【作者】 张媛；

【导师】 丁树哲；

【作者基本信息】 华东师范大学 ， 运动人体科学， 2009， 硕士

【摘要】 高脂膳食与缺乏运动是危害人体健康的不良习惯,它使机体代谢性组织的脂肪酸供应持续增高,继而导致机体对自身胰岛素敏感性降低,很容易造成胰岛素抵抗(IR)现象,引发相关代谢综合症。长期体育锻炼对防治代谢性疾病的效果有目共睹,耐力训练时脂肪为主要供能物质,可以有效的缓解高脂膳食对机体的负作用;另一方面还可提高线粒体功能、增强线粒体脂肪氧化酶活性及上调相关基因的表达。脂肪在人体内的贮存量比糖丰富,但机体氧化脂肪酸的能力有限,限制利用贮存脂肪的原因至今尚未完全阐明。线粒体脂肪氧化作为脂肪代谢的限速步骤,从许多方面影响机体脂肪酸氧化,如线粒体膜上的肉碱酰基转移酶(CPT)系统、线粒体脂肪氧化酶活性、多种线粒体膜结合蛋白、磷酸腺苷活化蛋白激酶(AMPK)等。此外,过氧化物酶体增殖物激活受体γ辅激活因子1(PGC-1)是近年来倍受关注的辅激活因子,其中PGC-1α具有多种生理学的功能:在线粒体生物合成、肌纤维类型的转化、葡萄糖代谢、脂肪酸氧化等方面都起重要作用。目的:研究耐力训练对高脂膳食大鼠骨骼肌线粒体脂肪氧化过程相关酶活性及相关基因表达的影响,探讨耐力训练对提高高脂膳食大鼠脂肪氧化水平及降低高脂膳食诱发IR指数升高的机制。方法:将24只雄性SD大鼠,约4周龄,体重100±5g随即分成普通膳食对照组(C,n=6)、普通膳食耐力训练组(E,n=6)、高脂膳食对照组(H,n=6)、高脂膳食耐力训练组(R,n=6)。耐力训练组大鼠进行8周的跑台训练,每周训练6天,每天一次,起始跑速为0.8km/h,最大速度不超过1.2km/h,前四周每天训练40分钟,后四周每天训练1小时。经过8周饲养,所有大鼠处死后用酶联免疫法测试血浆胰岛素浓度,用比色法测试血糖浓度及线粒体羟脂酰辅酶A脱氢酶(β-HAD)、柠檬酸合成酶(CS)活性。采用实时荧光定量PCR法检测CPT-1β、PGC-1α基因转录水平,Western Blotting检测CPT-1β、PGC-1α基因蛋白表达水平。结果:1)耐力训练有效降低高脂膳食大鼠较高的IR指数。[IR指数=(空腹血糖浓度×空腹胰岛素浓度)/22.5)];2)耐力训练使高脂膳食大鼠骨骼肌线粒体β-HAD、CS活性显著升高;3)耐力训练上调高脂膳食大鼠CPT-1β基因转录水平,对线粒体内CPT-1β蛋白表达水平并无显著影响;4)耐力训练下调高脂膳食大鼠PGC-1α基因转录水平,但却上调细胞核内PGC-1α蛋白表达水平。结论:1)耐力训练可以显著控制高脂膳食大鼠体重增长;2)耐力训练有利于高脂膳食大鼠胰岛素抵抗指数维持在正常水平;(3)耐力训练上调高脂膳食大鼠CPT-1β基因转录,提高线粒体脂肪氧化酶活性,缓解高脂膳食对机体的不利影响。(4)耐力训练通过适度调节PGC-1α蛋白表达水平显著提高高脂膳食大鼠线粒体脂肪氧化水平,可能在协调β氧化与TCA两者关系中发挥了重要作用。更多还原

【Abstract】 High-fat diet and inactivity are the bad even harmful habit to human health, which makes fatty acid supply in organizations continued to increase,this continuing high fat status will cause the body to be lower insulin sensitivity,even is more likely to result in insulin resistance(IR)phenomenon,induced other metabolic syndrome. The effects of long-term physical training on preventing metabolic disorders are well known.Fat is the major energe material during endurance exercise training,which can effectively alleviate the negative effects that high-fat diet induced;on the other hand,endurance training have an significant effect in improving mitochondrial function,enhancing the activity of mitochondrial lipid oxidation and related gene expression.In human body,stored fat is richer than carbohydrate,but the capacity of fatty acid oxidation is limited,the reasons for this restriction on the use of stored fat have not yet been fully explained.Mitochondrial lipid oxidation as the rate-limiting step in fat metabolism,which affect fatty acid oxidation from many aspects,such as the existence of mitochondrial membrane carnitine acyltransferase(CPT)system,various of mitochondrial membrane-binding proteins,phosphoric acid AMP-activated protein kinase(AMPK),and so on.In addition,peroxisome proliferator-activated receptory coactivator 1(PGC-1)has drawn greater attention in recent years,PGC-lαhas a variety of physiological functions and plays an important role in mitochondrial biosynthesis,transformation of muscle fiber types,glucose metabolism,fatty acid oxidation,etc.Thus,the aim of this study was to investigate the effects of 8-week endurance training on mitochondrial lipid oxidation-related enzymes and genes expression in high-fat diet Sprague-Dawley rats,discuss the mechanism of endurance training role on improving the lipid oxidation level and reducing the IRI in high-fat diet rats. Methods:24 four-week-old male Sprague-Dawley rats,with a body weight of 100±5g were randomly assigned to standard diet control group(C,n=6),standard diet endurance training group(E,n=6),high-fat diet control group(H,n=6),high-fat diet endurance training group(R,n=6).Endurance training group rats were accustomed to 8-week treadmill training with a speed of 0.8km/h-1.2km/h at an 0%incline,for 40min/d during the first 4-week time,then maintained for 60min/d for the following four weeks.After all Rats were sacrificed,plasma insulin concentration was measured using Enzyme-Linked ImmunoSorbant Assay(ELISA)method;blood glucose concentration and mitochondrial acyl-coenzyme A hydroxybutyrate dehydro-genase (β-HAD)activity,citrate synthase(CS)activity were measured using Colori-metry method.Detected CPT-1β、PGC-lαgene transcription and protein expression level with real-time quantitative PCR(RT-Q-PCR)and Western Blotting respectively. Results:1)Endurance training reduced high IR index in the high-fat diet rats.(IR index=Fasting blood glucose concentrations×fasting insulin concentration)/22.5); 2)Endurance training significantly increased the activity ofβ-HAD,CS in skeletal muscle mitochondrial of high-fat diet rats;3)Endurance training increased CPT-1βgene transcription level in high-fat diet rats,but had no apparent effect on CPT-1βprotein expression;4)Endurance training decreased PGC-lαgene transcription level in high-fat diet rats,but up-regulated PGC-lαprotein expression.Conclusion:1)Endurance training can significantly control the gain in weight in high-fat diet rats;2)Endurance training would help the high-fat diet rats maintain a normal level in insulin resistance index;3)Endurance training upregulated CPT-1βgene transcription,Enhance the activity of mitochondrial fat oxidation,alleviate the negative effects of high-fat diet rats;4)Endurance training significantly increased mitochondrial fat oxidation level in high-fat diet rats by regulating PGC-lαprotein expression,which may be played a key role in the coordination between mitochondrialβ-oxidation and TCA.更多还原