亞麻籽油對於高油脂/膽固醇飲食下倉鼠血脂的影響效果

Effects of Flaxseed Oil on Serum Lipids in Hamsters Fed High-Fat/Cholesterol Diets

楊慧君(Hui-Chun Yang)

指導教授 ： 陳億乘

中山醫學大學/健康管理學院/營養學研究所/碩士(2008年)

摘要

心血管疾病是國人十大死因第三位，不飽和脂肪酸中的ω-3 PUFA被認為可以降低心血管疾病的發生，α-次亞麻油酸(Alpha-linolenic acid)簡稱ALA (18:3)，為EPA (20:5)與DHA (22:6)的先驅物，是人體所必需的不飽和脂肪酸，不能自身合成只能從自然界攝取，而亞麻籽油(flaxseed oil, FX)為自然界植物油中ALA含量最高者。本研究欲探討FX對血脂的影響，因此以倉鼠為實驗動物模式，32隻5週齡的Syrian hamsters先飼養一週習慣環境後，再隨機被分配成四組：1) Control: chow diet (5%脂肪/ 0%膽固醇)；2) CO (coconut): 92.9% chow diet +7%椰子油/0.1%膽固醇；3) BU (butter): 92.9% chow diet +7%奶油/0.1%膽固醇；4) FX (flaxseed): 92.9% chow diet +7% FX/0.1%膽固醇。本研究發現在高油脂/膽固醇飲食下，FX對倉鼠血液中的總膽固醇及三酸甘油酯有降低的現象(P<0.05)，並改善了倉鼠血液中HDL-C/TC之值(P<0.05)，而血清高密度脂蛋白膽固醇(HDL-C)方面，高油脂/膽固醇飲食的組別則無顯著差異(P>0.05)。而肝臟脂肪方面，高油脂/膽固醇飲食中添加FX具有降低肝臟中膽固醇及三酸甘油酯的作用(P<0.05)；另外FX則會增加糞便中排泄之膽固醇及三酸甘油酯(P<0.05)。在膽固醇代謝相關基因表現量上，高油脂/膽固醇的組別其肝臟HMG-CoA reductase mRNA表現量皆顯著地高於Control組(P<0.05)；LDL-receptor mRNA表現量皆較Control低，其中分別只有CO、BU組與Control組有統計上的差異(P<0.05)；各組間CYP7A1 mRNA表現量在統計上並無顯著差異(P<0.05)。在肝損傷指數方面，FX組之GOT及GPT值皆較CO與BU組顯著降低(P<0.05)。在肝臟氧化壓力方面，FX組之GSH值皆較CO與BU組顯著升高(P<0.05)，各組之MDA值則無顯著差異，但是在餵食高油脂/膽固醇飼料之倉鼠中，其中CO及BU組之MDA又高於FX組。
本研究結果指出亞麻籽油在高油脂/膽固醇飲食習慣下具有改善血脂情形與減緩因高油脂膽固醇引起的肝損傷與氧化壓力。

關鍵字

亞麻籽油 ； 膽固醇 ； 三酸甘油酯 ； 膽固醇代謝基因表現 ； 肝損傷指數 ； 肝臟氧化壓力

並列摘要

The cardiovascular disease (CVD) has been the number one leading cause of human death in the United States since 1990. The similarity is observed in Taiwan since 1980. As we know, omega-3 polyunsaturated fatty acids (ω-3 PUFAs) can reduce a risk of CVD. ω-3 FAs include alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Sources of EPA and DHA are mainly from marine organisms while ALA is mainly obtained in vegetable oils, especially flaxseed oil (FX). Although ALA, EPA, and DHA are belonging to an ω-3 FA family, the cardioprotective effects of ALA are controversial.
FX contains 53.3% ALA and 12.7% linoleic acid. After an acclimation for one week, 32 Syrian hamsters (5-wk age) with two hamsters per cage were divided randomly into four different dietary groups: 1) Control: chow diet (5% fat/0% cholesterol); 2) CO: 92.9% (w/w) chow diet with 7% (w/w) coconut oil/ 0.1% (w/w) cholesterol; 3) BU: 92.9% (w/w) chow diet with 7% (w/w) butter/ 0.1% (w/w) cholesterol; 4) FX: 92.9% (w/w) chow diet with 7% (w/w) FX/ 0.1 % (w/w) cholesterol. Six weeks later, in high-fat/cholesterol dietary groups, FX showed a hypolipidemic effect (P<0.05), and also improved (P<0.05) HDL-C/TC. Lower (P<0.05) hepatic triglyceride and cholesterol contents were measured in FX groups than CO and BU groups; whereas, higher (P<0.05) fecal triglyceride and cholesterol contents were observed in FX groups. When hamsters were fed high-fat/cholesterol diets, HMG-CoA reductase mRNA expression was upregulated (P<0.05) but LDL-receptor mRNA expression of CO and BU groups was downregulated compared to that of control groups. Meanwhile, no (P>0.05) difference on CYP7A1 mRNA expression was recorded among all groups. To concern about liver damage, the lower (P<0.05) serum GOT and GPT values were measured in FX groups compared to other two high-fat/cholesterol dietary groups. The hepatic glutathione (GSH) content in FX groups was higher than those in other two high-fat/cholesterol dietary groups. Although no (P>0.05) differences on malondialdehyde (MDA) levels were detected among all groups, there was a trendeny toward higher MDA levels of CO and BU groups than that of FX groups.
We concluded that hypocholesterolemic effect of flaxseed oil might result from an increase of LDL receptor mRNA expression and more fecal lipid excretion. Meanwhile, flaxseed oil also alleviated liver damage induced by high-fat/cholesterol dietary habit.

並列關鍵字

flaxseed oil ； cholesterol ； triglyceride ； gene expression of cholesterol metabolism ； liver damage

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