硒和砷对HepG2细胞氧化应激和DNA氧化损伤及修复的作用

目的研究硒和砷单独及联合作用对HepG2细胞氧化应激和DNA氧化损伤及修复的影响。方法采用不同浓度的硒(2.5、5.0和10.0μmol/L亚硒酸钠)和砷(1.56、3.13、6.25、12.5和25.0μmol/L亚砷酸)为受试物单独或联合处理HepG2细胞。荧光法测定丙二醛(MDA)作为氧化应激的指标,高效液相色谱-电化学检测法(HPLC-EC)测定8-羟基鸟苷(8-OHdG)作为DNA氧化损伤的指标,Western Blot检测hOGG1表达作为DNA氧化损伤修复的指标。结果在硒和砷单独作用的条件下,可观察到:(1)5.0、10.0μmol/L的亚硒酸钠和6.25、12.5、25.0μmol/L的亚砷酸均引起HepG2细胞MDA含量增加、8-OHdG生成增多、hOGG1表达明显下降(P<0.05,P<0.01);(2)较低浓度的亚硒酸钠(2.5μmol/L)具有有限的抑制8-OHdG生成的作用(P>0.05)。在硒和砷联合作用的条件下,可观察到:(1)2.5μmol/L的亚硒酸钠和6.25μmol/L的亚砷酸同时染毒使MDA含量和8-OHdG的生成均较相应砷剂量组下降(P<0.05);(2)2.5μmol/L的亚硒酸钠与6.25、12.5和25.0μmol/L的亚砷酸同时染毒,hOGG1表达与相应砷剂量组比较没有明显差异(P>0.05)。结论5.0、10.0μmol/L的亚硒酸钠和6.25、12.5、25.0μmol/L的亚砷酸均可引起HepG2细胞氧化应激增强、8-OHdG生成增多、hOGG1表达明显下降;一定剂量的硒(2.5μmol/L的亚硒酸钠)对砷诱导的HepG2细胞氧化应激和DNA氧化损伤具有抑制作用,但对砷所致的DNA氧化损伤修复不产生明显影响。     

砷毒性作用氧化应激机制研究进展

砷作为确定的人类致癌物,其作用机制尚不明确。近年来就砷中毒作用机制提出了多种假说,其中氧化应激机制逐渐成为砷中毒机制研究的热点。砷诱发氧化应激理论认为甲基化胂具有更强的诱发氧化应激的能力,砷的甲基化代谢是一个毒性增强过程,并且与砷毒性密切相关。本文就砷诱发氧化应激机制研究进展做一综述。     

外源性谷胱甘肽对慢性砷暴露小鼠尿砷代谢及氧化应激的影响

目的探讨给与谷胱甘肽(GSH)及其拮抗剂——丁硫氨酸亚砜胺(BSO)对慢性砷暴露小鼠体内砷代谢及氧化应激的影响。方法将SPF级雌性昆明小鼠随机分为对照组(蒸馏水)、单纯染砷组(50 mg/L亚砷酸钠)、GSH干预组(50 mg/L亚砷酸钠+400 mg/kg GSH)和BSO(50 mg/L亚砷酸钠+600mg/kg BSO)干预组,除对照组小鼠饮用蒸馏水外,其余各组均饮用含50 mg/L亚砷酸钠的水溶液连续染毒30周,然后给予400 mg/kg GSH或600 mg/kg BSO,用蒸馏水配制GSH和BSO水溶液,每天两次腹腔注射,连续2 d,用氢化物发生-超低温捕集-原子吸收分光光度法测定尿液各形态砷水平,用DTNB及试剂盒法分别测定全血及肝脏中GSH和总抗氧化能力(T-AOC)水平。结果 GSH干预组小鼠尿中二甲基胂(DMA)、DMA含量构成比、二甲基化率(SMR)及总砷含量高于单纯染砷组(P<0.05),而BSO干预组各形态砷、DMA含量构成比、一甲基化率(FMR)、SMR及总砷含量均低于单纯染砷组(P<0.05);单纯染砷组小鼠肝脏和血液GSH和T-AOC的水平均低于对照组(P<0.05)。给予GSH干预后,肝脏和血液GSH和T-AOC水平均高于单纯染砷组(P<0.05)且与对照组差异无统计学意义(P>0.05)。BSO干预组小鼠肝脏和血液GSH和T-AOC的水平均低于其他各组(P<0.05)。结论外源性GSH干预可以增强砷暴露小鼠的砷甲基化能力,增加砷从尿液中的排出,拮抗砷所致的GSH和T-AOC水平下降,从而减少了砷对机体造成的氧化损伤。     

氧化应激致慢性水砷暴露小鼠肝损伤作用

目的 比较不同价态的砷对小鼠脐组织中谷胱甘肽过氧化物酶(GSH-Px)和胎盘型谷胱甘肽-S-转移酶(GST-Pi)表达的影响,探讨氧化应激在慢性砷暴露致肝损伤中的作用.方法 60只雄性昆明种小鼠,体重(20±2)g,随机分为对照组、亚砷酸钠组和砷酸钠组.染毒10个月后处死小鼠,检测血清肝功能;测定肝组织总砷含量;做病理检查;Trizol-酚-氯仿一步法提取小鼠肝组织总RNA,紫外分光光度法测定总RNA浓度及纯度.逆转录PCR(RT-PCR)技术测定小鼠肝组织中GSH-Px和GST-Pi mRNA的表达,以18S基因作为质控.结果 亚砷酸钠组在肝组织中的砷蓄积量[(3992±250)ng/g组织]高于砷酸钠组[(2603±357)ng/g组织](P<0.05);砷暴露组的肝组织病理检查显示有明显组织损伤;与对照组比较,亚砷酸钠组的血清丙氨酸转氨酶(ALT)[(61.46±13.85)U/L]、天冬氨酸转氨酶(AST)[(510.86±59.01)U/L]、球蛋白(Glb)[(26.94±3.73)g/C)]L值均显著升高,肝组织中GST-Pi mRNA的表达(163.3±11.6)降低,P<0.05.结论 砷致小鼠肝损伤与砷在肝组织中的蓄积有关.氧化应激可能是慢性饮水砷中毒致小鼠肝损伤的机制之一.     

Testicular torsion, oxidative stress and the role of antioxidant therapy

Testicular torsion is a urological syndrome caused mainly by a twist in the spermatic cord. It constitutes a surgical emergency and affects newborns, children and adolescent boys. The torsion must be treated promptly to avoid loss of function of ipsilateral and contralateral testis. This syndrome often leads to infertility of the ipsilateral (torted) and contralateral (not torted) testis,but the mechanisms of cellular injury remain still incompletely understood. The primary pathophysiologic event in testicular torsion is ischemia followed by reperfusion; thus, testicular torsion/detorsion is an ischemia/reperfusion (I/R) injury to the testis. Testicular torsion and detorsion causes morphological and biochemical changes by both ischemia and reperfusion of the tissues. These I/R injury is associated with overgeneration of reactive oxygen species (ROS) and reactive nitrogen species (RNS), and also with a common mechanism to other organs such as brain, heart and kidneys. Although the results are not conclusive and the molecular mechanism by which antioxidants control male fertility have not yet been clearly identified, several antioxidant enzymes and antioxidant drugs have been studied to prevent such I/R injury in testis. As a result, antioxidant therapy may represent a new non-hormonal option within a broader therapeutic strategy in men with ROS-mediated infertility such as testicular torsion.     

Effect of water management, tillage options and phosphorus status on arsenic uptake in rice

High arsenic (As) concentrations in soil may lead to elevated concentrations of arsenic in agricultural products. Field experiments were conducted to examine the effects of water management (WM) and Phosphorus (P) rates on As uptake, rice growth, yield and yield attributes of winter (boro) and monsoon (aman) rice in an As contaminated soil-water at Gobindagonj, Gaibandha, Bangladesh in 2004 and 2005. Significantly, the highest average grain yields (6.88±0.07 t ha⁻¹ in boro 6.38±0.06 t ha⁻¹ in aman) were recorded in permanent raised bed (PRB; aerobic WM: Eh=+360 mV) plus 100% P amendment. There was a 12% yield increase over conventional till on flat (CTF; anaerobic WM: Eh=−56 mV) at the same P level. In boro, the As content in grain and As content in straw were about 3 and 6 times higher in CTF compared to PRB, respectively. The highest total As content (0.646±0.01 ppm in grain and 10.93±0.19 ppm in straw) was recorded under CTF, and the lowest total As content (0.247±0.01 and 1.554±0.09 ppm in grain and straw, respectively) was recorded under PRB (aerobic WM). The results suggest that grain and straw As are closely associated in boro rice. The furrow irrigation approach of the PRB treatments consistently reduced irrigation input by 29-31% for boro and 27-30% for aman rice relative to CTF treatments in 2004 and 2005, respectively, thus reducing the amount of As added to the soil from the As-contaminated irrigation water. Yearly, 30% less As was deposited to the soil compared to CTF system through irrigation water during boro season. High As concentrations in grain and straw in rice grown using CTF in the farmers' field, and the fact that using PRB reduced grain As concentrations to value less than half of the proposed food hygiene standard.     

Chronic arsenic exposure and oxidative stress: OGG1 expression and arsenic exposure, nail selenium, and skin hyperkeratosis in Inner Mongolia

Arsenic, a human carcinogen, is known to induce oxidative damage to DNA. In this study we investigated oxidative stress and As exposure by determining gene expression of OGG1, which codes for an enzyme, 8-oxoguanine DNA glycosylase, involved in removing 8-oxoguanine in As-exposed individuals. Bayingnormen (Ba Men) residents in Inner Mongolia are chronically exposed to As via drinking water. Water, toenail, and blood samples were collected from 299 Ba Men residents exposed to 0.34-826 microg/L As. RNA was isolated from blood, and mRNA levels of OGG1 were determined using real-time polymerase chain reaction. OGG1 expression levels were linked to As concentrations in drinking water and nails, selenium concentrations in nails, and skin hyperkeratosis. OGG1 expression was strongly associated with water As concentrations (p < 0.0001). Addition of the quadratic term significantly improved the fit compared with the linear model (p = 0.05) . The maximal OGG1 response was at the water As concentration of 149 microg/L. OGG1 expression was also significantly associated with toenail As concentrations (p = 0.015) but inversely associated with nail Se concentrations (p = 0.0095) . We found no significant differences in the As-induced OGG1 expression due to sex, smoking, or age even though the oldest group showed the strongest OGG1 response (p = 0.0001) . OGG1 expression showed a dose-dependent increased risk of skin hyperkeratosis in males (trend analysis, p = 0.02) , but the trend was not statistically significant in females. The results from this study provide a linkage between oxidative stress and As exposure in humans. OGG1 expression may be useful as a biomarker for assessing oxidative stress from As exposure.     

雄黄与亚砷酸钠亚急性暴露对小鼠砷代谢及氧化应激影响的比较

目的探讨经口染毒雄黄、亚砷酸钠后,小鼠体内砷代谢及氧化应激指标的变化,为评价雄黄的毒性提供实验数据。方法清洁级雌性昆明小鼠随机分为对照组(0.5%羧甲基纤维素钠)、0.5 g/kg雄黄组和0.1 g/kg亚砷酸钠组,各组均灌胃染毒3 d,用氢化物发生-超低温捕集-原子吸收分光光度法分别测定尿液和肝组织中无机砷(iAs)、一甲基胂(MMA)和二甲基胂(DMA)。用试剂盒法测定全血中GSH和肝脏T-AOC水平。结果雄黄组小鼠尿液和肝脏中各形态砷和总砷含量高于对照组,但低于亚砷酸钠组;一甲基化率(FMR)和二甲基化率(SMR)高于亚砷酸钠组,差异均有统计学意义(P<0.05)。雄黄组全血GSH和肝脏T-AOC水平均高于亚砷酸钠组(P<0.05),其全血GSH和肝脏T-AOC水平与对照组相比差异均无统计学意义(P>0.05)。结论与亚砷酸钠相比,雄黄中的砷在小鼠体内代谢较慢,对氧化应激指标影响较小。     

Effect of mixed flavonoids, n-3 fatty acids, and vitamin C on oxidative stress and antioxidant capacity before and after intense cycling

Consumption of plant flavonoids, antioxidants, and n-3 fatty acids is proposed to have many potential health benefits derived primarily through antioxidant and anti-inflammatory activities. This study examined the effects of 1,000 mg quercetin + 1,000 mg vitamin C (QC); 1,000 mg quercetin, 1,000 mg vitamin C, 400 mg isoquercetin, 30 mg epigallocatechin gallate, and 400 mg n-3 fatty acids (QFO); or placebo (P), taken each day for 2 wk before and during 3 d of cycling at 57% W(max) for 3 hr, on plasma antioxidant capacity (ferricreducing ability of plasma [FRAP], oxygen-radical absorbance capacity [ORAC]), plasma oxidative stress (F(2)-isoprostanes), and plasma quercetin and vitamin C levels. Thirty-nine athletes were recruited and randomized to QC, QFO, or P. Blood was collected at baseline, after 2 wk supplementation, immediately postexercise, and 14 hr postexercise. Statistical design used a 3 (groups) × 4 (times) repeated-measures ANOVA with post hoc analyses. Plasma quercetin was significantly elevated in QC and QFO compared with P. Plasma F(2)-isoprostanes, FRAP, and vitamin C were significantly elevated and ORAC significantly decreased immediately postexercise, but no difference was noted in the overall pattern of change. Post hoc analyses revealed that the QC and QFO groups did not exhibit a significant increase in F(2)-isoprostanes from baseline to immediately postexercise compared with P. This study indicates that combining flavonoids and antioxidants with n-3 fatty acids is effective in reducing the immediate postexercise increase in F(2)-isoprostanes. Moreover, this effect occurs independently of changes in plasma antioxidant capacity.     

Hepatoprotective and antioxidant activities of grapeseeds against ethanol-induced oxidative stress in rats

The present study was carried out to evaluate the hepatoprotective effect and antioxidant role of grape (Vitis vinifera L.) seeds (GS) against ethanol-induced oxidative stress. The hepatoprotective and antioxidant roles of the GS supplementation feed against ethanol-induced oxidative stress were evaluated by measuring liver damage serum marker enzymes, aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transpeptidase and lactate dehydrogenase, antioxidant defence system such as GSH, glutathione reductase, superoxide dismutase, glutathione S-transferase and glutathione peroxidase and malondialdehyde (MDA) content in various tissues of rats. Rats were divided into four experimental groups: I (control), II (20?% ethanol), III (15?% GS) and IV (20?% ethanol+15?% GS). According to the results, the level of serum marker enzymes was significantly increased in group II as compared to that of group I, but decreased in group IV as compared to that of group II. Also, administration of GS-supplemented food restored the ethanol-induced MDA, which was increased near the control level. The results indicated that GS could be as important as diet-derived antioxidants in preventing oxidative damage in the tissues by reducing the lipid oxidation or inhibiting the production of ethanol-induced free radicals in rats.     

Dietary modification and moderate antioxidant supplementation differentially affect serum carotenoids, antioxidant levels and markers of oxidative stress in older humans

Oxidative stress is thought to be a factor in the progression of chronic diseases, and even the aging process itself. We examined the effect of two moderate vitamin, mineral and phytochemical supplements and a dietary intervention on markers of oxidative stress and antioxidant status in older humans. Subjects (n = 60, 65-85 y old) were enrolled in a 5-wk, double-blind, placebo-controlled study. The subjects were randomly assigned to a group with one of four interventions: antioxidant supplement capsule, antioxidant supplement tablet, high carotenoid diet or placebo. Postintervention serum levels of some of the supplemented carotenoids and alpha-tocopherol were higher in all treated groups compared with the placebo group and with preintervention levels within groups. Markers of oxidative stress or antioxidant capacity were not significantly different from preintervention levels, although the diet and supplement capsule groups had lower levels of some of those markers than the placebo group postintervention. The results suggest that both moderate antioxidant supplementation and a diet high in carotenoids elevate serum carotenoids and antioxidant levels in an older adult population, although with different specific effects.     

Modulation of antioxidant defence system for arsenic detoxification in Indian mustard

This study investigates the modulation of antioxidant defence system of Indian mustard (cv. Pusa Jai Kisan) against the arsenic (As)-induced toxicity in 20-day-old plants, exposed to 5 and 25 microM As for 96 h in hydroponic culture. Reduction in plant growth, measured in terms of root and shoot dry weights, was insignificant with 5 microM, but highly significant with 25 microM As treatment. Shoots accumulated more As than roots. The extent of oxidative stress in the leaves was measured as the rate of lipid peroxidation. The As treatments significantly increased the activities of antioxidative enzymes (superoxide dismutase, ascorbate peroxidase and glutathione reductase) and the contents of antioxidants metabolites (glutathione and ascorbate), the increase being dependent on exposure time. Increase in the activity of catalase was not significant, however. In conclusion, Indian mustard was able to detoxify the low As level through induction of antioxidant defence mechanism.     

The effect of different training programs on antioxidant status, oxidative stress, and metabolic control in type 2 diabetes

We compared the effects of 12 weeks of 3 different exercise types on type 2 diabetic (T2DM) male and female human subjects, randomly divided into 4 groups: aerobic training (AT; n = 11), strength training (ST; n = 10), combined training (CBT; n = 10), and no training (NT; n = 12). Metabolic control, anthropometric parameters, lipid and hematological profiles, kidney and liver function markers, hormones, antioxidant enzymes, and oxidative stress markers were assessed prior to and after the training programs. At baseline, fasting blood glucose and hemoglobin A(1c) in the ST group were higher than in the NT group; after the training, we no longer observed differences in these groups, suggesting an improvement on these parameters. In the AT group, catalase and superoxide dismutase activity, nitrite concentration, levels of sulfhydryl groups, and peak rate of oxygen consumption were elevated after the training (p < 0.05). No changes were observed in antioxidant enzymes or oxidative stress markers in the ST group. The levels of sulfhydryl groups diminished in the NT group (p < 0.01) and increased in the CBT group (p < 0.05). These data demonstrate that the AT program for the T2DM subjects provided important upregulation in antioxidant enzymes and increased nitric oxide bioavailability, which may help minimize oxidative stress and the development of the chronic complications of diabetes. We propose that the beneficial effects observed in the metabolic parameters of the ST group occurred in response to the poor baseline metabolic health n this group, and not necessarily in response to the training itself.     

Panax ginseng reduces oxidative stress and restores antioxidant capacity in aged rats

Nutritional antioxidants interact with cells in an active mode, including retrieving and sparing one another, to diminish oxidative stress. However, the intracellular balance of prooxidants and antioxidants becomes unbalanced, favoring prooxidants during the aging process. One hypothesis is that an aging-associated increase in oxidative stress is the primary cause of aging. Hence, the research hypothesis for this study is that Korean red ginseng reduces oxidative stress in vivo. Therefore, we investigated the efficacy of Korean red ginseng water extract (GWE) in reducing aging-associated oxidative stress by measuring lipid peroxidation and antioxidant levels in older rats compared with young rats. We observed a significant increase in the markers for oxidative damage (eg, lipid peroxidation) and markers for vital organ damage (eg, aspartate aminotransferase, alanine aminotransferase, urea, and creatinine levels) in aged rats. The oxidative damage was accompanied by a significant decrease in enzymatic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase, and nonenzymatic antioxidants such as reduced glutathione, vitamin E, and vitamin C. Aged rats fed a diet supplemented with Korean red ginseng water extract had significantly less oxidative damage, possibly by enhancing the enzymatic and nonenzymatic antioxidants status. Our data suggest that consumption of Korean red ginseng reduces lipid peroxidation and restores antioxidant capacity by suppressing oxidative stress in rats.     

氟对大鼠自由基、氧化应激及超微结构影响

目的 研究不同浓度氟对大鼠肝脏自由基和氧化应激及超微结构的影响.方法 在饮水中加入不同剂量的氟化钠喂饲大鼠1个月后,测定血清氟含量,肝组织中的一氧化氮(NO)、丙二醛(MDA)含量及谷胱甘肽过氧化物酶(GSH-Px)活性,并观察大鼠肝脏超微结构变化.结果 随染氟剂量的增加,1个月后各剂量组大鼠血氟浓度相应增加,存在剂量-效应关系(R=0.884,P<0.01),但各剂量组间血氟浓度差异无统计学意义;NO含量与对照组比较差异无统计学意义(P>0.05),但存在剂量-效应关系(R=0.361,P<0.05);各剂量组大鼠MDA含量升高,与对照组比较差异有统计学意义(P<0.01),存在剂量-效应关系(R=0.797,P<0.01);各剂量组大鼠GSH-Px活性下降,与对照组比较差异有统计学意义(P<0.01),存在剂量-效应关系(R=-0.912,P<0.01),特别是高氟剂量组MDA的含量最高,而GSH-Px活性最低;中、高剂量组大鼠肝细胞超微结构可见线粒体肿胀,有较多脂肪变性.结论 氟中毒可导致大鼠肝脏处于氧化应激状态、肝细胞超微结构改变.     

Antioxidant action of soy isoflavones on oxidative stress and antioxidant enzyme activities in exercised rats

BACKGROUND/OBJECTIVES

Isoflavones are widely believed to be beneficial to human health, in relation to their antioxidant potentials. Exercise can cause an imbalance between reactive oxygen species (ROS) and antioxidants. This study was conducted in order to investigate the ability of isoflavones in amelioration of oxidative stress induced by exercise.

MATERIALS/METHODS

Male Sprague-Dawley rats were assigned to one of four groups: isoflavone-free with no exercise (CON-sd), isoflavone-free with exercise (CON-ex), isoflavone-supplemented with no exercise (ISF-sd), and isoflavone-supplemented with exercise (ISF-ex). Animals exercised on the treadmill for 30 minutes per day, five days per week. TBARS as a marker of oxidative stress and antioxidant enzyme activity, including SOD, GSH-px, and catalase were determined in liver tissue. Serum lipid profile was also examined.

RESULTS

A significant effect of isoflavone alone was observed on abdominal fat pad mass. ISF-ex had significantly less abdominal fat pad than CON-ex. Both exercise and isoflavone treatment had significant effects on lowering plasma triglyceride (TG), thus, the ISF-ex group had a significantly lower TG level than the CON-sd group, by 30.9%. However, no differences were observed in plasma cholesterol, HDL-C, and cholesterol/HDL-C ratio. Exercise, isoflavone, and exercise-isoflavone interaction effects were significant on thiobarbituric acid reactive substances (TBARS) (P = 0.001, 0.002, and 0.005, respectively). The CON-ex group showed a higher TBARS level than the other three groups. By contrast, in the ISF-ex group, TBARS was restored to the level of the ISF-sd or CON-sd group. Isoflavone had a significant effect on superoxide dismutase (SOD) (P = 0.022) and catalase activities (P = 0.049). Significantly higher SOD and catalase activities were observed in ISF-ex than CON-ex. SOD and catalase activities showed an inverse pattern of TBARS. Taken together, isoflavones increased the activities of SOD and catalase with concomitant decreases in TBARS, indicative of decreased oxidative stress.

CONCLUSIONS

Isoflavone supplementation enhances antioxidant action with attenuation of exercise-induced oxidative stress, as measured by decreases in TBARS, and inhibits body fat accumulation and plasma TG increase. Antioxidative effects ascribed to isoflavones may be partially exerted via enhancement of antioxidant enzyme activities.     

Induction of oxidative stress by arsenic in Clarias batrachus: involvement of peroxisomes

Indian catfish, Clarias batrachus, were exposed to two nonlethal doses of arsenic for 10 days, which induced tissue lipid peroxidation, increased the ratio of oxidized to reduced glutathione and produced excess H(2)O(2) within 1-2 days of exposure. Furthermore, arsenic treatment increased the activity of antioxidant enzymes such as glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase but decreased glutathione reductase (GR) activity within a day of exposure, indicating the generation of oxidative stress in fish at an early stage. Reversibility of these arsenic-induced responses by pretreatment with N-acetylcysteine indicates that the oxidative stress was due to excess H(2)O(2) production, which was found to be partially contributed by altered H(2)O(2) metabolism in the peroxisomes. It is therefore concluded that peroxisomal H(2)O(2) metabolizing enzymes are potential targets of arsenic toxicity in C. batrachus.