【作者】 许明佳；

【导师】 杨年红； 应晨江；

【作者基本信息】 华中科技大学 ， 营养与食品卫生学， 2006， 硕士

【摘要】 目的:以SD大鼠为研究对象,研究高脂饮食诱导大鼠发生肥胖及对肥胖大鼠进行饮食干预后血管窖蛋白-1(caveolin-1)、内皮型一氧化氮合酶(endothelial nitricoxide synthase, eNOS)表达的变化,以探讨饮食影响肥胖与心血管疾病的可能机制,为预防肥胖及肥胖相关心血管疾病的发生提供切实可行的依据。方法:清洁级雄性SD大鼠36只,体重150～160g,按体重随机分为两组:基础对照组(9只,CF)喂以基础饲料,试验组(27只)用高脂饲料喂养15周诱导大鼠肥胖。第15周时,大鼠体重稳定,根据对照组体重判断肥胖大鼠(DIO),将DIO组一半改用基础饲料喂养(DIO-HF/LF),另一半继续高脂饮食(DIO-HF);对照组维持基础饲料喂养,继续喂养8周。实验开始和干预实验前,过夜禁食10h采尾血,分离血清检测空腹血糖和血脂。实验期间每日观察大鼠一般情况,每周称体重。实验结束时各组大鼠过夜禁食10h断头处死,收集全血,分离血浆和血清,置- 20℃冰箱保存,以备血糖、血脂等指标的测定。分离睾周(睾丸周围)、肾周、腰周和肠系膜等部位脂肪组织并准确称重。分离主动脉置液氮冻存后转移至-80℃冰箱保存,用免疫印迹(Western Blot)方法测定窖蛋白-1和eNOS蛋白表达水平,免疫组化方法原位观察窖蛋白-1的表达,并用逆转录-聚合酶链反应(RT-PCR)测定窖蛋白-1的基因水平。结果:饮食干预前,DIO大鼠体重、空腹血糖(FBG)、总胆固醇(TC)、甘油三酯(TG)等指标与对照组相比均有显著性差异(P<0.05)。低脂饮食干预后, DIO-HF组体重、脂肪湿重、脂体比、TG、血管caveolin-1结果高于DIO- HF/LF和CF组(P <0.05),血管eNOS表达DIO-HF组低于DIO- HF/LF和CF组(P <0.05),而DIO- HF/LF组与CF组相比,除体重有显著性差异外(P <0.05),其余各指标之间差异无统计学意义(P>0.05)。结论:①高脂饲料可诱导SD大鼠发生肥胖,对肥胖大鼠进行低脂饮食干预可减少脂肪的蓄积,有利于控制肥胖发展的趋势。②肥胖大鼠中窖蛋白-1表达升高、eNOS表达降低,可导致内皮功能失调从而增加心血管疾病的危险性。③肥胖大鼠改喂低脂饮食可降低血管caveolin-1的表达,并恢复eNOS的蛋白水平,通过改善内皮功能降低心血管疾病的危险性。创新点:目前国内外对窖蛋白-1的研究主要集中在对内皮功能的调节及其与冠心病的关系方面,而饮食诱导肥胖对窖蛋白-1的影响,尤其是膳食干预对肥胖大鼠窖蛋白-1及其下游eNOS表达的影响尚未见相关报道,因而本研究在国内外具有一定程度的创新性。更多还原

【Abstract】 Objective To study the effect of high-fat diet on obesity in rats and the effect of dietary fat on the expression of caveolin-1, endothelial nitricoxide synthase (eNOS) in artery of rats. Reveal the possible mechanisms of diet induced obesity and cardiovascular diseases, and provide evidences for preventing obesity and cardiovascular diseases.Methods Thirty-six male SPF Sprague-Dawley rats (150g~160g) were randomly divided into high-fat diet group (HF, n=27) and control group (CF, n=9) on the basis of body weight after acclimated to the environment and chow diet for 1 week. Then either high-fat or chow diet were given for fifteen weeks. The dietary induced obesity (DIO) rats were designated from HF group according to the final body weight (weights more than x +1.96s of control group). Then half of the DIO rats were switched to standard diet (DIO- HF/LF), the other DIO rats (DIO-HF) and CF rats continued their primary diet for another eight weeks. Blood samples were collected by caudal vein for the measurement of fast blood glucose and blood lipid levels at the beginning of the test and before the DIO rats were switched with different diets. General conditions were observed daily, and body weights were measured weekly. At the end of the experiment by the 23rd week, all rats were sacrificed by decollation after 10h fasting, plasma and serum were collected for testing the concentrations of blood glucose and blood lipids. The abdominal white adipose tissue (testicular, renal and waist sites) were separated and weighed. Arteries were immediately excised, frozen in liquid nitrogen and stored at -80°C until analysis. The expressions of caveolin-1 were measured by reverse transcription-polymerase chain reaction (RT-PCR), western blotting and immunohistochemistry. And the expressions of eNOS was also measured using western blotting.Results At the end of 15 weeks, 14 of the 27 rats fed with high-fat diet were designated as diet induced obesity (DIO). The levels of body weight, fast blood glucose, total cholesterol and triglycerides were higher significantly in DIO group than those in control groups (P<0.05), and no significant difference were found between DIO-HF/LF and DIO-HF groups. After switched to chow diet for 8 weeks, the final weights of DIO- HF/LF were lower than that of DIO-HF rats whereas higher than that of CF rats (P<0.05). Fat deposits, adipose relative weight, and the level of caveolin-1 expression in DIO-HF group were the highest among the three groups, while the expression of eNOS protein was the lowest (P<0.05), and no significant difference was found in the other two groups.Conclusions①High-fat diet (4.62kcal/g )has an impact on the development of obesity in SD rats. When switched to chow diet for another 8 weeks, DIO rats gained much less body weight.②Increased expression of caveolin-1 and decreased expression of eNOS were associated with the obesity of DIO rats, and might increase the risk of cardiovascular disease.③Switched to chow diet of DIO rats could reduce the body weight gain and decrease the expression of caveolin-1, which might reduce the risk of cardiovascular disease by decreased the expression of eNOS.更多还原