κB) activity. In rats treated with betanin, paraquat-induced ALI was attenuated in a dose-dependent manner. In conclusion, our results indicate that betanin attenuates paraquat-induced ALI possibly via antioxidant and anti-inflammatory mechanisms. Thus, the potential for using betanin as an auxilliary therapy for ALI should be explored further.

Epalrestat increases glutathione, thioredoxin, and heme oxygenase-1 by stimulating Nrf2 pathway in endothelial cells

Epalrestat (EPS) is the only aldose reductase inhibitor that is currently available for the treatment of diabetic neuropathy. Recently, we found that EPS at near-plasma concentration increases the intracellular levels of glutathione (GSH) in rat Schwann cells. GSH plays a crucial role in protecting endothelial cells from oxidative stress, thereby preventing vascular diseases. Here we show that EPS increases GSH levels in not only Schwann cells but also endothelial cells. Treatment of bovine aortic endothelial cells (BAECs), an in vitro model of the vascular endothelium, with EPS caused a dramatic increase in intracellular GSH levels. This was concomitant with the up-regulation of glutamate cysteine ligase, an enzyme catalyzing the first and rate-limiting step in de novo GSH synthesis. Moreover, EPS stimulated the expression of thioredoxin and heme oxygenase-1, which have important redox regulatory functions in endothelial cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that regulates the expression of antioxidant genes. EPS increased nuclear Nrf2 levels in BAECs. Nrf2 knockdown by siRNA suppressed the EPS-induced glutamate cysteine ligase, thioredoxin-1, and heme oxygenase-1 expression. Interestingly, LY294002, an inhibitor of phosphatidylinositol 3-kinase, abolished the EPS-stimulated GSH synthesis, suggesting that the kinase is associated with Nrf2 activation induced by EPS. Furthermore, EPS reduced the cytotoxicity induced by H2O2 and tert-butylhydroperoxide, indicating that EPS plays a role in protecting cells from oxidative stress. Taken together, the results provide evidence that EPS exerts new beneficial effects on endothelial cells by increasing GSH, thioredoxin, and heme oxygenase-1 levels through the activation of Nrf2. We suggest that EPS has the potential to prevent several vascular diseases caused by oxidative stress.

Selenium modulates β-cyfluthrin-induced liver oxidative toxicity in rats

This study was designed to investigate the possibility of β-cyfluthrin to induce oxidative stress and biochemical perturbations in rat liver and the role of selenium in alleviating its toxic effects. Male Wister rats were randomly divided into four groups of seven each, group I served as control, group II treated with selenium (200 µg/kg BW), group III received β-cyfluthrin (15 mg/kg BW, 1/25 LD50 ), and group IV treated with β-cyfluthrin plus selenium. Rats were orally administered their respective doses daily for 30 days. The administration of β-cyfluthrin caused elevation in lipid peroxidation (LPO) and reduction in the activities of antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR). A decrease in reduced glutathione (GSH) content was also observed. Liver aminotransferases (AST and ALT) and alkaline phosphatase (ALP) were decreased, whereas lactate dehydrogenase (LDH) was increased. Selenium in β-cyfluthrin-induced liver oxidative injury of the rats modulated LPO, CAT, SOD, GSH, GST, GPx, and GR. Also, liver AST, ALT, ALP, and LDH were maintained near normal level due to selenium treatment. It is concluded that selenium scavenges reactive oxygen species and render a protective effect against β-cyfluthrin toxicity.

The relationship between platelet endothelial cell adhesion molecule-1 and paraquat-induced lung injury in rabbits

BACKGROUND

Platelet endothelial cell adhesion molecule-1 (PECAM-1), also known as CD31, is mainly distributed in vascular endothelial cells. Studies have shown that PECAM-1 is a very significant indicator of angiogenesis, and has been used as an indicator for vascular endothelial cells. The present study aimed to explore the relationship between the expression of PECAM-1 and the degree of acute lung injury (ALI) and fibrosis in paraquat (PQ) induced lung injury in rabbits.

METHODS

Thirty-six adult New Zealand rabbits were randomly divided into three groups (12 rabbits in each group) according to PQ dosage: 8 mg/kg (group A), 16 mg/kg (group B), and 32 mg/kg (group C). After PQ infusion, the rabbits were monitored for 7 days and then euthanized. The lungs were removed for histological evaluation. Masson staining was used to determine the degree of lung fibrosis (LF), and semi-quantitative immune-histochemistry analysis to determine the expression of PECAM-1. Pearson's product-moment correlation analysis was performed to evaluate the relationship between the expression of PECAM-1 and the extent of lung injuries expressed by ALI score and degree of LF.

RESULTS

Rabbits in the three groups showed apparent poisoning. The rabbits survived longer in group A than in groups B and C (6.47±0.99 days vs. 6.09±1.04 days vs. 4.77±2.04 days) (P<0.05). ALI score was lower in group A than in groups B and C (8.33±1.03 vs. 9.83±1.17 vs. 11.50±1.38) (P<0.05), and there was statistically significant difference between group B and group C (P=0.03). LF was slighter in group A than in groups B and C (31.09%±2.05 % vs. 34.37%±1.62 % vs. 36.54%±0.44%) (P<0.05), and there was statistically significant difference between group B and group C (P=0.026). The PEACAM-1 expression was higher in group A than in groups B and C (20.31%±0.70% vs. 19.34%±0.68% vs. 18.37%±0.46%) (P<0.05), and there was statistically significant difference between group B and group C (P=0.017). Pearson's correlation analysis showed that the expression of PECAM-1 was negatively correlated to both ALI score (Coe=-0.732, P=0.001) and degree of LF (Coe=-0.779, P<0.001).

CONCLUSIONS

The PECAM-1 expression significantly decreases in New Zealand rabbits after PQ poisoning, and the decrease is dose-dependent. The PECAM-1 expression is negatively correlated with ALI score and LF, showing a significant role in the development of lung injuries induced by PQ.

Gene expression markers in the zebrafish embryo reflect a hepatotoxic response in animal models and humans

The zebrafish embryo (ZFE) is a promising non-rodent model in toxicology, and initial studies suggested its applicability in detecting hepatotoxic responses. Here, we hypothesize that the detailed analysis of underlying mechanisms of hepatotoxicity in ZFE contributes to the improved identification of hepatotoxic properties of new compounds and to the reduction of rodents used for screening. ZFEs were exposed to nine reference hepatotoxicants, targeted at induction of cholestasis, steatosis and necrosis, and two non-hepatotoxic controls. Histopathology revealed various specific morphological changes in the ZFE hepatocytes indicative of cell injury. Gene expression profiles of the individual compounds were generated using microarrays. Regulation of single genes and of pathways could be linked to hepatotoxic responses in general, but phenotype-specific responses could not be distinguished. Hepatotoxicity-associated pathways included xenobiotic metabolism and oxidoreduction related pathways. Overall analysis of gene expression identified a limited set of potential biomarkers specific for a common hepatotoxicity response. This set included several cytochrome P450 genes (cyp2k19, cyp4v7, cyp2aa3), genes related to liver development (pklr) and genes important in oxidoreduction processes (zgc:163022, zgc:158614, zgc:101858 and sqrdl). In conclusion, the ZFE model allows for identification of hepatotoxicants, without discrimination into specific phenotypes.

Antioxidant effect of propolis against exposure to chromium in Cyprinus carpio

The aim of the present study was to investigate the ameliorative properties of propolis against the toxic effects of chromium (VI) by examining oxidative damage markers such as lipid peroxidation and the antioxidant defence system components in carp (Cyprinus carpio). The fish were exposed to sublethal concentrations of chromium. Propolis was simultaneously administered to chromium-exposed fish. Treatment was continued for 28 days, and at the end of this period, blood and tissue (liver, kidney, spleen, and gill) samples were collected. Levels of malondialdehyde (MDA) and reduced glutathione (GSH) as well as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were determined in blood and tissues for measurement of oxidant-antioxidant status. The levels of MDA, as an index of lipid peroxidation, increased in blood and tissues. Antioxidant enzyme activities in blood and tissues were modified in chromium groups compared to controls. Simultaneous administration of propolis ameliorated these parameters. The present results suggest that administration of propolis might alleviate chromium-induced oxidative stress.

Glyphosate commercial formulation causes cytotoxicity, oxidative effects, and apoptosis on human cells: differences with its active ingredient

In the present study, the effects on oxidative balance and cellular end points of glyphosate, aminomethylphosphonic acid (AMPA), and a glyphosate formulation (G formulation) were examined in HepG2 cell line, at dilution levels far below agricultural recommendations. Our results show that G formulation had toxic effects while no effects were found with acid glyphosate and AMPA treatments. Glyphosate formulation exposure produced an increase in reactive oxygen species, nitrotyrosine formation, superoxide dismutase activity, and glutathione (GSH) levels, while no effects were observed for catalase and GSH-S-transferase activities. Also, G formulation triggered caspase 3/7 activation and hence induced apoptosis pathway in this cell line. Aminomethylphosphonic acid exposure produced an increase in GSH levels while no differences were observed in other antioxidant parameters. No effects were observed when the cells were exposed to acid glyphosate. These results confirm that G formulations have adjuvants working together with the active ingredient and causing toxic effects that are not seen with acid glyphosate.

Antioxidant effect of selenium on lipid peroxidation, hyperlipidemia and biochemical parameters in rats exposed to diazinon

Diazinon (DZN) is one of the most organophosphate insecticides that widely used in agriculture and industry. Selenium is generally recognized to be a trace mineral of great importance for human health, protecting the cells from the harmful effects of free radicals. Therefore, the present study was carried out to investigate the alterations in biochemical parameters, free radicals and enzyme activities induced by diazinon in male rat serum, and the role of selenium in alleviating the negative effects of DZN. Animals were divided into four groups of seven rats each; the first group was used as control. Groups 2, 3 and 4 were treated with selenium (Se; 200μg/kg BW), diazinon (DZN; 10mg/kg BW) and diazinon plus selenium, respectively. Rats were orally administered their respective doses daily for 30 days. Results obtained showed that DZN significantly induced thiobarbituric acid reactive substances (TBARS) and decreased the activities of glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) and the levels of reduced glutathione (GSH) in rat sera. Aminotransferases (AST, ALT), phosphatases (AlP, AcP) and lactate dehydrogenase (LDH) activities were significantly increased while acetylcholinesterase (AChE) activity was decreased due to DZN administration. Also, DZN treatment caused significant perturbations in lipids profile and serum biochemical parameters. On the other hand, Se alone significantly decreased the levels of TBARS, total lipids, cholesterol, urea and creatinine, while increased the activities of antioxidant enzymes and glutathione content, total protein (TP) and albumin. In addition, Se in combination with DZN partially or totally alleviated its toxic effects on the studied parameters. In conclusion, Se has beneficial effects and could be able to antagonize DZN toxicity.

Epalrestat increases intracellular glutathione levels in Schwann cells through transcription regulation

Epalrestat (EPS), approved in Japan, is the only aldose reductase inhibitor that is currently available for the treatment of diabetic neuropathy. Here we report that EPS at near-plasma concentration increases the intracellular levels of glutathione (GSH), which is important for protection against oxidative injury, through transcription regulation. Treatment of Schwann cells with EPS caused a dramatic increase in intracellular GSH levels. EPS increased the mRNA levels of γ-glutamylcysteine synthetase (γ-GCS), the enzyme catalyzing the first and rate-limiting step in de novo GSH synthesis. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that plays a central role in regulating the expression of γ-GCS. ELISA revealed that EPS increased nuclear Nrf2 levels. Knockdown of Nrf2 by siRNA suppressed the EPS-induced GSH biosynthesis. Furthermore, pretreatment with EPS reduced the cytotoxicity induced by H₂O₂, tert-butylhydroperoxide, 2,2'-azobis (2-amidinopropane) dihydrochloride, and menadione, indicating that EPS plays a role in protecting against oxidative stress. This is the first study to show that EPS induces GSH biosynthesis via the activation of Nrf2. We suggest that EPS has new beneficial properties that may prevent the development and progression of disorders caused by oxidative stress.

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Epalrestat is available for the treatment of diabetic neuropathy.

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Epalrestat stimulated GSH biosynthesis by up-regulating γ-GCS via Nrf2 activation.

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Epalrestat reduced the cytotoxicity induced by oxidants.

Protective effect of lycopene on oxidative stress and antioxidant status in Cyprinus carpio during cypermethrin exposure

The aim of this study was to investigate the ameliorative properties of lycopene against the toxic effects of cypermethrin (CYP) by examining oxidative damage markers such as lipid peroxidation and the antioxidant defense system components in carp (Cyprinus carpio). The fish were divided into seven groups of 10 fish each and received the following treatments: group 1, no treatment; group 2, orally administered corn oil; group 3, oral lycopene (10 mg/kg body weight); group 4, exposure to 0.202 μg/L CYP; group 5, exposure to 0.202 μg/L CYP plus oral administration of 10 mg/kg lycopene; group 6, exposure to 0.404 μg/L CYP; and group 7, exposure to 0.404 μg/L CYP plus oral administration of 10 mg/kg lycopene. Treatment was continued for 28 days, and at the end of this period, blood and tissue (liver, kidney, and gill) samples were collected. Levels of malondialdehyde (MDA) and reduced glutathione (GSH) as well as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were determined in blood and tissues for measurement of oxidant-antioxidant status. MDA level, as an index of lipid peroxidation, increased in blood and tissues. Antioxidant enzyme activities in blood and tissues were modified in CYP groups compared with controls. Administration of lycopene ameliorated these parameters. The present results suggest that administration of lycopene might alleviate CYP-induced oxidative stress.

Paraquat poisoning induces TNF-α-dependent iNOS/NO mediated hyporesponsiveness of the aorta to vasoconstrictors in rats

Paraquat is a toxic herbicide that may induce acute lung injury, circulatory failure and death. The present work aimed at investigating whether there is systemic inflammation and vascular dysfunction after paraquat exposure and whether these parameters were related. There was neutrophilia and accumulation of neutrophils in lung and bronchoalveolar lavage of animals given paraquat. This was associated with an increase in serum levels of TNF-α. In rats given paraquat, the relaxant response of aortic rings to acetylcholine was not modified but the contractile response to phenylephrine was greatly reduced. Endothelium removal or treatment with non-selective (L-NAME) or selective (L-NIL) inhibitors of inducible nitric oxide synthase (iNOS) restored contraction of aortas. There was greater production of nitric oxide (NO), which was restored to basal level by L-NIL, and greater expression of iNOS in endothelial cells, as seen by Western blot analyses and confocal microscopy. Blockade of TNF-α reduced pulmonary and systemic inflammation and vascular dysfunction. Together, our results clearly show that paraquat causes pulmonary and systemic inflammation, and vascular dysfunction in rats. Vascular dysfunction is TNF-α dependent, associated with enhanced expression of iNOS in aortic endothelial cells and greater NO production, which accounts for the decreased responsiveness of aortas to vasoconstrictors. Blockers of TNF-α may be useful in patients with paraquat poisoning.

Multidrug resistance associated protein 1 together with glutathione plays a protective role against 4-hydroxy-2-nonenal-induced oxidative stress in bovine aortic endothelial cells

4-Hydroxy-2-nonenal (HNE), an aldehyde produced by lipid peroxidation, induces cytotoxicity and oxidative stress. Glutathione (GSH) protects against the cytotoxicity of HNE. However, the protective mechanism of GSH has not been fully examined. We examined the protective role played by the relationship between GSH and multidrug resistance associated protein 1 (MRP1) against the HNE-induced oxidative stress in bovine aortic endothelial cells (BAECs). HNE induced the loss of viability of BAECs. Exogenous GSH, which is membrane-impermeable, prevented the loss of viability induced by HNE by inhibiting HNE uptake in BAECs, probably due to the formation of the HNE-SG complex in the extracellular space. We demonstrated that HNE induced the expression of MRP1 protein, which can transport the HNE-SG complex. The induction of MRP1 protein expression by HNE disappeared in BAECs pretreated with L-buthionine sulfoximine, a GSH-depleting agent. This result suggests that HNE, together with intracellular GSH, contributes to the regulation of MRP1 protein expression. Moreover, we found that MK571, an MRP1 inhibitor, promoted the HNE-induced oxidative stress and cell death. Taken together, these findings suggest that MRP1, together with GSH, plays a protective role against the HNE-induced oxidative stress in BAECs.

Bark extract of Bathysa cuspidata attenuates extra-pulmonary acute lung injury induced by paraquat and reduces mortality in rats

This study investigated the effect of the bark extract of Bathysa cuspidata on paraquat (PQ)-induced extra-pulmonary acute lung injury (ALI) and mortality in rats. ALI was induced with a single dose of PQ (30 mg/kg, i.p.), and animals were treated with B. cuspidata extract (200 and 400 mg/kg). Analyses were conducted of survival, cell migration, lung oedema, malondialdehyde, proteins carbonyls, catalase, superoxide dismutase, histopathology and the stereology of lung tissue. Rats exposed to PQ and treated with 200 and 400 mg of the extract presented lower mortality (20% and 30%), compared with PQ alone group (50%). Furthermore, lung oedema, septal thickening, alveolar collapse, haemorrhage, cell migration, malondialdehyde and proteins carbonyl levels decreased, and catalase and superoxide dismutase activity were maintained. These results show that the bark extract of B. cuspidata reduced PQ-induced extra-pulmonary ALI and mortality in rats and suggest that these effects may be associated with the inhibition of oxidative damage.

The protective effect of C-phycocyanin on paraquat-induced acute lung injury in rats

To investigate the potential protective effect of C-phycocyanin (PC) on paraquat (PQ)-induced acute lung injury, rats were divided into control, PQ-treated and PQ+PC-treated groups. Rats in PQ-treated group were orally administered with 50mg/kg PQ, and rats in PQ+PC-treated group were intraperitoneally injected with 50mg/kg PC after administration of PQ. At 8, 24, 48 and 72h after treatments, GSH-Px and SOD activities, MDA levels in plasma and BALF, HYP, NF-κB, IκB-α and TNF-α contents in lung tissues were measured. The pathological changes in lung were observed. After treatment with PC, the levels of MDA and the relative contents of NF-κB and TNF-α were significantly decreased, the activities of GSH-Px and SOD and the relative contents of IκB-α were significantly increased. The degree of rat lung damage was obviously reduced in PQ+PC-treated group. The results suggested that PC treatment significantly attenuated PQ-induced acute lung injury.

Multidrug-resistance-associated protein plays a protective role in menadione-induced oxidative stress in endothelial cells

AIMS

Menadione, a redox-cycling quinone known to cause oxidative stress, binds to reduced glutathione (GSH) to form glutathione S-conjugate. Glutathione S-conjugates efflux is often mediated by multidrug-resistance-associated protein (MRP). We investigated the effect of a transporter inhibitor, MK571 (3-[[3-[2-(7-chloroquinolin-2-yl)vinyl]phenyl]-(2-dimethylcarbamoylethylsulfanyl)methylsulfanyl] propionic acid), on menadione-induced oxidative stress in bovine aortic endothelial cells (BAECs).

MAIN METHODS

BAECs were treated with menadione and MK571, and cell viability was measured. Modulation of intracellular GSH levels was performed with buthionine sulfoximine and GSH ethyl ester treatments. Intracellular superoxide was estimated by dihydroethidium oxidation using fluorescence microscopy or flow cytometry. Expression of MRP was determined by flow cytometry using phycoerythrin-conjugated anti-MRP monoclonal antibody.

KEY FINDINGS

Intracellular GSH depletion by buthionine sulfoximine promoted the loss of viability of BAECs exposed to menadione. Exogenous GSH, which does not permeate the cell membrane, or GSH ethyl ester protected BAECs against the loss of viability induced by menadione. The results suggest that GSH binds to menadione outside the cells as well as inside. Pretreatment of BAECs with MK571 dramatically increased intracellular levels of superoxide generated from menadione, indicating that menadione may accumulate in the intracellular milieu. Finally, we found that MK571 aggravated menadione-induced toxicity in BAECs and that MRP levels were increased in menadione-treated cells.

SIGNIFICANCE

We conclude that MRP plays a vital role in protecting BAECs against menadione-induced oxidative stress, presumably due to its ability to transport glutathione S-conjugate.

Paraquat-induced oxidative stress and dysfunction of cellular redox systems including antioxidative defense enzymes glutathione peroxidase and thioredoxin reductase

We examined if paraquat-induced oxidative stress and cytotoxicity in pulmonary microvascular endothelial cells are associated with cellular redox systems such as the glutathione system and the thioredoxin system. Loss of viability, accompanied by marked decreases in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and thioredoxin reductase activities, occurred 48 h after exposure to 1mM paraquat. These changes were preceded by an increased production of hydrogen peroxide after the decrease in glutathione peroxidase activity. Glutaredoxin activity was not decreased even after exposure to paraquat for 48 h, whereas thioredoxin activity was slightly decreased at 48 h. Unexpectedly, the activity of peroxiredoxin, a non-selenoenzyme, was almost completely lost at 24h. Loss of GAPDH activity and viability was notably aggravated by mercaptosuccinate. Selenium supplementation suppressed the loss of activities of glutathione peroxidase and thioredoxin reductase and alleviated paraquat-induced cytotoxicity. An in vitro experiment demonstrated that GAPDH was highly susceptible to reactive oxygen species generated in the xanthine-xanthine oxidase system, whereas thioredoxin reductase was considerably resistant. Taken together, the results suggest that the reduced regenerative ability of oxidatively damaged proteins including GAPDH due to the inactivation of thioredoxin reductase and glutathione peroxidase by paraquat may contribute to increasing oxidative stress, leading to cell death.

Glyphosate-induced antioxidant imbalance in HaCaT: The protective effect of Vitamins C and E

Roundup 3 plus(®), a glyphosate-based herbicide, is widely used in the ground, but its extensive use has posed a health risk in man. The aim of this study was firstly to investigate how glyphosate alone or included in Roundup 3 plus(®) affected the antioxidant defense system and lipid peroxidation of human cutaneous cells, and secondly, to evaluate the ameliorating effects of antioxidants, as Vitamin C (VitC) and Vitamin E (VitE), against Roundup 3 plus(®)-induced epidermal antioxidant impairment. Our results showed that glyphosate alone or included in Roundup 3 plus(®), induced significant changes in cellular antioxidant status as a glutathione depletion, enzymatic (catalase, glutathione-peroxidase and superoxide dismutase) disorders, and increased lipid peroxidation. VitC or VitE supplementation increased superoxide dismutase, glutathione-reductase and -peroxidase activities and reduced lipid peroxidation in Roundup 3 plus(®)-treated keratinocytes. These in vitro data indicated that VitC and VitE might have preventive effects against deleterious cutaneous cell damage caused by Roundup 3 plus(®).

Subacute pulmonary manifestation in a survivor of severe paraquat intoxication

Paraquat has been widely used as a nonselective contact herbicide since 1962. It is highly toxic for humans, and many cases of acute poisoning, especially intentional self-poisoning, have been reported over the past few decades in developing countries. Ingestion of a threshold volume results in multiple organ failure and death after a longer period of time, but aggressive clinical studies are rarely done when the diagnosis is clear. We report the case of a patient who survived severe paraquat intoxication; he presented with subacute pulmonary manifestations including physiologic dysfunction and abnormalities on radiographs.

The bipyridyl herbicide paraquat produces oxidative stress-mediated toxicity in human neuroblastoma SH-SY5Y cells: relevance to the dopaminergic pathogenesis

Paraquat (PQ) is a cationic nonselective bipyridyl herbicide widely used to control weeds and grasses in agriculture. Epidemiologic studies indicate that exposure to pesticides can be a risk factor in the incidence of Parkinson's disease (PD). A strong correlation has been reported between exposure to paraquat and PD incidence in Canada, Taiwan, and the United States. This correlation is supported by animal studies showing that paraquat produces toxicity in dopaminergic neurons of the rat and mouse brain. However, it is unclear how paraquat triggers toxicity in dopaminergic neurons. Based on the prooxidant properties of paraquat, it was hypothesized that paraquat may induce oxidative stress-mediated toxicity in dopaminergic neurons. To explore this possibility, dopaminergic SH-SY5Y cells were treated with paraquat, and several biomarkers of oxidativestress were measured. First, a specific dopamine transporter inhibitor GBR12909 significantly protected SY5Y cells against the toxicity of paraquat, indicating that paraquat exerts its toxicity by a mechanism involving the dopamine transporter (DAT). Second, paraquat increased intracellular levels of reactive oxygen species (ROS), but decreased the levels of glutathione. Third, paraquat inhibited glutathione peroxidase activity, but did not affect glutathione reductase activity. On the other hand, paraquat increased GST activity by 24 h, after which GST activity returned to the control value at 48 h. Fourth, paraquat dissipated mitochondrial transmembrane potential (MTP). Fifth, paraquat produced increases of malondialdehyde (MDA) and protein carbonyls, as well as DNA fragmentation, indicating oxidative damage to major cellular components. Sixth, paraquat increased the protein level of heme oxygenase-1 (HO-1). Taken together, these findings verify our hypothesis that paraquat produces oxidative stress-mediated toxicity in SH-SY5Y cells. Thus, current findings suggest that paraquat may induce the pathogenesis of dopaminergic neurons through oxidative stress.