The quality of the antioxidant defence system in term and preterm twin neonates

Abstract

Objective: Multiple pregnancy is associated with an enhanced metabolism and demand for O2, which may lead to the overproduction of reactive oxygen species and the development of oxidative stress. The degree of oxidative damage depends on the level of the antioxidant protection system of the foetus. The objective of the study was to identify the relationship between the state of the maturity and the antioxidant status of twin neonates. Investigations of the umbilical cord blood were carried out to detect differences in the antioxidant defence system between mature and premature twin neonates.

Methods: The activities of the superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) enzymes, the levels of reduced glutathione (GSH), protein carbonyls and oxidized lipids and the total antioxidant capacity of the plasma were determined.

Results: The level of lipid peroxidation was significantly higher in the premature neonates. An increase in the total antioxidant capacity was accompanied by a decrease in the damaged protein concentration. Significantly elevated activities of GPx alone were observed in the premature twins, though the GSH content too tended to be increased. The activity of SOD was decreased in the premature neonates.

Discussion: The antioxidant status of twin neonates are mainly influenced by maturity. We suggest that the level of lipid peroxidation might be of clinical value as a marker of pre- and perinatal distress in twins.     

Blood glutathione homeostasis as a determinant of resting and exercise-induced oxidative stress in young men

Abstract

Although the importance of glutathione in protection against oxidative stress is well recognised, the role of physiological levels of glutathione and other endogenous antioxidants in protecting against exercise-induced oxidative stress is less clear. We evaluated the role of glutathione and selected antioxidant enzymes as determinants of lipid peroxidation at rest and in response to exercise in men (n = 13–14) aged 20–30 years, who cycled for 40 min at 60% of their maximal oxygen consumption (VO_2max). Levels of plasma thiobarbituric acid reactive substances (plasma TBARS) and blood oxidised glutathione (GSSG) increased by about 50% in response to exercise. Mean blood reduced glutathione (GSH)decreased by 13% with exercise. Of the measured red blood cell (RBC)antioxidant enzyme activities, only selenium-dependent glutathione peroxidase (Se-GPX) activity rose following exercise. In univariate regression analysis, plasma TBARS levels at rest predicted postexercise plasma TBARS and the exercise-induced change in total glutathione (TGSH). Blood GSSG levels at rest were strongly determinant of postexercise levels. Multiple regression analysis showed blood GSH to be a determinant of plasma TBARS at rest. The relative changes in TGSH were determinant of postexercise plasma TBARS. In summary, higher blood GSH and lower plasma TBARS at rest were associated with lower resting, and exercise-induced, lipid peroxidation. Subjects with a favourable blood glutathione redox status at rest maintained a more favourable redox status in response to exercise-induced oxidative stress. Changes in blood GSH and TGSH in response to exercise were closely associated with both resting and exercise-induced plasma lipid peroxidation. These results underscore the critical role of glutathione homeostasis in modulating exercise-induced oxidative stress and, conversely, the effect of oxidative stress at rest on exercise-induced changes in glutathione redox status.     

Short-term gemfibrozil treatment reverses lipid profile and peroxidation but does not alter blood glucose and tissue antioxidant enzymes in chronically diabetic rats

In this study, we investigated the efficiency of short-term treatment with gemfibrozil in the reversal of diabetes-induced changes on carbohydrate and lipid metabolism, and antioxidant status of aorta. Diabetes was induced by a single injection of streptozotocin (45 mg/kg, i.p.). After 12 weeks of induction of diabetes, the control and diabetic rats were orally gavaged daily with a dosing vehicle alone or with 100 mg/kg of gemfibrozil for 2 weeks. At 14 weeks, there was a significant increase in blood glucose, plasma cholesterol and triglyceride levels of untreated-diabetic animals. Diabetes was associated with a significant increase in thiobarbituric acid reactive substances (TBARS) in both plasma and aortic homogenates, indicating increased lipid peroxidation. Diabetes caused an increase in vascular antioxidant enzyme activity, catalase, indicating existence of excess hydrogen peroxide (H₂O₂). However, superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) activities in aortas did not significantly change in untreated-diabetic rats. In diabetic plus gemfibrozil group both plasma lipids and lipid peroxides showed a significant recovery. Gemfibrozil treatment had no effect on blood glucose, plasma insulin and vessel antioxidant enzyme activity of diabetic animals. Our findings suggest that the beneficial effect of short-term gemfibrozil treatment in reducing lipid peroxidation in diabetic animals does not depend on a change of glucose metabolism and antioxidant status of aorta, but this may be attributed to its decreasing effect on circulating lipids. The ability of short-term gemfibrozil treatment to recovery of metabolism and peroxidation of lipids may be an effective strategy to minimize increased oxidative stress in diabetic plasma and vasculature.     

Oxidative damages in erythrocytes of patients with metabolic syndrome

The aim of the study was to estimate the changes caused by oxidative stress in structure and function of membrane of erythrocytes from patients with metabolic syndrome (MS). The study involved 85 patients with MS before pharmacological treatment and 75 healthy volunteers as a control group. Cholesterol level, lipid peroxidation, glutathione level (GSH), and antioxidant enzyme activities in erythrocytes were investigated. The damage to erythrocyte proteins was also indicated by means of activity of ATPase (total and Na⁺,K⁺ ATPase) and thiol group level. The membrane fluidity of erythrocytes was estimated by the fluorescent method. The cholesterol concentration and the level of lipid peroxidation were significantly higher, whereas the concentration of proteins thiol groups decreased in the patient group. ATPase and GSH peroxidase activities diminished compared to those in the control group. There were no differences in either catalase or superoxide dismutase activities. The membrane fluidity was lower in erythrocytes from patients with MS than in the ones from control group. These results show changes in red blood cells of patients with MS as a consequence of a higher concentration of cholesterol in the membrane and an increased oxidative stress.     

Blood glutathione homeostasis as a determinant of resting and exercise-induced oxidative stress in young men

Although the importance of glutathione in protection against oxidative stress is well recognized, the role of physiological levels of glutathione and other endogenous antioxidants in protecting against exercise-induced oxidative stress is less clear. We evaluated the role of glutathione and selected antioxidant enzymes as determinants of lipid peroxidation at rest and in response to exercise in men (n = 13-14) aged 20-30 years, who cycled for 40 min at 60% of their maximal oxygen consumption (VO2max). Levels of plasma thiobarbituric acid reactive substances (plasma TBARS) and blood oxidised glutathione (GSSG) increased by about 50% in response to exercise. Mean blood reduced glutathione (GSH) decreased by 13% with exercise. Of the measured red blood cell (RBC) antioxidant enzyme activities, only selenium-dependent glutathione peroxidase (Se-GPX) activity rose following exercise. In univariate regression analysis, plasma TBARS levels at rest predicted postexercise plasma TBARS and the exercise-induced change in total glutathione (TGSH). Blood GSSG levels at rest were strongly determinant of postexercise levels. Multiple regression analysis showed blood GSH to be a determinant of plasma TBARS at rest. The relative changes in TGSH were determinant of postexercise plasma TBARS. In summary, higher blood GSH and lower plasma TBARS at rest were associated with lower resting, and exercise-induced, lipid peroxidation. Subjects with a favourable blood glutathione redox status at rest maintained a more favourable redox status in response to exercise-induced oxidative stress. Changes in blood GSH and TGSH in response to exercise were closely associated with both resting and exercise-induced plasma lipid peroxidation. These results underscore the critical role of glutathione homeostasis in modulating exercise-induced oxidative stress and, conversely, the effect of oxidative stress at rest on exercise-induced changes in glutathione redox status.     

Aerobic and anaerobic training effects on the antioxidant enzymes of the blood.

The purpose of the present study was to investigate the effects of aerobic and anaerobic training on serum lipid peroxidation levels and on antioxidant enzyme activities. Long distance runners for aerobic training group, and wrestlers for anaerobic training group were chosen. Non-sporting men were used as control group. When the aerobic power was compared; indirect VO2max of long-distance runners were found higher than wrestlers and control group (p<0.001, p<0.001). When lipid peroxidation levels were compared; levels of the thiobarbituric acid reactive substances (TBARS) of long distance runners were found to be lower than those in the control group (p<0.05), but similar to those found in wrestlers. Comparison of antioxidant enzyme activities in erythrocytes show that there were no significant difference among the groups in superoxide dismutase enzyme activities, but glutathione peroxidase (GPx) activity of long distance runners was higher than that measured in wrestlers (p<0.05). These results suggest that aerobic training increased in erythrocytes GPx activity with a subsequent decrease in plasma TBARS levels but anaerobic training had no effect on this process.     

Protective effect of glutathione and selenium against alloxan induced lipid peroxidation and loss of antioxidant enzymes in erythrocytes

Alloxan is a diabetogenic drug and is known to induce diabetes through generation of free radicals. The toxic oxygen species can be detoxified by antioxidant enzyme system and thus reduce the deleterious effect of lipid peroxidation. Erythrocytes exposed to alloxan induced lipid peroxidationin vivo as well asin vitro. Although alloxan treatment produced a deleterious effect on antioxidant enzymes, pretreatment with glutathione and selenium led to a recovery of the activities of superoxide dismutase and glutathione peroxidase. However, catalase activity increased on alloxan treatment. Alloxan reduced blood glucose level significantly within 60 min but thereafter a slow and steady rise was observed.     

Cholesterol-rich diets have different effects on lipid peroxidation, cholesterol oxides, and antioxidant enzymes in rats and rabbits

The objective of this study was to compare the effect of cholesterol feeding of rats and rabbits. The levels of lipid peroxidation products and oxysterols in the plasma of the two species plus the antioxidant enzyme activities in the liver and erythrocytes were measured to explain their different susceptibilities to atherosclerosis. Our study showed that rats are less susceptible than are rabbits to the atherogenic effect of a cholesterol-rich diet because of differences in lipid peroxidation products as well as antioxidant enzymes activities in their livers. In rabbits, cholesterol feeding produced severe hypercholesterolemia (43-fold increase) and increased plasma and liver lipid peroxidation. Total as well as the individual oxysterol contents of 7alpha-, 7beta-hydroxycholesterol, alpha-epoxy, beta-epoxycholesterol, cholestanetriol, 7-keto, and 27-hydroxycholesterol significantly increased in the plasma of hypercholesterolemic (HC) rabbits. Erythrocyte glutathione peroxidase (GSH-Px) activity significantly decreased whereas catalase activity significantly increased in HC rabbits. In rats cholesterol feeding increased the plasma cholesterol only twofold and had no effect on plasma or liver lipid peroxidation. Only 7alpha- and 7beta-hydroxycholesterol increased and no change was observed in any of the antioxidant enzymes activity in the erythrocytes. Although cholesterol feeding caused a 10-fold increase of liver cholesterol as ester in both rats and rabbits, the antioxidant enzyme GSH-Px and catalase activities in the liver significantly increased in rats but significantly decreased in rabbits. The increase of GSH-Px and catalase activities in the liver of cholesterol fed rats could have a protective role against oxidation, thus preventing the formation of lipid peroxidation and oxysterols.     

Lipid peroxidation and antioxidant status in blood of patients with uterine myoma, endometrial polypus, hyperplastic and malignant endometrium

Oxidative stress is considered to be involved in pathogenesis of many disorders of the female genital tract. In this study, we explored the lipid peroxidation levels and antioxidant enzyme activities in women diagnosed with different forms of uterine diseases in order to evaluate the extent of oxidative stress in blood of such patients. Blood samples of healthy subjects and gynecological patients were collected and subjected to assays for superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and lipid hydroperoxides. The results show that alterations of measured parameters vary with the enzyme type and diagnosis. However, both reduction in antioxidants and elevation of lipid peroxidation were observed in general. Lipid hydroperoxides level was negatively correlated to superoxide dismutase and glutathione peroxidase activities, as well as positively correlated to catalase activity. In addition, the lipid hydroperoxides/ glutathione peroxidase ratio was found to be increased, according to the type of uterine disease. The obtained results show that perturbation of antioxidant status is more pronounced in blood of patients with premalignant (hyperplastic) and malignant (adenocarcinoma) lesions, compared to those with benign uterine changes such as polypus and myoma.     

Oxidant/antioxidant status in blood of patients with malignant breast tumour and benign breast disease

The aim of this study was to investigate the alterations in lipid peroxidation and antioxidant enzyme defences in the blood of patients with malignant breast tumour and benign breast disease. Forty patients with malignant breast tumour, 20 patients with benign breast disease and also 20 healthy control subjects were recruited for the study. Malondialdehyde levels in plasma and erythrocytes, and the activities of erythrocyte CuZn-superoxide dismutase, catalase, glutathione peroxidase and glucose-6-phosphate dehydrogenase were measured. Malondialdehyde levels were higher in patients with both benign breast disease and malignant breast tumour compared with control subjects. The activities of all antioxidant enzymes were higher in patients with malignant breast tumour, while only glutathione peroxidase and CuZn-superoxide dismutase activities were higher in patients with benign breast disease. Except for glucose-6-phosphate dehydrogenase, the antioxidant enzymes studied correlated positively with the malondialdehyde levels in patients with malignant breast tumour. On the other hand, only glucose-6-phosphate dehydrogenase activity was increased by the level of malignancy. The activity increases in erythrocyte antioxidant enzymes may be a compensatory upregulation in response to increased oxidative stress especially in patients with malignant breast tumour.     

Antioxidant enzyme activities and lipid peroxidation in the freshwater cladoceran Daphnia magna exposed to redox cycling compounds

Contaminant-related changes in antioxidative processes in the freshwater crustacea Daphnia magna exposed to model redox cycling contaminant were assessed. Activities of key antioxidant enzymes including catalase, superoxide dismutase, glutathione peroxidase and glutathione S-transferases and levels of lipid peroxidation measured as thiobarbituric acid-reactive substances (TBARS) and lipofucsin pigment content were determined in D. magna juveniles after being exposed to sublethal levels of menadione, paraquat, endosulfan, cadmium and copper for 48 h. Results denoted different patterns of antioxidant enzyme responses, suggesting that different toxicants may induce different antioxidant/prooxidant responses depending on their ability to produce reactive oxygen species and antioxidant enzymes to detoxify them. Low responses of antioxidant enzyme activities for menadione and endosulfan, associated with increasing levels of lipid peroxidation and enhanced levels of antioxidant enzyme activities for paraquat, seemed to prevent lipid peroxidation, whereas high levels of both antioxidant enzyme activities and lipid peroxidation were found for copper. For cadmium, low antioxidant enzyme responses coupled with negligible increases in lipid peroxidation indicated low potential for cadmium to alter the antioxidant/prooxidant status in Daphnia. Among the studied enzymes, total glutathione peroxidase, catalase and glutathione S-transferase appeared to be the most responsive biomarkers of oxidative stress.     

Cold-stress-induced modulation of antioxidant defence: role of stressed conditions in tissue injury followed by protein oxidation and lipid peroxidation

The aim of this study was to determine the effects of cold stress on antioxidant enzyme activities and examine protein oxidation and lipid peroxidation in various tissues (brain, liver, kidney, heart and stomach). Twenty male Wistar rats (3 months old) weighing 220 ± 20 g were used. The rats were randomly divided into two groups of ten: the control group and the cold stress group. Cold stress was applied to the animals by maintaining them in a cold room (5 °C) for 15 min/day for 15 days. Blood samples were taken for measuring plasma corticosterone levels. Tissues were obtained from each rat for measuring the antioxidant enzyme activities, protein oxidation and lipid peroxidation. Corticosterone levels were increased in the cold stress group. Copper, zinc superoxide dismutase activities were increased in the brains, livers and kidneys, whereas they decreased in the hearts and stomachs of rats in the cold stress group. Catalase activities were increased in the brains, livers, kidneys and hearts, whereas they decreased in the stomachs of rats in the cold stress group. Selenium-dependent glutathione peroxidase activities were increased in the brain, liver, heart and stomach. Reduced glutathione levels were decreased, while levels of protein carbonyl, conjugated diene and thiobarbituric-acid-reactive substances were increased in all tissues of the cold stress group. These results lead us to conclude that cold stress can disrupt the balance in an oxidant/antioxidant system and cause oxidative damage to several tissues by altering the enzymatic and non-enzymatic antioxidant status, protein oxidation and lipid peroxidation.     

Lipid peroxidation and antioxidant enzyme activities in erythrocytes of type I and II alcoholics

Reduced and oxidized glutathione (GSH and GSSG), protein-bound glutathione, lipid peroxidation and antioxidant enzyme activities were determined in the erythrocyte lysates and membranes of type I and II alcoholics in order to clarify the effect of age-of-onset and the duration of the alcohol consumption on erythrocyte oxidant and antioxidant status. The osmotic fragility and susceptibility of the erythrocytes to haemolysis were also determined. Erythrocyte lipid peroxidation was significantly increased but, GSH and protein-bound GSH, GSH/GSSG ratio and antioxidant enzyme activities were markedly decreased in the erythrocytes of the alcoholic subgroups. Erythrocyte count and haemoglobin content in the blood of alcoholics were found to be decreased in accordance with the finding that erythrocytes were more fragile and less resistant to haemolysis particularly in type II alcoholics. The present study showed that ethanol-induced oxidative stress in erythrocytes can lead to haemolysis and membrane-specific injuries in erythrocytes of the alcoholic subtypes.     

Effect of chromium(VI) on the status of plasma lipid peroxidation and erythrocyte antioxidant enzymes in chromium plating workers

OBJECTIVES: The present study was carried out to determine the effect of chromium(VI) on the status of plasma lipid peroxidation and erythrocyte antioxidant enzymes in workers exposed to chromium during chromium plating process. METHODS: Fifty subjects working in chromium plating process formed the study group. An equal number of age-sex matched subjects working in administrative units formed the control group. The control subjects were residing in the same city but away from the work place of study group subjects. Urinary chromium levels were determined by using a graphite furnace atomic absorption spectrophotometer. The plasma lipid peroxidation and erythrocyte antioxidant enzymes were determined by using spectrophotmetric methods. RESULTS: A significant increase of plasma lipid peroxidation and a significant decrease of superoxide dismutase and glutathione peroxidase levels were noted in the study group as compared with the controls. The level of plasma lipid peroxidation was positively and erythrocyte antioxidant enzymes were negatively and significantly correlated with chromium levels in urine. Multiple regression analysis was assessed the oxidative stress associated with chromium and life style confounding factors such as BMI, coffee, tea, alcohol and smoking. The multiple regression analysis showed that the urine chromium levels >10 micro g/g of creatinine, smoking, consumption of green vegetables and BMI variables were significantly associated with the levels of oxidative stress. CONCLUSION: The results show that the increased plasma lipid peroxidation and decreased antioxidant enzymes (superoxide dismutase and glutathione peroxidase) observed in chromium-exposed workers could be used as biomarkers of oxidative stress.     

Ursodeoxycholic acid in primary biliary cirrhosis improves glutathione status but fails to reduce lipid peroxidation

Abstract

Background: Ursodeoxycholic acid (UDCA) may slow progression in primary biliary cirrhosis (PBC), but its effect on survival is controversial. We have previously demonstrated that oxidant stress, with severely depressed plasma glutathione, is a feature of untreated PBC; this study examines the effect of UDCA on lipid peroxidation, antioxidant status and associated processes.

Patients and Methods: Markers of lipid peroxidation, antioxidant status, hepatic fibrogenesis, inflammation, cholestasis and synthetic function were measured at 0, 3, 6, 9 and 12 months in blood and urine from 35 PBC patients receiving UDCA.

Results: Plasma glutathione, reflecting intrahepatic levels, climbed steadily on UDCA; although still subnormal, the median value at 12 months was 2.4-fold higher than the untreated level. Liver enzyme markers and C-reactive protein also improved, whilst PIIINP improved steadily, but the change did not attain statistical significance. Serum bilirubin remained unchanged and total antioxidant capacity, albumin and vitamin E decreased after 12 months' UDCA treatment. 8-Isoprostane increased and malondialdehyde was unchanged.

Conclusions: UDCA treatment partially corrected plasma glutathione status and some other biomarkers greatly improved, but lipid peroxidation was not reduced. UDCA may, therefore, require supplementation with glutathione precursors and/or antioxidant cocktails to reduce oxidant stress and thus delay disease progression to cirrhosis.     

Ganoderma lucidum total triterpenes prevent γ-radiation induced oxidative stress in Swiss albino mice in vivo

Objectives: The in vivo radio-protective effect of total triterpenes isolated from Ganoderma lucidum (Fr.) P. Karst was evaluated using Swiss albino mice, by pre-treatment with total triterpenes for 14 days, followed by a whole body exposure to γ-radiation.

Methods: The activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), and the level of reduced glutathione (GSH) were analysed in liver and brain homogenates. The extent of lipid and protein peroxidation was also estimated in liver and brain homogenates after irradiation. Protection of radiation-induced DNA strand breaks in peripheral blood lymphocytes and bone marrow cells was assessed using the comet assay.

Results: Total triterpenes were highly effective in reducing the levels of lipid peroxidation and protein oxidation to near normal values in both liver and brain tissues. Total triterpenes, when administered in vivo, were also found to be successful in restoring the antioxidant enzyme activities and GSH level in liver and brain of irradiated mice. Administration of total triterpenes, prior to radiation exposure, significantly decreased the DNA strand breaks.

Discussion: The results of the present study thus revealed the potential therapeutic use of Ganoderma total triterpenes as an adjuvant in radiation therapy.     

Effects of simvastatin treatment on oxidant/antioxidant state and ultrastructure of streptozotocin-diabetic rat lung

In the present study, we investigated the effects of simvastatin, a 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitor, on lipid metabolism, lipid peroxidation, antioxidant enzyme activities and ultrastructure of diabetic rat lung. Diabetes was induced by a single injection of streptozotocin (45 mg kg(-1), i.p.). After 8 weeks induction of diabetes, some control and diabetic rats were treated with simvastatin (10 mg kg(-1) rat day(-1); orally) for 4 weeks. Diabetes resulted in significantly high levels of blood glucose and plasma lipids. Malondialdehyde levels were unchanged after 12-week-old diabetic rats, whereas catalase activity significantly decreased in the lung. Glutathione peroxidase activity and nitric oxide level were significantly elevated in the diabetic lung. Histological analysis of the diabetic lung revealed some deterioration in the structure. Simvastatin treatment reduced plasma lipid levels and partially decreased the severity of hyperglycaemia. Catalase, glutathione peroxidase activities and nitric oxide levels were partially restored and accompanied by improved structure in diabetic lung by the simvastatin treatment. These results suggest that structural disturbances and alteration of antioxidative enzyme activities occurred in diabetic lung. Simvastatin treatment may provide some benefits in the maintenance of antioxidant status and structural organization of diabetes-induced injury of lung.     

Effect of nicotinamide on the reactions of peroxide oxidation of biomolecules in the rat brain and erythrocytes in 1,2-dichloroethane toxic injury

It was established that acute poisoning of rats by 1,2-dichloroethane induced considerable changes in lipid peroxidation indices, glutathione content and activity of antioxidant enzymes--superoxidase, catalase, glutathione peroxidase in the brain tissue, erythrocytes and blood plasma. It was shown that nicotinamide in the dose of 200 mg/kg prevented considerable degree of the intoxication caused by 1,2-dichloroethane as well as activation of lipid peroxidation and inhibition of antioxidant defens enzyme activities in tissue of experimental animals.     

Effects of Lead on the Activities of Antioxidant Enzymes in Watercress, <Emphasis Type="Italic">Nasturtium officinale</Emphasis> R. Br.

The aim of the present study is to evaluate the oxidative effects of lead with increased concentrations by the determination of antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (AP)) and lipid peroxidation levels in the stem and leaves of watercress (Nasturtium officinale R. Br.) which was exposed to lead acetate, Pb (CH₃COOH)₂ regime with concentrations of 0, 50, 100, 200, 250, and 500 mg/L Pb in a hydroponic culture. After 14 days, accumulation of lipid peroxidation in stems and leaves and changes in activity of antioxidant enzymes were determined spectrophotometrically. The maximum accumulation was observed in the highest concentration group. In this group, lipid peroxidation levels were three times higher than the control group in the stem and leaves. The highest induction in SOD and GR activities were determined at 200 mg/L Pb group in stem, whereas CAT and AP activities were higher than other groups at the concentration of 250 and 100 mg/L Pb, respectively. The increase in CAT activity was found to be greater than GR, SOD, and AP activities in stems of watercress under Pb treatment. Both lead accumulation and antioxidant enzyme responses were higher in stems than in leaves. The results of the present study suggested that the induction in antioxidant responses could be occurring as an adaptive mechanism to the oxidative potential of lead accumulation.     

Alterations of Antioxidant Enzymes and Oxidative Damage to Macromolecules in Different Organs of Rats During Aging

Oxygen free radicals have been hypothesized to play an important role in the aging process. To investigate the correlation between the oxidative stress and aging, we have determined the levels of oxidative protein damage and lipid peroxidation in the brain and liver, and activities of antioxidant enzymes in the brain, liver, heart, kidney, and serum from the Fisher 344 rats at ages of 1, 6, 12, 18, and 24 months. The results showed that the level of oxidative protein damage (measured as carbonyl content) in the brain and liver was significantly higher in older animals than in young animals. No statistical difference was observed in the lipid peroxidation of the liver and brain between young and old animals. The activities of antioxidant enzymes in most tissues displayed an age-dependent decline. Superoxide dismutases in the heart, kidney, and serum, glutathione peroxidase activities in the serum and kidney, and catalase activities in the brain, liver, and kidney, significantly decreased during aging. Cytochrome c oxidase, an enzyme involved in electron transport in mitochondria, initially increased, but subsequently decreased in the aged brain, whereas no significant alteration was observed in the liver mitochondrial antioxidant enzymes. The present studies suggest that the accumulation of oxidized proteins during aging is most likely to be linked with an age-related decline of antioxidant enzyme activities, whereas lipid peroxidation is less sensitive to predict the aging process.