【作者】 刘皓；

【导师】 杨军；

【作者基本信息】 中国医科大学 ， 营养与食品卫生学， 2010， 硕士

【摘要】 前言膳食营养与慢性病,尤其是心血管疾病(Cardiovascular disease, CVD)的发生发展密切相关。随着我国经济水平的提高和居民膳食结构的改变,CVD已成为危害人类健康的主要疾病。而血脂异常特别是高胆固醇血症是导致心血管疾病发生发展的主要危险因素,因此,预防和控制血脂异常和高胆固醇血症的发生发展对降低心血管疾病的发病率和改善其预后有着极为重要的意义。橄榄油富含单不饱和脂肪酸(Mono-unsaturated fatty acid, MUFA),此外橄榄油还含有多种维生素、人体必需的微量元素以及抗氧化物质。关于橄榄油的研究目前主要集中于降脂作用方面,多数研究认为其富含油酸,在降低TC、TG、LDL水平的同时,对HDL无影响或有升高作用,其机制是MUFA能够促进卵磷脂的合成,提高卵磷脂-胆固醇酰基转移酶(Lecithin-cholesterolacyltransferase,LCAT)的活性,从而促进胆固醇的转运及排泄。但是,也有新近研究表明,保持一定剂量持续摄入MUFA可能会导致人体内胆固醇油酸盐的聚集,而胆固醇油酸盐的聚集与动脉粥样硬化的发生密切相关。目前,关于橄榄油降脂作用的机制还不十分明确,多数研究采用的动物模型为高脂肪高胆固醇模型。本研究通过建立不同高脂大鼠模型(单纯高脂肪模型,高脂肪高胆固醇模型),并在设置基础对照组的同时,设置与橄榄油同等剂量的猪油对照组,从新的角度来探讨橄榄油对大鼠血脂及脂质过氧化水平的影响。材料与方法1、实验动物的分组和处理选择健康雄性Wistar大鼠45只,体重100-150g,由中国医科大学动物部提供。大鼠适应性喂养1w后,将其按体重随机分为5组(n=9)：基础对照组、猪油Ⅰ组、猪油Ⅱ组、橄榄油Ⅰ组、橄榄油Ⅱ组。2、实验动物的饲喂及干预实验期间,各组大鼠自由摄食、饮水,各组饲料配方如下：基础对照组——100%基础饲料猪油Ⅰ组——93.26%基础饲料、6.74%猪油猪油Ⅱ组——91.97%基础饲料、6.78%猪油、1%胆固醇、0.25%胆盐橄榄油Ⅰ组——93.26%基础饲料、6.74%橄榄油橄榄油Ⅱ组——91.97%基础饲料、6.78%橄榄油、1%胆固醇、0.25%胆盐3、样品的采集和指标的测定实验期间,每日记录喂食量,每3d记录一次撒食量,每w称量1次体重,共干预饲喂8w。喂养8w后,于乙醚麻醉下,经腹主动脉取血,分离血清后测定大鼠血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、血清丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化酶(GSH-Px)和总抗氧化能力(T-AOC)等指标。将大鼠脱颈椎处死,分离肝脏并观察肝脏形态改变。将肝脏称重后取部分肝组织固定,制作病理切片,在光学显微镜下观察肝脏病理改变。分离肠系膜周围、双侧肾脏周围及附睾周围脂肪垫并分别称重。计算大鼠的肝指数,内脏周围脂肪与体重比值。4、数据的处理和分析实验结果用x±s表示,用SPSS13.0统计软件进行单因素方差分析,组间两两比较用LSD法,检验水准α=0.05。结果1、动物一般状况及体重变化实验期间,各组大鼠生长发育未见异常表现。各组大鼠体重增量以橄榄油Ⅱ组最高,与基础组、猪油Ⅰ组比较具有统计学意义(p<0.05)。2、各组大鼠肝指数和内脏脂肪与体重比值观察各组肝指数：橄榄油Ⅱ组最高,橄榄油Ⅰ组次之,两个橄榄油组不仅高于基础组,也高于同等剂量的猪油组(p<0.05)。内脏脂肪与体重比值显示,猪油Ⅱ组>猪油Ⅰ组,橄榄油Ⅰ组>橄榄油Ⅱ组；同等水平的橄榄油组与猪油组比较,橄榄油组的内脏脂肪与体重比值均高于猪油组,但只有橄榄油Ⅰ组与猪油Ⅰ组比较具有统计学意义(p<0.05)。3、各组大鼠肝脏大体及病理改变各高胆固醇模型组肝脏明显发黄有油腻感,边缘变钝,切面突出,呈现颗粒感。而橄榄油Ⅰ组肝脏的大体改变接近于各高胆固醇组。猪油Ⅰ组和基础组肝脏的大体改变无明显差异,颜色鲜红,边缘锐利,切面无颗粒感。病理切片显示,基础组大鼠肝细胞形态正常,胞浆中几乎没有脂肪空泡；猪油Ⅰ组和橄榄油Ⅱ组大鼠的肝脏中有大量肝细胞发生了脂肪变性；猪油Ⅱ组大鼠的肝脏中部分肝细胞明显肿胀,显示出水变性样改变；橄榄油Ⅰ组大鼠的肝脏中大量肝细胞明显肿胀,普遍发生了水变性。4、各组大鼠血脂水平各组大鼠血清TC水平以橄榄油Ⅱ组最高,橄榄油Ⅰ组次之,与其他各组比较均具有统计学意义(p<0.05)；猪油Ⅰ组和Ⅱ组的TC水平,从测定值上看也明显高于基础组,但其间差异没有统计学意义(p>0.05)。LDL-C方面,显示出各橄榄油Ⅰ组最高,且各橄榄油组均高于基础组和同等剂量的猪油组(p<0.05)。HDL-C水平从趋势上看,橄榄油Ⅰ组、Ⅱ组及猪油Ⅱ组明显高于基础组和猪油Ⅰ组(p<0.05)。5、各组大鼠脂质过氧化水平各组大鼠的脂质过氧化水平：在GSH-Px上,橄榄油Ⅱ组、猪油Ⅱ组与基础组基本一致,无明显降低,其他两组则低于基础组但各组间差异未显示出统计学意义(p>0.05)；在T-AOC水平上,橄榄油Ⅱ组最高且与基础组比较具有统计学意义(p<0.05)；其余各组在数值均略高于基础组,但与之比较不具有统计学意义。在SOD水平上,橄榄油和猪油各组均是Ⅱ组>Ⅰ组>基础组的趋势,但组间两两比较不具有统计学意义。在血清MDA水平上,各组之间的差异均无统计学意义(p>0.05)。结论在本研究条件下,得出如下结论：1.橄榄油不能明显减少高脂模型大鼠体脂含量并引起了明显的肝脏损伤。2.橄榄油使不同高脂大鼠模型血清TC明显升高,并且没有显现出降低LDL-C的作用。3.橄榄油没有明显的抗脂质过氧化能力。更多还原

【Abstract】 Nutrition is closely related with the occurrence and development of chronic diseases, particularly cardiovascular disease (CVD). As China’s economy increasing and diet change of residents, CVD has become a hazard to human health of major diseases. And dyslipidemia, especially hypercholesterolemia, is critical risk factors leading to the development of cardiovascular disease. Therefore prevention and control of dyslipidemia and hypercholesterolemia has a very significance on reducing the incidence of CVD and improve their prognosis.Olive oil is rich in monounsaturated fatty acids(MUFA), it also contains multivitamin, essential trace elements and antioxidants. Research on the olive oil currently focused on lipid-lowering effect, the majority of studies suggest that it is rich in oleic acid and can reduce TC, TG, LDL level but doesn’t affect the level of HDL or increase it. Its mechanism is to promote the synthesis of lecithin and increase lecithin-cholesterol acyltransferase (LCAT) activity, thereby promoting cholesterol transport and excretion. However, a recent study showed that to maintain a certain dose of continuous intake of MUFA may cause the accumulation of cholesterol oleate in body, and cholesterol oleate accumulation is closely related with the occurrence of atherosclerosis. At present, the mechanism of lipid lowering on the olive oil is not very clear, most studies used high-fat and high cholesterol animal models. In this study, through the establishment of different fat rat models (simple model of high-fat, high-fat and high cholesterol model), set the basis for the control group, and set the same dose of lard with olive oil control group at the same time, we tried to investigate olive oil’s effect on the level of lipid and lipid peroxidation in rat serum from a new perspective.Materials and Methods1.The grouping and processing of laboratory animalsSelect healthy male Wistar rats 45, weight 100-150g, from the China Medical University experimental animal department. The male rats were randomly divided into 5 groups (n= 9) after 1 week adaptive feeding:basic control group, lard oil groupⅠ, lard oil groupⅡ, olive oil groupⅠ, olive oil groupⅡ.2. Experimental animals feeding and interventionDuring the experimental session, the rats free feeding, drinking water, feed formula in each group are as follows:Basic control group------100%standard dietLard oil groupⅠ------93.26%standard diet,6.74%lard oilLard oil groupⅡ------91.97%standard diet,6.78%lard oil,1%cholesterol, 0.25%bile saltOlive oil groupⅠ------93.26%standard diet,6.74%olive oilOlive oil groupⅡ------91.97%standard diet,6.78%olive oil,1%cholesterol, 0.25%bile salt3. Sample collection and determination of parametersDuring the experiment, we made a daily record of feeding amount, recorded food remaining amount every three days and the weight of rats every week. After feeding 8 weeks, animals were anesthetized by ethyl ether, and then we took blood sample from abdominal aorta, separated blood serum, mensurated serum total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipid protein cholesterol (LDL-C), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC).The rats were sacrificed dislocation of cervical vertebra, separating the liver and observing liver morphological changes. After weighing the liver, partial liver was taken to manufacture section for observing pathological changes in the optical microscope. Fats around kidney, mesentery and epididymis were separated and weighed. Then we calculate liver fat body ratio and visceral fat body ratio.4. Data processing and analysisThe results indicated that with x±s, using statistical software SPSS13.0 to make univariate ANOVA, comparison between groups using LSD method, the examine level:α=0.05. 1. General condition and body weight changeDuring the experimental session, the rats showed normal growth and development performance. The weight-increasing of rats in olive oil groupⅡwas highest, and had statistics significance compared with basic control group and lard oil group I (p<0.05).2. Liver fat body ratio and visceral fat body ratio.The liver fat body ratio of olive oil groupⅡis highest, and followed by olive oil groupⅠ’s, the two olive oil groups were higher not only than the basic control group but also than the same dose of lard oil groups respectivey (p<0.05). Observing the visceral fat body ratio, we found that lard oil groupⅡwas higher than lard oil groupⅠ, olive oil groupⅡwas higher than olive oil groupⅠ; The visceral fat body ratio of the two olive oil groups were both higher than the same dose of lard oil groups respectively, but only olive oil groupⅠcomparing with lard oil groupⅠhad statistics significance (p<0.05).3. Morphological and pathological changes in liverObserving the morphological changes of rat’s liver in every group, we found that the livers in high cholesterol group were significantly yellow and felt greasy, blunt edge, section highlighted, showing grainy; The changes of liver in lard oil group I was similar to the basic control group’s, the color red, sharp edges, no grainy aspect. Pathology changes showed that a large number of rat liver cells of lard groupⅠand olive oil groupⅡoccurenced fatty degeneration. Part of the rat liver cells of lard oil groupⅡand a large number of olive oil groupⅠhad a significant swelling and hydropic degeneration view.4. Serum lipids levelsThe serum TC level of olive oil groupⅡwas the highest, and followed by olive oil groupⅠ’s, and the two olive oil groups had statistics significance compared with other groups(p<0.05); The lard oil groupⅠandⅡ’levels were higher than base control group’s, but had no-statistics significance (p>0.05). The serum LDL-C level of olive oil group I was highest, and the two olive oil groups were both higher than the same dose of lard oil groups (p<0.05). At the level of HDL-C, olive oil groupⅠandⅡ, lard oil groupⅡwere significantly higher than base control group and lard oil groupⅠ(p<0.05).5. Lipid peroxidation levelsAt the level of GSH-PX, olive oil groupⅡand lard oil groupⅡwere approximately consistent with base control group, no significant decrease; The other two groups were lower than base control group, but it had no-statistic significance (p>0.05). At the level of T-AOC, olive oil groupⅡis highest and had statistics significance compared with basic control group (p<0.05). At the level of SOD, lard oil groups and olive oil groups both presented this trend:groupⅡ> groupⅠ> basic control group, but it had no-statistic significance between groups. At the level of MDA, no-statistic significance was observed among the groups (p> 0.05). ConclusionsIn such study conditions, it followed conclusions:1. Olive oil can’t significantly reduce the body fat of hyperlipidemic rats and causes significant liver damage.2. Olive oil increases the serum level of TC in the different hyperlipidemic rats significantly, and do not show a lower LDL-C effect.3. Olive oil has no significant capability of anti-lipid peroxidation.更多还原