Nrf2-ARE Pathway Research Articles

Enriched environment improves post-stroke cognitive impairment and inhibits neuroinflammation and oxidative stress by activating Nrf2-ARE pathway

Introduction Neuroinflammation and oxidative stress are major mechanisms of post-stroke cognitive impairment (PSCI) neural injury and decreased spatial and memory capacity. Enriched environment (EE) is an effective method to improve cognitive dysfunction. However, the regulation by EE of neuroinflammation, oxidative stress and associated mechanisms in animal models remains unclear. Materials and methods In this study, a rat PSCI model was established by middle cerebral artery occlusion (MCAO). Rats were randomly divided into the control group, standard environment (SE) group and EE group for 28 days. A Morris water-maze test was used to measure cognitive function at 7, 14 and 28 days after MCAO. Rats were sacrificed on the 28th day. Quantitative PCR, immunohistochemistry and ELISA were respectively used to detect mRNA expression of NF-E2-related factor 2 (Nrf2) and Nrf2 response genes, the expression of IL-1β and levels of proinflammatory cytokines in the hippocampus. Results EE improved mNSS scores and cognitive ability in PSCI rats. EE increased mRNA expression of the Nrf2 and Nrf2 response genes, including heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1). EE significantly decreased the level of malondialdehyde (MDA) and increased the levels of superoxide dismutase (SOD) and glutathione (GSH), in the hippocampus of PSCI rats. EE reduced the number of IL-1β positive cells in the hippocampus, and IL-1β levels in the hippocampus and serum. EE increased GFAP-positive astrocytes in the hippocampus, and BDNF levels in the hippocampus and serum. Conclusions EE can improve cognitive function in PSCI rats by inhibiting neuroinflammation and oxidative stress.

Agarwood Alcohol Extract Ameliorates Isoproterenol-Induced Myocardial Ischemia by Inhibiting Oxidation and Apoptosis.

Agarwood is a traditional medicine used for treating some diseases, including painful and ischemic diseases. This study was carried out to investigate the potential cardioprotective effect of the whole-tree agarwood-inducing technique-produced agarwood alcohol extract (WTAAE) on isoproterenol- (ISO-) induced myocardial ischemia (MI) in rats and explore the underlying molecular mechanisms. Compared to the MI group, WTAAE pretreatment significantly improved ST wave abnormal-elevation, mitigated myocardial histological damage; decreased creatinine kinase (CK), lactate dehydrogenase (LDH), alanine transaminase (ALT), and aspartate transaminase (AST) levels; reduced hydrogen peroxide (H2O2) and lipid peroxide (LPO) production; and increased total antioxidant capacity (T-AOC) and catalase (CAT) activities. Moreover, agarwood alcohol extracts (AAEs) markedly enhanced the mRNA levels of Nrf2-ARE pathway, and Bcl-2 reduced the apoptotic Bax family mRNA expressions. In addition, the effect of WTAAE was greater than that of wild agarwood alcohol extract (WAAE) and burning-chisel-drilling agarwood alcohol extract (FBAAE). All of these data indicate that WTAAE exerted the protective effects of MI, and its mechanism was associated with upregulating Nrf2-ARE and suppressing Bcl-2 pathways.

USP9X prevents AGEs-induced upregulation of FN and TGF-β1 through activating Nrf2-ARE pathway in rat glomerular mesangial cells

Oxidative stress is a key pathological factor for diabetic renal fibrosis by activating TGF-β/Smad pathway in glomerular mesangial cells (GMCs) to promote the synthesis of extracellular matrix such as fibronectin (FN). Nuclear factor-E2-related factor (Nrf2)- anti-oxidant response element (ARE) anti-oxidative pathway has crucial renoprotective effects, and inhibiting ubiquitin-mediated degradation of Nrf2 delays diabetic renal fibrosis development. Ubiquitin-specific protease 9X (USP9X) has close relationship with oxidative stress and TGF-β/Smad pathway, but whether it regulate diabetic renal fibrosis remains unclarified. Here, we found that advanced glycation-end products (AGEs) dose- and time-dependently reduced the protein expression and deubiquitinase activity of USP9X in GMCs. USP9X overexpression attenuated AGEs-induced upregulation of FN, TGF-β1, and Collagen Ⅳ, three fibrosis-related marker proteins, in a deubiquitinase activity-dependent manner. While USP9X depletion with siRNAs further promoted the expressions of those proteins in AGEs-treated GMCs. Under AGEs treatment conditions, USP9X overexpression markedly increased the total and nuclear levels, ARE-binding ability, and transcriptional activity of Nrf2, upregulated the protein expressions of Nrf2 downstream genes HO-1 and NQO1, and eventually reduced the excessive production of ROS. Overexpression of the deubiquitinase catalytically inactive USP9X–C1556S mutant failed to exert such effects. Silencing Nrf2 abolished the renoprotective effects of USP9X. Further study showed that upon AGEs stimulation, Nrf2 transferred into the nucleus and the interaction between USP9X and Nrf2 was weakened. AGEs also increased Nrf2 ubiquitination level, and overexpression of USP9X, instead of USP9X–C1556S, significantly reduced the ubiquitination level of Nrf2. Taken together, USP9X reduced Nrf2 ubiquitination level and promoted Nrf2-ARE pathway activation to prevent the accumulation of extracellular matrix, eventually alleviated the pathological process of diabetic renal fibrosis.

Effect of Polydatin on Neurological Function and the Nrf2 Pathway during Intracerebral Hemorrhage.

This study investigates the effect of polydatin on the neurological function of cerebral hemorrhage rats and on the Nrf2 pathway of the endogenous antioxidant system in tissues around cerebral hematoma. Further, the study also aims to provide solid insights for clinical diagnosis and treatment. A total of 54 SPF grade male Wistar rats were divided into three groups: the sham group, model group, and polydatin group. Various parameters such as neurological deficit score, brain water content, pathological morphology, oxidative stress index content, Nrf2, NQO1, HO-1 mRNA expression, and the expression of HO-1, Nrf2, and kelch-like epichlorohydrin-1 (Keap1) protein were observed. Compared with the sham group, the mNSS score and brain water content of rats in the model group increased significantly after dosing (P < 0.05). When compared with the model group, the mNSS score and brain water content of rats in the polydatin group decreased significantly after dosing (P < 0.05). Compared with the other group, the serum NSE content of rats in the polydatin group decreased (P < 0.05). An increase was observed in the contents of NO, SOD, MDA, GSSG, and GSH in the brain tissue of rats in the model group when compared with the sham group. Compared with the model group, the contents of NO and MDA in the brain tissue of rats in the polydatin group decreased, while the contents of SOD, GSSG, and GSH increased (P < 0.05). The relative expressions of Nrf2, NQO1, and HO-1mRNA in the brain tissue of rats in the polydatin group was relatively high compared with both groups (P < 0.05). Polydatin can improve the neurological function of ICH rats and reduce the oxidative stress response by regulating the Nrf2-ARE pathway and downstream gene expression. This study preliminarily discussed the relevant mechanism of polydatin in the treatment of ICH rats, thus providing a theoretical reference to ICH treatment.

Autophagy inducer activates Nrf2-ARE pathway to attenuate aberrant alveolarization in neonatal rats with bronchopulmonary dysplasia

AimsBronchopulmonary dysplasia (BPD) is a severe respiratory complication in preterm infants. This study reveals the molecular mechanism of autophagic agonists regulating the Nrf2-ARE pathway via p62 to improve alveolar development in BPD rats. Main methodsNewborn Sprague-Dawley rats were randomly exposed to a hyperoxic environment (FiO2 = 0.85) for 14 days and rapamycin (RAPA) was intraperitoneally injected on alternate days into hyperoxia-exposed mice. Alveolar development was assessed using HE and RAC values. Markers associated with the p62-Keap1-Nrf2-ARE pathway were detected by western blot, immunohistochemistry, and RT-PCR. Co-localization of proteins was determined using double immunofluorescence staining. Key findingsAt the levels of lung tissue and primary type II alveolar epithelial cells, the enhanced binding between phosphorylated p62 and Keap1 disrupted the nuclear transport of Nrf2. The activated Nrf2 was insufficient to reverse alveolar simplification. The autophagy agonist was able to inhibit p62 phosphorylation, promote Keap1 degradation, increase Nrf2 nuclear transport, augment downstream antioxidant enzyme expression, and enhance antioxidant capacity, thereby improving the simplification of alveolar structure in BPD rats. SignificanceThe use of autophagy agonists to enhance the Nrf2-ARE pathway activity and promote alveolar development could be a novel target in antioxidant therapy for BPD.

Combined Peptide and Small-Molecule Approach toward Nonacidic THIQ Inhibitors of the KEAP1/NRF2 Interaction.

The NRF2-ARE pathway is an intrinsic mechanism of defense against oxidative stress. Inhibition of the interaction between NRF2 and its main negative regulator KEAP1 is an attractive strategy toward neuroprotective agents. We report here the identification of nonacidic tetrahydroisoquinolines (THIQs) that inhibit the KEAP1/NRF2 protein-protein interaction. Peptide SAR at one residue is utilized as a tool to probe structural changes within a specific pocket of the KEAP1 binding site. We used structural information from peptide screening at the P2 pocket, noncovalent small-molecules inhibitors, and the outcome from an explorative SAR at position 5 of THIQs to identify a series of neutral THIQ analogs that bind to KEAP1 in the low micromolar range. These analogs establish new H-bond interactions at the P3 and P2 pockets allowing the replacement of the carboxylic acid functionality by a neutral primary carboxamide. X-ray crystallographic studies reveal the novel binding mode of these molecules to KEAP1.

Regulation of antioxidant systems in response to anoxia and reoxygenation in Rana sylvatica.

The wood frog (Rana sylvatica) is a remarkable species. These frogs can endure prolonged oxygen deprivation as well as dehydration to ~60% of total body water lost and, combining these two abilities, they survive whole body freezing for weeks at a time during the winter. Episodes of anoxia/reoxygenation or freeze/thaw can trigger elevated production of reactive oxygen species (ROS) causing cellular damage, especially when oxygen is reintroduced during reoxygenation or thawing. To mitigate ROS damage, stress-responsive transcription factors such as the Octamer Binding Transcription factor (OCT4) and Nuclear factor (erythroid-derived 2)-like 2 transcription factor (Nrf2) were postulated to be involved in enhancing pro-survival pathways and antioxidant defenses. The present study used immunoblotting to analyze OCT4 and Nrf2 responses (and downstream factors under their control) to 24h anoxia and 4h reoxygenation in liver and skeletal muscle of wood frogs, with an emphasis on antioxidant systems. Surprisingly, no change was observed in relative total protein expression of either of the two transcription factors in liver. Furthermore, a significant decrease in total protein levels of OCT4 and Nrf2 occurred in skeletal muscle after 4h recovery. However, essential cofactors of OCT4 and Nrf2 were significantly upregulated during anoxia and/or recovery. Downstream targets of the Nrf2-ARE pathway were evaluated, including glutathione-S-transferases (GSTs) and aldo-keto reductases (AKRs). Significant increases in GSTT1 and GSTP1 were observed in liver and muscle whereas AKRs showed a tissue specific response to both anoxia and recovery from anoxia. This study demonstrates activation of antioxidants as a cell protective mechanism against generation of reactive oxygen species during anoxia in wood frogs.

Rice protein stimulates endogenous antioxidant response attributed to methionine availability in growing rats.

Methionine sulfoxide reductase (Msr) and glutathione (GSH) are two endogenous antioxidant systems for depressing oxidative stress. The aim of this study is to investigate the role of methionine in involving the stimulation of endogenous antioxidant capacity of rice protein (RP). Seven-week-old male Wistar rats (body weight 180-200g) were fed with commercial pellets (as control), methionine, and RP for 2 weeks. Compared with control, GSH synthesis and expressions of MsrA, MsrB2, and MsrB3 were stimulated by methionine and RP. After 2 weeks of feeding, Nrf2 was activated by RP and methionine, whereas the expressions of Keap1 and Cul3 were depressed. The ARE-driven antioxidant expressions (GCLC, GCLM, GS, HO-1, NQO1, CAT, SOD, GR, GST, GPx) were upregulated by methionine and RP. Results suggest that the endogenous antioxidant response induced by RP is primarily attributed to the methionine availability, in which the stimulation of Msr and GSH antioxidant system via Nrf2-ARE pathway. PRACTICAL APPLICATIONS: Rice protein is a major plant protein, which is rich in sulfur-containing amino acids and widely consumed in the world. This paper emphasizes that the amino acid plays a key role in inducing the antioxidant activity of rice protein. The present study provides an insight that the methionine availability of rice protein will be a useful target for health promoting by activating endogenous antioxidant response against ROS-induced oxidative damage.

Methionine augments endogenous antioxidant capacity of rice protein through stimulating MSR antioxidant system and activating Nrf2-ARE pathway in growing and adult rats

To elucidate the influence of methionine on the endogenous antioxidant activity of rice protein (RP), growing and adult rats were fed with RP and methionine-supplemented RP (RM). After 2 weeks feeding, hepatic contents of ROS were significantly reduced by RP and RM. The endogenous antioxidant responses were induced by RP and increased by RM, in which methionine sulfoxide reductases (MsrA, MsrB2, MsrB3) expression and glutathione synthesis were uniformly stimulated and up-regulated with increasing consumption of methionine. With the intake of RP and RM, Nrf2 was activated through depressing Keap1 and Cul3, resulting in the up-regulation of antioxidant-responsive element (ARE)-driven antioxidant expressions (GCLC, GCLM, CAT, SOD, HO-1, NQO1) with increasing dietary level of methionine. The present study demonstrates that methionine can augment the endogenous antioxidant activity of rice protein, which is primarily attributed to stimulating methionine sulfoxide reductases expression and enhancing glutathione synthesis via Nrf2-ARE pathway. Results suggest that the methionine availability might play a key role in inducing and augmenting the endogenous antioxidant response exerted by rice protein, which is independent of age.

Quercetin protects the buffalo rat liver (BRL-3A) cells from aflatoxin B1-induced cytotoxicity via activation of Nrf2-ARE pathway

Aflatoxin B1 (AFB1) is the most toxic mycotoxin widely presented in agricultural products, and the protective effect of quercetin (QUE), a natural antioxidant, against AFB1-induced cytotoxicity to the buffalo rat liver (BRL-3A) cells was investigated. With an IC50 of 23 μM, AFB1 induced a significant oxidative stress to BRL-3A cells evidenced by a dose-dependent reduction of mitochondria membrane potential (MMP), ATP content, and activities of endogenous antioxidant enzymes along with increased levels of reactive oxygen species (ROS) and lipid peroxidation biomarker of malondialdehyde (MDA). The activity of CYP1A2, the key enzyme to convert AFB1 to reactive AFB1 exo-8,9- epoxide, was also increased, which, probably in together with ROS, led to cell apoptosis with DNA fragmentation, chromatin condensation and increased lactate dehydrogenase release. After the BRL cells were pre-treated by low level QUE (2.5 and/or 5 μM) for 24 h and then exposed to AFB1, the activities of antioxidant enzymes including haeme oxygenase-1, glutathione S-transferase, superoxide dismutase, and the ratio of reduced to oxidised glutathione were significantly increased whereas the levels of intracellular ROS and MDA were reduced. The QUE pre-treatment also increased the levels of MMP, ATP and DNA integrity, and reduced the expression of apoptosis related genes ofBax andCaspase-3. The Western blotting study revealed increased content of phosphorylated Akt and nuclear NF-E2-related factor 2 (Nrf2), indicating an activation of Nrf2-ARE pathway in counteracting oxidative stress and cytotoxicity of AFB1. Thus, the QUE pre-treatment enhanced the anti-stress capacity of the cells through the activation of the Nrf2-ARE pathway, and QUE-based measures could be developed to ameliorate the toxicity caused by AFB1.

Gut microbial fatty acid metabolites (KetoA and KetoC) affect the progression of nonalcoholic steatohepatitis and reverse cholesterol transport metabolism in mouse model.

Nonalcoholic steatohepatitis (NASH) is a common liver disease that occurs in both alcoholics and nonalcoholics. Oxidative stress is a possible causative factor for liver diseases including NASH. Gut microorganisms, especially lactic acid bacteria, can produce unique fatty acids, including hydroxy, oxo, conjugated, and partially saturated fatty acids. The oxo fatty acid 10-oxo-11(E)-octadecenoic acid (KetoC) provides potent cytoprotective effects against oxidative stress through activation of Nrf2-ARE pathway. The aim of this study was to explore the preventive and therapeutic effects of gut microbial fatty acid metabolites in a NASH mouse model. The mice were divided into 3 experimental groups and fed as follows: (1) high-fat diet (HFD) (2) HFD mixed with 0.1% KetoA (10-oxo-12(Z)-octadecenoic acid), and (3) HFD mixed with 0.1% KetoC. After 3 weeks of feeding, plasma parameters, liver histology, and mRNA expression of multiple genes were assessed. There was hardly any difference in fat accumulation in the histological study; however, no ballooning occurred in 2/5 mice of KetoC group. Bridging fibrosis was not observed in the KetoA group, although KetoA administration did not significantly suppress fibrosis score (p = 0.10). In addition, KetoC increased the expression level of HDL related genes and HDL cholesterol levels in the plasma. These results indicated that KetoA and KetoC may partly affect the progression of NASH in mice models.

Sodium aescinate provides neuroprotection in experimental traumatic brain injury via the Nrf2-ARE pathway

Sodium aescinate (SA), a natural plant extract, has been proven to provide neuroprotection in neurological diseases. However, its role and the underlying pathophysiological mechanisms in traumatic brain injury (TBI) are still not well understood. The present study was aimed to investigate the protective effects of SA in both in vivo and in vitro TBI models. Mice or neurons were randomly divided into control, TBI, TBI + vehicle and TBI + SA groups. Neurologic severity score (NSS) was used to evaluate the neurological impairment. Brain water content and lesion volume were used to assess the brain injury degree. Malondialdehyde (MDA) and glutathione peroxidase (GPx) levels were used to estimate oxidative stress. Western blot was used to determine the protein levels. Nissl and terminal deoxynucleotidyl transferase-mediated dUTP nick 3’-end labeling (TUNEL) staining were used to measure cell death and apoptosis. Our results revealed that treatment of SA could improve neurological function, decrease cerebral edema and attenuate brain lesion after TBI. Furthermore, administration of SA suppressed TBI-induced oxidative stress, neuron cell death and apoptosis. In addition, SA activated the nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway after TBI. However, SA failed to provide neuroprotection following TBI in Nrf2−/− mice. Taken together, our results provided the first evidence that SA treatment played a key role in neuroprotection after TBI through the Nrf2-ARE pathway.

Farrerol Directly Targets GSK-3β to Activate Nrf2-ARE Pathway and Protect EA.hy926 Cells against Oxidative Stress-Induced Injuries.

Oxidative stress-mediated endothelial injury is considered to be involved in the pathogenesis of various cardiovascular diseases. Farrerol, a typical natural flavanone from the medicinal plant Rhododendron dauricum L., has been reported to show protective effects against oxidative stress-induced endothelial injuries in our previous study. However, its action molecular mechanisms and targets are still unclear. In the present study, we determined whether farrerol can interact with glycogen synthase kinase 3β- (GSK-3β-) nuclear factor erythroid 2-related factor 2- (Nrf2-) antioxidant response element (ARE) signaling, which is critical in defense against oxidative stress. Our results demonstrated that farrerol could specifically target Nrf2 negative regulator GSK-3β and inhibit its kinase activity. Mechanistic studies proved that farrerol could induce an inhibitory phosphorylation of GSK-3β at Ser9 without affecting the expression level of total GSK-3β protein and promote the nuclear translocation of Nrf2 as well as the mRNA and protein expression of its downstream target genes heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1) in EA.hy926 cells. Further studies performed with GSK-3β siRNA and specific inhibitor lithium chloride (LiCl) confirmed that GSK-3β inhibition was involved in farrerol-mediated endothelial protection and Nrf2 signaling activation. Moreover, molecular docking and molecular dynamics studies revealed that farrerol could bind to the ATP pocket of GSK-3β, which is consistent with the ATP-competitive kinetic behavior. Collectively, our results firstly demonstrate that farrerol could attenuate endothelial oxidative stress by specifically targeting GSK-3β and further activating the Nrf2-ARE signaling pathway.

Florfenicol induces oxidative stress and hepatocyte apoptosis in broilers via Nrf2 pathway.

In order to explore the mechanism of liver injury induced by florfenicol (FFC) in broilers, one hundred and twenty broilers were randomly divided into six groups, twenty broilers in each group. Except for control group, the other five groups were given different doses of FFC (0.15g/L, 0.3g/L, 0.6g/L, 1.2g/L and 1.8g/L) in drinking water. After five days of continuous use, blood was collected from the subpterional vein and the chickens' liver were obtained. Chicken weight gain and liver indices were calculated; blood routine analysis was performed; the oxidative stress and apoptosis of hepatocytes was detected. The results showed that compared with the control group, except for 0.15g/L FFC, the other doses of FFC significantly decreased the weight gain, white blood cell (WBC) and platelet (PLT) contents in blood, 0.3g/mL FFC and 1.8g/L FFC significantly reduced the content of hemoglobin (RGB) (P<0.05); all doses of FFC significant decreased red blood cell (RBC) increased Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) contents in serum of chickens (P<0.05), and significantly decreased the contents of albumin (ALB) and total protein (TP) in serum (P<0.05), but had no significant effect on alkaline phosphatase (ALP) contents(P>0.05). FFC significantly increased malondialdehyde (MDA) content in serum and liver tissues, but decreased glutathione (GSH), Superoxide dismutase (SOD) and catalase (CAT) content (P<0.05), and significantly inhibited the mRNA transcription and protein expression of antioxidant proteins nuclear factor-erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and NAD(P)H dehydrogenase quinone-1 (NQO-1)(P<0.05). FFC also inhibited the content and the transcription level of cytochrome P4501A1(CYP1A1) and CYP2H1 in liver (P<0.05). At the same time, FFC significantly promoted the apoptotic rate of hepatocytes and the mRNA transcription and protein expression of caspase-3 and caspase-6 (P<0.05). With the increase of FFC concentration, liver injury became more and more serious, which affected liver function in chickens by inhibiting enzyme activity in Nrf2-ARE pathway to increase oxidative stress and promoting apoptotic protein expression to accelerate hepatocyte apoptosis.

Protective Effect of 2',3'-Dihydroxy-4',6'-dimethoxychalcone on Glutamate-Induced Neurotoxicity in Primary Cortical Cultures.

We have previously isolated 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC) from green perilla leaves as the activator of the nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway. This study aims to evaluate the effects of DDC against glutamate neurotoxicity using rat primary cortical cultures. Treatment of cultures with DDC for 24 h before glutamate exposure significantly inhibited glutamate neurotoxicity in a concentration-dependent manner. The involvement of hemeoxygenase-1 (HO-1) and reduced glutathione (GSH) in the protective effects of DDC on cortical cultures was also evaluated. While an HO-1 inhibitor did not have a significant effect on DDC-induced neuroprotection, a γ-glutamylcystein synthetase (γ-GCS) inhibitor significantly suppressed the protective effect of DDC. In an astrocyte culture, DDC induced a marked increase in the levels of intracellular reduced GSH. These results suggest that DDC mainly activates the Nrf2-ARE pathway of astrocytes, resulting in the increased extracellular release of reduced GSH, protecting neurons from glutamate neurotoxicity.

Study on mechanism of synthetic astaxanthin and Haematococcus pluvialis improving the growth performance and antioxidant capacity under acute hypoxia stress of golden pompano (Trachinotus ovatus) and enhancing anti-inflammatory by activating Nrf2-ARE pathway to antagonize the NF-κB pathway

A nutritional feeding experiment with synthetic astaxanthin and Haematococcus pluvialis supplemented was conducted to determine growth performance, antioxidant capacity and anti-inflammation in golden pompano (Trachinotus ovatus).Three diets were formulated with or without H. pluvialis and synthetic astaxanthin supplemented to feed fish for 8 weeks. As the results showed, growth performance (FBW, WG and SGR) significantly increased with synthetic astaxanthin and H. Pluvialis supplemented. Feed coefficient ratio (FCR) of T. ovatus fed diets with H. Pluvialis and astaxanthin supplemented was lower than that of fish fed the control diet. The hepatic total antioxidant capacity (T-AOC) in T. ovatus fed diet with H. Pluvialis and astaxanthin supplemented was higher than that of fish fed the control one. Superoxide dismutase (SOD) and hepatic malondialdehyde (MDA) declined slightly with astaxanthin and H. Pluvialis supplementated than that in control group without significant differences. Under normal rearing experiments, there was no significant difference among the treatments in Nrf2-ARE related genes. However, after the acute hypoxia trial, the relative expression of Nrf2, Keap1, CAT, SOD, GSH-PX and HO-1 were all significantly higher in astaxanthin and H. Pluvialis treatments than that in the control group. After LPS administration, the mRNA relative expression of Nrf2-ARE related genes including Keap1, Nrf2, CAT, GSH-PX, HO-1 and SOD were all significantly higher in astaxanthin and H. Pluvialis treatments than that in the control group. The mRNA relative expression of NF-κB related genes IKK, IκB, and P65 as well as IL1β were all significantly lower in astaxanthin and H. Pluvialis treatments than that in the control group. These results indicated that dietary astaxanthin and H. Pluvialis improved the growth performance and antioxidant capacity under acute hypoxia stress, and alleviated the inflammatory response by activating Nrf2-ARE pathway to antagonize the NF-κB pathway.

Nrf2-ARE signaling in cellular protection: Mechanism of action and the regulatory mechanisms.

Oxidative stress is the increase in cellular oxidant concentration in comparison to antioxidant titer. Toxic insults and many other diseased conditions are mediated through the formation of such condition. Once the redox equilibrium is disrupted, the cellular antioxidant system functions to bring back the cell to redox homeostasis state. The field players of the cytoprotective machinery are the xenobiotic-metabolizing enzymes that are transcriptionally controlled by upstream regulatory pathways like the Nrf2-ARE pathway and AhR-XRE pathway. The importance of Nrf2 lies in the fact that it is activated by a variety of compounds and has a wide range of inducers including metals, organic toxicants and so forth. The present review article aims to discuss the role of Nrf2 in cellular protection and also intends to illuminate the regulatory mechanisms that control Nrf2 itself. This can add to our knowledge of how the cell reacts and survives against such stressed conditions.

Schizonepeta tenuifolia reduces methylglyoxal-induced cytotoxicity and oxidative stress in mesangial cells

Abstract Methylglyoxal (MG) is known to form advanced glycation end products (AGEs) and has emerged as a leading cause of diabetes and the associated complications. We aimed to explore the therapeutic effects and action mechanism of Schizonepeta tenuifolia, by investigating its protective effect on MG-induced cytotoxicity in mouse mesangial cells. Schizonepeta tenuifolia exerted inhibitory effect on MG-mediated AGE formation and AGE–protein cross-linking. MG treatment also reduced cell viability and increased reactive oxygen species (ROS), but S. tenuifolia treatment reversed these phenomena. We also confirmed that S. tenuifolia can activate the Nrf2-ARE pathway. While MG treatment reduced the expression of Nrf2 and its downstream molecules, S. tenuifolia treatment upregulated these protein expression. In conclusion, S. tenuifolia ameliorates cytotoxicity and oxidative stress in mouse mesangial cells via inhibition of AGE formation and AGE–protein cross-linking. Thus, S. tenuifolia can serve as a health food and potential candidate for treating MG-induced glucotoxicity.

Protective Effect of Green Perilla-Derived Chalcone Derivative DDC on Amyloid β Protein-Induced Neurotoxicity in Primary Cortical Neurons.

Amyloid β protein (Aβ) causes neurotoxicity and cognitive impairment in Alzheimer's disease (AD). Oxidative stress is closely related to the pathogenesis of AD. We have previously reported that 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC), a component of green perilla, enhances cellular resistance to oxidative damage through the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway. Here, we investigated the effects of DDC on cortical neuronal death induced by Aβ. When Aβ and DDC had been preincubated for 3 h, the aggregation of Aβ was significantly suppressed. In this condition, we found that DDC provided a neuroprotective action on Aβ-induced cytotoxicity. Treatment with DDC for 24 h increased the expression of heme oxygenase-1 (HO-1), and this was controlled by the activation of the Nrf2-ARE pathway. However, DDC did not affect Aβ-induced neuronal death under any of these conditions. These results suggest that DDC prevents the aggregation of Aβ and inhibits neuronal death induced by Aβ, and although it activates the Nrf2-ARE pathway, this mechanism is less involved its neuroprotective effect.

Effects of 2′-3′-dihydroxy-4′,6′-dimethoxychalcone derived from green perilla on auricle thickness in chronic contact dermatitis model mice

Oxidative stress has been implicated in the pathogenesis of allergic contact dermatitis. The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway, an in vivo antioxidant system, induces antioxidant enzymes. In our previous studies, we isolated 2ʹ,3ʹ-dihydroxy-4ʹ,6ʹ-dimethoxychalcone (DDC) from green perilla and identified it as a novel activator of the Nrf2-ARE pathway. We also discovered that it exerted cytoprotective effects against oxidative stress in PC12 cells. However, its effects on skin disease model animals in vivo remain unclear. In the present study, auricular thickness time-dependently increased with the repeated application of picryl chloride, and significant increases were observed from Day 2 in chronic contact hypersensitivity (cCHS) model mice. Histological changes, such as higher numbers of cells in the epidermis, were observed with increases in auricular thickness. The administration of DDC every two days from Day 6 suppressed the increases in auricular thickness and the number of scratching events in a dose-dependent manner. The expression levels of antioxidant enzymes increased in the mouse auricle 24 h after the administration of DDC. These results presume that DDC inhibits increases in auricular thickness in cCHS mice by up-regulating the expression of antioxidative enzymes through the activation of the Nrf2-ARE pathway.