Oxidative stress induced by chronic administration of sodium dichromate [Cr(VI)] to rats

Chromium occurs in the workplace primarily in the valence forms Cr(III) and Cr(VI). Recent studies have demonstrated that sodium dichromate [Cr(VI)] induces greater oxidative stress as compared with Cr(III), as indicated by the production of reactive oxygen species by peritoneal macrophages and hepatic mitochondria and microsomes, and enhanced excretion of urinary lipid metabolites and hepatic DNA-single strand breaks (SSB) following acute oral administration of Cr(III) and Cr(VI). We have therefore examined the chronic effects of sodium dichromate dihydrate [Cr(VI); 10 mg (33.56 μmol)/kg/day] on hepatic mitochondrial and microsomal lipid peroxidation, enhanced excretion of urinary lipid metabolites including malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT), acetone (ACON) and propionaldehyde (PROP), and hepatic DNA damage over a period of 90 days. The maximal increases in hepatic lipid peroxidation and DNA damage were observed at approximately 45 days of treatment. Maximum increases in the urinary excretion of MDA, FA, ACT, ACON and PROP were 3.2-, 2.6-, 4.1-, 3.3- and 2.1-fold, respectively, while a 5.2-fold increase in DNA-SSB was observed. The results clearly indicate that chronic sodium dichromate administration induces oxidative stress resulting in tissue damaging effects which may contribute to the toxicity and carcinogenicity of hexavalent chromium.     

Cadmium-induced excretion of urinary lipid metabolites,DNA damage,glutathione depletion,and hepatic lipid peroxidation in sprague-dawley rats

Recent studies have described lipid peroxidation to be an early and sensitive consequence of cadmium exposure, and free radical scavengers and antioxidants have been reported to attenuate cadmium-induced toxicity. These observations suggest that cadmium produces reactive oxygen species that may mediate many of the untoward effects of cadmium. Therefore, the effects of cadmium (II) chloride on reactive oxygen species production were examined following a single oral exposure (0.50 LD₅₀) by assessing hepatic mitochondrial and microsomal lipid peroxidation, glutathione content in the liver, excretion of urinary lipid metabolites, and the incidence of hepatic nuclear DNA damage. Increases in lipid peroxidation of 4.0- and 4.2-fold occurred in hepatic mitochondria and microsomes, respectively, 48 h after the oral administration of 44 mg cadmium (II) chloride/kg, while a 65% decrease in glutathione content was observed in the liver. The urinary excretion of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT), and acetone (ACON) were determined at 0–96 h after Cd administration. Between 48 and 72 h posttreatment maximal excretion of the four urinary lipid metabolites was observed with increases of 2.2- to 3.6-fold in cadmium (II) chloride-treated rats. Increases in DNA single-strand breaks of 1.7-fold were observed 48 h after administration of cadmium. These results support the hypothesis that cadmium induces production of reactive oxygen species, which may contribute to the tissue-damaging effects of this metal ion.     

Effects of carbon tetrachloride,menadione, and paraquat on the urinary excretion of malondialdehyde,formaldehyde, acetaldehyde,and acetone in rats

Excretions of the lipid peroxidation products, formaldehyde (FA), acetaldehyde (ACT), malondialdehyde (MDA), and acetone (ACON), were simultaneously identified and quantitated in the urine of female Sprague-Dawley rats by gas chromatography-mass spectroscopy (GC-MS) and high pressure liquid chromatography (HPLC) following the acute administration of carbon tetra-chloride, a model alkylating agent that does not induce glutathione depletion, and the redox cycling compounds paraquat and menadione. All three xenobiotics are well-known inducers of oxidative stress. Oxidative stress was induced by oral administration of single doses of 2.5 mL of carbon tetrachloride/kg, 60 mg menadione/kg, and 75 mg paraquat/kg. These doses are approximately 50% of the LD₅₀'s for the three xenobiotics. Urinary excretion of FA, ACT, MDA, and ACON increased relative to control animals following treatment with all xenobiotics. Over the 48 hours of the study, the greatest increases in the excretion of MDA, FA, ACT, and ACON occurred after paraquat administration, with increases of approximately 2.7-, 2.6-, 4.3-, and 11.0-fold, respectively. This technique may have wide-spread applicability as an effective biomarker for investigating altered lipid metabolism in disease states and exposure to environmental pollutants/xenobiotics.     

Chromium-induced excretion of urinary lipid metabolites,DNA damage,nitric oxide production,and generation of reactive oxygen species in Sprague-Dawley rats

Chromium and its salts induce cytotoxicity and mutagenesis, and vitamin E has been reported to attenuate chromate-induced cytotoxicity. These observations suggest that chromium produces reactive oxygen species which may mediate many of the untoward effects of chromium. We have therefore examined and compared the effects of Cr(III) (chromium chloride hexahydrate) and Cr(VI) (sodium dichromate) following single oral doses (0.50 ld₅₀) on the production of reactive oxygen species by peritoneal macrophages, and hepatic mitochondria and microsomes in rats. The effects of Cr(III) and Cr(VI) on hepatic mitochondrial and microsomal lipid peroxidation and enhanced excretion of urinary lipid metabolites as well as the incidence of hepatic nuclear DNA damage and nitric oxide (NO) production were also examined. Increases in lipid peroxidation of 1.8- and 2.2-fold occurred in hepatic mitochondria and microsomes, respectively, 48 hr after the oral administration of 25 mg Cr(VI)/kg, while increases of 1.2- and 1.4-fold, respectively, were observed after 895 mg Cr(III)/kg. The urinary excretion of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) were determined at 0–96 hr after Cr administration. Between 48 and 72 hr post-treatment, maximal excretion of the four urinary lipid metabolites was observed with increases of 1.5- to 5.4-fold in Cr(VI) treated rats. Peritoneal macrophages from Cr(VI) treated animals 48 hr after treatment resulted in 1.4- and 3.6-fold increases in chemiluminescence and iodonitrotetrazolium reduction, indicating enhanced production of Superoxide anion, while macrophages from Cr(III) treated animals showed negligible increases. Increases in DNA single strand breaks of 1.7-fold and 1.5-fold were observed following administration of Cr(VI) and Cr(III), respectively, at 48 hr post-treatment. Enhanced production of NO by peritoneal exudate cells (primarily macrophages) was monitored following Cr(VI) administration at both 24 and 48 hr post-treatment with enhanced production of NO being observed at both timepoints. The results indicate that both Cr(VI) and Cr(III) induce an oxidative stress at equitoxic doses, while Cr(VI) induces greater oxidative stress in rats as compared with Cr(III) treated animals.     

Teduglutide,a glucagon-like peptide 2 analogue: A novel protective agent with anti-apoptotic and anti-oxidant properties in mice with lung injury

Teduglutide is a long-acting synthetic analogue of human glucagon-like peptide-2 (GLP-2). GLP-2 regulates cell proliferation and apoptosis as well as normal physiology in the gastrointestinal tract. In the present study, possible cytoprotective and reparative effects of teduglutide were analyzed on a mouse model with lung injury induced by tumor necrosis factor-alpha (TNF-α) and actinomycin D (Act D). BALB/c mice were divided into six groups: control mice (I), mice injected intraperitoneally with 15 μg/kg TNF-α (II), 800 μg/kg Act D (III), Act D 2 min prior to TNF-α administration with the same doses (IV), mice injected subcutaneously with 200 μg/kg teduglutide every 12 h for 10 consecutive days (V), and mice given Act D 2 min prior to TNF-α administration on day 11 after receiving teduglutide for 10 days (VI). The TNF-α/Act D administration made the lung a sensitive organ to damage. Mice lung subjected to TNF-α/Act D were characterized by the disruption of alveolar wall, induced pulmonary endothelial/epithelial cell apoptosis and expression of active caspase-3. These mice exhibited an increase in lipid peroxidation, glutathione levels, and activities of myeloperoxidase, superoxide dismutase, catalase, glutathione peroxidase and xanthine oxidase, as well as reduced tissue factor and sodium–potassium/ATPase activities. Teduglutide pretreatment regressed the structural damage, cell apoptosis and oxidative stress by reducing lipid peroxidation in mice received TNF-α/Act D. GLP-2 receptors were present on the cell membrane of type II pneumocytes and interstitial cells. Thus, teduglutide can be suggested as a novel protective agent, which possesses anti-apoptotic and anti-oxidant properties, against lung injury.     

The effect of vitamin E and plant extract mixture composed of carvacrol, cinnamaldehyde and capsaicin on oxidative stress induced by high PUFA load in young pigs

The objective of our study was to determine the antioxidative potential of a plant extract (PE) mixture composed of carvacrol, capsicum oleoresin and cinnamaldehyde against high n-3 polyunsaturated fatty acid (PUFA)-induced oxidative stress in young pigs. Thirty-two weaned castrated male crossbred pigs (BW 10.9 kg; n = 32) were randomly assigned to four dietary treatments (n = 8). The negative control diet (Cont) contained 17.2% energy from fat. Oxidative stress was induced in three of the four experimental groups with the inclusion of n-3 PUFA rich linseed oil. Linseed oil substituted wheat starch in the diet to elevate the amount of energy from fat to 34.1%. One of these diets served as a positive control (Oil), one was additionally supplemented with 271.2 mg/kg of PE mixture and one with 90.4 mg/kg α-tocopheryl acetate (Vit E). After 14 days of treatment, blood and urine were collected for the determination of lipid peroxidation and DNA damage. Lipid peroxidation was studied by plasma malondialdehyde (MDA) concentrations, 24 h urinary MDA and F2-isoprostane (iPF2α-VI) excretion, total antioxidant status of plasma and glutathione peroxidase assays. Lymphocyte DNA fragmentation and 24 h urinary 8-hydroxy-2'-deoxyguanosine excretion were measured to determine DNA damage. Consumption of n-3 PUFA rich linseed oil increased the amount of MDA in plasma and urine, and induced DNA damage in lymphocytes, but did not elevate the amount of iPF2α-VI excreted in the urine. The supplementation with PE and with Vit E did not reduce MDA levels in plasma and urine, but it decreased the percentage of DNA damage in lymphocytes (P < 0.001). The PE reduced the urinary iPF2α-VI excretion in comparison to the Cont diet. The results show that PE and Vit E supplemented to pigs in concentrations of 271.2 mg/kg and 90.4 mg/kg, respectively, can effectively protect pig's blood lymphocytes against oxidative DNA damage, thus suggesting their potentially beneficial effects on the immune system under dietary-induced oxidative stress.     

Oxidant/anti-oxidant dynamics in patients with advanced cervical cancer: correlation with treatment response

The present study was designed to investigate the effects of benzyloxicarbonyl-l-phenylalanyl-alanine-fluoromethylketone (Z-FA.FMK), an inhibitor of cathepsin B on lung injury that occurs concurrently with liver injury induced by d-galactosamine/tumor necrosis factor-alpha (d-GalN/TNF-α). Four groups of BALB/c male mice were treated as follows: Group 1—mice receiving intravenous (iv) injections of physiological saline; Group 2—administered with 8 mg/kg Z-FA.FMK by iv injection; Group 3—mice treated with 700 mg/kg d-GalN and 15 μg/kg TNF-α by sequential intraperitoneal (ip) injection; Group 4—treated with 700 mg/kg d-GalN and 15 μg/kg TNF-α by sequential ip injection 1 h after administration with 8 mg/kg Z-FA.FMK. Mice from Groups 3 and 4 were sacrificed 4 h after d-GalN/TNF-α injections. The mice treated with d-GalN/TNF-α showed lung damage; increased TNF receptor-associated factor immunoreactivity, lipid peroxidation, protein carbonyl content, and lactate dehydrogenase activity; decreased catalase, superoxide dismutase, and paraoxonase activities. Treatment with Z-FA.FMK resulted in an improvement of these alterations in d-GalN/TNF-α-administered mice. The apoptotic index of type-II pneumocytes was the almost same in the four study groups, but pneumocytes labeled with proliferating cell nuclear antigen antibody was more numerous in Group 4 mice. Our results show that d-GalN/TNF-α results in lung damage without induction of apoptosis. Treatment with Z-FA.FMK stimulates proliferation of type-II pneumocytes and improves degenerative alterations in injured lung occurred with liver injury induced by d-GalN/TNF-α.     

High-fat diet–induced obesity and insulin resistance were ameliorated via enhanced fecal bile acid excretion in tumor necrosis factor-alpha receptor knockout mice

Tumor necrosis factor-α (TNF-α) is one of the main mediators of inflammatory response activated by fatty acids in obesity, and this signaling through TNF-α receptor (TNFR) is responsible for obesity-associated insulin resistance. Recently, TNF-α has shown to affect lipid metabolism including the regulation of lipase activity and bile acid synthesis. However, there is scanty in vivo evidence for the involvement of TNF-α in this process, and the mechanistic role of TNFR remains unclear. In this study, TNFR2 knockout mice (R2KO) and wild-type (WT) mice were fed commercial normal diet (ND) or high-fat diet (HFD) for 8 weeks. In R2KO/HFD mice, the increase in body weight and the accumulation of fat were significantly ameliorated compared with WT/HFD mice in association with the decrease in plasma total cholesterol (137.7±3.1 vs. 98.6±3.1 mg/dL, P<0.005), glucose (221.9±14.7 vs. 167.3±8.1 mg/dL, P<0.01), and insulin (5.1±0.3 vs. 3.4±0.3 ng/mL, P<0.05). Fecal excretion of lipid contents was significantly increased in R2KO mice. In R2KO/HFD mice, the decrease in hepatic cholesterol-7a-hydroxylase activity, the rate-limiting enzyme in bile acid synthesis, was inhibited (1.7±0.2 vs. 8.1±1.0 pmol/min/mg protein, P<0.01). These results suggested that HFD-induced obesity with metabolic derangements could be ameliorated in mice lacking TNF-α receptor 2 via increasing fecal bile acid and lipid content excretion. Therefore, TNF-α signaling through TNFR2 is essentially involved in the bile acid synthesis and excretion of lipids, resulting in its beneficial effects.     

Urinary excretion of 8-hydroxydeoxyguanosine and malondialdehyde after high dose radiochemotherapy preceding stem cell transplantation

The urinary excretion of the hydroxylated DNA base 8-hydroxydeoxyguanosine (8-OHdG) and the lipid peroxidation product malondialdehyde (MDA) was monitored in 11 patients with hematological malignancies undergoing total body irradiation and high-dose chemotherapy preceding bone marrow transplantation. Nine patients showed a prompt increase in urinary 8-OHdG (8-25 times the initial baseline level) on days 0-7 after irradiation onset; the excretion then decreased during the aplastic period and increased again when engraftment took place (in 7 patients). A significant positive correlation was found between urinary 8-OHdG and whole blood leukocyte count, both on day 5 (p =.04, r =.72) and on day 22 (p =.009, r =.80) after irradiation onset. One patient who lacked the first peak of 8-OHdG excretion showed low blood leukocyte counts (less than 2 x 10(9)/l) before therapy onset; this patient, however, later had a successful engraftment and then also showed considerable increases in both 8-OHdG excretion and leukocyte count. These observations suggest leukocytes play a part in the excretion of 8-OHdG after conditioning therapy preceding bone marrow transplantation. As opposed to the biphasic 8-OHdG excretion, the excretion of MDA showed a single peak appearing on days 11-19 after radiochemotherapy onset, i.e., during the period in which the patients suffered from cytopenia, mucositis, and other side effects of the treatment. It is suggested, therefore, that these clinical manifestations are associated with increased lipid peroxidation. Altogether, these findings illustrate the utility of serial urinary samples for monitoring oxidative stress due to conditioning therapy in clinical practice. They also demonstrate that different oxidative stress markers may behave quite differently regarding their appearance in the urine after whole-body oxidative stress.     

Dietary α- and γ-tocopherol supplementation attenuates lipopolysaccharide-induced oxidative stress and inflammatory-related responses in an obese mouse model of nonalcoholic steatohepatitis

Oxidative stress contributes towards the development of nonalcoholic steatohepatitis (NASH). Thus, antioxidants may decrease oxidative stress and ameliorate the events contributing to NASH. We hypothesized that α- or γ-tocopherol would protect against lipopolysaccharide (LPS)-triggered NASH in an obese (ob/ob) mouse model. Five-week-old obese mice (n=18/dietary treatment) were provided 15 mg/kg each of α- and γ-tocopherol or 500 mg/kg of α- or γ-tocopherol for 5-weeks. Then, all mice were injected ip once with LPS (250 μg/kg) before being sacrificed at 0, 1.5 or 6 h. Body weight and hepatic steatosis were unaffected by tocopherols and LPS. Hepatic α- and γ-tocopherol increased (P<.05) ~9.8- and 10-fold in respective tocopherol supplemented mice and decreased in response to LPS. LPS increased serum alanine aminotransferase (ALT) by 86% at 6 h and each tocopherol decreased this response by 29–31%. By 6 h, LPS increased hepatic malondialdehyde (MDA) and tumor necrosis factor-α by 81% and 44%, respectively, which were decreased by α- or γ-tocopherol. Serum ALT was correlated (P<.05) to hepatic tumor necrosis factor-α (r=0.585) and MDA (r=0.592), suggesting that inflammation and lipid peroxidation contributed to LPS-triggered hepatic injury. α- and γ-Tocopherol similarly attenuated LPS-triggered increases in serum free fatty acid, and α-tocopherol only maintained the LPS-triggered serum triacylglycerol responses at 6 h. These findings indicate that increasing hepatic α- or γ-tocopherol protected against LPS-induced NASH by decreasing liver damage, lipid peroxidation, and inflammation without affecting body mass or hepatic steatosis. Further study is needed to define the mechanisms by which these tocopherols protected against LPS-triggered NASH.     

Tetramethylpyrazine protects mice against thioacetamide-induced acute hepatotoxicity

In this study, the intraperitoneal administration of 1 mg/kg thioacetamide (TAA) produced hepatotoxicity in mice. The increase in serum SGOT and SGPT produced at 24 h by this regimen was decreased in a dose-dependent manner by coadministration of tetramethylpyrazine (TMP; 10, 25 and 50 mg/kg). A rise in serum interleukin-2 was similarly prevented. Increased concentrations of malondialdehyde (MDA) generated in vitro in liver homogenates prepared from TAA-treated mice were decreased by TMP treatments. The increase in MDA produced by TAA was also prevented by in vitro addition of TMP to liver homogenates. These results suggest that part of the hepatocellular injury induced by TAA is mediated by oxidative stress caused by the action of cytokines through lipid peroxidation. TMP appears to act by preventing lipid peroxidation.     

Antioxidant treatment normalizes nitric oxide production, renal sodium handling and blood pressure in experimental hyperleptinemia

Recent studies suggest that adipose tissue hormone, leptin, is involved in the pathogenesis of arterial hypertension. However, the mechanism of hypertensive effect of leptin is incompletely understood. We investigated whether antioxidant treatment could prevent leptin-induced hypertension. Hyperleptinemia was induced in male Wistar rats by administration of exogenous leptin (0.25 mg/kg twice daily s.c. for 7 days) and separate groups were simultaneously treated with superoxide scavenger, tempol, or NAD(P)H oxidase inhibitor, apocynin (2 mM in the drinking water). After 7 days, systolic blood pressure was 20.6% higher in leptin-treated than in control animals. Both tempol and apocynin prevented leptin-induced increase in blood pressure. Plasma concentration and urinary excretion of 8-isoprostanes increased in leptin-treated rats by 66.9% and 67.7%, respectively. The level of lipid peroxidation products, malonyldialdehyde + 4-hydroxyalkenals (MDA+4-HNE), was 60.3% higher in the renal cortex and 48.1% higher in the renal medulla of leptin-treated animals. Aconitase activity decreased in these regions of the kidney following leptin administration by 44.8% and 45.1%, respectively. Leptin increased nitrotyrosine concentration in plasma and renal tissue. Urinary excretion of nitric oxide metabolites (NO(x)) was 57.4% lower and cyclic GMP excretion was 32.0% lower in leptin-treated than in control group. Leptin decreased absolute and fractional sodium excretion by 44.5% and 44.7%, respectively. Co-treatment with either tempol or apocynin normalized 8-isoprostanes, MDA+4-HNE, aconitase activity, nitrotyrosine, as well as urinary excretion of NO(x), cGMP and sodium in rats receiving leptin. These results indicate that oxidative stress-induced NO deficiency is involved in the pathogenesis of leptin-induced hypertension.     

Time-course of lipid peroxidation in different organs of mice treated with Echis pyramidum snake venom

This study examined the effect of Echis pyramidum (EP) venom on time-course of lipid peroxidation in different vital organs of mice. Adult male Swiss albino mice were injected with EP venom (2 mg/kg, i.p.); control mice received vehicle alone (normal saline). Mice were killed at 1, 3, 6, 12, and 24 h post-envenomation. The liver, lung, kidney, heart, and brain (cerebrum and cerebellum) were collected for the estimation of malondialdehyde (MDA), an index of lipid peroxidation. The results of this study showed that a single injection of EP venom caused a significant lipid peroxidation in all the organs studied. The onset of lipid peroxidation was as early as 1 h and persisted for several hours, suggesting an important role of oxidative stress in the cytotoxicity of EP venom.     

Protective effects of lazaroid U74389F (16-desmethyl tirilazad) on endrin-induced lipid peroxidation and DNA damage in brain and liver and regional distribution of catalase activity in rat brain

Endrin, a poly-halogenated cyclic hydrocarbon, induces hepatic lipid peroxidation, modulates calcium homeostasis, decreases membrane fluidity, and increases nuclear DNA damage. Little information is available on the neurotoxicity of endrin. The effects of endrin on lipid peroxidation, DNA damage, and regional distribution of catalase activity were assessed in rat brain and liver 24 h following an acute oral dose of 4.5 mg endrin/kg. Lipid peroxidation associated with whole brain mitochondria increased 2.4-fold, whereas microsomal lipid peroxidation increased 2.8-fold following endrin administration. Lipid peroxidation also increased 2.0-fold both in hepatic mitochondria and microsomes. Catalase activity decreased 24% in the hypothalamus, 23% in the cortex, 38% in the cerebellum, and 11% in the brain stem in response to endrin. A 4.3-fold increase in brain nuclear DNA-single strand breaks (SSB) was observed in endrin-treated rats. Pretreatment of rats intraperitoneally with the lazaroid U74389F (16-desmethyl tirilazad) (10 mg/kg in two doses) attenuated the biochemical consequences of endrin-induced oxidative stress. The administration of U74389F in citrate buffer (pH 3.8) provided better protection than administering the lazaroid in corn oil, decreasing endrin-induced lipid peroxidation by 50–80% and DNA-SSB by approximately 72% in liver and 85% in brain, while ameliorating the suppressed catalase activity. The data suggest an involvement of an oxidative stress in the neurotoxicity and hepatotoxicity induced by endrin, which can be attenuated by the lazaroid U74389F.     

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     

Creatine supplementation decreases oxidative DNA damage and lipid peroxidation induced by a single bout of resistance exercise

Rahimi, R. Creatine supplementation decreases oxidative DNA damage and lipid peroxidation induced by a single bout of resistance exercise. J Strength Cond Res 25(12): 3448-3455, 2011-Creatine (Cr), or methyl guanidine-acetic acid, can be either ingested from exogenous sources, such as fish or meat, or produced endogenously by the body, primarily in the liver. It is used as an ergogenic aid to improve muscle mass, strength, and endurance. Heretofore, Cr's positive therapeutic benefits in various oxidative stress-associated diseases have been reported in the literature and, recently, Cr has also been shown to exert direct antioxidant effects. Therefore, the purpose of this study was to investigate the effects of an acute bout of resistance exercise (RE) on oxidative stress response and oxidative DNA damage in male athletes and whether supplementation with Cr could negate any observed differences. Twenty-seven resistance-trained men were randomly divided into a Cr supplementation group (the Cr group [21.6 ± 3.6 years], taking 4 × 5 g Cr monohydrate per day) or a placebo (PL) supplementation group (the PL group [21.2 ± 3.2 years], taking 4 × 5 g maltodextrin per day). A double-blind research design was employed for a 7-day supplementation period. Before and after the seventh day of supplementation, the subjects performed an RE protocol (7 sets of 4 exercises using 60-90 1 repetition maximum) in the flat pyramid loading pattern. Blood and urine samples taken before, immediately, and 24-hour postexercise were analyzed for plasma malondialdehyde (MDA) and urinary 8-hydroxy-2-deoxyguanosine (8-OHdG) excretion. Before the supplementation period, a significant increase in the urinary 8-OHdG excretion and plasma MDA levels was observed after RE. The Cr supplementation induces a significant increase in athletics performance, and it attenuated the changes observed in the urinary 8-OHdG excretion and plasma MDA. These results indicate that Cr supplementation reduced oxidative DNA damage and lipid peroxidation induced by a single bout of RE.     

Disparate patterns of age-related changes in lipid peroxidation in long-lived naked mole-rats and shorter-lived mice

A key tenet of the oxidative stress theory of aging is that levels of accrued oxidative damage increase with age. Differences in damage generation and accumulation therefore may underlie the natural variation in species longevity. We compared age-related profiles of whole-organism lipid peroxidation (urinary isoprostanes) and liver lipid damage (malondialdehyde) in long living naked mole-rats [maximum lifespan (MLS) > 28.3 years] and shorter-living CB6F1 hybrid mice (MLS approximately 3.5 years). In addition, we compared age-associated changes in liver non-heme iron to assess how intracellular conditions, which may modulate oxidative processes, are affected by aging. Surprisingly, even at a young age, concentrations of both markers of lipid peroxidation, as well as of iron, were at least twofold (P < 0.005) greater in naked mole tats than in mice. This refutes the hypothesis that prolonged naked mole-rat longevity is due to superior protection against oxidative stress. The age-related profiles of all three parameters were distinctly species specific. Rates of lipid damage generation in mice were maintained throughout adulthood, while accrued damage in old animals was twice that of young mice. In naked mole-rats, urinary isoprostane excretion declined by half with age (P < 0.001), despite increases in tissue iron (P < 0.05). Contrary to the predictions of the oxidative stress theory, lipid damage levels did not change with age in mole-rats. These data suggest that the patterns of age-related changes in levels of markers of oxidative stress are species specific, and that the pronounced longevity of naked mole-rats is independent of oxidative stress parameters.     

Assessment of hepatoprotective and nephroprotective potential of withaferin A on bromobenzene-induced injury in Swiss albino mice: possible involvement of mitochondrial dysfunction and inflammation

Bromobenzene is a well-known environmental toxin which causes liver and kidney damage through CYP450-mediated bio-activation to generate reactive metabolites and, consequently, oxidative stress. The present study aimed to evaluate the possible protective role of withaferin A against bromobenzene-induced liver and kidney damage in mice. Withaferin A (10 mg/kg) was administered orally to the mice for 8 days before intragastric intubation of bromobenzene (10 mmol/kg). As results of this experiment, the levels of liver and kidney functional markers, lipid peroxidation, and cytokines (TNF-α and IL-1β) presented an increase and there was a decrease in anti-oxidant activity in the bromobenzene-treated group of mice. Pre-treatment with withaferin A not only significantly decreased the levels of liver and kidney functional markers and cytokines but also reduced oxidative stress, as evidenced by improved anti-oxidant status. In addition, the mitochondrial dysfunction shown through the decrease in the activities of mitochondrial enzymes and imbalance in the Bax/Bcl-2 expression in the livers and kidneys of bromobenzene-treated mice was effectively prevented by pre-administration of withaferin A. These results validated our conviction that bromobenzene caused liver and kidney damage via mitochondrial pathway and withaferin A provided significant protection against it. Thus, withaferin A may have possible usage in clinical liver and kidney diseases in which oxidative stress and mitochondrial dysfunction may be existent.     

Urinary isoprostane excretion is not confounded by the lipid content of the diet.

This study aims to determine if isoprostanes accurately reflect in vivo lipid peroxidation or whether they are influenced by the lipid content of the diet. Isoprostanes were measured in urine of healthy subjects under different conditions of lipid intake and under conditions of oxidative stress (fasting). We found that isoprostanes were not influenced by the lipid content of the diet: the urinary level remained constant over 24 h as well as over 4 consecutive days when switching from high to low lipid intake. Urinary isoprostane excretion was increased by 40% following a 24 h fast. We concluded that urinary isoprostane excretion reflects endogenous lipid peroxidation in vivo.