The difference of glutathione antioxidant system in newly weaned and young mice liver and its involvement in isoline-induced hepatotoxicity

A short-term exposure to saxitoxin triggers a multitude of deleterious effects in Daphnia magna at levels deemed safe for human health

Harmful algal blooms and the toxins produced during these events are a human and environmental health concern worldwide. Saxitoxin and its derivatives are potent natural aquatic neurotoxins produced by certain freshwater cyanobacteria and marine algae species during these bloom events. Saxitoxins effects on human health are well studied, however its effects on aquatic biota are still largely unexplored. This work aims at evaluating the effects of a pulse acute exposure (24 h) of the model cladoceran Daphnia magna to 30 μg saxitoxin L-1, which corresponds to the safety guideline established by the World Health Organization (WHO) for these toxins in recreational freshwaters. Saxitoxin effects were assessed through a comprehensive array of biochemical (antioxidant enzymes activity and lipid peroxidation), genotoxicity (alkaline comet assay), neurotoxicity (total cholinesterases activity), behavioral (swimming patterns), physiological (feeding rate and heart rate), and epigenetic (total 5-mC DNA methylation) biomarkers. Exposure resulted in decreased feeding rate, heart rate, total cholinesterases activity and catalase activity. Contrarily, other antioxidant enzymes, namely glutathione-S-transferases and selenium-dependent Glutathione peroxidase had their activity increased, together with lipid peroxidation levels. The enhancement of the antioxidant enzymes was not sufficient to prevent oxidative damage, as underpinned by lipid peroxidation enhancement. Accordingly, average DNA damage level was significantly increased in STX-exposed daphnids. Total DNA 5-mC level was significantly decreased in exposed organisms. Results showed that even a short-term exposure to saxitoxin causes significant effects on critical molecular and cellular pathways and modulates swimming patterns in D. magna individuals. This study highlights sub-lethal effects caused by saxitoxin in D. magna, suggesting that these toxins may represent a marked challenge to their thriving even at a concentration deemed safe for humans by the WHO.

Diagnosis, toxicological mechanism, and detoxification for hepatotoxicity induced by pyrrolizidine alkaloids from herbal medicines or other plants

Pyrrolizidine alkaloids (PAs) are one type of phytotoxins distributed in various plants, including many medicinal herbs. Many organs might suffer injuries from the intake of PAs, and the liver is the most susceptible one. The diagnosis, toxicological mechanism, and detoxification of PAs-induced hepatotoxicity have been studied for several decades, which is of great significance for its prevention, diagnosis, and therapy. When the liver was exposed to PAs, liver sinusoidal endothelial cells (LSECs) loss, hemorrhage, liver parenchymal cells death, nodular regeneration, Kupffer cells activation, and fibrogenesis occurred. These pathological changes classified the PAs-induced liver injury as acute, sub-acute, and chronic type. PAs metabolic activation, mitochondria injury, glutathione (GSH) depletion, inflammation, and LSECs damage-induced activation of the coagulation system were well recognized to play critical roles in the pathological process of PAs-induced hepatotoxicity. A lot of natural compounds like glycyrrhizic acid, (-)-epicatechin, quercetin, baicalein, chlorogenic acid, and so on were demonstrated to be effective in alleviating PAs-induced liver injury, which rendered them huge potential to be developed into therapeutic drugs for PAs poisoning in clinics. This review presents updated information about the diagnosis, toxicological mechanism, and detoxification studies on PAs-induced hepatotoxicity.

Chronic Variable Stress Induces Hepatic Fe(II) Deposition by Up-Regulating ZIP14 Expression via miR-181 Family Pathway in Rats

Simple Summary

Modern intensive production methods attract accusations of poor animal welfare due to long-term exposure to stressors including high temperature, persistent humidity and overcrowding. Stress can be defined as any condition that threatens the physiological homoeostasis and hypothalamic-pituitary-adrenal (HPA) axis responses that tend to restore the prior stable status of the organism. Uncontrollable and unpredictable sources of stress can cause various forms of damage to the liver, which is the central mediator of systemic iron balance. Iron, notably, is an essential element for maintaining health in virtually all organisms. We found that chronic variable stress can cause weight loss and disorders of the liver iron metabolism in rats, thereby triggering liver oxidative damage. Our results also suggest that the miR-181 family is a potential target for treating iron overload-associated diseases.

Abstract

It is well-known that hepatic iron dysregulation, which is harmful to health, can be caused by stress. The aim of the study was to evaluate chronic variable stress (CVS) on liver damage, hepatic ferrous iron deposition and its molecular regulatory mechanism in rats. Sprague Dawley rats at seven weeks of age were randomly divided into two groups: a control group (Con) and a CVS group. CVS reduces body weight, but increases the liver-to-body weight ratio. The exposure of rats to CVS increased plasma aspartate aminotransferase (AST), alkaline phosphatase (ALP) and hepatic malondialdehyde (MDA) levels, but decreased glutathione peroxidase (GSH-Px) activity, resulting in liver damage. CVS lowered the total amount of hepatic iron content, but induced hepatic Fe(II) accumulation. CVS up-regulated the expression of transferrin receptor 1 (TFR1) and ZRT/IRT-like protein 14 (ZIP14), but down-regulated ferritin and miR-181 family members. In addition, miR-181 family expression was found to regulate ZIP14 expression in HEK-293T cells by the dual-luciferase reporter system. These results indicate that CVS results in liver damage and induces hepatic Fe(II) accumulation, which is closely associated with the up-regulation of ZIP14 expression via the miR-181 family pathway.

NMR-based metabolomics approach to study the effects of Wu-Zi-Yan-Zong-Wan on triptolide-induced oligospermia in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Wu-Zi-Yan-Zong-Wan (WZYZW) is a commonly used Chinese medicinal recipe for oligozoospermia. Oligozoospermia is a common disease that harms human fertility, there is no effective therapeutic medicine at present. However, the underlying pharmacological mechanism remains unclear.

METHODS

Oligozoospermia rats model induced by Tripterygium glycosides (TG) was established to inspect the efficiency of WZYZW in the treatment of oligozoospermia by traditional pharmacodynamics combined with NMR-based metabolomics. Multivariate statistics were used to extracted the underlying biomarkers and metabolic pathways of WZYZW in the treatment of oligozoospermia.

RESULTS

The results showed that TG disturbed many metabolites and metabolic pathways such as oxidative stress (choline, O-phosphocholine, betaine and ascorbate), energy metabolism in mitochondria (glucose, lactate, succinate, fumarate, 3-hydroxybutyrate and alanine), mitochondrial apoptosis markers (Bax and Bcl-2) and amino acids metabolisms (arginine, branched-chain amino acids, taurine and myo-inositol).

CONCLUSIONS

WZYZW could significantly reverse the disturbed metabolites to their normal status by their abilities of anti-oxidation, anti-apoptosis, balancing the osmotic pressure regulatory molecules and regulating the amino acids metabolism. This study provides pharmacological basis and guidance for the clinical usage of WZYZW.

RNA-Seq provides new insights on the relative mRNA abundance of antioxidant components during mouse liver development

Mammals have developed a variety of antioxidant systems to protect them from the oxygen environment and toxic stimuli. Little is known about the mRNA abundance of antioxidant components during postnatal development of the liver. Therefore, the purpose of this study was to compare the mRNA abundance of antioxidant components during liver development. Livers from male C57BL/6J mice were collected at 12 ages from prenatal to adulthood. The transcriptome was determined by RNA-Seq with transcript abundance estimated by Cufflinks. RNA-Seq provided a complete, more accurate, and unbiased quantification of the transcriptome. Among 33 known antioxidant components examined, three ontogeny patterns of liver antioxidant components were observed: (1) Prenatal-enriched, in which the mRNAs decreased from fetal livers to adulthood, such as metallothionein and heme oxygenase-1; (2) adolescent-rich and relatively stable expression, such as peroxiredoxins; and (3) adult-rich, in which the mRNA increased with age, such as catalase and superoxide dismutase. Alternative splicing of several antioxidant genes, such as Keap1, Glrx2, Gpx3, and Txnrd1, were also detected by RNA-Seq. In summary, RNA-Seq revealed the relative abundance of hepatic antioxidant enzymes, which are important in protecting against the deleterious effects of oxidative stress.

Age-associated changes in GSH S-transferase gene/proteins in livers of rats

OBJECTIVES

Glutathione S-transferases (GSTs) are phase-II metabolic enzymes playing important roles in drug metabolism, anti-oxidative stress and anti-aging. Age is a key factor influencing GSTs expression. Thus, age-related changes of 10 GSTs were examined.

METHODS

Livers from male Sprague-Dawley rats at fetus (-2 d), neonates (1, 7, 14 and 21 d), puberty (28 and 35 d), adulthood (60 and 180 d), and aging (540 and 800 d), were collected and subjected to qPCR analysis. Liver proteins from 14, 28, 60, 180, 540 and 800 d were also extracted for selected protein analysis by Western-blot.

RESULTS

The expression of GSTA1 and GSTP1 increased over the life span and the expression of GSTA4, GSTO1 and GSTZ1 gradually increased until adulthood, and slightly decreased at 800 days. The expression of GSTM1, GSTM3, GSTT1, GSTT2 and GSTK1 gradually increased until adulthood, but significantly decreased during aging of 540 and 800 days. There is a small peak at 7-14 d for GSTA1, GSTP1 and GSTZ1. The protein expression of GSTA1, GSTM1 and GSTP1 followed the trend of mRNA changes.

DISCUSSION

This study characterized three expression patterns of 10 GSTs during development and aging in rat liver, adding to our understanding of anti-aging role of GSTs.

Ontogeny and aging of Nrf2 pathway genes in livers of rats

The Nrf2/Keap1 antioxidant system plays important roles in protecting against oxidative stress and toxic stimuli, which may vary in infants, elderly, and females.

AIM

The constitutive expression of the Nrf2 genes during development and aging in both sexes would help our understanding of the Nrf2/Keap1 pathway in toxicological studies.

MAIN METHODS

Sprague Dawley rat livers were collected at 11 age points from prenatal (-2 d), neonatal (1, 7, 14 and 21 d), at puberty (28 and 35 d), at adulthood (60 and 180 d), to aging (540 and 800 d) from both sexes. Total RNA and proteins were extracted for real-time RT-PCR and Western-blot analysis.

KEY FINDINGS

The abundant mRNA expression was in the order of Nrf2, Gclm, Nqo1, Gclc, Ho-1, and Keap1. The expression of these genes except Gclc was high in fetal livers, decreased at birth, reached the first peak at 7 days of age, and gradually decreased to adult levels till 180 days of age. All these genes remained high at 540 days of age, but declined at 800 days of age, with more increases with Nqo1 and Ho-1. Females had lower fetal, neonatal, and aged levels than males. Protein expressions of Nrf2, Nqo1, Ho-1, GCLC and GCLM agree with mRNA analysis.

SIGNIFICANCE

This study characterized the age- and sex-related changes of Nrf2-related gene/proteins in livers of rats, and higher expressions in newborns and aged rats could cope with increased oxidative stress in infants and elderly.

Neuroprotective Effects of Four Phenylethanoid Glycosides on H₂O₂-Induced Apoptosis on PC12 Cells via the Nrf2/ARE Pathway

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor against oxidative stress and neurodegenerative disorders. Phenylethanoid glycosides (PhGs; salidroside, acteoside, isoacteoside, and echinacoside) exhibit antioxidant and neuroprotective bioactivities. This study was performed to investigate the neuroprotective effect and molecular mechanism of PhGs. PhGs pretreatment significantly suppressed H₂O₂-induced cytotoxicity in PC12 cells by triggering the nuclear translocation of Nrf2 and reversing the downregulated protein expression of heme oxygenase 1 (HO-1), NAD(P)H quinone oxidoreductase 1 (NQO1), glutamate cysteine ligase-catalytic subunit (GCLC), and glutamate-cysteine ligase modifier subunit (GCLM). Nrf2 siRNA or HO-1 inhibitor zinc protoporphyrin (ZnPP) reduced the neuroprotective effect. PhGs showed potential interaction with the Nrf2 binding site in Kelch-like ECH-association protein 1 (Keap1). This result may support the hypothesis that PhGs are activators of Nrf2. We demonstrated the potential binding between PhGs and the Keap1-activated Nrf2/ARE pathway, and that PhGs with more glycosides had enhanced effects.

Caffeic acid prevents acetaminophen-induced liver injury by activating the Keap1-Nrf2 antioxidative defense system

Acute liver failure induced by acetaminophen (APAP) overdose is the main cause of drug-induced liver injury (DILI). Caffeic acid (CA) is a phenolic compound from many natural products. This study aims to investigate the protective mechanism of CA in APAP-induced liver injury. The results of serum alanine/aspartate aminotransferases (ALT/AST), liver myeloperoxidase (MPO) activity, liver glutathione (GSH) and reactive oxygen species (ROS) levels demonstrated the protection of CA against APAP-induced liver injury. Liver histological observation provided further evidences of CA-induced protection. CA was found to reverse the APAP-induced decreased cell viability in human normal liver L-02 cells and HepG2 cells. CA also reduced the increased cellular ROS level induced by APAP in hepatocytes. The results of luciferase assay and Western-blot analysis showed that CA increased the transcriptional activation of nuclear factor erythroid 2-related factor 2 (Nrf2) in the presence of APAP. Nrf2 siRNA reduced the protection of CA against APAP-induced hepatotoxicity. CA also reversed the APAP-induced decreased mRNA and protein expression of heme oxygenase 1 (HO-1) and

NAD(P)H

quinone oxidoreductase 1(NQO1). In addition, HO-1 inhibitor zinc protoporphyrin (ZnPP) and NQO1 inhibitor diminutol (Dim) reduced the protection of CA against APAP-induced hepatotoxicity. CA also decreased the expression of kelch-like ECH-associated protein-1(Keap1). Molecular docking indicated the potential interacting of CA with Nrf2 binding site in the Keap1 protein. CA had little effect on the enzymatic activity of cytochrome P450 (CYP) 3A4 and CYP2E1 in vitro. In conclusion, we demonstrated that CA prevented APAP-induced hepatotoxicity by decreasing Keap1 expression, inhibiting binding of Keap1 to Nrf2, and thus activating Nrf2 and leading to increased expression of antioxidative signals including HO-1 and NQO1.

Therapeutic detoxification of quercetin against carbon tetrachloride-induced acute liver injury in mice and its mechanism

This study observes the therapeutic detoxification of quercetin, a well-known flavonoid, against carbon tetrachloride (CCl4) induced acute liver injury in vivo and explores its mechanism. Quercetin decreased CCl4-increased serum activities of alanine and aspartate aminotransferases (ALT/AST) when orally taken 30 min after CCl4 intoxication. The results of a histological evaluation further evidenced the ability of quercetin to protect against CCl4-induced liver injury. Quercetin decreased the CCl4-increased malondialdehyde (MDA) and reduced the glutathione (GSH) amounts in the liver. It also reduced the enhanced immunohistochemical staining of the 4-hydroxynonenal (4-HNE) in the liver induced by CCl4. Peroxiredoxin (Prx) 1, 2, 3, 5, 6, thioredoxin reductase 1 and 2 (TrxR1/2), thioredoxin 1 and 2 (Trx1/2), nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) all play critical roles in maintaining cellular redox homeostasis. Real-time polymerase chain reaction (PCR) results demonstrated that quercetin reversed the decreased mRNA expression of all those genes induced by CCl4. In conclusion, our results demonstrate that quercetin ameliorates CCl4-induced acute liver injury in vivo via alleviating oxidative stress injuries when orally taken after CCl4 intoxication. This protection may be caused by the elevation of the antioxidant capacity induced by quercetin.

Scutellarin protects against the liver injury induced by diosbulbin B in mice and its mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Diosbulbin B (DB) is the main hepatotoxic compound distributed in Dioscorea bulbifera L., which is widely used for the treatment of cancer and thyroid disorders in Asia. Scutellarin (SC) is the main compound in medicinal herb Scutellaria barbata D. Don, which is usually combined with Dioscorea bulbifera used for cancer therapy in clinic.

AIM OF THE STUDY

This study aims to investigate the protection of SC against the liver injury induced by DB and its engaged mechanism. In addition, the anti-tumor effect of DB and SC is further observed in vivo.

MATERIALS AND METHODS

The protection of SC against DB-induced liver injury was evaluated by detecting serum alanine/aspartate aminotransferases (ALT/AST) and alkaline phosphatase (ALP) activities, and further liver histological observation. The inflammatory response was assessed by detecting liver myeloperoxidase (MPO) activity, and serum levels of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and interferon-γ (IFN-γ). Western-blot analysis was used to detect the protein expression. The oxidative liver injury was evaluated by detecting liver malondialdehyde (MDA) and glutathione (GSH) contents, and glutathione peroxidase (GPx) enzymatic activity. In vivo anti-tumor activity was analyzed in S180 tumor-bearing mice.

RESULTS

SC significantly decreased the increased serum ALT/AST, and ALP activities induced by DB. Liver histological observation evidenced the protection of SC against DB-induced liver injury. SC obviously reduced the increased liver MPO activity and the number of MPO-positive staining cells induced by DB. SC also reversed the decreased expression of inhibitor of κB (IκB) and the translocation of nuclear factor κB (NF-κB) p65 from cytoplasm to nucleus induced by DB. In addition, SC significantly abrogated the increased serum levels of TNF-α, IL-6, and IFN-γ induced by DB. SC decreased the increased liver MDA content induced by DB significantly, and it also increased liver GSH level. The decreased GPx protein expression and its enzymatic activity induced by DB were both obviously reversed after SC treatment. The results in S180 tumor-bearing mice showed that SC combined with DB significantly inhibited tumor growth in vivo.

CONCLUSIONS

Our results demonstrate that SC prevents DB-induced liver injury by attenuating NF-κB-mediated hepatic inflammation and ameliorating liver oxidative stress injury. Meanwhile, DB plus SC has significant anti-tumor activity in vivo. This study indicates the potential combination of DB with SC for the treatment of cancer in clinic.

Quercetin ameliorates liver injury induced with Tripterygium glycosides by reducing oxidative stress and inflammation

Quercetin (Que) is one of main compounds in Lysimachia christinae Hance (Christina loosestrife), and has both medicinal and nutritional value. Glycosides from Tripterygium wilfordii Hook.f. (léi gōng téng [the thunder duke vine]; TG) have diverse and broad bioactivities but with a high incidence of liver injury. Our previous study reported on the hepatoprotective properties of an ethanol extract from L. christinae against TG-induced liver injury in mice. This research is designed to observe, for the first time, the possible protective properties of the compound Que against TG-induced liver injury, and the underlying mechanisms that are involved in oxidative stress and anti-inflammation. The results indicated that TG caused excessive elevation in serum levels of alanine/aspartate transaminase (ALT/AST), alkaline phosphatase (ALP), gamma glutamyl transferase (γ-GT), and pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α), as well as hepatic lipid peroxidation (all P < 0.01). On the other hand, following TG exposure, we observed significantly reduced levels of biomarkers, including hepatic glutathione (GSH), glutathione-S-transferase (GST), glutathione peroxidase (GPx), and the anti-inflammatory cytokine interleukin (IL)-10, as well as the enzyme activity and mRNA expression of copper- and zinc-containing superoxide dismutase (CuZn-SOD) and catalase (CAT) (all P < 0.01). Nevertheless, all of these alterations were reversed by the pre-administration of Que or the drug bifendate (positive control) for 7 consecutive days. Therefore, this study suggests that Que ameliorates TG-induced acute liver injury, probably through its ability to reduce oxidative stress and its anti-inflammatory properties.

Geniposide protects against acute alcohol-induced liver injury in mice via up-regulating the expression of the main antioxidant enzymes

Geniposide (GP) is one of main compounds in Gardenia jasminoides Ellis, with both medicinal and nutritional value. This study was designed to determine, for the first time, how GP from G. jasminoides protects against acute alcohol-induced liver injury, and the underlying mechanisms. Mice were orally administered alcohol (6.0 g/kg body mass) 2 h after intragastric administration of GP and bifendate, every day for 7 continuous days. Six hours after the alcohol was administered, levels of serum alanine/aspartate transaminase (ALT/AST), hepatic lipid peroxidation (LPO), glutathione (GSH), glutathione-S-transferase (GST), glutathione peroxidase (GPx), copper- and zinc-containing superoxide dismutase (CuZn-SOD), and catalase (CAT), and mRNA expression of CuZn-SOD and CAT were assayed. The results demonstrated that GP (20.0, 40.0, or 80 mg/kg) significantly reversed the excessive, alcohol-induced elevation in both serum ALT/AST and hepatic LPO levels. Moreover, hepatic GSH, GST, GPx, CuZn-SOD, and CAT levels were all decreased in the alcohol-treated mice, whereas treatment with GP reversed these decreases. Further analysis indicated that hepatic mRNA expression of CuZn-SOD and CAT in the alcohol-treated mice was significantly down-regulated, whereas GP up-regulated such decreases. Taken together, this study shows that GP protects against acute alcohol-induced liver injury via up-regulating the expression of the main antioxidant enzymes, and thus ameliorates alcohol-induced oxidative stress injury in the liver.

Quercetin prevents pyrrolizidine alkaloid clivorine-induced liver injury in mice by elevating body defense capacity

Quercetin is a plant-derived flavonoid that is widely distributed in nature. The present study is designed to analyze the underlying mechanism in the protection of quercetin against pyrrolizidine alkaloid clivorine-induced acute liver injury in vivo. Serum transaminases, total bilirubin analysis, and liver histological evaluation demonstrated the protection of quercetin against clivorine-induced liver injury. Terminal dUTP nick end-labeling assay demonstrated that quercetin reduced the increased amount of liver apoptotic cells induced by clivorine. Western-blot analysis of caspase-3 showed that quercetin inhibited the cleaved activation of caspase-3 induced by clivorine. Results also showed that quercetin reduced the increase in liver glutathione and lipid peroxidative product malondialdehyde induced by clivorine. Quercetin reduced the enhanced liver immunohistochemical staining for 4-hydroxynonenal induced by clivorine. Results of the Mouse Stress and Toxicity PathwayFinder RT² Profiler PCR Array demonstrated that the expression of genes related with oxidative or metabolic stress and heat shock was obviously altered after quercetin treatment. Some of the alterations were confirmed by real-time PCR. Our results demonstrated that quercetin prevents clivorine-induced acute liver injury in vivo by inhibiting apoptotic cell death and ameliorating oxidative stress injury. This protection may be caused by the elevation of the body defense capacity induced by quercetin.

The age-related change of glutathione antioxidant system in mice liver

Cellular glutathione (GSH) antioxidant system is an important defensive system of the body, which is crucial in the protection against oxidative stress-induced liver injury. The present study was designed to observe the difference of this system in the liver of mice with 1-month- and 12-month-old. Liver reduced GSH level was showed no difference between these two groups of mice. Next, the results showed that liver glutamate-cysteine ligase (GCL) activity was higher in mice of 1-month- than 12-month-old, while glutathione-S-transferase (GST) activity was higher in mice of 12-month- than 1-month-old. Further results showed that the higher activity of liver GCL in 1-month-old mice was due to the higher expression of catalytic subunit of GCL (GCLc) mRNA, while the higher activity of liver GST in 12-month-old mice might be due to the higher expression of GSTA1, GSTA2, GSTP1 and GSTP2 mRNA. Taken together, our results revealed the age-related change of liver GSH antioxidant system in mice, which may be helpful for elucidating some age-related liver injury or diseases.

Dietary flavonoid genistein induces Nrf2 and phase II detoxification gene expression via ERKs and PKC pathways and protects against oxidative stress in Caco-2 cells

SCOPE

Flavonoids have well-known antioxidant, anti-inflammatory, and anti-cancer activities. Isoflavone genistein is considered a potent antioxidant agent against oxidative stress. Although several mechanisms have been proposed, a clear antioxidant mechanism of genistein is still remained to be answered.

METHODS AND RESULTS

In this study, we focused on the concerted effects on expression of Nrf2 and phase II enzyme pathway components. Transient transfection assays, RT-PCR and immunoblot analysis were performed to study its molecular mechanisms of action. In Caco-2 cells, treatment with genistein markedly attenuated H(2)O(2) -induced peroxide formation; this amelioration was reversed by buthionine sulfoximine(GCLC inhibitor) and zinc protoporphyrin(HO-1 inhibitor). Genistein increased HO-1 and GCLC mRNA and protein expression. Genistein treatment activated the ERK1/2 and PKC signaling pathway; therefore increased Nrf2 mRNA and protein expression. The roles of the ERK1/2 and PKC signaling pathway were determined using PD98059 (ERK1/2 inhibitor) and GF109203X (PKC inhibitor) and RNA interference directed against Nrf2. Both inhibitors and siNrf2 abolished genistein-induced HO-1 and GCLC protein expression. These results suggest the involvement of ERK1/2, PKC, and Nrf2 in inducing HO-1 and GCLC by genistein.

CONCLUSION

Our studies show that genistein up-regulated HO-1 and GCLC expression through the EKR1/2 and PKC /Nrf2 pathways during oxidative stress.

Resveratrol attenuates hepatotoxicity of rats exposed to arsenic trioxide

Arsenic trioxide (As(2)O(3)) is an environmental pollutant and potent toxicant to humans. However, it also shows substantial anti-cancer activity in individuals with acute promyelocytic leukemia (APL). Unfortunately, As(2)O(3)-treated leukemia patients suffer hepatotoxicity. Resveratrol has been demonstrated to have efficient antioxidant and antineoplastic activities. The study that how As(2)O(3) in combination with resveratrol affects hepatotoxicity and arsenic accumulation in the liver is lacking, and the present study tackles this question. Wistar rats were injected with 3mg/kg As(2)O(3) on alternate days; resveratrol (8mg/kg) was administered 1h before As(2)O(3). Rats were killed on the 8th day to determine histological liver damage, the antioxidant enzymes in serum, the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG), and arsenic accumulation in the liver. In the resveratrol+As(2)O(3) group, activities of superoxide dismutase, catalase in serum and GSH/GSSG were significantly increased, histopathological effects were reduced, and arsenic accumulation markedly decreased in the liver, compared with the As(2)O(3)-treated group. Thus, resveratrol attenuated As(2)O(3)-induced hepatotoxicity by decreasing oxidative stress and arsenic accumulation in the liver. These data suggest that use of resveratrol as post-remission therapy of APL and adjunctive therapy in patients with chronic exposure to arsenic may decrease arsenic hepatotoxicity.