Hepatocyte mitochondrion respiratory chain in rats with experimental toxic hepatitis

The purpose of this study was to examine hepatocyte mitochondrion respiratory chain in rats subjected to ethanol and CCl4 administration within 4 weeks to induce an experimental hepatitis. Oxygen consumption was determined as a measure of mitochondrion respiration chain function. The development of liver pathology was accompanied by fat accumulation, fibrosis, triglycerides and lipid peroxidation increase. Respiratory chain characteristics damage was found. Endogenous oxygen consumption by hepatocytes isolated from pathological liver was found 34% higher compared to control. Exogenous malate and pyruvate substrates delivery didn't stimulate cell respiration. Rotenone (the inhibitor of the I complex) decreased 27% oxygen consumption by pathological hepatocytes while dinitrophenol produced 37% cell respiration increase. States 3 (V3) and 4 (V4) mitochondrial respiration with malate + glutamate as substrates were found to be 70 and 56% higher accordingly compared to control level. V3 and Vd (dinitrophenol respiration) for mitochondria from pathological liver didn't differ from control when being tested with malate + glutamate or succinate as substrates. Cytochrome c oxidase activity increased (+ 80%) as compared to control. Administration of hypolipidemic agent simvastatin simultaneously with ethanol and CC14 resulted in decrease liver fat accumulation, fibrosis and peroxidation products. Simvastatin administration caused hepatocyte endogenous respiration decrease while malate + pyruvate, dinitrophenol or rotenone delivery produced oxygen consumption alterations similar to control. However, when isolated mitochondria from liver of simvastatin treated animals being tested the decrease of oxidative phosphorylation coupling for substrates malate + glutamate was found. While simvastatin did not cause changes in cytochrome c oxidase activity. We propose the hypothesis that the NCCR complex in rat mitochondria with experimental toxic hepatitis works extensively on superoxydanion production. Alterations of SCCR, Coenzyme Q-cytochrome c-reductase, cytochrome c oxidase and ATP-synthase activities have an adaptive nature to compensate for impaired NCCR function.     

Superoxide anion production by the mitochondrial respiratory chain of hepatocytes of rats with experimental toxic hepatitis

The progression of toxic hepatitis is accompanied by the activation of oxidative processes in the liver associated with an enhancement of the mitochondrial respiratory chain activity and superoxide anion production (О₂^˙-). The purpose of this study was to examine our previously formulated assumption concerning the predominant contribution of the complex I to О₂^˙- production increase by the mitochondrial respiratory chain of hepatocytes in toxic hepatitis (Shiryaeva et al. Tsitologiia, 49, 125–132 2007). Toxic hepatitis was induced by a combined application of ССl₄ and ethanol. Respiratory chain function analysis was executed with submitochondrial particles (SP) in the presence of specific inhibitors. It was shown that the rate of О₂^˙- production by SP of animals with toxic hepatitis, when NADH was delivered, was 2.5-fold higher as compared with the control. The rates of О₂^˙- production by SP of rats with toxic hepatitis in the presence of NADH or NADH + rotenone were similar. The О₂^˙- production rate by control SP in the presence of NADH + rotenone corresponded to the О₂^˙- production rate by toxic hepatitis SP when only NADH was delivered. When NADH + myxothiazol were delivered to the incubation system, О₂^˙- production by toxic hepatitis SP was 72% higher than for the control. Conversely, in the presence of antimycin A, the production of О₂^˙- by toxic hepatitis SP was lower compared to the control. Collectively, the presented data indicate that the О₂^˙- production rate was enhanced by the complex I of the hepatocyte mitochondrial respiratory chain in experimental toxic hepatitis. Complex III contribution to the production of О₂^˙- was insignificant. We assume that the increase in О₂^˙- production by the respiratory chain may be considered not only as the mechanism of pathology progression, but also as a compensatory mechanism preserving the electron transport function of the mitochondrial respiratory chain when complex I functioning is blocked in part.     

Galangin,a natural flavonoid reduces mitochondrial oxidative damage in streptozotocin-induced diabetic rats

Objective: We designed this study to observe the effect of galangin on damaged mitochondria in the liver of diabetic rats.

Methods: Male albino Wistar rats were made diabetic by injecting streptozotocin (STZ) intraperitoneally (40?mg?kg^?1 body weight (BW)). Galangin (8?mg?kg^?1 BW) or glibenclamide (600?µg?kg^?1 BW) was given orally daily once for 45 days to both healthy and diabetic rats.

Results: Diabetic rats showed significant (P?P?P?P?P?Conclusion: From the results, we conclude that galangin could maintain liver mitochondrial function in diabetic rats.     

Inhibition of mitochondrial respiratory chain in brain of rats subjected to an experimental model of depression

Depressive disorders, including major depression, are serious and disabling. However, the exact pathophysiology of depression is not clearly understood. Life stressors contribute in some fashion to depression and are an extension of what occurs normally. In this context, chronic stress has been used as an animal model of depression. Based on the hypothesis that metabolism impairment might be involved in the pathophysiology of depression, in the present work we evaluated the activities of mitochondrial respiratory chain complexes and creatine kinase in brain of rats subjected to chronic stress. After 40 days of mild stress, a reduction in sweet food ingestion was observed, as well as increased adrenal gland weight, when compared to control group. We also verified that control group gained weight after 40 days, but stressed group did not. Moreover, our findings showed that complex I, III and IV were inhibited in stress group only in cerebral cortex and cerebellum. On the other hand, complex II and creatine kinase were not affected in stressed group. Although it is difficult to extrapolate our findings to the human condition, the inhibition of mitochondrial respiratory chain by chronic stress may be one mechanism in the pathophysiology of depressive disorders.     

Characteristics of Fe(II)ATP complex-induced damage to the rat liver mitochondrial membrane

It is well established that several iron complexes can induce oxidative damage in hepatic mitochondrial membranes by catalyzing the formation of ·OH radicals and/or by promoting lipid peroxidation. This is a relevant process for the molecular basis of iron overload diseases. The present work demonstrates that Fe(II)ATP complexes (5–50M) promote an oxygen consumption burst in a suspension of isolated rat liver mitochondria (either in the absence or presence of Antimycin A), caused mainly by lipid peroxidation. Fe(II)ATP alone induced small levels of oxygen uptake but no burst. The time course of Fe(II)ATP oxidation to Fe(III)ATP in the extramitochondrial media also reveals a simultaneous burst phase. The iron chelator Desferal (DFO) or the chain-break antioxidant butylated hydroxytoluene (BHT) fully prevented both lipid peroxidation (quantified as oxygen uptake burst) and mitochondrial swelling. DFO and BHT were capable of stopping the ongoing process of peroxidation at any point of their addition to the mitochondrial suspension. Conversely, DFO and BHT only halted the Fe(II)ATP-induced mitochondrial swelling at the onset of the process. Fe(II)ATP could also cause the collapse of mitochondrial potential, which was protected by BHT if added at the onset of the damaging process. These results, as well as correlation studies between peroxidation and mitochondrial swelling, suggest that a two phase process is occurring during Fe(II)ATP-induced mitochondrial damage: one dependent and another independent of lipid peroxidation. The involvement of lipid peroxidation in the overall process of mitochondrial membrane injury is discussed.Abbreviations AA Antimycin A - BHT butylated hydroxytoluene - EGTA ethylene glycol-bis(-aminoethyl ether) - N,N,N,N tetraacetic acid - DFO Desferal - HEPES N-(2-hydroxyethyl)piperazine-N-2-ethanesulfonic acid - SOD superoxide dismutase - TPP+ tetraphenylphosphonium bromide - TBARS thiobarbituric acid reactive substances     

Dysfunction of the mitochondrial respiratory chain in the rostral ventrolateral medulla during experimental endotoxemia in the rat

We investigated the functional changes in the mitochondrial respiratory chain at the rostral ventrolateral medulla (RVLM), the medullary origin of sympathetic vasomotor tone, in an experimental model of endotoxemia that mimics systemic inflammatory response syndrome. In Sprague-Dawley rats maintained under propofol anesthesia, intravenous administration ofEscherichia coli lipopolysaccharide (LPS; 30 mg/kg) induced a reduction (Phase I), followed by an augmentation (Phase II) and a secondary decrease (Phase III) in the power density of vasomotor components (0–0.8 Hz) in systemic arterial pressure signals. LPS also elicited progressive hypotension, and death ensued within 4 h. Enzyme assay revealed significant depression of the activity of nicotinamide adenine dinucleotide cytochromec reductase (Complexes I + III) and cytochromec oxidase (Complex IV) in the RVLM during all three phases of endotoxemia. On the other hand, the activity of succinate cytochromec reductase (Complexes II + III) remained unaltered. We conclude that selective dysfunction of respiratory enzyme Complexes I and IV in the mitochondrial respiratory chain at the RVLM, whose neuronal activity is intimately related to the death process, is closely associated with fatal endotoxemia in the rat.     

Hepatocyte mitochondrion electron-transport chain alterations in CCl<Subscript>4</Subscript> and alcohol induced hepatitis in rats and their correction with simvastatin

The goal of this study was to examine the state of hepatocyte mitochondrial respiratory chain of rats with toxic hepatitis induced by CCl₄ and ethanol. Oxygen consumption by hepatocytes and mitochondria was determined. Endogenous oxygen consumption by pathological hepatocytes was 1.3-fold higher compared with control. Rotenone resulted in 27% suppression of respiration by pathological hepatocytes whereas 2,4-dinitrophenol produced a 1.4-fold increase of respiration. States 3 and 4 of mitochondrial respiration with malate and glutamate were found to be higher as compared to control. State dinitrophenol and state 3 respirations were similar within every group of animals when being tested with malate and glutamate or succinate. Cytochrome c oxidase activity in hepatitis was 1.8-fold higher compared with control. Simvastatin administration resulted in a decrease in hepatocyte endogenous respiration in hepatitis. The presented data lead to the assumption that the increased oxygen consumption by the respiratory chain of pathological mitochondria to be linked mainly with the altered function of complex I.     

Effect of Melafen on functional efficiency of mitochondrial membranes from sugar beet taproots

Mitochondria were isolated from sugar beet (Beta vulgaris L) taproots and incubated in the presence of low concentrations of Melafen (2 × 10^?9 and 4 × 10^?12 M). This treatment of mitochondrial membranes induced an appreciable decrease in microviscosity of superficial lipids in the lipid bilayer and a parallel increase in microviscosity of the deeply immersed lipid regions adjacent to membrane proteins. Melafen had no effect on fluorescence of lipid peroxidation products in membranes of freshly prepared mitochondria but declined this fluorescence to control values in artificially aged mitochondria. Melafen raised the maximum rates for oxidation of NAD-dependent substrates, elevated the efficiency of oxidative phosphorylation, and activated electron transport in the terminal (cytochrome oxidase) step of mitochondrial respiratory chain, which implies the activation of energy metabolism within the cell. The acceleration of electron transport through the terminal step of mitochondrial respiratory chain was apparently accompanied by retardation of lipid peroxidation, which prevented impairment of mitochondrial membranes under stress conditions. A proposal is put forward that some properties of Melafen are favorable for adaptogenesis because its effects on mitochondrial energy metabolism depended on the functional state of mitochondria.     

Chlorogenic acid ameliorates intestinal mitochondrial injury by increasing antioxidant effects and activity of respiratory complexes

Dietary polyphenols are thought to be beneficial for human health by acting as antioxidants. Chlorogenic acid (CGA) is abundant in plant-based foods as an ester of caffeic acid and quinic acid. In this study, we investigated the effects of CGA on mitochondrial protection. Our results demonstrated that pretreatment with CGA ameliorated the intestinal mitochondrial injury induced by H₂O₂; membrane potential was increased, mitochondrial swelling, levels of reactive oxygen species, contents of 8-hydroxy-2-deoxyguanosine, and cytochrome c released were decreased. The beneficial effects of CGA were accompanied by an increase in antioxidant and respiratory-chain complex I, IV, and V activities. In trinitrobenzene-sulfonic acid-induced colitic rats indicated that CGA supplementation improved mitochondria ultrastructure and decreased mitochondrial injury. Our results suggest a promising role for CGA as a mitochondria-targeted antioxidant in combating intestinal oxidative injury. Daily intake of diets containing CGA, such as coffee and honeysuckle, may be useful for prevention of intestinal diseases.     

不同低氧训练模式对大鼠力竭运动后骨骼肌线粒体抗氧化能力及呼吸链酶复合体活性的影响

本研究旨在观察4种低氧训练模式对大鼠骨骼肌线粒体抗氧化能力及呼吸链酶复合体活性的影响。将雄性Wistar大鼠40只随机均分为5组(n=8):常氧训练组(LoLo)、高住高练组(HiHi)、高住低训组(HiLo)、低住高练组(LoHi)和高住高练低训组(HiHiLo)。各组大鼠分别在常氧(海拔1500m,大气压632mmHg)或/和低氧(模拟海拔3500m,大气压493mmHg)环境中居住及递增负荷训练5周,每周训练6天。各组大鼠在最后一次训练后,在常氧环境恢复3天,然后进行力竭运动,之后即刻取骨骼肌样本,用差速离心法提取骨骼肌线粒体,分光光度法测定丙二醛(malondialdehyde,MDA)含量及超氧化物歧化酶(su-peroxide dismutase,SOD)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)和过氧化氢酶(catalase,CAT)活性及呼吸链酶复合体Ⅰ～Ⅲ(CⅠ～Ⅲ)活性。结果显示,与LoLo组相比,HiHi和HiHiLo组骨骼肌组织MDA含量均显著升高(P<0.01),SOD、GSH-Px和CAT活性均显著升高(P<0.05或P<0.01)。与LoL...     

Curcumin prevents maleate-induced nephrotoxicity: Relation to hemodynamic alterations,oxidative stress,mitochondrial oxygen consumption and activity of respiratory complex I

Abstract

The potential protective effect of the dietary antioxidant curcumin (120 mg/Kg/day for 6 days) against the renal injury induced by maleate was evaluated. Tubular proteinuria and oxidative stress were induced by a single injection of maleate (400 mg/kg) in rats. Maleate-induced renal injury included increase in renal vascular resistance and in the urinary excretion of total protein, glucose, sodium, neutrophil gelatinase-associated lipocalin (NGAL) and N-acetyl β-D-glucosaminidase (NAG), upregulation of kidney injury molecule (KIM)-1, decrease in renal blood flow and claudin-2 expression besides of necrosis and apoptosis of tubular cells on 24 h. Oxidative stress was determined by measuring the oxidation of lipids and proteins and diminution in renal Nrf2 levels. Studies were also conducted in renal epithelial LLC-PK1 cells and in mitochondria isolated from kidneys of all the experimental groups. Maleate induced cell damage and reactive oxygen species (ROS) production in LLC-PK1 cells in culture. In addition, maleate treatment reduced oxygen consumption in ADP-stimulated mitochondria and diminished respiratory control index when using malate/glutamate as substrate. The activities of both complex I and aconitase were also diminished. All the above-described alterations were prevented by curcumin. It is concluded that curcumin is able to attenuate in vivo maleate-induced nephropathy and in vitro cell damage. The in vivo protection was associated to the prevention of oxidative stress and preservation of mitochondrial oxygen consumption and activity of respiratory complex I, and the in vitro protection was associated to the prevention of ROS production.     

线粒体蛋白质组学研究进展

线粒体是真核生物中重要的细胞器,其包含的全部蛋白质称为线粒体蛋白质组。人类线粒体大约包含1500多种蛋白质,由核基因和线粒体基因共同编码。线粒体是细胞能量合成和物质代谢的中心,其功能障碍将直接或问接引起许多疾病。目前线粒体蛋白质组学正是系统性地研究线粒体在生理、病理过程中的功能变化以及研究疾病发生机制的重要方法。将线粒体蛋白质组的研究方法、研究进展、线粒体蛋白质组的性质及其在相关疾病研究中的作用进行综述,并对线粒体蛋白质组学在疾病发生机制和诊断治疗中的发展前景进行展望。     

Effect of amiodarone (AMD) on the antioxidant enzymes,lipid peroxidation and mitochondrial metabolism

The effects of amiodarone (AMD) on lipid peroxidation of rat liver mitochondria, the formation of superoxide anions at the respiratory chain level, and the cytosolic and mitochondrial enzymatic protective mechanisms of oxidative stress were studied. An attempt to classify AMD according to its toxic ability to interfere with the integrated function of electron transport enzymes was also investigated. The results confirm the effects of AMD on complex I and permit the placing of this drug in class A of the classification of Knobeloch, together with rotenone, amytal and chaotropic agents. AMD has no effect on the activity of the enzymes superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase, nor on glucose 6-phosphate dehydrogenase. AMD did not promote an increase in the formation of anion superoxide at the respiratory chain level. Pre-incubation with AMD (16·6 μM ) inhibited about 70 per cent of lipid peroxidation. The results suggest a protective effect of AMD against lipid peroxidation in mitochondrial membranes by iron-dependent systems. © 1997 John Wiley & Sons, Ltd.     

Protective effect of black tea extract on the levels of lipid peroxidation and antioxidant enzymes in liver of mice with pesticide-induced liver injury

Sub-acute hepatotoxicity was induced in mice by exposure to pesticides. The effect of pretreatment with aqueous black tea extract on lipid peroxidation and antioxidants in the liver was investigated. Administering a combination dose of chlorpyriphos and cypermethrin (20 mg kg(-1) each) on alternate days over a 15-day period to male mice resulted in induction of sub-acute toxicity as reflected by elevated levels of liver damage marker enzymes alkaline phosphatase(ALP), aspartate transaminase(AST) and alanine transaminase(ALT). Significantly elevated levels of lipid peroxidation were observed in the experimental group (group III) as compared with control mice. Decreased activities of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), total thiol, glutathione peroxidase (GPx), glutathione reductase(GR) and glutathione-S-transferase (GST) were also observed in pesticide-treated as compared to control mice. Aqueous black tea extract was given as a pretreatment to group IV mice at a dose of 200 mg ml(-1) polyphenols before the pesticide dose, which significantly decreased the levels of lipid peroxidation and significantly elevated the activities of SOD, CAT, GSH, total thiol, GPx, GR and GST in liver to levels similar to the controls. Thus, the data offer support for the claim that the central mechanism of pesticide action occurs via changes in cellular oxidative status and shows conclusively that supplementation with black tea extract protects against the free radical-mediated oxidative stress in hepatocytes of animals with pesticide-induced liver injury.     

New concepts on the role of ubiquinone in the mitochondrial respiratory chain

Ubiquinone participates in the oxidation-reduction reactions of the mitochondrial respiratory chain. In addition, this molecule possesses the necessary properties to function as a hydrogen carrier, thereby stoichiometrically coupling proton translocation to respiration by a direct chemiosmotic mechanism. This review discusses recent experimental evidence and new concepts relating to ubiquinone function in the mitochondrial respiratory chain. Emphasis is placed on possible protonmotive mechanisms of ubiquinone function, recent evidence implicating stable forms of ubisemiquinone in the respiratory chain, and properties of the ubiquinone molecule which may relate to its biological function.     

CLA对急性缺氧大鼠肝脏线粒体呼吸链酶活性及氧化应激的影响

目的:观察共轭亚油酸(CLA)对急性缺氧大鼠肝脏线粒体呼吸链酶活性及肝脏内氧化应激(OS)的影响。方法:将60只SD大鼠随机分为正常对照组,模拟海拔5000米高原环境连续缺氧暴露3d的急性缺氧组,急性缺氧CLA干预组。生化法测定肝脏组织中丙二醛(MDA)、还原型谷胱甘肽(GSH)含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性,Clark氧电极法观察大鼠肝脏线粒体呼吸链酶活性。结果:成功诱导大鼠急性缺氧模型。与对照组比,急性缺氧组大鼠肝脏MDA含量明显升高(P<0.05),同时肝脏线粒体呼吸链酶活性以及抗氧化酶活性(SOD,CAT)及GSH显著降低(P<0.05),与急性缺氧相比,CLA治疗组大鼠以上各项指标均有改善,并存在一定的剂量效应关系。结论:CLA通过抑制氧化应激增强大鼠肝脏线粒体呼吸链酶活性改善了急性缺氧大鼠肝脏的能量代谢障碍,对急性缺氧引起的氧化损伤有保护作用。     

Role of endogenous and exogenous antioxidants in the defence against functional damage and lipid peroxidation in rat liver mitochondria

Mitochondria are cellular organelles where the generation of reactive oxygen species may be high. They are, however, effectively protected by their high capacities of antioxidative systems, as enzymes and either water or lipid soluble low molecular weight antioxidants.These antioxidative defence systems can be effectively regenerated after or during an oxidative stress as long as the mitochondria are in an energized state. Energization of mitochondria mainly depends on the availability of suitable respiratory substrates which can provide hydrogen for the reduction of either the glutathione- or -tocopherol-system, since GSH is regenerated by glutathione reductase with the substrate NADPH and the -tocopheroxyl-radical likely by reduced coenzyme Q. It was shown that mitochondria do not undergo damages as long as they can keep a high energy state. The delicate balance between prooxidative/antioxidative activities can be shifted towards oxidation, if experimentally prooxidants were added. After exhaustion of the antioxidative defence systems damages of rnitochondrial functions become expressed followed by membrane injuries along with the oxidation and degradation of mitochondrial lipids and proteins leading finally to the total degradation of the mitoc hondria.Extramitochondrial antioxidants may assist the mitochondrial antioxidative defence systems in a complex way, whereby particularly ascorbic acid can act both as prooxidant and as antioxidant. (Mol Cell Biochem 174: 199–205, 1997)     

Elevation as a selective force on mitochondrial respiratory chain complexes of the Phrynocephalus lizards in the Tibetan plateau

Animals living in extremely high elevations have to adapt to low temperatures and low oxygen availability (hypoxia), but the underlying genetic mechanisms associated with these adaptations are still unclear. The mitochondrial respiratory chain can provide >95% of the ATP in animal cells, and its efficiency is influenced by temperature and oxygen availability. Therefore, the respiratory chain complexes (RCCs) could be important molecular targets for positive selection associated with respiratory adaptation in high-altitude environments. Here, we investigated positive selection in 5 RCCs and their assembly factors by analyzing sequences of 106 genes obtained through RNA-seq of all 15 Chinese Phrynocephalus lizard species, which are distributed from lowlands to the Tibetan plateau (average elevation >4,500 m). Our results indicate that evidence of positive selection on RCC genes is not significantly different from assembly factors, and we found no difference in selective pressures among the 5 complexes. We specifically looked for positive selection in lineages where changes in habitat elevation happened. The group of lineages evolving from low to high altitude show stronger signals of positive selection than lineages evolving from high to low elevations. Lineages evolving from low to high elevation also have more shared codons under positive selection, though the changes are not equivalent at the amino acid level. This study advances our understanding of the genetic basis of animal respiratory metabolism evolution in extreme high environments and provides candidate genes for further confirmation with functional analyses.