The lipid peroxidation system in the retina and brain of rats during early postnatal ontogeny

The content of the lipid peroxidation products in the rat retina and brain tissues during the early postnatal period (20-45 day of life) was estimated. It was shown during this period the content of conjugated dienes was decreased: the content of malondialdehyde and Schiff bases was without changes in the rat retina. At the same time the content of the conjugated dienes and Schiff bases in the brain tissue was proportionally increased. The activity of glutathioneperoxidase and glutathionereductase was decreased in the retina and not changed in brain. In the same period of the life the content of alpha-tocopherol in the retina was increased. We observed also the enhance of the rate of the induced lipid peroxidation in brain and retina of older animals.     

Activation of lipid peroxidation processes in chronic ischemic heart disease

The content of lipid peroxidation products--hydroperoxides with conjugated double bonds and fluorescent compounds, which are formed on interaction of primary lipid peroxidation products and proteins, considerably increases in blood plasma of patients suffering from coronary heart disease. Treatment with combined vitamins E and C enables the blood plasma lipid peroxidation products to be decreased to a far greater extent as compared with conventional therapy.     

The study of cytokine content and ganglioside metabolism in experimental brain edema

A blood cytokine profile and also the brain content of lipid peroxidation (LPO) products and gangliosides were investigated in rats with experimental brain edema. The development of brain edema was accompanied by the increase in pro-inflammatory and a decrease in anti-inflammatory cytokine content. In parallel, accumulation of LPO products (conjugated dienes, hydroperoxides, and malondialdehyde) was observed. The study of ganglioside content under conditions of experimental brain edema revealed a decrease of their hydrolytic degradation product, sphingosine.     

Ultraviolet-treated lipoproteins as a model system for the study of the biological effects of lipid peroxides on cultured cell. I. Chemical modifications of ultraviolet-treated low-density lipoproteins

A new experimental model system constituted by ultraviolet-treated low-density lipoproteins (LDL) has been designed in order to investigate the biological effects of lipid peroxides entering the cell through the endocytotic pathway. This paper reports the chemical modifications of the lipid components and apolipoproteins of the ultraviolet-treated LDL. Human LDL were submitted to short ultraviolet radiations (254 nm, 0.5 mW/cm2, for variable periods of time) and compared to LDL peroxidized by iron. The lipid peroxidation was monitored by following the formation of the peroxidation products (conjugated dienes, thiobarbituric acid-reactive substances (TBARS) and fluorescent lipid-soluble products) and the change of the composition in polyunsaturated fatty acids, carotenes and vitamin E. Several parameters of the apo B-100 structure were investigated: molecular size (by SDS-PAGE) and TNBS-reactive amino groups (chemical determination by trinitrobenzene sulfonic acid). The most important feature was the absence of major modification of apo B-100 in ultraviolet-treated LDL: the molecular weight and the content in TNBS-reactive amino groups of apo B-100 were not modified. In contrast, iron-treated LDL exhibited a loss of the apo B-100 band and a decrease in the number of TNBS-reactive amino group. Both ultraviolet radiations and iron ions induced a significant decrease in the content of polyunsaturated fatty acids, carotenes and vitamin E together with a large formation of lipid peroxidation products. However, the time-course of the formation of conjugated dienes, TBARS and fluorescent lipid-soluble products was quite different using the two oxidative systems. These results demonstrate that ultraviolet radiations induced a strong peroxidation of the lipid content of LDL and no (or only minor) changes in the apolipoprotein moiety whereas iron-catalyzed peroxidation resulted in the formation fo lipid peroxidation products as well as apo B alterations.     

<Emphasis Type="Italic">Zingiber officinale</Emphasis> extends <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> life span in xenobiotic-induced oxidative stress conditions

Background

The possibility of dietary ginger to enhance oxidative stress resistance and to extend life span was studied on Drosophila melanogaster.

Methods

Oxidative stress was induced by a reducing agent dithiothreitol. Experimental groups of male D. melanogaster were cultured on media containing: 1) no additive; 2) dithiothreitol, added into the nutritional mixture to the final concentration of 10 mM; 3) 25 mg of ginger powder g^–1 of the nutritional mixture; and 4) 10 mM of dithiothreitol and 25 mg of ginger powder g^–1 of the nutritional mixture. The number of alive fruit flies was inspected daily, and mean life span was determined for each experimental group.

Results

The addition of dithiothreitol to D. melanogaster nutritional mixture was established to result in an increase in concentration of two markers of oxidative stress conditions (thiobarbituric acid reactive substances as products of lipid peroxidation and carbonylated proteins as products of protein oxidation) in fly tissues. It was followed by significant reduction of mean life span and maximum life span of the last 10% of flies. Plant preparation, being added simultaneously with dithiothreitol, significantly diminished the negative effects of this xenobiotic. In conditions of additional stress load induced by hydrogen peroxide or high temperature, survival of insects treated with dithiothreitol on the background of ginger powder was the highest.

Conclusions

Thus, the presented data give the evidence that ginger preparations can reduce oxidative stress outcomes and significantly increase the life expectancy of fruit flies in stress conditions.

     

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.     

Effect of bacterial lipopolysaccharide on the content of lipid peroxidation products in lungs and other organs of mice

The influence of lipopolysaccharide fromEscherichia coli (LPS, 17 mg/kg body weight) on the lipid peroxidation process in organs of mice was studied. The content of conjugated dienes (CD), lipid peroxides (LP), malondialdehyde (MDA) (all three lipid peroxidation by-products), peroxidase (PO) activity and wet-to-dry weight ratio in lungs, heart, spleen, kidneys and liver were determined 1.5 h after intravenous injection of LPS. Animals observed at this time-point had reduced activity and decreased body temperature by about 2°C, however, all analysed organs did not reveal any changes of wet-to-dry weight ratio comparing to organs from mice injected with sterile, pyrogen free 0,9% NaCl. Only extracts from heart and lungs showed significant increase in the tissue level of at least two lipid peroxidation products. The heart content of CD, MDA, and LP was about 1.5-, 1.3-, and 2.4-fold higher than in control group. In lungs CD and MDA increased 3.3- and 1.3-times but in spleen only content of LP was elevated. In these organs the suppression of PO activity was also observed. Liver and kidneys did not reveal any convincing enhancement of lipid peroxidation process and alterations of PO activity. Since free radical reactions are involved in lipid peroxidation process and inactivation of PO these results suggest that heart, lungs and spleen are the organs mostly exposed to oxidative stress during the first 1.5 h after single injection of LPS in mice.Abbreviations CD conjugated dienes - LP lipid peroxides - LPS lipopolysaccharide - MDA malondialdehyde - PMNL polymorphonuclear leukocytes - PO peroxidase - TBA thiobarbituric acid     

Lipid peroxidation cannot be used as a universal criterion of oxidative stress

Oxidative stress is a term used to denote the imbalance between the concentrations of reactive oxygen and nitrogen species and the defense mechanisms of the body. Although it is generally accepted that such an imbalance plays a pivotal role in many pathologies, the term "oxidative stress" remains ill defined. In an attempt to evaluate the relationship between various assays of oxidative stress, we have analyzed the correlations between the results reported in those publications in which "oxidative stress" has been assayed by at least two methods. We found good correlations between the concentrations of several peroxidation products, including malondialdehyde, F2-Isoprostanes, lipid hydroperoxides, conjugated dienes, glutathione and protein carbonyls, but not with other criteria of "individual oxidative status" such as the concentration of antioxidants and products of DNA fragmentation (the "comet" assay). In light of these findings, we divide the assays used for evaluation of "oxidative stress" into the following three categories: (i) assays based on measuring the concentrations of oxidation products of lipids, proteins and DNA, as well as the concentrations of antioxidants, (ii) assays used to evaluate the oxidative and reductive capacity of biological fluids and (iii) assays used to evaluate the ex vivo susceptibility of lipids to oxidation upon their exposure to a source of free radicals. Our analyses demonstrate that oxidative stress cannot be defined in universal terms. Two results are of special interest:1.the commonly used criteria based on lipid peroxidation can not be regarded as a general estimate of the individual "oxidative status".2.the levels of antioxidants exhibit a non-monotonic relation with other criteria for oxidative stress. Further research is required to evaluate the significance of the latter finding.     

Feeding into old age: long-term effects of dietary fatty acid supplementation on tissue composition and life span in mice

Smaller mammals, such as mice, possess tissues containing more polyunsaturated fatty acids (PUFAs) than larger mammals, while at the same time live shorter lives. These relationships have been combined in the ‘membrane pacemaker hypothesis of aging’. It suggests that membrane PUFA content might determine an animal’s life span. PUFAs in general and certain long-chain PUFAs in particular, are highly prone to lipid peroxidation which brings about a high rate of reactive oxygen species (ROS) production. We hypothesized that dietary supplementation of either n-3 or n-6 PUFAs might affect (1) membrane phospholipid composition of heart and liver tissues and (2) life span of the animals due to the altered membrane composition, and subsequent effects on lipid peroxidation. Therefore, we kept female laboratory mice from the C57BL/6 strain on three diets (n-3 PUFA rich, n-6 PUFA rich, control) and assessed body weights, life span, heart, and liver phospholipid composition after the animals had died. We found that while membrane phospholipid composition clearly differed between feeding groups, life span was not directly affected. However, we were able to observe a positive correlation between monounsaturated fatty acids in cardiac muscle and life span.     

Antioxidant activity of high density lipoproteins in vivo]

The paper deals with antioxidant effect of high density lipoproteins (HDL) in vivo. The effect of intravenous injection of large-dose HDL3 (200 mg protein), isolated from human plasma to rabbits with experimental hypercholesterolemia, on the content of primary products of lipid peroxidation in rabbit blood, the correlation between HDL cholesterol level and the content of lipid peroxide products in blood plasma of healthy persons and patients with IHD were studied. Intravenous injection of HDL3 to rabbits with experimental hypercholesterolemia has been shown to lead in 6 hr to a 24-hr significant (p < 0.01) decrease of conjugated dienes and trienes. The existence of negative correlation between HDL-cholesterol level and the content of conjugated dienes in blood plasma of healthy persons (N = 47) and patients with IHD (n = 64) is revealed. Basing on the data obtained conclusion of universal character of protective antiatherogenic effect of HDL is drawn.     

The accumulation of lipid peroxidation products in the eye structures of mice under whole-body x-ray irradiation

In studying the effect of whole-body X-irradiation on the accumulation of lipid peroxidation products (conjugated dienes, TBA-active products, and Schiff bases) in retina and retinal pigmented epithelium of pigmented and nonpigmented mice it was shown that irradiation of dark-pigmented mice does not cause even a slight accumulation of lipid peroxidation products as compared to that in the controls. Albino mice exhibited a marked increase in the level of lipid peroxidation products which was manifested soon after irradiation and persisted for at least 3 months after irradiation. Melanine is suggested to participate in protecting eye structures against pro-oxidizing action of ionizing radiation.     

Anti-oxidant effects of cinnamon (Cinnamomum verum) bark and greater cardamom (Amomum subulatum) seeds in rats fed high fat diet

In order to gain insight into the antioxidant effect of cinnamon (Cinnamomum verum; Lauraceae) and cardamom (Amomum subulatum; Zingiberaceae) hepatic and cardiac antioxidant enzymes, glutathione (GSH) content and lipid conjugated dienes were studied in rats fed high fat diet along with cinnamon or cardamom. The antioxidant enzyme activities were found to be significantly enhanced whereas GSH content was markedly restored in rats fed a fat diet with spices. In addition, these spices partially counteracted increase in lipid conjugated dienes and hydroperoxides, the primary products of lipid peroxidation. Thus, it appears that these spices exert antioxidant protection through their ability to activate the antioxidant enzymes.     

Antioxidant properties of dehydrozingerone and curcumin in rat brain homogenates

The present study investigates the inhibition of lipid peroxidation by dehydrozingerone and curcumin in rat brain homogenates. Both the test compounds inhibited the formation of conjugated dienes and spontaneous lipid peroxidation. These compounds also inhibited lipid peroxidation induced by ferrous ions, ferric-ascorbate and ferric-ADP-ascorbate. In all these cases, curcumin was more active than dehydrozingerone and dl--tocopherol.     

Biochemical mechanism of irreversible cell injury caused by free radical-initiated reactions

Effects of oxidative stress on isolated rat ventricular myocytes were studied. Myocyte viability was determined by the ability of these cells to retain rod-shaped morphology and to exclude trypan blue. The mean life time of myocytes was quantitated using the Weibull distribution function. Superfusion with 200 M tert-butyl hydroperoxide (t-BHP) led to a time-dependent loss of cell viability, generation of the products of lipid peroxidation, oxidation of protein and non-protein thiols, a decrease in [ATP]_i and in the cellular energy charge. Dithiothreitol (DTT, 5 mM) prolonged survival of myocytes exposed to t-BHP, attenuated oxidation of protein and non-protein thiols, and preserved the energy charge. Exposure to DTT did not affect the concentration of t-BHP-generated lipid peroxidation products. Promethazine (1 M) prevented t-BHP-induced increase in the concentration of lipid peroxidation products, but did not prevent either loss of thiols or loss of cell viability. Superfusion with N-ethylmaleimide (NEM, 5 M) also led to loss of cell viability, with accompanying decreases in protein and non-protein thiols, ATP and energy charge without the accumulation of the products of lipid peroxidation. Superfusion with FeSO₄ (400 M) and ascorbate (1 mM), (Fe-Asc) did not result in loss of cell viability or a decrease protein thiols or the energy charge. Superfusion with Fe-Asc, did, however, lead to a slight decrease in the concentration of non-protein thiols and ATP and a large increase in the concentration of lipid peroxidation products. Accumulation of lipid peroxidation products induced by Fe-Asc was prevented by promethazine. These results indicate that free radical-induced irreversible cell injury results from a loss of protein thiols. Changes in the cellular energy charge and lipid peroxidation do not bear a simple relationship to the survival of cardiac myocytes under oxidative stress.     

Role of tumor necrosis factor alpha and sphingomyelin cycle activation in the induction of apoptosis by ischemia/reperfusion of the liver

The signal transduction pathways triggering apoptotic mechanisms after ischemia/reperfusion may involve TNF- secretion, ceramide generation, and initiation of lipid peroxidation. In the present study involvement of the TNF-, sphingomyelin cycle, and lipid peroxidation in the initiation of apoptosis induced in liver cells by ischemia and reperfusion was investigated. Wistar rats were subjected to total liver ischemia (for 15, 30 min, and 1 h) followed by subsequent reperfusion. Ischemia caused sharp decrease of neutral sphingomyelinase activity. Activity of acidic sphingomyelinase initially decreased (during 15-30 min ischemia) but then increased (after 1 h of ischemic injury). Reperfusion of the ischemic lobe of the liver caused increase in neutral sphingomyelinase activity and decrease in acidic sphingomyelinase activity. A small amount of TNF- detected by immunoblotting analysis was accumulated in the ischemic area of liver rapidly and the content of this cytokine dramatically increased after the reperfusion. TNF- is known to induce free radical production. We found that the accumulation of TNF and increase of sphingomyelinase activity during the development of ischemic/reperfusion injury coincided with increase in content of lipid peroxidation products (conjugated dienes) and DNA degradation detected by gel electrophoresis. Recently it was shown that superoxide radicals are used as signaling molecules within the sphingomyelin pathway. This suggests the existence of cross-talk between the oxidation system and the sphingomyelin cycle in cells, which may have important implications for the initial phase and subsequent development of post-ischemic injury.     

Insertion of cyanobacterial desA gene coding for Δ12-acyl-lipid desaturase increases potato plant resistance to oxidative stress induced by hypothermia

The role of Δ12-acyl-lipid desaturase in plant resistance to hypothermia-induced oxidative stress was investigated. This study focused on modulation of free-radical processes occurring at low temperature in leaf cells of potato plants (Solanum tuberosum L., cv. Desnitsa) transformed with the gene for Δ12-acyl-lipid desaturase from the cyanobacterium Synechocystis sp. PCC 6803. Nontransformed plants of the same cultivar were used as a control material. The plants were grown in vitro on Murashige and Skoog agarized medium containing 2% sucrose. During hypothermia the rate of superoxide anion generation and hydrogen peroxide concentration decreased significantly. In addition, the content of both primary products (conjugated dienes and trienes) and secondary products (malonic dialdehyde) of lipid peroxidation was lower in the transformed plant leaves than in leaves of wild-type plants. It is supposed that the insertion into the plant genome of Δ12-acyl-lipid desaturase stabilizes the composition and physical properties of biomembranes by promoting polyunsaturation of fatty acids, which averts the accelerated generation of O ₂ ^·? , — and suppresses lipid peroxidation during hypothermia. These changes improved cold resistance of potato plants, which was evident from the less severe injury of leaf blades in cold-treated transgenic plants, as compared to that in the wild-type line. The activity of superoxide dismutase, a key enzyme of the antioxidant defense system was lower in leaves of transformed plants than in leaves of wild-type plants. A comparatively low activity of superoxide dismutase in transgenic plants implies that these plants experience less severe thermal and oxidative stress upon cooling and can cope with the cold without considerable increase in the enzyme activity. It is concluded that the insertion of the desA gene encoding Δ12-acyl-lipid desaturase into cold-resistant potato plants improves plant resistance to cold-induced oxidative stress by decreasing the rate of intracellular free-radical processes.     

Synchronization of changes in the level of direct current potential and concentration of lipid peroxidation products in the developing rat brain]

The dynamics of the level of direct current potentials and the content of lipid hydroperoxides, conjugated dienes, Schiff bases of phospholipids and lipofuscin in the brain of rats during ontogenesis was studied. It is shown that changes in neurophysiological and biochemical characteristics have an M-shaped character. The synchronization of age-dependent changes in the content of lipid peroxidation products and the dynamics of direct current potentials was revealed.     

Lipid peroxidation and antielastase activity in the lung under oxidant stress: role of antioxidant defenses

The role of lipid peroxidation in the inactivation of alpha 1-protease inhibitor (alpha 1-PI) in the alveolar lining fluid of human subjects has been examined under oxidant stress. Exposure to nitrogen dioxide (NO2) at 4 ppm for 3 h resulted in a significant increase in the amount of lipid peroxidation products in the alveolar lining fluid, with conjugated dienes the predominant species. Four-week supplementation with vitamins C and E before NO2 exposure markedly decreased the levels of conjugated dienes (control 804 +/- 103 pmol/micrograms total phospholipids vs. vitamin-supplemented 369 +/- 58, P = 0.003). Malondialdehydes, although detectable in the lavage fluid, contributed little to the total amount of lipid peroxidation products, and the levels were comparable in both groups. NO2 exposure in the absence of vitamin supplementation caused a significant decrease in the elastase inhibitory capacity (EIC) of the alveolar lining fluid in the control group but not in the vitamin-supplemented group [control 3.67 +/- 0.32 micrograms alpha 1-PI/micrograms porcine pancreatic elastase (PPE) vs. vitamin-supplemented 2.75 +/- 0.17, P less than 0.03]. The vitamin-supplemented group had a lower level of conjugated dienes and a higher EIC. Conversely, the control group had higher levels of conjugated dienes and a lower EIC in their lavage fluid. These studies demonstrate that lipid peroxidation occurs as an early event during oxidant exposure in the lungs of normal subjects. The appearance of lipid peroxidation products in the lavage fluid is associated with a decrease in the EIC of the alveolar lining fluid. Vitamins C and E diminish lipid peroxidation and preserve the EIC of the lower respiratory tract fluid during oxidant stress.     

Lipid peroxidation and nutrition

Levels of conjugated dienes of fatty acids (first peroxidation product) in relation to their substrates and promotors (triacylglycerols, homocysteine, iron) as well as to their inhibitors (essential antioxidative vitamins) were assessed in a vegetarian group (n=24) and compared with subjects on a mixed diet (traditional nutrition, n=24). Positive significant linear correlation between conjugated dienes and triacylglycerols, homocysteine, iron as well as inverse relationship between conjugated dienes and vitamin E, vitamin C, beta-carotene were observed in pooled groups. Lipid peroxidation risk in vegetarians seems to be caused predominantly by hyperhomocysteinemia, whereas in a mixed diet group this was due to a higher supply of substrates or risk iron values. The incidence of only 8 % of risk conjugated diene values in vegetarians in contrast to 42 % in the group with traditional diet indicates that vegetarians have a better antioxidative status as a consequence of regular consumption of protective food.