邻苯二甲酸二丁酯对翡翠贻贝抗氧化酶及脂质过氧化水平的影响

实验室条件下,研究了不同浓度邻苯二甲酸二丁酯(DBP)长期胁迫(15 d)对翡翠贻贝内脏团和外套膜抗氧化酶(超氧化物歧化酶SOD、过氧化氢酶CAT)及脂质过氧化(LPO)水平(以MDA含量表示)的影响,以及受胁迫翡翠贻贝在清洁海水中恢复阶段上述生化指标的变化特征.结果表明:胁迫阶段,0.5和2.5 mg.L-1DBP下翡翠贻贝内脏团SOD活性表现为先抑制后逐渐恢复,12.5和62.5 mg.L-1下则持续受到显著抑制;不同浓度组CAT活性均明显被抑制.LPO水平明显升高.外套膜中,2.5 mg.L-1下SOD活性受到持续诱导,其他浓度组则先被抑制,后随曝露时间延长逐渐被诱导;各浓度组CAT的变化波动较大,没有明显规律;而LPO水平明显升高.净化恢复阶段,12.5和62.5 mg.L-1DBP胁迫下的内脏团SOD和CAT活性恢复较慢,其LPO水平随时间延长逐渐恢复至对照组水平;外套膜中SOD活性呈持续升高趋势,CAT活性和LPO水平则随时间延长恢复到对照组水平.     

Effects of thymoquinone on antioxidant enzyme activities, lipid peroxidation and DT-diaphorase in different tissues of mice: a possible mechanism of action

The present investigation focused, firstly, on the effects of oral administration of thymoquinone (TQ) on antioxidant enzyme activities, lipid peroxidation and DT-diaphorase activity in hepatic, cardiac and kidney tissues of normal mice. Superoxide dismutase (SOD; E.C:1.15.1.1), catalase (CAT; E.C:1.11.1.6), glutathione peroxidase (GSH-Px; E.C:1.11.1.9), glutathione-S-transferase (GST; E.C:2.5.1.18), and DT-diaphorase (E.C:1.6.99.2) enzyme activities in each tissue type were determined. Treatment of mice with the different doses of TQ (25, 50 and 100 mg kg(-1) day(-1) orally) for 5 successive days, produced significant reductions in hepatic SOD, CAT and GSH-Px activities. In addition cardiac SOD activity was markedly inhibited with the higher doses of TQ, (namely 50 and 100 mg kg(-1)). Moreover, TQ (100 mg kg(-1)) significantly reduced hepatic and cardiac lipid peroxidation as compared with the respective control group. Conversely, TQ (50,100 mg kg(-1)) and TQ (100 mg kg(-1)) enhanced cardiac and renal DT-diaphorase activity respectively. However, the selected doses of TQ neither produced any change in GST activity nor influenced reduced glutathione content in all tissues studied. TQ was tested, secondly, as a substrate for hepatic, cardiac and renal DT-diaphorase of normal mice in the presence of NADPH. Kinetic parameters for the reduction of TQ to dihydrothymoquinone (DHTQ) indicated that DT-diaphorase of different tissues can efficiently reduce TQ to DHTQ. K(m) and V(max) values revealed that hepatic DT-diaphorase exhibited the higher values, while the lower values were associated with renal DT-diaphorase. TQ and DHTQ were tested, thirdly, as specific scavengers for superoxide anion (generated biochemically) or as general scavengers for free radicals (generated photochemically). The results revealed that TQ and DHTQ acted not only as superoxide anion scavengers but also as general free radical scavengers. The IC(50) for TQ and DHTQ in biochemical and photochemical assays were in the nanomolar and micromolar range respectively. Our data may explain at least partly the reported beneficial in vivo protective effects of TQ through the combined antioxidant properties of TQ and its metabolite DHTQ.     

Sex-dependent antioxidant enzyme activities and lipid peroxidation in ageing mouse brain

We investigated whether oxidant status and antioxidant enzyme activities during ageing of mouse brain are regulated in sex-dependent manner. In the homogenate from the brain of 1, 4, 10 and 18 months old male and female CBA mice, lipid peroxidation (LPO), total superoxide dismutase (tSOD), catalase (CAT) and glutathione peroxidase (Gpx) were determined. LPO was age- and sex-related, favoring males over females throughout the lifespan with the peak in both sexes at 10 months of age. Throughout ageing, no difference in tSOD activity between male and female brains was observed, except in immature 1 month old mice. Gender-related difference in Gpx activity was observed, with higher level in females comparing to males, reaching statistical significance in senescent (18 months old) animals. CAT activity was drastically changed with ageing in both the male and female brain. We found different age associated trends in CAT activity in males and females: decreased with age in males and increased with age in females. Taken together, the present findings indicate that brains of female mice have lower oxidant and higher antioxidant capacity mostly related to CAT and to a lesser extent to Gpx activity.     

厚壳贻贝抗氧化酶活性和脂质过氧化物含量对Cd和Aroclor 1254胁迫的响应

以厚壳贻贝(Mytilus coruscus)为目标生物,研究了不同浓度Cd2+(0.194、0.388、0.775 mg·L-1)、Aroclor 1254(0.005、0.01、0.05 mg·L-1)单一和复合胁迫对其消化盲囊抗氧化酶活性及脂质过氧化产物丙二醛(MDA)含量的影响。结果表明:(1)单一和复合胁迫均可导致厚壳贻贝抗氧化酶的活性先升高后抑制。高浓度组(0.775 mg·L-1Cd2+、0.05mg·L-1Aroclor 1254)在单一胁迫第1天时,抗氧化酶的活性即达峰值。抗氧化酶活性的下降幅度和速率与胁迫物质作用时间和浓度呈正相关。(2)SOD、GSH-Px对胁迫的敏感性高于CAT。(3)各胁迫处理组MDA含量随胁迫时间延长均显著升高(P0.01)。单一胁迫的效应与剂量和时间呈正相关。(4)复合胁迫的效应强于单一胁迫。推测高于环境水平的Cd2+、Aroclor 1254对厚壳贻贝可产生明显氧化胁迫,抗氧化防御系统可以作为海洋环境重金属-有机物复合污染监测的潜在生物标志物。     

Micropropagation of gerbera: lipid peroxidation and antioxidant enzyme activities during acclimatization process

Gerbera jamesonii H. Bolus ex Hook (Family: Asteraceae) has been successfully acclimatized from temperate to subtropical North Indian plains of Lucknow through in vitro propagation. Flower heads were collected from greenhouse, segmented into 4–16 pieces and cultured in Murashige and Skoog’s medium (MS) (Physiol Plant 15:472–497, 1962) supplemented with 2.87 μM indole-3-acetic acid (IAA) and 8.88 μM N⁶-benzyladenine (BA) for shoot regeneration. Shoots were subcultured on growth regulator free MS medium. Apical shoot meristems from in vitro plantlets of gerbera were tested in MS medium with different combination of cytokinins [BA, kinetin, and thidiazuron (TDZ)] alongwith 2.68 μM 1-naphthaleneacetic acid (NAA) for shoot multiplication. The optimum results were obtained with 8.88 μM BA. Regenerated plants with well-established root system were transferred to pots containing soil and sand (1:1 v/v) and were kept in humidity chamber with 80–90% relative humidity for 0, 5, 10, 15, 20, and 25 days before they were transferred to field (during October, 2005 to February, 2006). Survival percentage was higher when regenerated plantlets were kept under humidity chamber for 15 days. An attempt was made to obtain basic information on different biochemical changes during acclimatization process of in vitro raised plantlets. Increased lipid peroxidation and high H₂O₂ content in early stages of acclimatization process reflected a similar process of oxidative stress. Our work suggests that tissue-cultured plants develop antioxidant enzymatic protective system which determine the ability to survive in oxidative stress and up regulation of these enzymes would help to reduce the built up of reactive oxygen species (ROS).     

Water availability effects on antioxidant enzyme activities, lipid peroxidation, and reducing sugar contents of alfalfa (Medicago sativa L.)

To understand alfalfa (Medicago sativa L.) reactions to osmotic stress, solutions with −0.5, −1 and −1.5 MPa osmotic potentials using PEG (Poly ethyleneglycol) and distilled water as control were prepared. In a germination test, eleven alfalfa cultivar seeds were allowed to germinate in these solutions. M. sativa cv. Yazdi and M. sativa cv. Gharayonje, selected as tolerant and sensitive cultivars, respectively, and were used for further studies. In all PEG solutions, root and shoot dry weights decreased in both cultivars. Under different levels of osmotic stress, root to shoot ratio increased significantly in Yazdi, whereas this parameter showed no significant differences in Gharayonje. Yazdi cultivar also showed higher activities of SOD (Superoxide dismutase), APX (Ascorbate peroxidase), CAT (Catalase), POD (Peroxidase), and higher reducing sugar contents of leaves in comparison with Gharayonje. These higher antioxidant activities help the tolerant cultivar to decrease oxidative damages of osmotic stress to membrane lipids as compared with its sensitive counterpart. As a result, electrolyte leakage and the amounts of MDA (Malondialdehyde), were higher in Gharayonje. This study highlights the importance of enzymatic and non-enzymatic antioxidant systems in scavenging reactive oxygen species which is caused by osmotic stress. It is seems that antioxidant systems are more active in tolerant cultivars than those of sensitive ones.     

Effect of transition metals on stress, lipid peroxidation and antioxidant enzyme activities in tobacco cell cultures

to-baccoBright Yellow 2 (BY-2) suspension culture to understand the mechanisms of metal resistance in plant cells.We have analysed superoxide dismutase, catalase, and ascorbate peroxidase enzyme activities and superoxidedismutase-isoforms by isoelectric focusing gels in tobacco cells grown at two different toxic concentrations ofeach of the transition metals: copper, iron, manganese and zinc. Exposure of tobacco cells to these metals causedchanges in total superoxide dismutase activity in a different manner, depending on the metal assayed: after cop-perand manganese treatments, total superoxide dismutase activity was enhanced, while it was reduced after ironand zinc exposure. Superoxide dismutase-isoforms were affected by the metal used, and a Fe-SOD band with thesame isoelectric point as a Cu, Zn-SOD from non-treated cells, was induced after iron and zinc treatments. Cu,Zn-SODs were present in all metal-treatments whereas Mn-SOD was not detected in any case. Concerning otherantioxidant enzymes tested, such as catalase and ascorbate peroxidase, the latter showed a remarkable increase inactivity in response to copper treatments and catalase activity was enhanced after iron and with the lowest man-ganeseconcentration. Lipid peroxidation was increased after each metal treatment, as an indication of the oxi-dativedamage caused by metal concentration assayed in tobacco cells. These results suggest that an activation ofsome antioxidant enzymes in response to oxidative stress induced by transition metals is not enough to confertolerance to metal accumulation.     

镉诱导萝卜幼苗活性氧产生、脂质过氧化和抗氧化酶活性的变化

通过水培试验,研究Cd2+胁迫对萝卜幼苗活性氧的产生、脂质过氧化和抗氧化酶活性的影响。超氧 阴离子(O 2)的产生速率和丙二醛(MDA)的含量与对照相比有不同程度的增加,表明Cd2+胁迫能导致萝卜体 内的氧化胁迫;超氧化物歧化酶(SOD)的活性,随着Cd2+浓度提高,首先明显上升,然后逐渐下降,甚至低于 对照,叶片过氧化氢酶(CAT)的活性明显增加,根系CAT活性则减少,根系以及较高浓度Cd2+处理后期叶片 谷胱甘肽还原酶(GR)的活性均显著增加。推测:胁迫初期可能主要由SOD和CAT发挥抗氧化作用;后期由 于抗坏血酸—谷胱甘肽(AsA GsH)循环途径的激活,以及还原型谷胱甘肽(GSH)和植物络合素(Phytochela tins,PCs)的合成,可能在清除活性氧或者直接鏊合Cd2+中起作用。     

铁镉互作对水稻脂质过氧化及抗氧化酶活性的影响

利用营养液培养方法,以‘沈农265’为供试品种,研究不同Fe(0、0.1、0.25、0.5mmolFe2+·L-1)、Cd(0、0.1、1.0μmolCd2+·L-1)处理对水稻植株体内脂质过氧化及抗氧化酶活性的影响.结果表明:单独供应Fe显著降低了水稻地上部和根系生物量,同时供应Cd后生物量不再下降;单独供应Cd降低了根系中丙二醛(MDA)和可溶性蛋白含量,而同时供应Fe时这种降低作用消失.Fe处理降低了水稻地上部和根系Cd含量,Cd处理也降低了Fe含量,两者表现出明显的相互抑制作用.高Cd(1.0μmol·L-1)和Fe互作,增加了水稻根系中MDA和可溶性蛋白含量,降低了超氧化物岐化酶(SOD)和过氧化氢酶(CAT)活性.表明在低Cd环境中为水稻提供一定数量的外源Fe能降低植株Cd含量;但高Cd胁迫将降低水稻对Fe的吸收,并导致植株体内产生脂质过氧化.     

Comparative study of alloxan effects in copper-loaded and iron-loaded rats: lipid peroxidation, protein oxidation, proteasome and antioxidant enzyme activities

The in-vivo effects of alloxan on protein oxidation and lipid peroxidation, as well as on proteasome and antioxidant enzyme activities in liver and kidney of copper-loaded and iron-loaded rats, were studied. In control animals, a single alloxan dose (120 mg/kg, i.p.) increased blood-glucose concentration at the 24^th hr and 48^th hr and, especially, on the 5^th day. For these periods of alloxan action, no changes in lipid peroxidation and antioxidant enzyme activities were found; only a slight increase of carbonyl content and strong increase of trypsin-like proteasome activity in rat liver on the 5^th day was observed. Five days after alloxan injection, the blood-glucose concentration in iron-pretreated rats was similar to that of the controls. However, it was significantly lower in copper-pretreated animals; hence, insulin-mimetic action of copper might be suggested. The lower proteasome activity, measured in liver of copper-pretreated diabetic rats is probably due to a potential copper-chelating ability of alloxan. The present results showed that the action of alloxan was different in copper-and iron-pretreated rats. Analogous studies, using pretreatment with other metals, would contribute to a further elucidation of the role of different metals in diabetes development, especially in regions with environmental metal contamination.     

Effects of thermal stress on lipid peroxidation and antioxidant enzyme activities of the predatory mite,Neoseiulus cucumeris (Acari: Phytoseiidae)

Changes in temperature are known to cause a variety of physiological stress responses in insects and mites. Thermal stress responses are usually associated with the increased generation of reactive oxygen species (ROS), resulting in oxidative damage. In this study, we examined the time-related effect (durations for 1, 2, 3, and 5 h) of thermal stress conditions—i.e., relatively low (0, 5, 10, and 15 °C) or high (35, 38, 41, and 44 °C) temperatures—on the activities of antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), glutathione S-transferases (GSTs), and total antioxidant capacity (T-AOC) of the predatory mite Neoseiulus cucumeris. Also the lipid peroxidation (LPO) levels of the predatory mite were measured under thermal stress conditions. The results confirmed that thermal stress results in a condition of so-called oxidative stress and the four antioxidant enzymes play an important role in combating the accumulation of ROS in N. cucumeris. CAT and POX activity changed significantly when the mites were exposed to cold and heat shock, respectively. The elevated levels of SOD and GSTs activity, expressed in a time-dependent manner, may have an important role in the process of antioxidant response to thermal stress. However, the levels of LPO in N. cucumeris were high, serving as an important signal that these antioxidant enzyme-based defense mechanisms were not always adequate to counteract the surplus ROS. Thus, we hypothesize that thermal stress, especially extreme temperatures, may contribute much to the generation of ROS in N. cucumeris, and eventually to its death.     

Effect of cadmium on antioxidant enzyme activities and lipid peroxidation in the gills of the clam Ruditapes decussatus

Metals are known to influence the oxidative status of marine organisms, and antioxidant enzymes have been often proposed as biomarkers of effect. The clam Ruditapes decussatus is a well-known metal bioindicator. In this species cadmium (Cd) induces metallothionein (MT) synthesis only after 7 days of exposure. Before MT synthesis is induced, the other mechanisms capable of handling the excess of Cd are unknown. In order to identify some of these mechanisms, variations in antioxidant systems (superoxide dismutase, catalase, selenium-dependent glutathione peroxidase and non-selenium-dependent glutathione peroxidase), malondialdehyde (MDA) and MT were studied in the gills of R. decussatus exposed to different Cd concentrations (4, 40 and 100 gl^-1) for 28 days. These parameters, together with total proteins and Cd concentrations, were measured in the gills of the clams over different periods of exposure. Results indicate that Cd accumulation increased linearly in the gills of R. decussatus with the increase in Cd concentration. This increase induces an imbalance in the oxygen metabolism during the first days of Cd exposure. An increase in cytosolic superoxide dismutase (SOD) activity and a decrease in mitochondrial SOD activity was observed at the same time as or after a decrease in cytosolic and mitochondrial catalase activity and of selenium-dependent and non-selenium-dependent glutathione peroxidase activity. After 14 days of exposure, Cd no longer affect these enzymes but there was elevation of other cellular activities, such as MDA and MT production. MT bound excess Cd present in the cell. These variations in these parameters suggest their potential use as biomarkers of effects such as oxidative stress resulting from Cd contamination in molluscs.     

Effect of cadmium on antioxidant enzyme activities and lipid peroxidation in the gills of the clam Ruditapes decussatus

Metals are known to influence the oxidative status of marine organisms, and antioxidant enzymes have been often proposed as biomarkers of effect. The clam Ruditapes decussatus is a well-known metal bioindicator. In this species cadmium (Cd) induces metallothionein (MT) synthesis only after 7 days of exposure. Before MT synthesis is induced, the other mechanisms capable of handling the excess of Cd are unknown. In order to identify some of these mechanisms, variations in antioxidant systems (superoxide dismutase, catalase, selenium-dependent glutathione peroxidase and non-selenium-dependent glutathione peroxidase), malondialdehyde (MDA) and MT were studied in the gills of R. decussatus exposed to different Cd concentrations (4, 40 and 100 gl^-1) for 28 days. These parameters, together with total proteins and Cd concentrations, were measured in the gills of the clams over different periods of exposure. Results indicate that Cd accumulation increased linearly in the gills of R. decussatus with the increase in Cd concentration. This increase induces an imbalance in the oxygen metabolism during the first days of Cd exposure. An increase in cytosolic superoxide dismutase (SOD) activity and a decrease in mitochondrial SOD activity was observed at the same time as or after a decrease in cytosolic and mitochondrial catalase activity and of selenium-dependent and non-selenium-dependent glutathione peroxidase activity. After 14 days of exposure, Cd no longer affect these enzymes but there was elevation of other cellular activities, such as MDA and MT production. MT bound excess Cd present in the cell. These variations in these parameters suggest their potential use as biomarkers of effects such as oxidative stress resulting from Cd contamination in molluscs.     

Effects of soy protein and genistein on blood glucose, antioxidant enzyme activities, and lipid profile in streptozotocin-induced diabetic rats

In the current study, the effect of soy protein and genistein, one of the main isoflavones in soybeans, on blood glucose, lipid profile, and antioxidant enzyme activities in streptozotocin (STZ)-induced diabetic rats was investigated. Male Sprague-Dawley rats were divided into nondiabetic control, STZ, STZ-genistein supplemented group (STZ-G; 600 mg/kg diet), and STZ-isolated soy protein supplemented group (STZ-ISP; 200 g/kg diet). Diabetes was induced by a single injection of STZ (50 mg/kg BW) freshly dissolved in 0.1 mol/L citrate buffer (pH 4.5) into the intraperitonium. Diabetes was confirmed by measuring the fasting blood glucose concentration 48-h post-injection. The rats with blood glucose level above 350 mg/dL were considered to be diabetic. Genistein and ISP were supplemented in the diet for 3 weeks. The supplementation of genistein and ISP increased the plasma insulin level but decreased the HbA(IC) level of the STZ-induced diabetic rats. The supplementation of genistein and ISP increased the glucokinase level of the STZ-induced diabetic rats. A significant reduction in glucose-6-phosphatase was observed in the groups treated with genistein and ISP in comparison with the diabetic control group. Hepatic superoxide dismutase, catalase, and glutathione peroxidase activities of the STZ-induced diabetic rats were significantly decreased in comparison with the control rats. Administering genistein and ISP to the STZ-induced diabetic rats significantly increased those enzyme activities. The concentration of thiobarbituric acid reactive substances in the STZ-induced diabetic rats was significantly elevated, while the genistein and ISP supplement decreased it to the control concentration. Genistein and ISP supplements seem to be beneficial for correcting the hyperglycemia and preventing diabetic complications.     

Thyroid hormones regulate lipid peroxidation and antioxidant enzyme activities in Anabas testudineus (Bloch)

Glutathione S-transferases (GST) play an important role in the detoxification of many substances including allelochemicals from plants. Brassicaceae plants contain glucosinolates and emit volatile isothiocyanates which affect the GST system. A comparison of the GST of two aphid species, the generalist Aulacorthum solani found on Brassicaceae and the Fabaceae specialist Acyrthosiphon pisum, was made to try to explain their respective feeding behaviour. Differences of GST were determined among the two aphid species based on purification by affinity chromatography, SDS-PAGE and on kinetic studies. Purification yields using an epoxy-activated Sepharose 6B column were highly different for the two aphid species (18% and 34% for A. solani and A. pisum, respectively). These variations were confirmed by SDS-PAGE. While only a 27-kDa band was observed for A. pisum, two bands of approximately 25-kDa were visualized for the generalist aphid, A. solani. Considering the kinetic results, differences of Km and Vmax were observed following the aphid species when a range of substrates (CDNB and DCNB) and GSH concentrations were tested. Studies on the detoxification enzymes of generalist and specialist herbivores would be undertaken to determine accurately the effect of the host plant on the organisms eating them, particularly in terms of biochemical and ecological advantages.     

The response of rat liver lipid peroxidation, antioxidant enzyme activities and glutathione concentration to the thyroid hormone.

1. In liver microsomes from hyperthyroid rats NADPH-dependent lipid peroxidation induces a hydroperoxide formation 56% higher than that in euthyroid ones. 2. The addition of 5 microM Fe2+ (or Fe3+) strongly decreases the hydroperoxide level in favour of that of TBA-reactive substances. Higher iron concentrations (30 microM) have no significant effect. 3. In hepatocytes from hyperthyroid rats CCl4-induced lipid peroxidation produces an amount of TBA-reactive substances four times higher than that in those from euthyroid rats. 4. In the liver of hyperthyroid rats a GSH concentration decrease (by about 35%) is found while the opposite occurs in the blood of the same animals where GSH increases 2.5 times. 5. It is shown that in the liver of hyperthyroid rats, besides higher lipid peroxidation, a more active defense mechanism is operating since both glutathione peroxidase and glutathione reductase specific activities are higher than in euthyroid rats.     

Age-related changes of antioxidant enzyme activities, glutathione status and lipid peroxidation in rat erythrocytes after heat stress

The aim of this study was to determine whether exposure to heat stress would lead to oxidative stress and whether this effect varied with different exposure periods. We kept 1-, 6- and 12-month-old male Wistar rats at an ambient temperature of either 22 degrees C or 40 degrees C for 3 and 7 days and measured glucose-6-phosphate dehydrogenase (G-6-PD), Cu,Zn-superoxide dismutase (Cu,Zn-SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GSH-Px) and glutathione-S-transferase (GST) activities and levels of thiobarbituric acid-reactive substances (TBARS), reduced glutathione (GSH) and oxidized glutathione (GSSG) in erythrocytes and determined GSH/GSSG ratio, total glutathione and the redox index. G-6-PD and CAT activities were found to be significantly increased in 1- and 6-month-old rats after 3 and 7 days of heat stress, but G-6-PD activities decreased in 12-month-old rats. Cu, Zn-SOD activity decreased in 1-month-old rats after heat stress, whereas it increased in 6- and 12-month-old rats. GST activity increased in all groups. GSH and total GSH levels and GSH/GSSG ratios decreased in 1- and 6-month-old rats but they increased in 12-month-old rats after heat stress. GSSG levels increased in 1- and 6-month-old rats but decreased in 12-month-old rats after heat stress. TBARS levels increased in all groups. Seven days of stress is more effective in altering enzyme activities and levels of GSH, GSSG and TBARS. When the effects of both heat stress and aging were examined together, it was interesting to note that they mostly influenced G-6-PD activity.     

Changes in antioxidant enzyme activities, fatty acid composition and lipid peroxidation in Daphnia magna during the aging process

Age-related changes in the balance between endogenous pro-oxidative and antioxidative processes in the freshwater cladoceran Daphnia magna (Crustacea) were assessed. The activities of key antioxidant enzymes including catalase, superoxide dismutase and glutathione peroxidase and levels of lipid peroxidation measured as thiobarbituric acid-reactive substances (TBARS) were determined in eight age classes, covering juvenile, young and senescent adults. Age-related changes in fatty acid composition were also measured to examine the contribution of polyunsaturated fatty acids (PUFA) in the peroxidation status of animals. Biochemical responses depicted in this study demonstrated that age-related decline in survival was accompanied by increasing oxidative stress and oxidative damage. Enhanced oxidative stress in aging D. magna was suggested by the significant increase in the formation of lipid peroxides, and a concomitant reduction of unsaturated fatty acids of 20 or more carbon atoms. Because aging was accompanied by selective loss of key antioxidant enzymes and small changes in the amount of PUFA, the breakdown of antioxidant defences might have directly contributed to oxidative stress, membrane lipid peroxide and a decline of survival. Indeed, the results reported here, indicate that age-related increases of lipid peroxides were at least partially due to the functional imbalance of enzymatic antioxidant defences.     

Immobilization stress in rat tissues: alterations in protein oxidation, lipid peroxidation and antioxidant defense system

We determined the effects of immobilization stress on antioxidant status, protein oxidation and lipid peroxidation in brain, liver, kidney, heart and stomach of rats. Sixteen male Wistar rats (3 months old) were divided into controls (C) and immobilization stress group (IS). IS rats were immobilized for 180 min/day for 15 days. Plasma corticosterone levels were increased in IS group. Copper,zinc-superoxide dismutase activities were increased in brain, liver and kidney, but decreased in the heart and stomach after immobilization. Catalase activities were increased in brain, kidney and heart, and decreased in liver and stomach. Selenium-dependent glutathione peroxidase activities were decreased in brain and kidney, but increased in heart and stomach. Reduced glutathione levels were decreased, while protein carbonyl, conjugated dienes and thiobarbituric acid-reactive substances levels were increased in all tissues. Our results showed that the response of antioxidant defense system to stress differs for each tissue, and protein oxidation and lipid peroxidation is induced by immobilization stress in peripheral tissues.