Overexpression of manganese superoxide dismutase protects lung epithelial cells against oxidant injury

To determine whether overexpression of antioxidant enzymes in lung epithelial cells prevents damage from oxidant injury, stable cell lines were generated with complementary DNAs encoding manganese superoxide dismutase (MnSOD) and/or catalase (CAT). Cell lines overexpressing MnSOD, CAT, or MnSOD + CAT were assessed for tolerance to hyperoxia or paraquat. After exposure to 95% O(2) for 10 d, 44 to 57% of cells overexpressing both MnSOD and CAT and 37 to 47% of cells overexpressing MnSOD alone were viable compared with 7 to 12% of empty vector or parental cells (P < 0.05). To assess if viable cells were capable of cell division after hyperoxic exposures (up to 5 d), a clonogenicity assay was performed. The clonogenic potential of cells overexpressing MnSOD + CAT and MnSOD alone were significantly better than those expressing CAT alone or empty vector controls. In addition, 54 to 72% of cells overexpressing both MnSOD and CAT survived in 1 mM paraquat compared with 58 to 73% with MnSOD alone and 27% with control cells. Overexpression of CAT alone did not improve survival in hyperoxia or paraquat. The combination of MnSOD + CAT did not provide additional protection from paraquat. Data demonstrate that overexpression of MnSOD protects cells from oxidant injury and CAT offers additional protection from hyperoxic injury when co-expressed with MnSOD.     

Transient supplementation of superoxide dismutase protects endothelial cells against Plasmodium falciparum-induced oxidative stress

The pathogenesis of cerebral malaria, a major complication of Plasmodium falciparum infection, relies on mechanisms such as cytokine production and cytoadherence of parasitized red blood cells (PRBCs) on microvascular endothelial cells. In this way parasites avoid spleen clearance by sequestration in post-capillary venules of various organs including the brain. Infected erythrocytes adhesion has also been shown to have molecular signaling consequences providing insight on how tissue homeostasis could be comprised by endothelium perturbation. Our previous work demonstrated that PRBCs adhesion to human lung endothelial cells (HLEC) induces caspases activation, oxidative stress and apoptosis. Cytoplasmic Cu/Zn superoxide dismutase (SOD1), which provides the first line of defense against oxidative stress within a cell, is now used as a treatment of numerous diseases including traumatic brain injury and ischemic stroke. In this report, we demonstrated that transient supplementation of SOD1 protects endothelial cells against P. falciparum induced oxidative stress and apoptosis. We also showed a significant decrease in PRBCs cytoadherence through a downregulation of ICAM-1 and an induction of iNOS. Protection of endothelium via antioxidant delivery may constitute a relevant strategy in cerebral malaria treatment.     

Extracellular superoxide dismutase overexpression protects against aging-induced cognitive impairment in mice

Extracellular superoxide dismutase (EC-SOD) controls the availability of extracellular superoxide and appears to play a role in controlling oxidative stress and intercellular signaling. Whether EC-SOD overexpression would help or hinder neurobehavioral function appears to depend on the age of the individual. In young adult mice, we have found that EC-SOD overexpression can interfere with learning on the radial-arm maze, possibly by reducing control over nitric oxide neurotransmission. In aged mice, we found, in the current study, that EC-SOD overexpression greatly improves learning on the radial-arm maze. Control (N = 17) and EC-SOD overexpressing mice (N = 13) acquired the 8-arm radial maze over 21 sessions of training. The EC-SOD overexpressing mice had significantly better choice accuracy than the control mice (p < 0.005). The EC-SOD overexpressing mice averaged 6.34 ± 0.22 correct arm entries before an error (entries to repeat) during the acquisition phase, while the control mice averaged 5.18 ± 0.22 entries to repeat. EC-SOD genotype did not cause a main effect on response latency. The advantage held by the EC-SOD overexpressing mice persisted during the eight-session post-acquisition phase of testing (p < 0.01). When there was a shift from high to low levels of motivation by reducing the period of food restriction before testing, the EC-SOD overexpression-induced improvement was reduced slightly, but it was still significant compared with the wild-type controls (p < 0.025). Then, after 4 months of no testing, the mice were tested for retention and reacquisition of performance on the radial-arm maze. The EC-SOD overexpressing mice maintained their significantly better choice accuracy (p < 0.05). Enhancement of EC-SOD activity appears to improve learning and memory performance, specifically in aging mice. EC-SOD mimetic treatment during the course of aging may hold promise for aging-induced cognitive impairment.     

Extracellular superoxide dismutase protects against matrix degradation of heparan sulfate in the lung

Asbestosis is a form of interstitial lung disease caused by the inhalation of asbestos fibers, leading to inflammation and pulmonary fibrosis. Inflammation and oxidant/antioxidant imbalances are known to contribute to the disease pathogenesis. Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that has been shown to protect the lung from oxidant-mediated damage, inflammation, and interstitial fibrosis. Extracellular matrix (ECM) components, such as collagen and glycosaminoglycans, are known to be sensitive to oxidative fragmentation. Heparan sulfate, a glycosaminoglycan, is highly abundant in the ECM and tightly binds EC-SOD. We investigated the protective role of EC-SOD by evaluating the interaction of EC-SOD with heparan sulfate in the presence of reactive oxygen species (ROS). We found that ROS-induced heparin and heparan sulfate fragments induced neutrophil chemotaxis across a modified Boyden chamber, which was inhibited by the presence of EC-SOD by scavenging oxygen radicals. Chemotaxis in response to oxidatively fragmented heparin was mediated by Toll-like receptor-4. In vivo, bronchoalveolar lavage fluid from EC-SOD knockout mice at 1, 14, and 28 days after asbestos exposure showed increased heparan sulfate shedding from the lung parenchyma. We demonstrate that one mechanism through which EC-SOD inhibits lung inflammation and fibrosis in asbestosis is by protecting heparin/heparan sulfate from oxidative fragmentation.     

Salvianic acid A protects human neuroblastoma SH-SY5Y cells against MPP+-induced cytotoxicity

1-methyl-4-phenylpyridinium ion (MPP(+)), an inhibitor of mitochondrial complex I, has been widely used as a neurotoxin because it elicits a severe Parkinson's disease-like syndrome with elevation of intracellular reactive oxygen species (ROS) level and apoptotic death. Salvianic acid A (SA), isolated from the Chinese herbal medicine Salvia miltiorrhiza, is capable of protecting diverse kinds of cells from damage caused by a variety of toxic stimuli. In the present study, we investigated the protective effects of SA on MPP(+)-induced cytotoxicity in human neuroblastoma SH-SY5Y cells, as well as the underlying mechanism. Treatment of SH-SY5Y cells with MPP(+) caused the loss of cell viability, and condensation and fragmentation of nuclei, which was associated with the elevation of ROS level, the increase in Bax/Bcl-2 ratio, and the activation of caspase-3. MPP(+) induced mitochondria dysfunction characterized by mitochondrial membrane potential loss and cytochrome c release. These phenotypes induced by MPP(+) were reversed by SA. Our results suggested that the protective effects of SA on MPP(+)-induced cytotoxicity may be ascribed to its antioxidative properties and anti-apoptotic activity via regulating the expression of Bcl-2 and Bax. These data indicated that SA might provide a useful therapeutic strategy for the treatment of progressive neurodegenerative disease such as Parkinson's disease.     

Evaluation of Brucella abortus DNA vaccine by expression of Cu-Zn superoxide dismutase antigen fused to IL-2

The Cu-Zn superoxide dismutase (SOD) antigen of Brucella abortus was previously identified to be a T cell antigen which induces both proliferation of and gamma interferon (IFN-gamma) secretion by T cells from infected mice. In an earlier study, we demonstrated that intramuscular injection of mice with a plasmid DNA carrying the gene for SOD leads to the development of significant protection against B. abortus challenge. It has been reported that the antigen-specific immune responses generated by a DNA vaccine can be enhanced by co-delivery of certain cytokine genes. In this study, we evaluated the effect of delivering IL-2 on the efficacy of SOD DNA vaccine by generating a plasmid (pSecTag-SOD-IL2) that codes for a secretory fusion protein of SOD and IL-2. Another plasmid (pSecTag-SOD) that codes for only SOD as a secretory protein was used for comparison. BALB/c mice injected intramuscularly with pSecTag-SOD or pSecTag-SOD-IL2, but not the control plasmid pSecTag, developed SOD-specific antibody and T cell immune responses. Upon in vitro stimulation with recombinant SOD (rSOD) antigen, T cells from mice immunized with pSecTag-SOD-IL2, in comparison with those from mice immunized with pSecTag-SOD, exhibited a lower proliferation response but produced significantly higher concentrations of IFN-gamma. Both DNA vaccines, however, induced similar levels of SOD-specific antibodies and cytotoxic T cell response. Although mice immunized with pSecTag-SOD-IL2 showed increased resistance to challenge with B. abortus virulent strain 2308, this increase was not statistically significant from that of pSecTag-SOD vaccinated mice. These results suggest that a SOD DNA vaccine fused to IL2 did not improve protection efficacy.     

Differential regulation of copper-zinc superoxide dismutase and manganese superoxide dismutase by progesterone withdrawal in human endometrial stromal cells.

The present study was undertaken to investigate the role of estrogen and progesterone in the expression of copper-zinc superoxide dismutase (Cu,Zn-SOD) and manganese SOD (Mn-SOD) in human endometrial stromal cells (ESC). ESC were incubated with estradiol (10(-8) mol/l), medroxyprogesterone acetate (MPA, 10(-6) mol/l), or estradiol + MPA for 18 days. MPA significantly increased Cu,Zn-SOD and Mn-SOD mRNA levels and enzyme activities as well as the mRNA level of insulin-like growth factor-binding protein-1 (IGFBP-1), a marker for decidualization. Estradiol only augmented the effects of MPA on Cu,Zn-SOD activity and IGFBP-1 mRNA level, and estradiol alone had no effect. To study the withdrawal of estrogen and progesterone (EP withdrawal), ESC that had been treated with estradiol + MPA for 12 days were washed and then incubated with or without estradiol + MPA for a further 11 days. Cu,Zn-SOD mRNA levels and activities declined after EP withdrawal, while they were gradually increased by the continuous treatment with estradiol + MPA. In contrast, Mn-SOD mRNA levels and activities were not affected by EP withdrawal. IGFBP-1 mRNA levels were significantly increased 4 days after EP withdrawal and decreased thereafter, whereas they were gradually increased by the continuous treatment with estradiol + MPA. In conclusion, Cu,Zn-SOD, Mn-SOD and IGFBP-1 are differently regulated by estrogen and progesterone in human ESC. The decrease in Cu,Zn-SOD after the ovarian steroid withdrawal may be involved in endometrial breakdown.     

Induction of superoxide dismutase by decidualization in human endometrial stromal cells

The present study was undertaken to investigate the effect of decidualization on superoxide dismutase (SOD) expression in human endometrial stromal cells (ESC). To induce decidualization, isolated ESC were incubated with medroxyprogesterone acetate (MPA, 10(-6) mol/l) and oestradiol (10(-8) mol/l) for 23 days. Insulin-like growth factor-binding protein-1 (IGFBP-1) was used as a marker of decidualization. SOD mRNA in ESC was significantly increased on day 12 of the hormone treatment (P < 0.01), which was concomitant with the onset of IGFBP-1 mRNA expression, and further increased until day 23 of the treatment in a manner similar to the change in IGFBP-1 expression. To examine the synergistic effect of human chorionic gonadotrophin (HCG) with MPA and oestradiol on SOD and IGFBP-1 expression, ESC were incubated with HCG in the presence or absence of MPA and oestradiol. HCG had no synergistic effect on SOD and IGFBP-1 expression. SOD activities in the decidualized endometrial tissue obtained from patients given oestradiol and progesterone for 7-10 days were significantly higher than those in the non-decidualized endometrial tissue from patients without the hormone treatment (P < 0.01). In conclusion, SOD expression in ESC was induced by MPA and oestradiol accompanied by decidualization, suggesting that SOD may play important roles in decidualization of ESC.     

Different mechanisms for the induction of copper-zinc superoxide dismutase and manganese superoxide dismutase by progesterone in human endometrial stromal cells

BACKGROUND: The present study was undertaken to investigate the cAMP-dependent regulation of copper-zinc superoxide dismutase (Cu,Zn-SOD) and manganese SOD (Mn-SOD) by ovarian steroids in human endometrial stromal cells (ESC). METHODS and RESULTS: To examine the effect of cAMP on SOD expression, ESC were incubated with dibutyryl-cAMP (db-cAMP, 0.5 mmol/l), forskolin (25 micromol/l), or estradiol (E(2), 10(-8) mol/l) + medroxyprogesterone acetate (MPA, 10(-6) mol/l), for 18 days. E(2) + MPA significantly increased Cu,Zn-SOD activity and mRNA concentrations, whereas db-cAMP and forskolin had no effect. On the other hand, Mn-SOD activity and mRNA concentration were significantly increased by all of these treatments. Insulin-like growth factor-binding protein-1, a marker of decidualization, was clearly induced by db-cAMP, forskolin or E(2) + MPA, accompanied by morphological changes characteristic of decidualization. To study whether the increase in Mn-SOD by db-cAMP or E(2) + MPA was mediated by cAMP-dependent protein kinase A (PKA), ESC were incubated with protein kinase inhibitor (PKI) (10 microg/ml), an inhibitor of PKA, in the presence of db-cAMP or E(2) + MPA. The increase in Mn-SOD activity following db-cAMP or E(2) + MPA was completely inhibited by PKI. CONCLUSIONS: In the process of decidualization, E(2) + MPA increases Mn-SOD expression via a cAMP-dependent pathway. Cu,Zn-SOD is also up-regulated by E(2) + MPA, but via a different pathway from that involving cAMP.     

Overexpression of mutant superoxide dismutase 1 causes a motor axonopathy in the zebrafish

The development of small animal models is of major interest to unravel the pathogenesis and treatment of neurodegenerative diseases, especially because of their potential in large-scale chemical and genetic screening. We have investigated the zebrafish as a model to study amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder characterized by the selective loss of motor neurons, caused by mutations in superoxide dismutase 1 (SOD1) in a subset of patients. Overexpression of mutant human SOD1 in zebrafish embryos induced a motor axonopathy that was specific, dose-dependent and found for all mutations studied. Moreover, using this newly established animal model for ALS, we investigated the role of a known modifier in the disease: vascular endothelial growth factor (VEGF). Lowering VEGF induced a more severe phenotype, whereas upregulating VEGF rescued the mutant SOD1 axonopathy. This novel zebrafish model underscores the potential of VEGF for the treatment of ALS and furthermore will permit large-scale genetic and chemical screening to facilitate the identification of new therapeutic targets in motor neuron disease.     

Distribution of superoxide dismutase, glutathione peroxidase and catalase in developing rat brain

This study was carried out to assess the developmental pattern of copper- and zinc-containing superoxide dismutase (CuZnSOD), manganese-containing superoxide dismutase (MnSOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activity in rat brain. The enzymes studied were assayed in different brain regions (cerebral cortex, striatum, cerebellum and brainstem) and enzyme values were corrected for erythrocyte contamination. The cerebral ontogenetic pattern of these enzymes is characterized by increasing CuZnSOD activity, a progressive decrease in CAT activity and, after an initial 10-day fall, increasing GSH-Px activity. The activity of MnSOD appeared to be quite stable up to 40 weeks of age. Similar and comparable changes were seen in all brain regions studied.     

超氧化物歧化酶对抗6-OHDA所致大鼠中脑多巴胺能神经元凋亡

帕金森病是一种与年龄相关的神经退行性疾病 ,主要是黑质纹状体区的多巴胺 (ＤＡ)神经元的减少或消失。许多研究已证实氧化应激状态在帕金森病的发病过程中起着重要作用。但对帕金森病模型大鼠中脑区的氧化应激状态与该区多巴胺能神经元减少和细胞凋亡程度之间的关系未见报道。本研究旨在研究 6 ＯＨＤＡ致细胞凋亡的机理和外源性超氧化物歧化酶 (ＳＯＤ)的对抗作用。1　材料和方法6 4只健康成年雄性Ｓｐｒａｇｕｅ Ｄａｗｌｅｙ(ＳＤ)大鼠 (第一军医大学实验动物中心提供 ) ,随机分组。腹腔内注射 10 %水合氯醛(0 4ｍＬ/ 10 0ｇ)麻醉 ,参…     

Day-night cycle of lipid peroxidation in rat cerebral cortex and their relationship to the glutathione cycle and superoxide dismutase activity

Lipoperoxidation, glutathione cycle components and superoxide dismutase activity show a day-night rhythm in the cerebral cortex of the rat. The highest lipoperoxidative activity is observed during the night (20.00-04.00 h). The enhancement in lipoperoxidation occurs concurrently with a decrease in glutathione peroxidase activity, an increase in superoxide dismutase activity and an increase in the double bonds in the brain cortex lipid fraction. The changes described in this paper seem to be related to a succession of light and dark periods, or to fasting and feeding periods. We propose that those fluctuations could act as a physiological oscillator with an important role in modulating the membrane properties of the nerve cell.     

Manganese superoxide dismutase protects from TNF-alpha-induced apoptosis by increasing the steady-state production of H2O2

Manganese superoxide dismutase (SOD2) has been well established to be essential for protection from a variety of apoptotic stimuli. Here we demonstrate that the antiapoptotic effects of SOD2 are attributed to its ability to generate H(2)O(2) and that its efficient removal resensitizes cells to tumor necrosis factor (TNF)-alpha-induced apoptosis. SOD2 overexpression in HT-1080 cells leads to a decrease in the fluorescence of the superoxidesensitive fluorophore, dihydroethidium, and a concomitant increase in oxidation of the H2O2-sensitive dye, dichlorodihydrofluorescein diacetate (DCFDA). The rate of aminotriazole-inhibited catalase activity also was increased when SOD2 is overexpressed and reflects a 1.6-fold increase in the steady-state production of H(2)O(2). The increase in H(2)O(2) was associated with decreased sensitivity to TNF-alpha-mediated apoptosis, as measured by monitoring the loss of mitochondrial membrane potential (MMP), caspase activation, poly-ADP ribose polymerase (PARP) cleavage, and accumulation of hypodiploid DNA content. Both the increase in H2O2 and resistance to TNF-mediated apoptosis were reversed by coexpression of catalase. The lipid hydroperoxide scavengers, beta-hydroxytoluene and trolox, and the iron chelator, desferroxamine, showed partial recovery of TNF-induced apoptosis. These findings indicate that increases in the intracellular steady-state production of H(2)O(2) by SOD2 can block the activation of key processes fundamental to the process of programmed cell death.     

Fraxetin prevents rotenone-induced apoptosis by induction of endogenous glutathione in human neuroblastoma cells

Fraxetin belongs to an extensive group of natural phenolic anti-oxidants. In the present study, using a human neuroblastoma SH-SY5Y cells, we have investigated the protective effects of this compound on modifications in endogenous reduced glutathione (GSH), intracellular oxygen species (ROS) and apoptotic death on rotenone-mediated cytoxicity. Incubation of cells with the fraxetin led to a significant elevation dose-dependent of cellular GSH and this was accompanied by a marked protection against rotenone-mediated toxicity, which was also significantly reversed in the cells with buthionine sulfoximine (BSO) co-treatment. Taken together, this study suggested that intracellular GSH appeared to be an important factor in fraxetin-mediated cytoprotection against rotenone-toxicity in SH-SY5Y cells. Fraxetin at 10-100 muM inhibited the formation of ROS, cytochrome c release, activation of caspase-3 and 9, and suppressed the up-regulation of Bax, whereas no significant change occurred in Bcl-2 levels. Our results indicated that the anti-oxidative and anti-apoptotic properties render this natural compound potentially protective against rotenone-induced cytotoxicity.     

Alteration of cellular phenotype and responses to oxidative stress by manganese superoxide dismutase and a superoxide dismutase mimic in RWPE-2 human prostate adenocarcinoma cells

To study biologic effects of increased manganese superoxide dismutase (MnSOD) on cell behavior, we overexpressed MnSOD in a human prostate cancer cell line RWPE-2 by cDNA transfection. Stable transfectants of MnSOD showed a two- to threefold increase in MnSOD protein and enzymatic activity and a decrease in growth rate with prolonged cell population doubling times. Western blot analysis showed a 1.5- to twofold increase in the cyclin-dependent kinase inhibitor p21(Waf1) in MnSOD transfectants. Overexpression of MnSOD resulted in a seven- to eightfold increase in reduced glutathione (GSH), 18- to 26-fold increase in oxidized glutathione (GSSG), and a two- to threefold decrease in the ratio of GSH to GSSG. MnSOD-overexpressing cells showed an increase in sensitivity to the cytotoxicity of buthionine sulfoximine, a glutathione-depleting agent, and vitamin C, but a decrease in sensitivity to sodium selenite. Treatment with a superoxide dismutase (SOD) mimic MnTMPyP resulted in similar effects of MnSOD overexpression on cell responses to vitamin C and selenium. These data demonstrate that overexpression of MnSOD or treatment with SOD mimics can result in antioxidant or prooxidant effects in cells, depending on the presence of other antioxidants and prooxidants. MnSOD also has redox regulatory effects on cell growth and gene expression. These findings suggest that MnSOD and SOD mimics have the potential for cancer prevention or treatment.     

Quercetin protects neuroblastoma SH-SY5Y cells against oxidative stress by inhibiting expression of Krüppel-like factor 4

Quercetin is one of flavonoids with cyto-protective activities. It has been demonstrated that quercetin inhibits oxidative stress in some animal models and specific cells, but the particular mechanism is known a little. In the present study, we found that quercetin could decrease the expression of Krüppel-like factor 4 (KLF4) induced by hydrogen peroxide (H₂O₂) in human neuroblastoma SH-SY5Y cells, further increase the expression ratio of bcl-2 to bax, which were apoptotic-related target genes of KLF4, thus alleviate the apoptotic rate and caspase-3 enzyme activity of SH-5YSY cells; the overexpression or inhibition of KLF4 demonstrated the mediated role of KLF4 for the protective effect of quercetin on cell damage induced by H₂O₂. All results suggest a potential molecular mechanism of quercetin protecting against the oxidative damage, which may be applied in the treatment of oxidative related diseases, such as neurodegeneration diseases.     

Construction of Cu-Zn superoxide dismutase deletion mutants of Brucella abortus: analysis of survival in vitro in epithelial and phagocytic cells and in vivo in mice.

Cu-Zn superoxide dismutase (SOD) deletion mutants of Brucella abortus S2308, a virulent strain, and S19, a vaccine strain, were generated by gene replacement. A deletion plasmid, pBA delta sodknr, was constructed by excising the Cu-Zn SOD gene (Cu-Zn sod) from a 2.3-kb B. abortus DNA fragment of plasmid pBA20-1527 and inserting a 1.4-kb DNA fragment encoding kanamycin resistance into the Cu-Zn sod excision site. The deletion plasmid was introduced into B. abortus by electroporation, and Southern blot analysis confirmed that the antibiotic resistance fragment had replaced Cu-Zn sod in kanamycin-resistant colonies. The survival and growth of Cu-Zn SOD mutant strains were compared with that of the parental strains in HeLa cells and in the mouse macrophagelike cell line J774. The survival and growth of the Cu-Zn SOD mutant strains were similar to those of their respective parental strains in HeLa and J774 cell lines. The kinetics of infection with these strains were examined in BALB/c mice. The splenic levels of the S19 Cu-Zn SOD mutant recovered from intraperitoneally infected BALB/c mice were approximately 10-fold lower than those of the parental strain through 26 days postinfection. Thereafter, infection sharply declined in both groups, and by 105 days postinfection, no organisms were detected. The splenic levels of the S2308 Cu-Zn SOD mutant were lower than those of wild-type S2308-infected mice. The spleen weights of mice infected with the S2308 Cu-Zn SOD mutant were consistently lower than those of wild-type S2308-infected mice. These results suggest that the antioxidant enzyme Cu-Zn SOD plays a role in the survival and pathogenicity of B. abortus in vivo.     

6,(5H)-phenanthridinone protects against carbon tetrachloride-induced cytotoxicity in human HepG2 cells

Carbon tetrachloride (CCl4) is a compound associated with free radical mediated hepatotoxicity in humans and laboratory animals. Previous research indicates that the cytotoxicity caused by CCl4 may be mediated by the rapid induction of PARP-1, a nuclear repair enzyme, which results in celluar depletion of NAD+ and ATP. Animal models indicate that the inhibition of PARP-1 after CCl4 exposure will attenuate cytotoxicity in mouse hepatocytes. In this investigation, the potential hepatoprotective effects of the PARP-1 inhibitor 6,(5H)-phenanthridinone against CCl4-induced hepatotoxicity was tested in human cells from the HepG2 primary hepatoma cell line. Cytotoxicity assay results indicate significant reductions in cell death with treatment of 20uM and 40uM solutions of 6,(5H)-phenanthridinone. PARP-1 activity assay results confirm that these protective effects correspond to the inhibition of PARP-1 by 6,(5H)-phenanthridinone. The findings in this study indicate that the effect of PARP-1 inhibition on cytotoxicity in human hepatocytes after CCl4 insult is consistent with the effect of PARP-1 inhibition on cytotoxicity found in animal models.     

Electroacupuncture reduces the extent of lipid peroxidation by increasing superoxide dismutase and glutathione peroxidase activities in ischemic-reperfused rat brains

Reactive oxygen species can be scavenged by superoxide dismutase (SOD) and glutathione peroxidase (GPx). During ischemia-reperfusion, the normal functioning of these antioxidant enzymes may be insufficient for the prevention of oxidant-induced peroxidation of membrane lipids and hence cerebral infarction. We therefore investigated whether electroacupuncture (EA) treatment at Fengchi points in post-ischemic rats could increase the antioxidant enzyme activities and thereby reduce the extent of lipid peroxidation. The results indicated that while EA did not alter the antioxidant enzyme activities in non-ischemic normal rat brains, ischemia-reperfusion caused significant increases in SOD and GPx activities. EA treatment further increased the antioxidant enzyme activities in ischemic-reperfused brain tissues, with a concomitant decrease in the extent of lipid peroxidation. Our finding suggests that EA treatment at Fengchi reduced the extent of lipid peroxidation in ischemic-reperfused rat brains, possibly by increasing the activities of SOD and GPx.