Inhibition of glutathione synthesis in the newborn rat: a model for endogenously produced oxidative stress.

A model for oxidative stress is described in which glutathione (GSH) synthesis is selectively blocked in newborn rats by administration of L-buthionine-(S,R)-sulfoximine (BSO). In this model, the normal endogenous physiological formation of reactive oxygen species is largely unopposed, and therefore oxidative tissue damage occurs; because GSH is used for reduction of dehydroascorbate, tissue ascorbate levels decrease. In lung there are decreased numbers of lamellar bodies and decrease of intraalveolar surfactant. Proximal renal tubular, hepatic, and brain damage also occur. A diastereoisomer of BSO that does not inhibit GSH synthesis, L-buthionine-R-sulfoximine, does not produce toxicity; this control experiment renders it unlikely that the observed effects of BSO are produced by the sulfoximine moiety itself. There is correlation between the decrease of mitochondrial GSH levels and mitochondrial and cell damage. Oxidative stress as evaluated by mitochondrial damage and mortality can be prevented by treatment with GSH esters or ascorbate. There is apparent linkage between the antioxidant actions of GSH and ascorbate. This model, which may readily be applied to evaluation of the efficacy of other compounds in preventing oxidative stress, offers an approach to study of other effects of GSH deficiency (e.g., on lipid metabolism, hematopoiesis), and closely resembles oxidative stress that occurs in certain human newborns and in other clinical states.     

Mitochondrial glutathione in hypermetabolic rats following burn injury and thyroid hormone administration: evidence of a selective effect on brain glutathione by burn injury.

Cerebral cortex, heart, skeletal muscle, and liver mitochondrial glutathione (GSH) levels in severely burned rats are decreased to between approximately 50% to 70% of sham-operated, normally fed controls. In semistarved rats, weight-matched with burned rats, mitochondrial GSH levels in these tissues are decreased to between approximately 70% to 91% of those in sham-operated rats. Total GSH levels in peripheral tissues and brain are decreased to approximately 60% to 65% of control levels in rats with burn injury and food restriction, suggesting a higher mitochondrial GSH turnover in burned rats than in semistarved rats, probably because of higher "stress hormone" levels in burned rats than in semistarved rats. Cerebral cortex mitochondrial GSH levels are unaffected by variations in thyroid hormone status, but liver mitochondrial GSH levels are decreased by triiodothyronine and increased by propylthiouracil. The present results suggest that mitochondrial GSH is not only regulated by the rate of GSH synthesis in the cytosol, but seems to be under hormonal influence as well; stress hormones and triiodothyronine may decrease mitochondrial GSH by increasing mitochondrial oxygen consumption with increased reactive oxygen species formation or by increasing GSH exchange between mitochondria and the cytosol. These findings may be of importance therapeutically in increasing antioxidative defenses to limit oxidative stress injury in hypermetabolic patients.     

Protein and lipid oxidative damage in streptozotocin-induced diabetic rats submitted to forced swimming test: the insulin and clonazepam effect

Diabetes may modify central nervous system functions and is associated with moderate cognitive deficits and changes in the brain, a condition that may be referred to as diabetic encephalopathy. The prevalence of depression in diabetic patients is higher than in the general population, and clonazepam is being used to treat this complication. Oxidative stress may play a role in the development of diabetes complications. We investigated oxidative stress parameters in streptozotocin-induced diabetic rats submitted to forced swimming test (STZ) and evaluated the effect of insulin (STZ-INS) and/or clonazepam (STZ-CNZ and STZ-INS-CNZ) acute treatment on these animal model. Oxidative damage to proteins measured as carbonyl content in plasma was significantly increased in STZ group compared to STZ treated groups. Malondialdehyde plasma levels were significantly reduced in STZ-INS and STZ-INS-CNZ groups when compared to STZ rats, being significantly reduced in STZ-INS-CNZ than STZ-INS rats. The activities of the antioxidant enzymes catalase, superoxide dismutase and glutathione peroxidase showed no significant differences among all groups of animals. These findings showed that protein and lipid damage occurs in this diabetes/depression animal model and that the associated treatment of insulin and clonazepam is capable to protect against oxidative damage in this experimental model.     

Age-related changes in the rat brain mitochondrial antioxidative enzyme ratios: Modulation by melatonin

Oxidative stress is an important factor for aging. The antioxidative enzymes glutathione peroxidase (GPx), glutathione reductase (GRd) and superoxide dismutase (SOD) play a crucial role protecting the organism against the age-dependent oxidative stress. Glutathione (GSH) is present in nearly all living cells. GSH is one of the main antioxidants in the cell and it serves several physiological functions. Our purpose was to evaluate the age-related changes in mitochondrial GPx, GRd and SOD activities, and mitochondrial GSH pool in the brains of young (3months) and aged rats (24months). We also investigated whether melatonin administration influences these brain mitochondrial enzyme activities and GSH levels in young and aged rats. The results showed that GPx activity increased with age, whereas melatonin treatment decreased GPx activity in the aged rats at levels similar to those in young and young+melatonin groups. The activities of GRd and SOD, however, did not change with age. But, melatonin treatment increased SOD activity in the aged rats. GSH levels, which also increased with age, were not modified by melatonin treatment. The reduction in the SOD/GPx and GR/GPx ratios with age was prevented by melatonin administration. Together, our results suggest that the age-related oxidative stress in rat brain mitochondria is more apparent when the antioxidant enzyme ratios are analyzed instead of their absolute values. The antioxidative effects of melatonin were also supported by the recovery of the enzyme ratios during aging.     

Diabetes enhances oxidative stress-induced TRPM2 channel activity and its control by N-acetylcysteine in rat dorsal root ganglion and brain

N-acetylcysteine (NAC) is a sulfhydryl donor antioxidant that contributes to the regeneration of glutathione (GSH) and also scavengers via a direct reaction with free oxygen radicals. Recently, we observed a modulatory role of NAC on GSH-depleted dorsal root ganglion (DRG) cells in rats. NAC may have a protective role on oxidative stress and calcium influx through regulation of the TRPM2 channel in diabetic neurons. Therefore, we investigated the effects of NAC on DRG TRPM2 channel currents and brain oxidative stress in streptozotocin (STZ)-induced diabetic rats. Thirty-six rats divided into four groups: control, STZ, NAC and STZ + NAC. Diabetes was induced in the STZ and STZ + NAC groups by intraperitoneal STZ (65 mg/kg) administration. After the induction of diabetes, rats in the NAC and STZ + NAC groups received NAC (150 mg/kg) via gastric gavage. After 2 weeks, DRG neurons and the brain cortex were freshly isolated from rats. In whole-cell patch clamp experiments, TRPM2 currents in the DRG following diabetes induction with STZ were gated by H₂O₂. TRPM2 channel current densities in the DRG and lipid peroxidation levels in the DRG and brain were higher in the STZ groups than in controls; however, brain GSH, GSH peroxidase (GSH-Px), vitamin C and vitamin E concentrations and DRG GSH-Px activity were decreased by diabetes. STZ + H₂O₂-induced TRPM2 gating was totally inhibited by NAC and partially inhibited by N-(p-amylcinnamoyl) anthranilic acid (ACA) and 2-aminoethyl diphenylborinate (2-APB). GSH-Px activity and lipid peroxidation levels were also attenuated by NAC treatment. In conclusion, we observed a modulatory role of NAC on oxidative stress and Ca²⁺ entry through the TRPM2 channel in the diabetic DRG and brain. Since excessive oxidative stress and overload Ca²⁺ entry are common features of neuropathic pain, our findings are relevant to the etiology and treatment of pain neuropathology in DRG neurons.     

The effect of alpha-lipoic acid on NOS dispersion in the lung of streptozotocin-induced diabetic rats

Oxidative stress and impaired bioactivity of nitric oxide (NO) play an important role in the organ pathogenesis and angiopathic complications of diabetes mellitus. In this study, we evaluated the effects of alpha-lipoic acid (ALA) on nitric oxide synthase (NOS) in lung tissues. ALA is a strong antioxidant. We wonder how it can affect oxidative stress and NO in the lung cells and vessels of diabetic rats. Wistar rats were divided into four groups; control, diabetic [65 mg/kg streptozotocin (STZ) for 15 days], STZ+ALA-treated (65 mg/kg ALA every 2 days for 15 days), and ALA-only-treated animals. At the end of the experimental period, lipid peroxidation, superoxide dismutase (SOD), and inducible NOS (iNOS) and endothelial NOS (eNOS) distribution were evaluated. Oxidative stress decreased with ALA in diabetic animals, and SOD also increased with ALA. iNOS and eNOS increased in diabetic animals, and ALA prevented iNOS increment in lung tissues. As a result, ALA can prevent some diabetic effects on the lungs and can also protect from vascular damages.     

Oxidative stress and respiratory muscle dysfunction in severe chronic obstructive pulmonary disease

RATIONALE: Oxidative stress is involved in the skeletal muscle dysfunction observed in patients with severe chronic obstructive pulmonary disease (COPD). We hypothesized that the diaphragms of such patients might generate greater levels of oxidants than those neutralized by antioxidants. OBJECTIVES: To assess the levels of both oxidative and nitrosative stress and different antioxidants in the diaphragms of those patients, and to analyze potential relationships with lung and respiratory muscle dysfunctions. METHODS AND MEASUREMENTS: We conducted a case-control study in which reactive carbonyl groups, hydroxynonenal-protein adducts, antioxidant enzyme levels, nitric oxide synthases, and 3-nitrotyrosine formation were detected using immunoblotting and immunhistochemistry in diaphragm specimens (thoracotomy) obtained from six patients with severe COPD, six patients with moderate COPD, and seven control subjects. MAIN RESULTS: Diaphragms of patients with severe COPD showed both higher protein carbonyl groups and hydroxynonenal-protein adducts than control subjects. When only considering patients with COPD, negative correlations were found between carbonyl groups and airway obstruction, and between hydroxynonenal-protein adducts and respiratory muscle strength. Although diaphragmatic neuronal nitric oxide synthase did not differ among the three groups and no inducible nitric oxide synthase was detected in any muscle, muscle endothelial nitric oxide synthase was lower in patients with severe COPD than in control subjects. Muscle nitrotyrosine levels were similar in both patients with severe COPD and control subjects. CONCLUSIONS: This study shows that oxidative stress rather than nitric oxide is likely to be involved in the respiratory muscle dysfunction in severe COPD.     

氧化应激相关线粒体功能障碍与支气管哮喘

支气管哮喘(简称哮喘)是一种以不同程度的气流阻塞、气道高反应性和气道炎症为特点的复杂的炎症性疾病,受到遗传和环境因素的共同影响.分子生物学、细胞学以及动物模型研究提示线粒体功能障碍和氧化应激在哮喘发病中起着重要作用.哮喘状态下,炎症细胞内活性氧自由基生成增加,线粒体功能出现障碍,同时伴随气道上皮细胞损伤,并影响气道平滑肌功能.过敏性哮喘小鼠模型研究以及利用哮喘患者的外周细胞和组织进行的研究提示,抗氧化治疗有望成为哮喘预防与治疗的有效方法.本文将主要对以下方面进行讨论:①健康状态下的线粒体结构与功能;②氧化应激与线粒体功能障碍;③肺部氧化应激的来源及中和机制;④哮喘状态下的氧化应激和线粒体功能障碍;⑤线粒体靶向抗氧化剂的研究进展.     

Pentoxifylline diminishes the oxidative damage to renal tissue induced by streptozotocin in the rat

Oxidative damage has been suggested to be a contributing factor in the development to diabetic nephropathy (DN). Recently, there has been evidence that pentoxifylline (PTX) has free radical-scavenging properties; thus, its anti-inflammatory and renoprotective effects may be related to a reduction in reactive oxygen species production. It is likely that the pharmacological effects of PTX include an antioxidant mechanism as shown in in vitro assays. The aim of this study was to evaluate whether the reported renoprotective effects of PTX could be the result of its antioxidant actions in streptozotocin (STZ)-induced DN in rats. The administration of PTX over a period of 8 weeks, in addition to displaying renoprotective effects, caused a significant reduction in lipoperoxide levels (LPOS) in the diabetic kidney (P < 0.05), compared to untreated rats. These levels were comparable to those in the healthy kidney of experimental animals (P > 0.05). All untreated STZ rats exhibited an increase in LPOS as opposed to healthy controls (H) (P < 0.001). The total antioxidant activity (TAA) in plasma was increased significantly already after 2 days of STZ (P < 0.05). When we examined the progression of TAA in STZ rats, there was a significant decrease over 8 weeks (P < 0.05). PTX treatment caused an increase in TAA when compared to untreated STZ rats (P < 0.05). Renal hypertrophy was less evident in PTX-treated STZ than in untreated STZ rats, evaluated by kidney weight/body weight ratio. These results indicate that PTX decreases the oxidative damage induced by these experimental procedures and may increase antioxidant defense mechanisms in STZ-induced diabetes in rats.     

Evidence that 2-methylacetoacetate induces oxidative stress in rat brain

In the present study we investigated the effects of 2-methylacetoacetate (MAA) and 2-methyl-3-hydroxybutyrate (MHB), the major metabolites accumulating in mitochondrial 2-methylacetoacetyl-CoA thiolase (KT) and 2-methyl-3-hydroxybutyryl-CoA dehydrogenase (MHBD) deficiencies, on important parameters of oxidative stress in cerebral cortex from young rats. We verified that MAA induced lipid peroxidation (increase of thiobarbituric acid-reactive substances (TBA-RS) and chemiluminescence values), whereas MHB did not alter these parameters. MAA-induced increase of TBA-RS levels was fully prevented by free radical scavengers, indicating that free radicals were involved in this effect. Furthermore, MAA, but not MHB, significantly induced sulfhydryl oxidation, implying that this organic acid provokes protein oxidative damage. It was also observed that MAA reduced GSH, a naturally-occurring brain antioxidant, whereas MHB did not change this parameter. Furthermore, the decrease of GSH levels caused by MAA was not due to a direct oxidative action, since this organic acid did not alter the sulfhydryl content of a commercial solution of GSH in a cell free medium. Finally, MAA and MHB did not raise nitric oxide production. The data indicate that MAA induces oxidative stress in vitro in cerebral cortex. It is presumed that this pathomechanism may be involved in the brain damage found in patients affected by KT deficiency.     

Inactivation of oxidized and S-nitrosylated mitochondrial proteins in alcoholic fatty liver of rats

Increased oxidative/nitrosative stress is a major contributing factor to alcohol-mediated mitochondrial dysfunction. However, which mitochondrial proteins are oxidatively modified under alcohol-induced oxidative/nitrosative stress is poorly understood. The aim of this study was to systematically investigate oxidized and/or S-nitrosylated mitochondrial proteins and to use a biotin-N-maleimide probe to evaluate their inactivation in alcoholic fatty livers of rats. Binge or chronic alcohol exposure significantly elevated nitric oxide, inducible nitric oxide synthase, and ethanol-inducible CYP2E1. The biotin-N-maleimide-labeled oxidized and/or S-nitrosylated mitochondrial proteins from pair-fed controls or alcohol-fed rat livers were subsequently purified with streptavidin-agarose. The overall patterns of oxidized and/or S-nitrosylated proteins resolved by 2-dimensional polyacrylamide gel electrophoresis were very similar in the chronic and binge alcohol treatment groups. Seventy-nine proteins that displayed differential spot intensities from those of control rats were identified by mass spectrometry. These include mitochondrial aldehyde dehydrogenase 2 (ALDH2), ATP synthase, acyl-CoA dehydrogenase, 3-ketoacyl-CoA thiolase, and many proteins involved in chaperone activity, mitochondrial electron transfer, and ion transport. The activity of 3-ketoacyl-CoA thiolase involved in mitochondrial beta-oxidation of fatty acids was significantly inhibited in alcohol-exposed rat livers, consistent with hepatic fat accumulation, as determined by biochemical and histological analyses. Measurement of activity and immunoblot results showed that ALDH2 and ATP synthase were also inhibited through oxidative modification of their cysteine or tyrosine residues in alcoholic fatty livers of rats. In conclusion, our results help to explain the underlying mechanism for mitochondrial dysfunction and increased susceptibility to alcohol-mediated liver damage.     

Memory loss in old rats is associated with brain mitochondrial decay and RNA/DNA oxidation: partial reversal by feeding acetyl-L-carnitine and/or R-alpha -lipoic acid

Accumulation of oxidative damage to mitochondria, protein, and nucleic acid in the brain may lead to neuronal and cognitive dysfunction. The effects on cognitive function, brain mitochondrial structure, and biomarkers of oxidative damage were studied after feeding old rats two mitochondrial metabolites, acetyl-l-carnitine (ALCAR) [0.5% or 0.2% (wt/vol) in drinking water], and/or R-alpha-lipoic acid (LA) [0.2% or 0.1% (wt/wt) in diet]. Spatial memory was assessed by using the Morris water maze; temporal memory was tested by using the peak procedure (a time-discrimination procedure). Dietary supplementation with ALCAR and/or LA improved memory, the combination being the most effective for two different tests of spatial memory (P < 0.05; P < 0.01) and for temporal memory (P < 0.05). Immunohistochemical analysis showed that oxidative damage to nucleic acids (8-hydroxyguanosine and 8-hydroxy-2'-deoxyguanosine) increased with age in the hippocampus, a region important for memory. Oxidative damage to nucleic acids occurred predominantly in RNA. Dietary administration of ALCAR and/or LA significantly reduced the extent of oxidized RNA, the combination being the most effective. Electron microscopic studies in the hippocampus showed that ALCAR and/or LA reversed age-associated mitochondrial structural decay. These results suggest that feeding ALCAR and LA to old rats improves performance on memory tasks by lowering oxidative damage and improving mitochondrial function.     

α-硫辛酸减弱线粒体氧化应激保护糖尿病心肌病的机制研究

目的探讨线粒体氧化应激（MOS）在糖尿病心肌病（DCM）发生发展中的作用和α-硫辛酸（α-LA）保护机制。方法大鼠分为正常对照（NC）组,糖尿病（DM）组,糖尿病α-LA治疗组（α-LA组）。4、8、12周末测定大鼠心功能、心脏胶原含量、线粒体谷胱甘肽（GSH）、MDA含量和Mn-SOD的活性,镜下观察心脏病理改变。结果随病程延长,DM组大鼠心功能受损加重、胶原含量增加,病理改变加重,心肌线粒体Mn-SOD的活性和GSH的含量下降,MDA的含量明显上升;α-LA治疗后能够显著逆转糖尿病大鼠上述指标的变化。MDA与心脏胶原含量呈正相关。结论糖尿病大鼠MOS与DCM发生发展密切相关,α-LA通过升高心肌线粒体Mn-SOD活性和GSH的含量减弱MOS损伤保护DCM。     

Interrelationships of liver and brain with special reference to reye syndrome

Summary Reye syndrome is an acute non-inflammatory encephalopathy that can be precipitated by toxic, infective, metabolic or hypoxic upsets. The biochemical changes point to mitochondrial dysfunction and this is substantiated by structural changes in mitochondria on electron microscopy. The toxic metabolites that accumulate are similar to those incriminated in hepatic encephalopathy and other metabolic diseases. These metabolites exert their deleterious effects by direct neuronal damage, neurotransmitter blockade, vascular damage, cerebral oedema, hypoxic ischaemic damage, demyelination, retardation of brain growth and neuronal storage. Brain capillary endothelial cells are very rich in mitochondria and mitochondrial disorders can effect the central nervous system primarily, and not just as a consequence of systemic metabolic upset.     

Decrease in mitochondrial oxidative protein damage parameters in the streptozotocin-diabetic rat

BACKGROUND: Many authors have shown that hyperglycemia leads to an increase in oxidative protein damage in diabetes. The aim of this study was to reveal the susceptibility of mitochondria from liver, pancreas, kidney, and skeletal muscle of diabetic Sprague-Dawley rats, a model of type 1 diabetes, to oxidative protein damage. METHODS: Mitochondrial fractions were obtained by differential centrifugation. To show the effect of hyperglycemia in promoting oxidative protein damage, we determined mitochondrial protein carbonyl, total thiol, nitrotyrosine, advanced oxidation protein products, and lipid hydroperoxide levels. The levels of the studied markers, except nitrotyrosine, were determined by colorimetric methods. Nitrotyrosine levels were measured by ELISA. All values were compared with those of the controls by using the Mann-Whitney U-test. RESULTS: Nitrotyrosine and lipid hydroperoxide levels were decreased and other parameters were not changed in liver mitochondria of diabetic rats. Protein carbonyl, nitrotyrosine, advanced oxidation protein products, and lipid hydroperoxide levels were decreased and total thiol levels were not changed in pancreas mitochondria of diabetic rats. Only advanced oxidation protein products and lipid hydroperoxide levels were decreased in kidney mitochondria of diabetic rats. The levels of the same parameters were not significantly different in muscle mitochondria of diabetic rats. CONCLUSIONS: The decrease in mitochondrial oxidative protein damage in diabetes may correspond to either an increase in antioxidant defense mechanisms or a different adaptive response of the cells to the increased extramitochondrial oxidative stress in diabetes. The mitochondrial oxidative protein damage-lowering mechanisms in diabetes remain to be clarified.     

Long-term melatonin administration protects brain mitochondria from aging

Abstract:  We tested whether chronic melatonin administration in the drinking water would reduce the brain mitochondrial impairment that accompanies aging. Brain mitochondria from male and female senescent prone (SAMP8) mice at 5 and 10 months of age were studied. Mitochondrial oxidative stress was determined by measuring the levels of lipid peroxidation and nitrite, glutathione/glutathione disulfide ratio, and glutathione peroxidase and glutathione reductase activities. Electron transport chain activity and oxidative phosphorylation capability of mitochondria were also determined by measuring the activity of the respiratory chain complexes and the ATP content. The results support a significant age-dependent mitochondrial dysfunction with a diminished efficiency of the electron transport chain and reduced ATP production, accompanied by an increased oxidative/nitrosative stress. Melatonin administration between 1 and 10 months of age completely prevented the mitochondrial impairment, maintaining or even increasing ATP production. There were no major age-dependent differences between males in females, although female mice seemed to be somewhat more sensitive to melatonin treatment than males. Thus, melatonin administration as a single therapy maintained fully functioning brain mitochondria during aging, a finding with important consequences in the pathophysiology of brain aging.     

<Emphasis Type="Italic">Moringa oleifera</Emphasis> supplemented diet modulates nootropic-related biomolecules in the brain of STZ-induced diabetic rats treated with acarbose

There are strong correlations between diabetes mellitus and cognitive dysfunction. This study sought to investigate the modulatory effects of Moringa oleifera leaf (ML) and seed (MS) inclusive diets on biomolecules [acetylcholinesterase (AChE), butyrylcholinesterase (BChE)] angiotensin-I converting enzyme (ACE), arginase, catalase, glutathione transferase (GST) and glutathione peroxidase (GSH-Px) activities, glutathione (GSH) and nitric oxide (NO) levels] associated with cognitive function in the brain of streptozotocin (STZ)-induced diabetic rats treated with acarbose (ACA). The rats were made diabetic by intraperitoneal administration of 0.1 M sodium-citrate buffer (pH 4.5) containing STZ [60 mg/kg b.w (BW)] and fed with diets containing 2 and 4% ML/MS. Acarbose (25 mg/kg BW) was administered by gavage daily for 14 days. The animals were distributed in eleven groups of eight animals as follows: control, STZ-induced, STZ?+?ACA, STZ?+?2% ML, STZ?+?ACA?+?2% ML, STZ?+?4% ML, STZ?+?ACA?+?4% ML, STZ?+?2% MS, STZ?+?ACA?+?2% MS, STZ?+?4% MS, STZ?+?ACA?+?4% MS. There were marked increase in AChE, BChE, arginase, ACE and concomitant decrease in catalase, GST, GSH-Px, activities and NO levels in STZ-diabetic group compared with the control. However, there was a decrease in AChE, BChE and ACE activities and concomitant increase in the antioxidant molecules in the groups fed with supplemented diets treated with/without ACA compared with the STZ-diabetic group. These findings suggest that ML/MS supplemented diet could prevent cognitive dysfunction-induced by chronic hyperglycemia.     

PTEN-inducible kinase 1 (PINK1)/Park6 is indispensable for normal heart function

Oxidative stress is caused by an imbalance between reactive oxygen species (ROS) production and the ability of an organism to eliminate these toxic intermediates. Mutations in PTEN-inducible kinase 1 (PINK1) link mitochondrial dysfunction, increased sensitivity to ROS, and apoptosis in Parkinson's disease. Whereas PINK1 has been linked to the regulation of oxidative stress, the exact mechanism by which this occurs has remained elusive. Oxidative stress with associated mitochondrial dysfunction leads to cardiac dysfunction and heart failure (HF). We hypothesized that loss of PINK1 in the heart would have deleterious consequences on mitochondrial function. Here, we observed that PINK1 protein levels are markedly reduced in end-stage human HF. We also report that PINK1 localizes exclusively to the mitochondria. PINK1(-/-) mice develop left ventricular dysfunction and evidence of pathological cardiac hypertrophy as early as 2 mo of age. Of note, PINK1(-/-) mice have greater levels of oxidative stress and impaired mitochondrial function. There were also higher degrees of fibrosis, cardiomyocyte apoptosis, and a reciprocal reduction in capillary density associated with this baseline cardiac phenotype. Collectively, our in vivo data demonstrate that PINK1 activity is crucial for postnatal myocardial development, through its role in maintaining mitochondrial function, and redox homeostasis in cardiomyocytes. In conclusion, PINK1 possesses a distinct, nonredundant function in the surveillance and maintenance of cardiac tissue homeostasis.     

Antioxidant properties of glutamine and its role in VEGF-Akt pathways in portal hypertension gastropathy

AIM: To investigate the effects of glutamine on oxidative/nitrosative stress and the vascular endothelial growth factor (VEGF)-Akt-endothelial nitric oxide synthase (eNOS) signaling pathway in an experimental model of portal hypertension induced by partial portal vein ligation (PPVL). METHODS: Portal hypertension was induced by PPVL. The PPVL model consists of a partial obstruction of the portal vein, performed using a 20 G blunt needle as a guide, which is gently removed after the procedure. PPVL model was performed for 14 d beginning treatment with glutamine on the seventh day. On the fifteenth day, the mesenteric vein pressure was checked and the stomach was removed to test immunoreactivity and oxidative stress markers. We evaluated the expression and the immunoreactivity of proteins involved in the VEGF-Akt-eNOS pathway by Western blotting and immunohistochemical analysis. Oxidative stress was measured by quantification of the cytosolic concentration of thiobarbituric acid reactive substances (TBARS) as well as the levels of total glutathione (GSH), superoxide dismutase (SOD) activity, nitric oxide (NO) production and nitrotyrosine immunoreactivity. RESULTS: All data are presented as the mean ± SE. The production of TBARS and NO was significantly increased in PPVL animals. A reduction of SOD activity was detected in PPVL + G group. In the immunohistochemical analyses of nitrotyrosine, Akt and eNOS, the PPVL group exhibited significant increases, whereas decreases were observed in the PPVL + G group, but no difference in VEGF was detected between these groups. Western blotting analysis detected increased expression of phosphatidylinositol-3-kinase (PI3K), P-Akt and eNOS in the PPVL group compared with the PPVL + G group, which was not observed for the expression of VEGF when comparing these groups. Glutamine administration markedly alleviated oxidative/nitrosative stress, normalized SOD activity, increased levels of total GSH and blocked NO overproduction as well as the formation of peroxynitrite. CONCLUSION