The inhibition stage of lipid peroxidation during stress

Stress is shown to induce at first the generalized inhibition of lipid peroxidation (LPO), and then the activation of LPO. In brain and blood serum of rats subjected to continuous footshock as well as to restraint stress LPO products decreased and superoxide scavenging activity increased during the initial period of stress, after 1 hour of footshock LPO indices nearly reached normal values, and after 2 hours of footshock the accumulation of LPO products and decrease of superoxide scavenging activity were seen. LPO inhibition was accompanied by accumulation of easy oxidizable brain phospholipids and by depletion of brain cholesterol, during LPO activation brain cholesterol content and cholesterol-phospholipid ratio increased. The content of LPO products--fluorescent Schiff bases in blood plasma of women suffering from algomenorrhea at first decreased (O-12 h) and then dramatically increased (12-24 h) after a onset of pain at the beginning of menstruation. The data suggest that the stage of LPO inhibition precedes its activation during stress.     

The effect of carnosine on indicators of free radical lipid oxidation during acute stress in rats

The effect of carnosine intraperitoneal injection in rats (in doses 0.2, 2.0 or 20 mg/kg) on the vegetative parameters (arterial blood pressure, Hildebrandt index), the content of free radical oxidation (FRO) products and superoxide dismutase activity in serum and brain homogenates and brain lipid composition under normal condition and after different stress forms have been investigated. The carnosine injection in dose 20 mg/kg preserves and increase in arterial pressure and Hildebrandt index at all steps of stress development. The phase non-unidirectional changes in studied biochemical parameters have been revealed depending on the level of stress development in animals under control. The unidirectional and dose-dependent changes of phospholipid content and the level of brain lipids, decrease of FRO products in tissue and brain cholesterol, the increase of the superoxide dismutase activity of serum and brain homogenates have been found in intact and stressed animals after carnosine injection. A comparison of carnosine pharmacokinetics with concentration dependences of the antioxidative effect under in vitro and in vivo experiments comes to conclusion concerning the carnosine indirect adaptogenic action.     

Effect of conditioned-reflex bilateral avoidance learning on lipid components of the rat brain

The active avoidance training of rats resulted in a depletion of lipid peroxidation (LPO) products in cerebral cortex. LPO inhibition was also shown in cerebral cortex of "active control" group receiving +non-combined stimuli (the effect of short-term stress). LPO inhibition was more pronounced in rats staining a training criterion compared to rats which received combined stimuli but did not reach the criterion. In the active control group LPO inhibition was accompanied by total phospholipids accumulation and cholesterol depletion in cortical lipid extracts. Irrespective of attaining the criterion in all rats trained for active avoidance the accumulation of cholesterol was seen. Active avoidance training affected also the phospholipid composition of cerebral cortex.     

Carnosine: An Endogenous Neuroprotector in the Ischemic Brain

1. The biological effects of carnosine, a natural hydrophilic neuropeptide, on the reactive oxygen species (ROS) pathological generation are reviewed.2. We describe direct antioxidant action observed in the in vitro experiments.3. Carnosine was found to effect metabolism indirectly. These effects are reflected in ROS turnover regulation and lipid peroxidation (LPO) processes.4. During brain ischemia carnosine acts as a neuroprotector, contributing to better cerebral blood flow restoration, electroencephalography (EEG) normalization, decreased lactate accumulation, and enyzmatic protection against ROS.5. The data presented demonstrate that carnosine is a specific regulator of essential metabolic pathways in neurons supporting brain homeostasis under unfavorable conditions.     

Role of carnosine in preventing thioacetamide-induced liver injury in the rat

Carnosine (beta-alanyl-L-histidine) is a dipeptide with antioxidant properties. Free radicals are involved in the pathogenesis of acute liver injury induced by thioacetamide (TAA). In this study, we investigated the effect of carnosine treatment on TAA-induced oxidative stress and hepatotoxicity. Rats were injected intraperitoneally with TAA (500 mg/kg) and carnosine (250 mg/kg, intraperitoneal) was co-administered with TAA. All animals were killed 24 h after injections. TAA administration resulted in hepatic necrosis, significant increases in plasma transaminase activities as well as hepatic lipid peroxide levels. In addition, hepatic antioxidant system was found to be depressed following TAA administration. When carnosine was co-administered with TAA in rats, plasma transaminase activities were found to approach to normal values in rats. Histological findings also suggested that carnosine has preventive effect on TAA-induced hepatic necrosis. Carnosine treatment caused significant decreases in lipid peroxide levels in TAA-treated rats without any changes in enzymatic and non-enzymatic antioxidants except vitamin E in the liver of rats. Our findings indicate that carnosine, in vivo may have a preventive effect on TAA-induced oxidative stress and hepatotoxicity by acting as an non-enzymatic antioxidant itself.     

Carnosine prevents the development of oxidative stress under the conditions of toxic action of cadmium

Protective effect of the natural dipeptide carnosine on the antioxidant system of rats under conditions of oxidative stress caused by chronic cadmium administration was investigated. Oxidative status of experimental animals were evaluated based on a number of informative parameters of iron-induced chemiluminescence. It was shown that the introduction of cadmium for 7 days reduces the duration of the latent period of chemiluminescence in the brain, liver, and blood plasma suggesting the depletion of endogenous antioxidant defense. Coexposure to carnosine and cadmium led to significant increase in the level of antioxidant protection in plasma, liver, and brain of animals. Carnosine also prevented the increase of lipid hydroperoxides in the brain and prevented the development of lipid peroxidation content in liver and plasma of animals. Mechanism of the protective effect of carnosine under conditions of oxidative stress induced by cadmium administration was shown on human neuroblastoma SH-SY5Y cell culture. Addition of the cadmium to the incubation medium to a final concentration of 5 μM reduced cell viability of a culture, as was determined by MTT assay; simultaneous addition of carnosine (0.25 mM final concentration) with cadmium resulted in increased cell viability during 24 hours of incubation. Thus, carnosine in a final concentration of 1 mM effectively prevented the development of necrotic lesions of neuroblastoma cells, inhibiting the formation of reactive oxygen species as measured by flow cytometry. The results indicate the ability of carnosine to prevent the development of oxidative stress under the toxic action of cadmium.     

In vitro and in vivo inhibition of muscle lipid and protein oxidation by carnosine.

Carnosine, a beta-alanyl-L-histidine dipeptide with antioxidant properties is present at high concentrations in skeletal muscle tissue. In this study, we report on the antioxidant activity of carnosine on muscle lipid and protein stability from both in vitro and in vivo experiments. Carnosine inhibited lipid peroxidation and oxidative modification of protein in muscle tissue prepared from rat hind limb homogenates exposed to in vitro Fenton reactant (Fe2+, H2O2)-generated free radicals. The minimum effective concentrations of carnosine for lipid and protein oxidation were 2.5 and 1 mM, respectively. Histidine and beta-alanine, active components of carnosine, showed no individual effect towards inhibiting either lipid or protein oxidation. Skeletal muscle of rats fed a histidine supplemented diet for 13 days exhibited a marked increase in carnosine content with a concomitant reduction in muscle lipid peroxidation and protein carbonyl content in skeletal muscle caused by subjecting rats to a Fe-nitrilotriacetate administration treatment. This significant in vitro result confirms the in vivo antioxidant activity of carnosine for both lipid and protein constituents of muscle under physiological conditions.     

Protective effect of Embelia ribes Burm on methionine-induced hyperhomocysteinemia and oxidative stress in rat brain

The present study was aimed to find out the protective effect of ethanolic extract of E. ribes fruits on homocysteine, lactate dehydrogenase (LDH) and lipid profile in serum, lipid peroxidation (LPO) and non-enzymatic antioxidant glutathione (GSH) levels in brain homogenates and histopathological examination of brain tissue in methionine (1 g/kg body weight, orally for 30 days) induced hyperhomocysteinemic rats. A significant increase in homocysteine, LDH, total cholesterol, triglycerides, low density lipoprotein (LDL-C) and very low density lipoprotein (VLDL-C) levels was observed in serum. Increased LPO levels in brain homogenates with reduced serum high density lipoprotein (HDL-C) levels and decreased GSH content were other salient features observed in methionine treated pathogenic control rats. Administration of ethanolic E. ribes extract (100 mg/kg body weight, orally) for 30 days to methionine-induced hyperhomocysteinemic rats produced a significant decrease in the levels of homocysteine, LDH, total cholesterol, triglycerides, LDL-C, VLDL-C in serum and LPO levels in brain homogenates with significant increase in serum HDL-C levels and GSH content in brain homogenates, when compared with pathogenic control rats. Biochemical observations were further substantiated with histological examination of brain. Degenerative changes of neuronal cells in methionine treated rats were minimized to near normal morphology by ethanolic E. ribes extract administration as evident by histopathological examination. The results provide clear evidence for the first time, that ethanolic E. ribes extract treatment enhances the antioxidant defense against methionine-induced hyperhomocysteinemia and oxidative stress in brain.     

The effect of carnosine on the liver enzyme system in the irradiated body]

The effect of carnosine on post-radioactive changes in lipid peroxidation (LPO) products in blood serum and cytochrome P-450 content in liver microsomes has been studied. Per os administration of carnosine 24 hours prior to irradiation in a minimal lethal dose (7 Gr) markedly decreases the post-radioactive accumulation of LPO products in rat blood serum one hour after irradiation and fully restores the post-radioactive decrease in the cytochrome P-450 content in rat liver microsomes on day 5 after irradiation. Besides, the ability of carnosine to prevent the post-radioactive decline in the activity of UDP-glucuronyl transferase. Another key enzyme of the liver detoxifying system, has been demonstrated. The data obtained testify to the ability of carnosine to provide effective protection against post-radioactive intensification of LPO in irradiated organisms.     

Growth and lipid composition of rat brain glial cells cultured in lipoprotein deficient serum

The purpose of this study was to examine the effects of substituting lipoprotein deficient serum (LPDS) for complete fetal calf serum (FCS) in culture media on the growth and lipid composition of cells dissociated from 1 to 2-day-old rat brain. The results show that in FCS cultures DNA, protein and all lipids increase with an increase in the number of days in culture. Substitution of LPDS for FCS in the culture media caused a slower increase in each of these constituents. Esterified cholesterol remained unaltered with time in LPDS cultures but increased continuously in FCS cultures. Substitution of LPDS for FCS reduced, the DNA: protein ratio, and unesterified cholesterol: phospholipid ratio but the protein: phospholipid ratio and the proportion of individual phospholipids were not affected The data indicate that removal of low density lipoprotein (LDL) from serum used, in culture media reduces cell proliferation and causes alterations in cellular lipid composition specifically ratio of cholesterol: phospholipids.     

Carnosine Protects the Brain of Rats and Mongolian Gerbils against Ischemic Injury: After-Stroke-Effect

Carnosine, a specific constituent of excitable tissues of vertebrates, exhibits a significant antioxidant protecting effect on the brain damaged by ischemic-reperfusion injury when it was administered to the animals before ischemic episode. In this study, the therapeutic effect of carnosine was estimated on animals when this drug was administered intraperitoneally (100 mg/kg body weight) after ischemic episode induced by experimental global brain ischemia. Treatment of the animals with carnosine after ischemic episode under long-term (7–14 days) reperfusion demonstrated its pronounced protective effect on neurological symptoms and animal mortality. Carnosine also prevented higher lipid peroxidation of brain membrane structures and increased a resistance of neuronal membranes to the in vitro induced oxidation. Measurements of malonyl dialdehyde (MDA) in brain homogenates showed its increase in the after brain stroke animals and decreased MDA level in the after brain stroke animals treated with carnosine. We concluded that carnosine compensates deficit in antioxidant defense system of brain damaged by ischemic injury. The data presented demonstrate that carnosine is effective in protecting the brain in the post-ischemic period. Special issue dedicated to Dr. Bernd Hamprecht     

Protection Against Adriamycin-Induced Cardiomyopathy by Carnosine in Rats: Role of Endogenous Antioxidants

The aim of this study was to investigate the effects of carnosine, a biological antioxidant, on the acute cardiac damage induced by a single dose of adriamycin in rats. The experimental design consisted of four groups: Control (saline, i.p.); carnosine (CAR; 10 mg/kg/day, i.p.); adriamycin (ADR; 16 mg/kg on the 14th day, i.p.); carnosine with adriamycin. Carnosine was given 2 weeks before and following adriamycin treatment. Blood samples were collected for analysis of plasma creatine kinase (CK) and plasma antioxidant enzymes, glutathione peroxidase (GSH-Px), Cu, Zn-superoxide dismutase (SOD), and catalase (CAT). The rats were then sacrificed, and the hearts were autopsied for hemodynamic study, ECG, and histopathological examination. Results showed that adriamycin produced evident cardiac damage revealed by hemodynamic change, histological alterations, decreased plasma antioxidant enzymes activities, and increased lipid peroxidation to the control value. Carnosine treatment led to significant attenuation of adriamycin-induced cardiomyopathy revealed by normalization of the LVDP, ST interval, CK, SOD, GSH-Px, CAT, and lipid peroxidation. An increase in oxidative stress and inactivation of SOD, GSH-Px, CAT by a single dose of adriamycin were prevented when carnosine was given 2 weeks before and on the same day adriamycin treatment was administered.     

Lipid peroxidation-induced changes in physical properties of annular lipids in rat brain synaptosomal membranes

The effects of lipid peroxidation (LPO) on the physical state (fluidity) of the rat brain synaptosomal lipid bilayer matrix and the annular lipid domains were investigated using the fluorescent probe pyrene. The parameters of pyrene fluorescence intensity alpha = IE/IM were measured at excitation wavelengths 280 nm and 340 nm (alpha 280 and alpha 340), reflecting fluidity of lipid bilayer matrix and annular lipids, respectively. LPO induction was shown to result in changes of fluidity of both the bilayer and annular lipids. Upon reducing formation of LPO products by carnosine, fluidity changes of both the lipid bilayer matrix and annular lipids were diminished. Conformational changes of the annular lipid domain by LPO may therefore be considered as a possible cause of the functional changes in the receptor mediated responses and of the inactivation of membrane-bound enzymes by oxidative stress.     

Effect of chronic effect of the electrostatic field on various biochemical indicators of the tissues

The action of electrostatic field (320 kV/m) on the adaptability has been studied in experiments on young Wistar rats (females). Some parameters of carbohydrate, lipid and protein metabolism, and the process of lipid peroxidation were observed in blood serum, liver and brain. Glucose content was observed to increase in all the tissues, liver glycogen, cholesterol/phospholipid ratio. The urea and malondialdehyde increased in the liver and brain. The experiments have shown that the physiological adaptability is high.     

Can Carnosine Prevent the Aging-Induced Changes of Blood Platelet and Brain Regional Monoamine Oxidase-A mRNA in Relation to its Activity?

It is well known that the monoamine oxidase (MAO) activity deregulates during aging along with anti-oxidant activity. Carnosine (β-Ala-l-His) is an endogenous dipeptide biomolecule, having both anti-oxidant and anti-glycating properties. The present study deals with the effect of carnosine on aging-induced changes in MAO-A mRNA expression of brain regions and blood platelets in relation to their MAO-A activity. Results showed that aging significantly and characteristically increased the brain regional MAO-A mRNA whereas, in blood platelets it was significantly reduced with an increase in blood platelet counts. Carnosine attenuated both aging-induced (i) increase in brain regional MAO-A mRNA expression and blood platelet count, (ii) decrease in blood platelet MAO-A mRNA expression and its (platelet MAO-A) activity without affecting the young rats’ brain regions and platelet. The present results thus suggest that carnosine attenuated and restored the aging-induced (a) increase of platelet count and (b) changes in brain regional and blood platelet MAO-A mRNA expression and (c) decrease in platelet MAO-A activity, towards their respective basal level that were observed in young rats.     

Free radical modification of lipoproteins and cholesterol accumulation in cells upon atherosclerosis.

An electron spin probe study was made of the effect of lipid peroxidation (LPO) on the structure of surface proteolipid layer of human serum low-density lipoproteins (LDL). The results obtained with a positively charged spin label and stearic acid spin probes with doxyl labels at positions 5, 12, and 16 revealed that LPO caused a decrease in phospholipid molecule mobility both in the region of polar heads and in the region of acyl chains till the depth of at least 1.7 mm from water-lipid interface. Under relatively high levels of oxidation (more than 6 mumol MDA/g LDL phospholipid) the polarity of lipid phase increased. The decrease in efficiency of tryptophan fluorescence quenching by nitroxide fragments incorporated in hydrophobic regions at the depth of approximately 2 nm from water-lipid interface indicated that lipid-protein interaction was disturbed as a result of oxidation of LDL lipids. In addition, the LPO-induced modification of apo-B, the main protein of LDL, was examined with maleimide spin label. LPO led to increase in mobility of strongly immobilized maleimide labels and in the number of weakly immobilized ones. Oxidized LDL revealed decreased ability to incorporate spin-labeled steroid (androstane) as compared to native ones. LPO-induced structural changes of LDL surface are supposed to be a reason of enhanced accumulation of cholesterol in human monocytes during their incubation with oxidized LDL. The cholesterol content in red cells was shown to be directly correlated to MDA content in apo-B containing lipoproteins but not in whole serum. Our findings suggest that free radical modification of serum lipoproteins but not solely an increased level of LPO products in blood is one important cause for cholesterol accumulation in cells and, apparently, for their transformation into foam cells during atherosclerosis.     

Effect of carnosine administration on metabolic parameters in bilharzia-infected hamsters

Carnosine is a naturally occurring dipeptide (beta-alanyl-L-histidine) found in muscles, brain and other tissues. This study was designed to test the ability of carnosine to offset metabolic disturbances induced by Schistosoma mansoni parasitism. Results indicate that parasitic infection caused elevation of liver weight/body weight in S. mansoni-infected hamsters, induced lipid peroxidation and reduced glycogen levels. Moreover, adenylate energy charge (AEC) and ATP/ADP and ATP/AMP concentration ratios were markedly lower in infected hamsters. Administration of carnosine (10 mg/day) for 15 days concurrent with infection effectively reduced worm burden and egg count. Administration of carnosine 2 and 4 weeks post-exposure only partially ameliorated the S. mansoni effects on metabolism. Carnosine treatment also normalized most of the parameters measured, including glycogen repletion, the antioxidant status and AEC. These finding support the use of carnosine for possible intervention in schistosomiasis.     

Biochemical and Physiological Evidence that Carnosine Is an Endogenous Neuroprotector Against Free Radicals

1. Carnosine, anserine, and homocarnosine are endogenous dipeptides concentrated in brain and muscle whose biological functions remain in doubt.2. We have tested the hypothesis that these compounds function as endogenous protective substances against molecular and cellular damage from free radicals, using two isolated enzyme systems and two models of ischemic brain injury. Carnosine and homocarnosine are both effective in activating brain Na, K-ATPase measured under optimal conditions and in reducing the loss of its activity caused by incubation with hydrogen peroxide.3. In contrast, all three endogenous dipeptides cause a reduction in the activity of brain tyrosine hydroxylase, an enzyme activated by free radicals. In hippocampal brain slices subjected to ischemia, carnosine increased the time to loss of excitability.4. In in vivo experiments on rats under experimental hypobaric hypoxia, carnosine increased the time to loss of ability to stand and breath and decreased the time to recovery.5. These actions are explicable by effects of carnosine and related compounds which neutralize free radicals, particularly hydroxyl radicals. In all experiments the effective concentration of carnosine was comparable to or lower than those found in brain. These observations provide further support for the conclusion that protection against free radical damage is a major role of carnosine, anserine, and homocarnosine.     

Role of lupeol and lupeol linoleate on lipemic-oxidative stress in experimental hypercholesterolemia

Epidemiological studies have shown that there is a positive correlation between the incidence of coronary heart disease (CHD) and the blood cholesterol level. To study the effect of plant derived triterpene, lupeol and its ester lupeol linoleate, on blood lipid status and oxidant stress in heart and hemolysate, male albino Wistar rats were fed high cholesterol diet (normal rat chow supplemented with 4% cholesterol and 1% cholic acid; HCD) for 30 days. A significant increase (p<0.05) in plasma total cholesterol (4.22 fold) and triglycerides (1.7 fold) was observed in HCD fed rats, along with elevated LDL (3.56 fold) and VLDL (1.99 fold) cholesterol and decreased HDL cholesterol (34.14%). Treatment with lupeol and its derivative normalized the lipid profile. The significant increase (p<0.05) in lipid peroxidation (LPO) was paralleled by significantly diminished (p<0.05) activities of antioxidant enzymes (SOD, CAT and GPx) and decreased (p<0.05) concentration of antioxidant molecules (GSH, Vit C and Vit E) in cardiac tissue and hemolysate of HCD fed rats. The oxidative tissue injury in hypercholesterolemic rats was substantiated by the increase in cardiac marker, serum CPK and the drop in its activity in the heart tissue. Lupeol and lupeol linoleate treatment decreased the LPO levels and increased enzymatic and nonenzymatic antioxidants. CPK activity in the treated group was comparable with that of the control. These observations highlight the beneficial effects of the triterpene, lupeol and its linoleate ester derivative, in ameliorating the lipidemic-oxidative abnormalities in the early stage of hypercholesterolemic atherosclerosis.     

Features of lipid peroxidation in brain and liver tissues from aging rats under stress

The lipid peroxidation (LPO) level between in the adult and old rats brain and liver was determined as to be essentially undiffering. Stress activated the LPO independence the age of animals and tissues investigated. The concentration changes of LPO products testify to it. In the adult rats under the stress capability of tissues to induction in vitro ferment and ascorbat-depending LPO, in comparison with the control, decreases, at old--does not change in the brain and considerably grows in the liver. Stress is accompanied by an oppression of Na, K-ATP-ase PM activity of hepatocytes, more expressed in the old animals.