Lipid peroxidation in erythrocytes

Erythrocytes might be expected to be highly susceptible to peroxidation. Their membranes are rich in polyunsaturated fatty acids; they are continuously exposed to high concentrations of oxygen; and they contain a powerful transition metal catalyst. In fact, autoxidation is held in check in vivo by extremely efficient protective antioxidant mechanisms. These involve cellular enzymes such as superoxide dismutase and glutathione peroxidase, as well as vitamin E; but they mainly reflect effective structural compartmentalisation. This review surveys mechanisms which lead to red cell lipid autoxidation and the role of haemoglobin in these processes. The influence of haemoglobinopathies, of lipid composition and of abnormalities in antioxidant mechanisms induced by exogenous oxidant stress is also considered.     

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.     

Lipid peroxidation in Plasmodium falciparum-parasitized human erythrocytes.

cis-Parinaric acid (PnA) was used as a fluorescent probe to study lipid peroxidation in nonparasitized and Plasmodium falciparum-parasitized erythrocytes, upon challenge by cumene hydroperoxide and tert-butyl hydroperoxide. Parasitized erythrocytes were less susceptible toward lipid peroxidation than nonparasitized erythrocytes with which they had been cultured. Furthermore, nonparasitized erythrocytes cultured together with parasitized cells, and thereafter isolated on a Percoll gradient, were less susceptible toward lipid peroxidation than erythrocytes kept under the same experimental conditions but in the absence of parasitized cells. We concluded, therefore, that the intracellular development of the parasite leads to an increase in the resistance against oxidative stress, not only of the host cell membrane of the parasitized erythrocyte, but also in the plasma membrane of the neighboring cells. The erythrocyte cytosol of parasitized cells and/or the intraerythrocytic parasite was required for the increased protection of the host cell membrane, since ghosts prepared from parasitized erythrocytes were more susceptible to lipid peroxidation than those prepared from nonparasitized ones. Vitamin E content of parasitized erythrocytes was lower than that of nonparasitized cells. However, parasitized erythrocytes promoted extracellular reduction of ferricyanide at higher rates, which might be indicative of a larger cytosolic reductive capacity. It is suggested that the improved response of intact erythrocytes is due to an increased reduction potential of the host-erythrocyte cytosol. The role of vitamin C as a mediator of this process is discussed.     

Lipid peroxidation in the aorta of normotensive and spontaneously hypertensive rats with diabetes mellitus]

We have studied the effects of streptozotocin-induced (STI) diabetes on the lipid peroxidation in the aorta from normotensive (NTR) and spontaneously hypertensive (SHR) rats. In the control SHR quantity of malonyldialdehyde (MDA), conjugated dienes (CD) and arterial pressure where higher than in NTR analogous group. It has been shown that Diabetes in NTR results in significantly increased arterial pressure and quantity of MDA and CD. Under certain conditions in SHR arterial pressure and the other factors remain almost unchanged. It is likely that completely different changes in intensity of lipid peroxidation may evidence breaking adaptation mechanism in diabetic SHR.     

Lipid peroxidation and retinopathy in streptozotocin-induced diabetes.

Using the streptozotocin (STZ)-induced diabetic rat model, we have established a time-related curve for lipid hydroperoxides (LHP) in plasma and have correlated the period corresponding to maximal increase with histologic changes in the outer retina. Measurement of thiobarbituric acid reacting substances (TBARS) provides a convenient assessment of LHP concentration in plasma. Our results demonstrate a seven-fold elevation of TBARS at 10 days post-induction which increased to fifteen times above normal at 22 days and then fell dramatically to below baseline values at 39 days. Structural damage to the retina consisted of a reduction in cell number throughout the inner and outer nuclear layers, disorganization and loss of photoreceptor segments, and dilation of the basal region of the retinal pigment epithelium. The present observations establish a correlation between LHP concentration and retinal structure and function. Taken together with other reports in the literature showing alterations of protective enzymes and antioxidants, it appears that free radicals and lipid peroxidation are involved in the etiology of diabetic retinopathy in the STZ rat model. The TBARS assay is a simple, sensitive and inexpensive method to monitor changes in oxidative status and may prove useful in diagnosis and monitoring of patients with diabetes.     

Lipid peroxidation and cataract formation in experimental diabetes

To investigate the role of lipid peroxidation in diabetic cataractogenesis, malondialdehyde, a breakdown product of lipid peroxidation, was measured in lenses with incipient opacities and in retinas from diabetic rats and in clear lenses and in retinas from normal rats. The malondialdehyde mean values obtained in the transparent and cataractous lenses showed non-significant differences, while non-diabetic rat retinas had a significantly lower mean level of malondialdehyde compared with diabetic rat retinas (p less than 0.01). This indicates that, in streptozotocin-induced diabetic rats, lipid peroxidation is apparently not involved in the development of cataract, but it is quite probably involved in retinal damage. The retina, richer in polyunsaturated fatty acids than other ocular structures, is the elective site of lipid peroxidation and from this membrane peroxidation products might probably diffuse and damage other ocular tissues.     

Lipid peroxidation and antioxidant defence enzyme activity in multiple sclerosis

Changes of state of lipid peroxidation and activity of antioxidant defence enzymes katalase, superoxide dismutase, glutathione peroxidase and glutathione reductase - in the brain and liver tissue of guinea-pig in conditions of different stages of experimental autoimmune encephalomyelitis (EAE; 11th, 21st, 27th day after inoculation) and in blood of multiple sclerosis (MS) patients with different types, degrees of severity and length of disease and blood level of reduced glutathione have been investigated. We have found, that the development of oxidative stress in animal organism during the disease development is progressive and intensive lipid peroxide oxidation without compensation by antioxidant mechanisms have been shown in the late period (27th day) of the experiment. In MS conditions this state was accompanied with high activity of demyelination process, severe degree of neuronal injury and length of disease above 5 years. In addition reduced glutathione level was increased in many patient groups: remitting type, light (II) degree of severity and among the patients with strongly disturbed neurological functions and long course of the disease. The obtained data allow us to suppose that the development of oxidative stress under demyelination conditions is a result of strong metabolic disorders and decrease of antioxidant defence in the patients during the disease development. The necessity of individual approaches for antioxidant therapy of patients with MS is discussed.     

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.     

Transferrin modifications and lipid peroxidation: implications in diabetes mellitus

Free iron is capable of stimulating the production of free radicals which cause oxidative damage such as lipid peroxidation. One of the most important mechanisms of antioxidant defense is thus the sequestration of iron in a redox-inactive form by transferrin. In diabetes mellitus, increased oxidative stress and lipid peroxidation contribute to chronic complications but it is not known if this is related to abnormalities in transferrin function. In this study we investigated the role of transferrin concentration and glycation. The antioxidant capacity of apotransferrin to inhibit lipid peroxidation by iron-binding decreased in a concentration-dependent manner from 89% at > or = 2 mg/ml to 42% at 0.5 mg/ml. Pre-incubation of apotransferrin with glucose for 14 days resulted in a concentration-dependent increase of glycation: 1, 5 and 13 micromol fructosamine/g transferrin at 0, 5.6 and 33.3 mmol/l glucose respectively, p < 0.001. This was accompanied by a decrease in the iron-binding antioxidant capacity of apotransferrin. In contrast, transferrin glycation by up to 33.3 mmol/l glucose did not affect chemiluminescence-quenching antioxidant capacity, which is iron-independent. Colorimetric evaluation of total iron binding capacity in the presence of an excess of iron (iron/transferrin molar ratio = 2.4) also decreased from 0.726 to 0.696 and 0.585mg/g transferrin after 0, 5.6 and 33.3 mmol/l glucose, respectively, p < 0.01. In conclusion, these results suggest that lower transferrin concentration and its glycation can, by enhancing the pro-oxidant effects of iron, contribute to the increased lipid peroxidation observed in diabetes.     

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.     

Lipid peroxidation and antioxidant enzyme activities of Euphorbia millii hyperhydric shoots

A large number of micropropagated Euphorbia millii shoots from temporary immersion bioreactor showed thick broad leaves that were translucent, wrinkled and/or curled and brittle, symptoms of hyperhydricity. The environment inside bioreactor normally used in plant micropropagation is characterised by high relative humidity, poor gaseous exchange between the internal atmosphere of the bioreactor and its surrounding environment, and the accumulation of ethylene, conditions that may induce physiological disorders. A comparison of hyperhydric shoots (HS) with normal plants shows marked increase in malondialdehyde (MDA) content in HS plants. MDA, a decomposition product of polyunsaturated fatty acids hydroperoxides, has been utilized very often as a suitable biomarker for lipid peroxidation, which is an effect of oxidative damage. This hypothesis is also confirmed by the higher lipoxygenase (LOX) activity in HS plants. The potential role of antioxidant enzymes in protecting hyperhydric shoots from oxidative injury was examined by analyzing enzyme activities and isozyme profiles of hyperhydric and non-hyperhydric leaves of E. millii. Superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activity were significantly higher in hyperhydric tissue as compared to non-hyperhydric normal leaf tissue. After native polyacrylamide gel electrophoresis (PAGE) analysis, seven SOD isoenzymes were detected and the increase in SOD activity observed in hyperhydric tissue seemed to be mainly due to Mn-SOD and Cu/Zn-SOD. The activity of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) was proportionally increased in HS tissue compared to normal leaves indicating a crucial role in eliminating toxic H₂O₂ from plant cells. The depletion of GSH and total glutathione in spite of higher GR activities observed in HS tissue indicates that mechanism of antioxidant defense was by enhanced oxidation of GSH to GSSG by DHAR yielding ascorbate (AA). The antioxidant metabolism has been shown to be important in determining the ability of plants to survive in hyperhydric stress and the up regulation of these enzymes would help to reduce the build up of ROS.     

Lipid peroxidation and antioxidant enzyme levels in patients with schizophrenia and bipolar disorder

Recent data from several reports indicate that free radicals are involved in aetiopathogenesis of many human pathologies including neuropsychiatric disorders such as schizophrenia, bipolar disorder etc. In the present study, we aimed at determining and evaluating levels of malondialdehyde (MDA), a product of lipid peroxidation, and antioxidant enzyme superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity levels in patients diagnosed with schizophrenia (n = 25) and bipolar disorder (n = 23). The control group was composed of 20 healthy subjects. There was a significant increase in MDA levels of patients with schizophrenia and bipolar disorder compared with controls. SOD and GSH-Px activity levels were significantly higher in the schizophrenic group compared with controls. SOD activity levels in bipolar the group were significantly higher than controls whereas there were no significant changes in GSH-Px activity levels in the bipolar group and controls. Significant differences between lipid peroxidation product and antioxidant enzyme (SOD and GSH-Px) activity levels in schizophrenic and bipolar disorder patients compared with controls leads us to believe that these differences are related to the heterogenities in aetiologies of these disorders.     

Lipid peroxidation and scavenging enzyme levels in the liver of streptozotocin-induced diabetic rats

In this study, alterations in the liver antioxidant enzymes status and lipid peroxidation in short-term (8-weeks) and long-term (24-weeks) diabetic rats were examined. Glutathione peroxidase (GSH-Px) activity and malondialdehyde (MDA) levels were significantly increased, but superoxide dismutase (SOD) activity was significantly reduced in 8-weeks diabetic rats, compared to control. Catalase (CAT) activity, however, was found unchanged. In 24-weeks diabetic rats, while GSH-Px activity was unchanged, but SOD and CAT activities and MDA levels were significantly increased, compared to control. These results suggest that diabetes-induced alterations in tissue antioxidant system may reflect a generalized increase in tissue oxidative stress. It can be concluded that lipid peroxidation and antioxidant enzyme levels are elevated in diabetic condition. Hence, diabetes mellitus, if left untreated, may increase degenerative processes due to accumulation of oxidative free radicals.     

Lipid peroxidation in liver, plasma, and erythrocytes of rats chronically treated with ethanol

The effect of ingestion of water containing 20% ethanol for 1-2 months on lipid peroxide levels of liver, plasma, and erythrocyte was investigated in rats. Our results show that elevated plasma lipid peroxide levels and erythrocyte susceptibility to lipid peroxidation may reflect stimulated lipid peroxidation in rat liver following chronic ethanol ingestion.     

Lipid peroxidation changes in the brain in fetal alcohol syndrome]

The study was performed upon three groups of 12-week-old male rats. The first group of rats received ethanol/9 g/kg/day as 6% aqueous solution/during pregnancy and lactation, the second group received ethanol only during lactation and the third group, controls, received equicaloric sucrose solution. The concentrations of LPO products were determined in the homogenates of tissue from frontal cortex, striatum, hypothalamus, hippocamp and cerebellum. The concentration of fluorescent products in the brain structures of rats treated perinatally with ethanol was several-fold increased as compared with controls. The levels of diene conjugates were increased in most brain structures of rats with FAS. It should be pointed out that there was the same degree of increase of the levels of both fluorescent products and diene conjugates in two groups of rats with FAS. Having in mind that in the rat the increased growth of the brain occurs during the first 10 postnatal days, it might be assumed that this period is favorable for LPO.     

Lipid order and composition of synaptic membranes in experimental diabetes mellitus

The effect of diabetes in rats on lipid composition and order of synaptosomal membranes (SM) was determined in streptozotocin-induced diabetic rats after 6 weeks of chronic hyperglycemia. The cholesterol content was slightly, but not significantly, higher in diabetic SM (0.287±0.042 vs. 0.209±0.061 mol/mg protein). The phospholipid concentration in diabetic SM was significantly increased (0.515±0.042 vs. 0.305±0.041 mol/mg protein;P<0.005). Neither the molar ratios of cholesterol to phospholipids in the SM nor the fatty acid composition of the SM was significantly altered with diabetes. Diabetes did not affect membrane order or the thermotropic transition temperature of the SM as determined fluorometrically. On the other hand, the SM of diabetic rats had significantly increased concentration of lipid peroxidation products, namely conjugated dienes (the calculated O.D./mol phospholipids was 11.56±1.83 in controls and 19.95 ±4.1 in diabetic ratsP<0.01). Despite the accumulation of lipid peroxidation byproducts in SM of diabetic rats the overall membrane order and the cholesterol to phospholipid molar ratio do not appear to be significantly altered.     

Lipid peroxidation in mitochondria

The present review article takes into consideration the most important aspects of lipid peroxidation in mitochondria. Firstly the various ways by which lipid peroxidation is induced and the relevant mechanisms are described and discussed. After examining the major effects of lipid peroxidation on mitochondrial enzymes and bioenergetic functions, some aspects of the pathophysiology of lipid peroxidation are considered in connection with maturation of reticulocytes, alternative oxidase of plant mitochondria, aging, and ischemia-reperfusion syndrome. The final part of the article is devoted to the regulation and control of lipid peroxidation in mitochondria with particular emphasis to the role of the respiratory substrates.