Enhanced lipid peroxidation by extracellular ATP in PC12 cells

Recently we have demonstrated that extracellular ATP acts as an excitatory neurotransmitter and enhances cell death in the presence of ferrous ions. By using a newly developed cis-parinaric acid fluorescence technique, we demonstrated that ATP, in a dose dependent manner, enhanced the increased membrane lipid peroxidation in PC12 cells when cells were incubated with micromolar FeCl₂/DTP. P₂ purinoceptor agonists, α,β-methylene ATP and 2-methylthio-ATP, induced PC12 cell lipid peroxidation, but to a lesser extent than ATP. ATP-induced Ca²⁺ influx via P₂ purinoceptor activation significantly increased the intracellular Ca²⁺ concentration, which may have triggered a free radical generating cascade(s), and led to membrane lipid peroxidation and cell death. Since oxidative stress has been implicated in certain neurodegenerative diseases such as aging, extracellular ATP may contribute to neuronal cell death by an oxidative mechanism involving 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.     

Age-related changes in antioxidant enzyme activities and lipid peroxidation in lungs of control and sulfur dioxide exposed rats

Antioxidant defenses within the lung are pivotal in preventing damage from oxidative toxicants. There have also been several reports with conflicting results on the antioxidant system during aging. In this study, we attempted to investigate age-related alterations in both antioxidant enzyme activities and thiobarbituric acid-reactive substances (TBARS), a product of lipid peroxidation, in the whole lung of control and sulfur dioxide (SO₂) exposed rats of different age groups (3-, 12-, and 24-months-old). Swiss-Albino Male rats were exposed to 10 ppm SO₂ 1 hr/day, 7 days/week for 6 weeks. The antioxidant enzymes examined include Cu,Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST). A mixed pattern of age-associated alterations in antioxidant activities was observed. SOD, GSH-Px and GST activities were increased with age, but CAT activity was decreased. Lung SOD, GSH-Px and GST activities were also increased in response to SO₂. The level of TBARS was increased with age. SO₂ exposure stimulated lipid peroxide formation in the lung as indicated by an increase in the level of TBARS. These findings suggest that both aging and SO₂ exposure may impose an oxidative stress to the body. We conclude that the increase in the activities of the antioxidant enzymes of the lung during aging, could be interpreted as a positive feedback mechanism in response to rising lipid peroxidation.     

Antioxidant status and lipid peroxidation in type II diabetes mellitus

Diabetes Mellitus (DM), a state of chronic hyperglycaemia, is a common disease affecting over 124 million individuals worldwide. In this study, erythrocyte glutathione levels, lipid peroxidation, superoxide dismutase, catalase, and glutathione peroxidase and some extracellular antioxidant protein levels of patients with type II diabetes mellitus and healthy controls were investigated. Thirty-eight patients (21 males; with age of mean +/- SD, 53.1+/-9.7 years) and 18 clinically healthy subjects (10 males; with age of mean +/- SD, 49.3+/-15.2 years) were included in the study. Levels of erythrocyte lipid peroxidation, serum ceruloplasmin and glucose levels, HbA1C levels, and erythrocyte catalase activity were significantly increased, whereas serum albumin and transferrin levels, erythrocyte glutathione levels, and glutathione peroxidase activity were significantly decreased compared to those of controls. There was no significant difference in superoxide dismutase activity compared to controls. The results suggest that the antioxidant deficiency and excessive peroxide-mediated damage may appear in non-insulin dependent diabetes mellitus.     

Antioxidant status,lipid peroxidation,mixed function oxidase and UDP-glucuronyl transferase activities in livers from control and DOCA salt-hypertensive male Sprague Dawley rats

The effects of DOCA-salt hypertensive treatment on hepatic glutathione-dependent defense system, antioxidant enzymes, lipid peroxidation, mixed function oxidase and UDP-glucuronyl transferase activities were investigated in male Sprague Dawley rats.Compared with controls, DOCA-salt hypertensive rats had lower body weights (linked to liver hypertrophy). Mixed function oxidase and p-nitrophenol-UGT activities were not affected by the treatment but a significant lower rate of the glucuronoconjugation rate of bilirubin (p < 0.001) was observed in DOCA-salt hypertensive rats. While cytosolic glutathione contents and glutathione reductase activity were not affected, glutathione peroxidase (p < 0.001), glutathione transferase (p < 0.001) and catalase (p < 0.01) activities were decreased and associated with higher malondialdehyde contents (p < 0.001) in treated rats. The imbalance in liver antioxidant status (increasing generation of cellular radical species), associated with increases in lipid peroxidation, suggests that oxidative stress might be directly related to arterial hypertension in DOCA-salt treated male Sprague Dawley rats.     

Mannosylerythritol lipid increases levels of galactoceramide in and neurite outgrowth from PC12 pheochromocytoma cells

We report here that a microbial extracellular glycolipid,mannosylerythritol lipid (MEL), induces the outgrowth ofneurites from and enhances the activity of acetylcholinesterase(AChE) in PC12 pheochromocytoma cells. Furthermore, treatment ofPC12 cells with MEL increased levels of galactosylceramide(Gal1-1Cer; GalCer). Exposure of PC12 cells to exogenous GalCer caused the dose-dependent outgrowth ofneurites. By contrast, treatment of PC12 cells with nerve growthfactor (NGF) did not increase the level of GalCer in the cells. The neurite-related morphological changes induced by GalCerdifferend from those induced by NGF, indicating differencesbetween the signal transduction pathways triggered by NGF and by GalCer.Both authors contributed equally to this work.     

Arachidonic acid converts the glutathione depletion-induced apoptosis to necrosis by promoting lipid peroxidation and reducing caspase-3 activity in rat glioma cells

Intracellular glutathione (GSH) depletion induced by buthionine sulfoximine (BSO) caused cell death that seemed to be apoptosis in C6 rat glioma cells. Arachidonic acid (AA) promoted BSO-induced cell death by accumulating reactive oxygen species (ROS) or hydroperoxides. AA inhibited caspase-3 activation and internucleosomal DNA fragmentation during the BSO-induced GSH depletion. Furthermore, AA reduced intracellular ATP content, induced dysfunction of mitochondrial membrane and enhanced 8-hydroxy-2'-deoxyguanosine (8-OH-dG) production. There was significant increase of 12-lipoxygenase activity in the presence of AA under the BSO-induced GSH depletion in C6 cells. These results suggest that AA promotes cell death by changing to necrosis from apoptosis through lipid peroxidation initiated by lipid hydroperoxides produced by 12-lipoxygenase under the GSH depletion in C6 cells. Some ROS such as hydroperoxide produced by unknown pathway make hydroxy radicals and induce 8-OH-dG formation in the cells. The conversion of apoptosis to necrosis may be a possible event under GSH depleted conditions.     

Paraquat-Induced Cell Death in PC12 Cells

Paraquat was taken up by PC12 cells in a carrier-mediated, saturable manner. When PC12 cells were permeabilized with digitonin (50 g/ml) lipid peroxidation was observed after paraquat treatment in the presence of NADPH and chelated iron. The fact that lipid peroxidation preceded the appearance of LDH release provides positive evidence that lipid peroxidation may be one of the important factors leading to cytotoxicity of cells. Furthermore, the fact that addition of superoxide dismutase, catalase and promethazine efficiently blocked the malondialdehyde formation and attenuated the cell death indicated the involvement of reactive oxygen radicals in mediating the cytotoxicity induced by paraquat. Taken together the results present in vitro evidence that neurotoxicity of paraquat may be a consequence of cellular lipid peroxidation, which leads to cell death and may have great implications in assessing the risk of exposure to paraquat in Parkinson's disease.     

Uniconazole-induced alleviation of freezing injury in relation to changes in hormonal balance, enzyme activities and lipid peroxidation in winter rape

Winter rape (Brassica napus L. cv. 601) seedlings were treated with 50 mg.l-1 of foliar-applied uniconazole and then exposed to freezing stress with a light/dark temperature regime of 2 °C/–3 °C for 5 days at the seedling stage. Stressed plants contained lower endogenous GA3 and IAA contents than the controls, while zeatin and ABA contents and ethylene levels were significantly increased. Uniconazole-treated plants had lower endogenous GA3 and IAA contents, and higher zeatin and ABA contents and ethylene levels. Leaf chlorophyll content and respiratory capacity of roots were reduced significantly after plants were subjected to freezing stress, and foliar sprays of uniconazole retarded the degradation of chlorophyll and increased respiratory capacity of roots. Uniconazole-induced freezing tolerance was accompanied by increased activities of various antioxidant enzymes, including superoxide dismutase, catalase and peroxidase. Foliar applications of uniconazole reduced electrolyte leakage and malondialdehyde accumulation caused by freezing stress, suggesting that uniconazole may have decreased freezing-induced lipid peroxidation and membrane damage.     

Uniconazole-induced tolerance of rape plants to heat stress in relation to changes in hormonal levels, enzyme activities and lipid peroxidation

Winter rape (Brassica napus L. cv. 601) seedlings were treated with 50 mg.l-1of foliar-applied uniconazole and then exposed to heat stress with a light/dark temperature regime of 43 °C/38 °C for 3 days at the stem elongation stage. Heat stressed plants contained lower endogenous GA3, IAA and zeatin contents than the controls, while ABA content and ethylene level were increased significantly. Uniconazole-treated plants had lower endogenous GA3 and IAA contents, and higher zeatin and ABA contents and ethylene levels. Leaf chlorophyll content and respiratory capacity of roots were reduced markedly after plants were subjected to heat stress, and foliar sprays of uniconazole retarded the degradation of chlorophyll and increased respiratory capacity of roots. Following exposure to heat, the activities of superoxide dismutase and peroxidase were significantly reduced. Uniconazole-induced heat tolerance was accompanied by increased activities of various antioxidant enzymes. Foliar applications of uniconazole reduced electrolyte leakage and malondialdehyde accumulation caused by heat stress, suggesting that uniconazole may have decreased heat-induced lipid peroxidation and membrane damage. Foliar sprays of uniconazole increased the tolerance of rape plants to heat stress.     

Protective effect of lipoic acid on adriamycin induced lipid peroxidation in rat kidney

Adriamycin, which is widely used in the treatment of various neoplastic conditions, exerts toxic effects in many organs. The present study was designed to investigate the effect of lipoic acid upon adriamycin induced peroxidative damages in rat kidney. The increase in peroxidated lipids on adriamycin administration was accompanied by alterations in the antioxidant defense systems. The extent of nephrotoxicity induced by adriamycin was evident from the decreased activities of the enzymes -glutamyl transferase and -glucuronidase in the rat renal tissues. The study was carried out with adult male albino rats of Wistar strain, which comprised of one control and three experimental groups. Group I rats served as controls. GroupII rats received adriamycin (1 mg kg^–1 body wt day^–1) intravenously through the tail vein. Group III rats were given lipoic acid (35 mg kg^–1 body wt day^–1) intraperitoneally. Group IV rats were given lipoic acid 24 h before the administration of adriamycin. Rats subjected to adriamycin administration showed a decline in the thiol capacity of the cell accompanied by high malondialdehyde levels along with lowered activities of catalase, superoxide dismutase, glutathione peroxidase and glutathione metabolizing enzymes (glutathione reductase, glucose-6-phosphate dehydrogenase, glutathione-S-transferase). Lipoic acid pretreatment also restored the activities of -glutamyl transferase and -glucuronidase nearly to control levels thereby suggesting nephroprotection. The study has highlighted the beneficial effects of lipoic acid pretreatment in reversing the damages caused by adriamycin and thereby bringing about an improvement in the oxidative stress parameters.     

Protection by ebselen against cisplatin-induced nephrotoxicity: Antioxidant system

This study was designed to investigate the cisplatin-induced alteration in renal antioxidant system and the nephroprotection with ebselen. Male Wistar rats were injected with (1) vehicle control; (2) cisplatin; (3) ebselen; and (4) cisplatin plus ebselen. Rats were sacrificed three days post-treatment and plasma as well as kidney were isolated and analyzed. Plasma creatinine increased 598% following cisplatin administration alone which decreased by 158% with ebselen pretreatment. Cisplatin-treated rats showed a depletion of renal glutathione (GSH) levels (52% of control), while cisplatin plus ebselen injected rats had GSH values close to the controls. Antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities decreased 38, 75 and 62% of control, respectively, and malondialdehyde (MDA) levels increased 174% of control following cisplatin administration, which were restored to control levels after ebselen treatment. The renal platinum level did not significantly change with ebselen pretreatment. This study suggests that the protection offered by ebselen against cisplatin-induced nephrotoxicity is partly related to the sparing of antioxidant system.     

蛇毒神经生长因子诱导PC12细胞分化超微结构的观察

目的观察蛇毒神经生长因子（Nerve growth factor,NGF）诱导大鼠肾上腺嗜铬细胞瘤细胞系（Pheo—chromocytoma cells。PC12）细胞分化后,细胞超微结构的改变。方法取对数生长期PC12细胞接种24孔板,设200ng／ml NGF实验组和对照组。培养72h,离心,分别收集细胞制成电镜标本,镜下观察各组细胞超微结构的改变。结果与对照组细胞相比,实验组细胞长出大量突起．并且胞质的细胞器逐渐消失．出现较多的脂滴。结论广西眼镜蛇毒神经生长因子可以促进PC12细胞增殖．并诱导其向神经样细胞分化,长出突触。     

Age-dependent changes in rat liver lipid peroxidation and glutathione content induced by acute ethanol ingestion

The study of the influence of the age of animals (13 to 53 weeks) on total liver thiobarbituric acid reactive substances (TBAR) content showed an increase which is maximal in rats of 39 weeks of age compared to young animals (13 weeks), followed by a dimunition in the 53 weeks old group. In this situation, the content of hepatic GSH and total GSH equivalents as well as the GSH/GSSG ratio were decreased with ageing, while GSSG levels were enhanced in the oldest group studied. Acute ethanol intoxication resulted in a marked increase in liver TBAR content in young animals, together with a decline in GSH, total GSH equivalents and GSH/GSSG ratio, and an enhancement in GSSG. These changes elicited by ethanol intake were reduced with ageing. It is concluded that ethanol-induced oxidative stress in the liver is diminished during ageing, despite the progressive decrease in the glutathione content of the tissue observed in control animals.     

Effect of cadmium on lipid peroxidation and activities of antioxidant enzymes in growing pigs

Malondialdehyde (MDA), glutathione (GSH) content, total antioxidant capacity (T-AOC) levels, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and glutathione transferase (GST) activities were studied in serum, liver, and kidney of growing pigs after graded doses of cadmium administration in diets. One hundred ninety-two barrows (Duroc x Landrace x Yorkshire), with similar initial body weight 27.67±1.33 kg, were randomly allotted into 4 different treatments with 3 replications (16 pigs per replication). The treatments received the same basal diet added with 0, 0.5, 5.0, and 10.0 mg/kg cadmium (as CdCl₂), respectively. The results showed pigs treated with 10 mg/kg cadmium significantly decreased average daily gain (ADG) (p<0.05) and increased feed/gain ratio (F/G) (p<0.05) compared to the control. In this treatment, the contents of MDA increased significantly (p<0.05), GSH concentrations, T-AOC levels, and the activities of SOD, GSH-PX, and GST decreased significantly (p<0.05). The results indicate 10 mg/kg cadmium could decrease pig antioxidant capacity after extended exposure and cadmium-induced increase lipid peroxidation might not be only the result of the possibility of lower level of GSH but could also be as a result of direct action of cadmium on peroxidation reaction.     

Formation of active oxygen species and lipid peroxidation induced by hypochlorite.

Hypochlorite or its acid, hypochlorous acid, may exert both beneficial and toxic effects in vivo. In order to understand the role and action of hypochlorite, the formation of active oxygen species and its kinetics were studied in the reactions of hypochlorite with peroxides and amino acids. It was found that tert-butyl hydroperoxide and methyl linoleate hydroperoxide reacted with hypochlorite to give peroxyl and/or alkoxyl radicals with little formation of singlet oxygen in contrast to hydrogen peroxide, which gave singlet oxygen exclusively. Amino acids and ascorbate reacted with hypochlorite much faster than peroxides. Free radical-mediated lipid peroxidation of micelles and membranes in aqueous suspensions was induced by hypochlorite, the chain initiation being the decomposition of hydroperoxides by hypochlorite. It was suppressed efficiently by ebselen which reduced hydroperoxides and by alpha-tocopherol, which broke chain propagation, but less effectively by hydrophilic antioxidants present in the aqueous phase. Cysteine suppressed the oxidation, but it was poorer antioxidant than alpha-tocopherol. Ascorbate also exerted moderate antioxidant capacity, but it acted as a synergist with alpha-tocopherol. Taken together, it was suggested that the primary target of hypochlorite must be sulfhydryl and amino groups in proteins and that the lipid peroxidation may proceed as the secondary reaction, which is induced by radicals generated from sulfenyl chlorides and chloramines.     

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.     

Plasma iron is associated with lipid peroxidation in an elderly population

Epidemiological evidence has raised concern that a moderate elevation in body iron stores may increase oxidative stress and risk of heart disease. We examined the cross-sectional association between plasma iron and factors that could affect its levels (antioxidant enzymes, diet), with the concentration of plasma malondialdehyde (MDA) as a marker of lipid peroxidation. Participants were 162 non-smoking institutionalised elderly. Our results show that those in the highest tertile of plasma iron were at least twice as likely to have higher plasma MDA levels. Among the factors affecting plasma iron levels, we found that the upper tertile of erythrocyte-superoxide dismutase (E-SOD) was inversely associated with higher plasma iron, and potato intake explained a sizeable proportion of the variation in plasma iron levels. In addition to potatoes, eggs, wine, fruit in men and green vegetables in women showed a positive association with plasma iron levels. Only potatoes in both sexes, wine in men and eggs in women had an independent effect on plasma MDA. Potatoes, wine, plasma lycopene and plasma iron accounted for 43% of the variability in plasma MDA for males, and E-SOD, potatoes, eggs, plasma lycopene and plasma iron explained 45% for women. A longitudinal study should confirm, whether these MDA levels are related to morbidity and mortality.     

Tissue lipid peroxidation and glutathione‐dependent enzyme status in patients with oral squamous cell carcinoma

We examined the extent of lipid peroxidation and the status of reduced glutathione (GSH) and the GSH‐dependent enzymes—glutathione peroxidase (GPx) and glutathione‐S‐transferase (GST)—in oral tumour tissues from 33 adult oral cancer patients and an equal number of age‐ and sex‐matched normal subjects. Diminished lipid peroxidation in the oral tumour tissue was accompanied by a significant decrease in phospholipids and an increase in the cholesterol/phospholipid (C/P) ratio. The concentration of glutathione and the activities of GPx and GST were elevated in oral tumour tissues. These findings suggest that GSH‐ and GSH‐dependent enzymes play a crucial role in tobacco‐related tumourigenesis and may be considered as markers of carcinogen exposure. Copyright © 1999 John Wiley & Sons, Ltd.