Significance of bilayer-forming phospholipids for skeletal muscle insulin sensitivity and mitochondrial function

Phosphatidylcholine(PC) and phosphatidylethanolamine(PE), which make up the bulk of mammalian cell membrane phospholipids, are recognized for their importance in metabolic health. Perturbations in the ratio of PC:PE can affect membrane integrity and function, which thus have serious health consequences. Imbalance in the hepatic PC and PE membrane content can be linked to metabolic disturbances such as ER stress, fatty liver and insulin resistance. Given that impaired insulin sensitivity underlies the pathology of many metabolic disorders and skeletal muscle is a significant regulator of energy metabolism, it is likely that aberrant phospholipid metabolism in skeletal muscle affects whole-body insulin sensitivity. Sarco/endoplasmic reticulum Ca^(2+) ATPase(SERCA) activity and mitochondrial function respond to alterations in PC:PE ratio and are associated with glucose homeostasis. Moreover, PC and PE content within the mitochondrial membrane influence mitochondrial respiration and biogenesis and thus, metabolic function. As skeletal muscle phospholipids respond to stimuli such as diet and exercise, understanding the implications of imbalances in PC:PE ratio is of great importance in the face of the rising epidemic of obesity related diseases. This review will summarize the current state of knowledge signifying the links between skeletal muscle PC:PE ratio and insulin sensitivity with respects to PC and PE metabolism, SERCA activity, mitochondrial function and exercise.

PROTECTIVE EFFECTS OF CAPTOPRIL AND COENZYME Q10 ON THE MITOCHONDRIAL MEMBRANE-PHOSPHOLIPID INJURY OF LYMPHOCYTES IN PATIENTS WITH DILATED CARDIOMYOPATHY.

The membrane-phospholipid (MPL)injury of myocardial cells may play an important role in the development of heart failure.In present study, peripheral lymphocytes were used as a study model in which the protective and reparative effects of Captopril and Cocnzyme 10 (Coo10)on mitochondrial MPL injury were observed. 42 hospitalized patients with dilated cardiomyopathy(DCM),on conventional anti-heart-failure therapy, were divided into three groups at random,and Captopil (Capton),Neuquinone 10 (CoQ10) and placebo were added respectively.The A4PL localization was proceeded by modified Demer's tricomplex flocculation.After mean 75'5 days observation,in Captopril and CoQ10 groups, heart function was improved,with circulatory A1 decreased,the degree of mitochondrial proliferation of lymphocytes decreased and the mitochondrial MPL injury repaired in certain degree.The percentages of the lymphocytes with less than 5 mitochondria per lymphocyte increased [(60.0± 9.4)vs (72.0± 6. 8)% for Captopril;(55.0±8.9) vs (73.1 ± 9. 8)% for CoQ10, P<0. 001];the percentages of mitochondria with intact MPL localization increased [(59. 1 ± 8. 1 ) vs (72. 0± 9. 4)% for Captopril;(56.6±9.3) vs (73.8±9. 4)% for CoQ10 P< 0.001].But no significant changes were found in either the proliferation or MPL injury in the con trols. In conclusion,Captopril and CoQ10 have a beneficial effects on the protection and reparation of mitochondrial injury in patients with DCM.

Dexamethasone treatment alters kinetics properties of liver mitochondrial F₀.F₁-ATPase and membrane lipid profiles in developing and adult rats

Dexamethasone—a potent synthetic glucocorticoid—has multiple diagnostic and therapeutic applications in wide range of age groups. However, the side-effects of dexamethasone (Dex) treatment including those on development are becoming increasingly apparent. Since the developmental processes are energy-dependent, we examined the effects of chronic Dex treatment on kinetics properties of liver mitochondrial F0.F1-ATPase and mitochondrial membrane lipid profiles in rats belonging to different developmental age groups (2, 3, 4 and 5 weeks) and in adults (~8 weeks). The animals were treated with a subcutaneous dose of 2 mg of Dex/kg body weight (or saline as vehicle) for three alternative days (at around 7.00 A.M.) prior to the day of sacrifice. Dex treatment resulted in significant reduction in F0.F1-ATPase activity in developmental age groups and in adults as compared to their age-matched vehicle-treated control group. The substrate kinetics analysis of F0.F1-ATPase resolved Km and Vmax values in 3 components in all the control age groups;whereas Dex treatment significantly altered the Km and Vmax values or abolished the entire components in age-specific manner. Dex treatment significantly lowered the energy of activation and altered phase transition temperature (TtoC) in all the developmental age groups and in adults. Dex treatment significantly increased the contents of total phospholipid (TPL), individual phospholipids classes and cholesterol (CHL) in all the developmental age groups whereas opposite pattern was observed in adults. The mitochondrial membrane became more fluidized in the developing age groups (2, 4 and 5 weeks);whereas no change was observed in 3-week and adult groups following Dex treatment. In present study, our data demonstrate comprehensive deleterious effects of chronic Dex treatment on liver mitochondrial membrane structure and F0.F1-ATPase functional properties with respect to energy metabolism. At the same time, our data also warns against excessive repeated use of antenatal DEX in treatments in growing and adult human patients.

A Model for the Formation of Ring Mitochondria in Retinal Pigment Epithelium

Purpose:To investigate the mechanism and sequence of formation of ring-shaped mitochondria in retinal pigment epithelial ce3lls of a chick model of gyrate atro-phy.Methods:Electron microscopic analysis of the ultrastructure of retinal pigment epithelial(RPE)mitochondria was carried out in chicks injected intravitreally with formoguanamine regularly(every4days)over the first 2weeksor4weeks post-hatching.Formoguanamine is a triazine drug which induces hyperor-nithinemic symptoms in the chick eye similar to those seen in human gyrate atro-phy.Results:A large population of irregularly shaped mitochondria was observed in the RPE of both peripheral and central retina.They showed extensive morpholog-ical changes.At 2wk,the mitochondria appeared enlarged and abnormal in shape with vacuolisation,partial loss of their double membrane and reduced mitochon-drial cristae.By 4wk,the mitochondria had assumed a rounder,almost circular profile,many with central holes,so-called ring mitochondria.Conclusion:The appearance of ring-shaped mitochondria has been previously as-cribed to the section of cupshaped three-dimensional structures.We present evi-dence that ring-shaped mitochondrial profiles arise through at least two different mechanisms of membrane breakdown and intraorganelle vacuoolisation.The nature of the three dimensional structures of these abnormal mit.

Hepatic CDP-diacylglycerol synthase 2 deficiency causes mitochondrial dysfunction and promotes rapid progression of NASH and fibrosis

Nonalcoholic fatty liver disease(NAFLD)encompasses a spectrum of pathologies,ranging from steatosis to nonalcoholic steatohepatitis(NASH).The factors promoting the progression of steatosis to NASH are still unclear.Recent studies suggest that mitochondrial lipid composition is critical in NASH develop-ment.Here,we showed that CDP-DAG synthase 2(Cds2)was downregulated in genetic or diet-induced NAFLD mouse models.Liver-specific deficiency of Cds2 provoked hepatic steatosis,inflammation and fibrosis in five-week-old mice.CDS2 is enriched in mitochondria-associated membranes(MAMs),and hepatic Cds2 deficiency impaired mitochondrial function and decreased mitochondrial PE levels.Overexpression of phosphatidylserine decarboxylase(PISD)alleviated the NASH-like phenotype in Cds2^(f/f);AlbCre mice and abnormal mitochondrial morphology and function caused by CDS2 deficiency in hepatocytes.Additionally,dietary supplementation with an agonist of peroxisome proliferator-activated receptor alpha(PPARa)attenuated mitochondrial defects and ameliorated the NASH-like phe-notype in Cds2^(f/f);AlbCre mice.Finally,Cds2 overexpression protected against high-fat diet-induced hepatic steatosis and obesity.Thus,Cds2 modulates mitochondrial function and NASH development.

Weight loss increases skeletal muscle mitochondrial energy efficiency in obese mice

Weight loss from an overweight state is associated with a disproportionate decrease in whole-body energy expenditure that may contribute to the heightened risk for weight regain.Evidence suggests that this energetic mismatch originates from lean tissue.Although this phenomenon is well documented,the mechanisms have remained elusive.We hypothesized that increased mitochondrial energy efficiency in skeletal muscle is associated with reduced expenditure under weight loss.Wildtype(WT)male C57BL6/N mice were fed with high-fat diet for 10 weeks,followed by a subset of mice that were maintained on the obesogenic diet(OB)or switched to standard chow to promote weight loss(WL)for additional 6 weeks.Mitochondrial energy efficiency was evaluated using high-resolution respirometry and fluorometry.Mass spectrometric analyses were employed to describe the mitochondrial proteome and lipidome.Weight loss promoted~50%increase in the efficiency of oxidative phosphorylation(ATP produced per O_(2) consumed,or P/O)in skeletal muscle.However,Weight loss did not appear to induce significant changes in mitochondrial proteome,nor any changes in respiratory supercomplex formation.Instead,it accelerated the remodeling of mitochondrial cardiolipin(CL)acyl-chains to increase tetralinoleoyl CL(TLCL)content,a species of lipids thought to be functionally critical for the respiratory enzymes.We further show that lowering TLCL by deleting the CL transacylase tafazzin was sufficient to reduce skeletal muscle P/O and protect mice from diet-induced weight gain.These findings implicate skeletal muscle mitochondrial efficiency as a novel mechanism by which weight loss reduces energy expenditure in obesity.

PHOSPHOLIPID STUDY IN THE EARLY DEVELOPMENT OF GOAT EMBRYOS

The experiment is to study the distribution and content of phospholipid and its relationship with cellular differentiation in the goat preimplantation development by electron cytochemistry. The zygotes and embryos at 2-cell, 4-cell, 8-cell, 16-cell morula and early blastocyst stage collected from the superovulated Heilongjiang goats with FSH were used to do ultrastructural localization of phospholipid with the method reported by Dermer (J.

Miga,the guardians of mitochondria to avoid neurodegeneration

Mitochondria undergo frequent morphological changes through fission and fusion.Mutations in core members of the mitochondrial fission/fusion machinery are responsible for severe neurodegenerative diseases.However,the mitochondrial fission/fusion mechanisms are still less understood.

COMPARISON OF MEMBRANE FLUIDITIES OF SEEDLING MITOCHONDRIA OF CHILLING-SENSITIVE RICE AND CHILLING-RESISTANT RICE

Miotchondria are relatively sensitive organelles, which can easily be changed both structurally and functionally by many environmental factors. Lyons et al. suggested there is correlation between the chilling-sensitivity of plant and the change in mitochondrial membrane after chilling treatment. We reported that the ultrastructure and oxidative phosphorylation efficiency of mitochondria isolated from the

水分胁迫对6种禾草叶绿体、线粒体超微结构及光合作用的影响

利用透射电镜技术,研究了水分胁迫下柳枝稷(Panicum virgatumL.)、巴哈雀稗(Paspalum notatumFlugge)、毛花雀稗(Paspalum dilatatumPoir)、羊茅黑麦草(×FestuloliumAsch.et Graebn.)、草芦(PhalarisarundinnaceaL.)及多年生黑麦草(Lolium perenneL.)6种禾本科牧草叶肉细胞叶绿体和线粒体超微结构的变化,并结合对叶绿素含量和光合速率的测定,分析了其生理功能对水分胁迫的响应,旨在为耐旱草种的选择、引种和选育提供形态学和生理学依据。结果表明,经过8 d水分胁迫后,6种牧草的叶绿体均膨大变圆并向细胞中央移动;叶绿体内分布有一定数量的嗜锇颗粒和少量淀粉粒,受伤害严重的叶绿体中的基粒和被膜破损;线粒体数目均增加,且对水分胁迫的耐受性强于叶绿体;光合速率的高低与叶绿体的结构变化相关。可将6种牧草分为3个不同的抗旱等级:柳枝稷和巴哈雀稗抗旱性较强,羊茅黑麦草和草芦抗旱性中等,多年生黑麦草和毛花雀稗抗旱性较弱。

磷脂在大鼠心肌线粒体上的超微结构定位方法

选用Wister成年大鼠心肌,对Dermer氏磷脂定位法加以改进。通过延长固定时间及将三合固定以外各步均在4℃进行,以增强对组织结构的保护作用,防止磷脂移位扩散。加以改进的方法,能清晰地显示富含磷脂的膜系结构,尤其是线粒体磷脂在嵴膜及内外膜的定位。此外,超薄切片均不经铅铀复染,以消除其它非磷脂成分的干扰。同时采用脱脂、去三合固定作双重阴性对照,证实了磷脂定位的特异性。

采前套袋对黄肉桃货架期果皮超微结构的影响

【目的】探讨黄肉桃采后果皮衰老期间细胞器的变化规律和细胞水平的衰老特征及其与果实耐贮性的相关性,为鲜食黄桃品种的改良和贮运技术的研究提供一定的科学依据和实践指导。【方法】以耐贮性较强的‘沪454’和耐贮性略差‘锦绣’黄桃为试材,利用透射电镜观察货架期间2个黄桃品种果皮细胞壁、有色体、嗜饿颗粒和线粒体的超微结构及其变化规律。【结果】随着贮藏时间的延长和果实的衰老,黄桃果实果皮细胞壁变形,部分降解,结构松散,细胞间隙增大;果皮有色体中嗜饿颗粒数目增多,后期嗜饿颗粒数目减少但体积增大,有色体中片层类囊体膜结构瓦解、变形;嗜饿颗粒数目的增多和个体的增大与果实的耐贮性有密切相关;果皮线粒体结构变得模糊,线粒体变形、拉长,内基数目减少,结构解体出现空洞;果皮中线粒体的衰老进程迟于有色体;‘沪454’黄桃果皮有色体和线粒体较‘锦绣’黄桃稳定。【结论】2个品种黄桃果皮中细胞超微结构及其稳定性与果实耐贮性密切相关。果皮组织细胞的超微结构变化可导致组织细胞功能衰弱和丧失,加速果实的衰老。

壳聚糖对实验性脂肪肝大鼠肝及线粒体的体视学分析

目的研究壳聚糖对实验性脂肪肝大鼠的防治作用及机理。方法采用低剂量CCl4 后肢注射 ,并高脂饮食复制大鼠脂肪肝动物模型 ,同时给予不同剂量的壳聚糖灌胃 ,通过计算机彩色图象分析及立体定量的体视学分析方法 ,测定脂肪肝大鼠肝脂变严重程度及线粒体超微结构的变化。结果 4g/ (kg·d)以上的壳聚糖可明显减轻脂肪肝大鼠肝脂变程度 ,改善肝细胞线粒体体视学参数 ,促进线粒体功能恢复。结论壳聚糖可通过受损线粒体结构功能的恢复 ,促进脂肪的氧化分解 ,而对脂肪肝的形成起到一定的防治作用。

氨基胍对局灶性脑缺血大鼠线粒体损伤的影响

目的观察选择性诱生型一氧化氮合酶抑制剂氨基胍(aminoguanidine,AG)对局灶性脑缺血大鼠脑线粒体损伤的作用,探讨其改善缺血性脑损伤的作用机制。方法将大鼠随机分为假手术组、缺血对照组、AG治疗组,采用线栓法复制大鼠大脑中动脉栓塞(MCAO)模型,分别于缺血后2、6、12h给药治疗3d,迅速断头取脑,差速离心法提取缺血侧脑组织线粒体,测定线粒体总ATP酶、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSHPx)活性,以及线粒体一氧化氮(NO)、丙二醛(MDA)含量;电镜观察了缺血后皮层神经元超微结构的改变及AG对此改变的影响。结果在大鼠MCAO后线粒体NO生成明显增加,线粒体总ATP酶、SOD、GSHPx活性均有明显下降,线粒体MDA含量明显升高;缺血2、6、12h给予AG治疗3d与缺血对照组相比NO生成有所下降,总ATP酶、SOD、GSHPx活性均升高,MDA含量下降。电镜结果显示脑缺血后皮层神经元水肿,线粒体肿胀、嵴断裂、溶解、消失,且随缺血时间延长损伤加重;AG能明显改善脑缺血引起的神经元水肿、线粒体肿胀和空泡化。结论AG能明显抑制脑缺血后线粒体NO生成,改善线粒体能量供应,增加线粒体抗氧化作用,从而减轻脑缺血损伤。

反复力竭运动后大鼠骨骼肌线粒体超微结构改变及维生素E的保护作用

目的探讨反复力竭运动后大鼠骨骼肌线粒体超微结构改变及维生素E的保护作用。方法雄性SD大鼠30只随机分为安静对照组、力竭对照组、维生素E组,每组10只,后两组大鼠进行4周的反复力竭跑台训练,取股四头肌作超薄切片,透射电镜观察骨骼肌及骨骼肌线粒体形态、结构。结果4周反复力竭运动后,力竭组大鼠骨骼肌肌丝排列紊乱,线粒体肿胀和空泡变性,维生素E组骨骼肌超微结构图接近正常。结论反复力竭运动导致骨骼肌细胞坏死丢失,线粒体形态异常,口服维生素E对反复力竭运动大鼠骨骼肌线粒体具有保护作用,减少反复力竭收缩骨骼肌的坏死丢失。

米酵菌酸对小鼠肝和心肌细胞毒性作用的超微结构研究

目的 :观察米酵菌酸对小鼠肝、心肌细胞毒性作用的超微结构改变 ,探讨米酵菌酸中毒的机理。方法 :小鼠腹腔注射不同剂量的米酵菌酸 ,2h后取其肝和心肌组织 ,通过电镜观察其细胞超微结构的改变。结果 :电镜下可见肝细胞和心肌细胞的线粒体肿胀 ,内嵴断裂、模糊或消失 ,基质局部或全部空亮 ,呈囊泡样变 ,偶见其中含髓样小体。上述线粒体内嵴和膜结构的病变随米酵菌酸剂量的增加而加重。结论 :米酵菌酸对小鼠肝、心肌细胞毒性作用以线粒体的损伤较为突出 ,因此我们认为 ,线粒体内膜的破坏造成线粒体的功能障碍 ,影响细胞呼吸 。

脑缺血及再灌流期间生物膜磷脂代谢特点

本文利用大白鼠４血管结扎法建立脑缺血再灌流模型，同时制备脑组织线粒体和微粒体组分，检测假手术组，缺血１５ｍｉｎ，再灌ｌｈ、ｌｄ和３ｄ各组生物膜主要磷脂的含量变化，发现再灌流时磷脂代谢变化比缺血期幅度大，并且线粒体主要组成磷脂和微粒体主要组成磷脂代谢变化规律并不一致，证明磷脂代谢异常导致了生物膜功能丧失，造成了神经元的损伤。

米糠肽对D-半乳糖致衰小鼠线粒体损伤的影响

利用D-半乳糖(D-gal)致衰小鼠模型,探讨了米糠肽对小鼠心、脑线粒体锰超氧化物歧化酶(Mn-SOD)活性、丙二醛(MDA)含量以及总抗氧化能力(T-AOC)和Ca2+泵、Na+泵活性的影响,并以透射电镜观察了该肽对小鼠肝细胞及线粒体超微结构的影响。结果显示,与衰老组相比,高剂量米糠肽(500 mg/kg)可明显降低小鼠心、脑线粒体MDA含量(P<0.01),显著提高T-AOC(P<0.01)、Mn-SOD活性(P<0.01)以及Ca2+泵、Na+泵活性,优于中、低剂量(200、100 mg/kg);透射电镜下可见衰老组肝线粒体肿胀明显,膜模糊不清,有空泡形成,而米糠肽各组线粒体损伤程度有所减轻。说明米糠肽对D-gal致衰小鼠线粒体损伤起到良好的保护作用,可能具有延缓衰老的效果。

盐胁迫下海马齿叶肉细胞超微结构观察

通过透射电镜,在超显微结构水平上对淡水和海水栽培的海马齿(Sesuvium portulacastrumL.)植物叶肉细胞结构进行了比较。结果显示:海水栽培的海马齿叶肉细胞质膜明显向内折叠,出现大量大小、形状各异的质膜突起,以及质膜片层;而淡水栽培的海马齿叶肉细胞质膜向内折叠不明显,质膜突起少见。相对于淡水栽培,海水栽培的海马齿植物叶肉细胞叶绿体变小、数量增多;形状变短,由肾形、梭形或弓形变成椭圆形或一端膨大的不规则形状;叶绿体基粒片层结构清晰完整,垛叠程度增加,叶绿体没有受到明显伤害;叶绿体中淀粉粒数量增多,体积变大,淀粉粒表面出现皱褶,形状由长椭圆型变成短椭圆形或不规则形状,电子密度变低;叶绿体上脂质体增多且体积变大。线粒体数量增加,但体积变小;形状由圆球状或棒状变成椭圆体状;线粒体内膜向内折叠所形成的嵴清晰,但海水栽培的海马齿叶肉细胞线粒体外膜模糊,受到轻微伤害。

异丙肾上腺素导致大鼠心肌损伤的酶组织化学及超微结构观察

健康成年Ｗｉｓｔａｒ大鼠５０只，雌雄各半，体重２１０±２０ｇ。正常对照组１０只，实验组４０只，每只大鼠皮下注射盐酸异丙肾上腺素（ＩＳＰ）５．０ｍｇ／ｋｇ，在注射后４、１２、２４、４８小时，分别处死１０只大鼠，取出心脏，进行（１）ＨＥ染色，（２）组化染色，按Ｐｅａｒｓｏｎ法显示ＳＤＨ，用物镜测微网计算每组ＳＤＨ活性产物的缺失面积；（３）超微结构观察，按立体学图像分析原理，用《多功能医学图像处理系统》微机计算各组电镜片中线粒体体密度值。本实验的观察表明：心肌细胞ＳＤＨ在注射ＩＳＰ后显示出不同的阶段性变化；ＳＤＨ的活性产物缺失部位与ＨＥ染色的心肌坏死部位一致；心肌ＳＤＨ的活性变化与线粒体的损伤同时出现，并与线粒体的破坏程度密切相关。