不同比例之不飽和脂肪酸組成對脂質代謝和體脂肪蓄積之影響

本研究旨在探討膳食油脂中的單元不飽和脂肪酸（MUFA）和多元不飽和脂肪酸（PUFA）對體脂蓄積之影響。首先，本論文實驗設計以2x2因子討論油脂中的MUFA比例和PUFA / SFA（P/S）比值，共計四種實驗調和油，其中固定高MUFA比例為60%且其P/S比值為5或3，另外兩種則固定MUFA比例為30%且其P/S比值為5或3，以大豆油作為對照組；倉鼠隨機分為五組以餵食12週不同之15% (w/w)調和油。結果發現，各組攝食量均無差異，而餵食P/S比值為5、MUFA比例60%調和油之倉鼠，有較輕的體重和白色脂肪組織重量，並降低血漿胰島素濃度、血漿游離脂肪酸濃度以及肝臟脂質合成酵素活性，且明顯提高肝臟脂肪酸氧化酵素：acyl-CoA oxidase（ACO）和carnitine palmitoyltransferase-I（CPT-I）活性，抑制體脂肪蓄積。再由飲食誘導肥胖倉鼠實驗模式，餵食8週4% (w/w)低油飲食發現，與肥胖對照組比較，P/S比值為5、MUFA比例60%調和油組有明顯減少白色脂肪組織重和血漿瘦體素濃度，降低白色脂肪組織PPARγ和脂蛋白脂解酶mRNA 表現，並增加肝臟脂質氧化酵素ACO和CPT-I活性；且P/S比值為5、MUFA比例60%調和油比橄欖油較能調節白色脂肪組織荷爾蒙敏感性脂解酶（hormone-sensitive lipase）的活化，顯示肥胖倉鼠的肝臟和白色脂肪組織都明顯促進脂肪消耗以減少體脂肪蓄積；相反地，肥胖倉鼠餵食橄欖油（高MUFA比例、極低P/S比值）則會明顯促進肝臟脂肪酸合成作用。另外，利用3T3-L1成熟脂肪細胞模式發現， P/S比值對影響體脂肪蓄積之重要性會明顯大於MUFA/PUFA比值，顯示油脂中的SFA、MUFA、PUFA需存在適當的比例（SFA：MUFA：PUFA為1：10：5）始能對促進脂質代謝和抑制體脂肪蓄積發揮較妥適的生理促進效果。本論文證實，脂肪酸組成為P/S比值等於5、MUFA比例60%之油脂可有效減少脂質合成作用和促進脂質氧化，以減少體脂肪蓄積。未來，可以提供國人在體重控制或是維持理想體重時，有更多的資訊選擇適當的油脂來源。

關鍵字

單元不飽和脂肪酸；多元不飽和脂肪酸/飽和脂肪酸比值；飲食誘導肥胖； PPARs ；脂蛋白脂解酶荷爾蒙敏感性脂解酶

並列摘要

The aim of this study was to assess the relationship between high monounsaturated fatty acid (MUFA) with different levels of polyunsaturated-to-saturated fatty acid (P/S) ratios and body fat accumulation. We designed a 2 x 2 factorial study, with 2 levels of MUFAs (60% and 30%) and 2 levels of the polyunsaturated-to-saturated fatty acid (P/S) ratio (5 and 3) to prepare four kinds of experimental oils consisting of 60% MUFAs with a high or low P/S ratio, or 30% MUFAs with a high or low P/S ratio. Forty male golden Syrian hamsters were randomly divided into five groups and fed the diets contained 15% (w/w) fat for 12 weeks. Hamsters fed soybean oil were as control group. No difference was observed in the mean daily food intake. Hamsters fed the high MUFA% with high P/S ratio diet had lower not only plasma insulin and free fatty acid concentrations but also hepatic acetyl-CoA carboxylase activities, and elevated hepatic acyl-CoA oxidase and carnitine palmitoyltransferase-I activities among the groups. The high MUFA% with high P/S ratio oil diet appeared to be beneficial in preventing white adipose tissue accumulation. In diet-induced obese (DIO) models, DIO hamsters fed the high MUFA% with high P/S ratio oil diet had significant reductions in white adipose tissue deposition and plasma leptin levels, suppression in adipose peroxisome proliferator-activated receptors (PPAR) γ and lipoprotein lipase (LPL) mRNA expressions and increases in hepatic lipolytic enzyme activities compared with those in the obese-control group. The high MUFA% with high P/S ratio oil group upregulated phosphorylation of hormone-sensitive lipase (HSL) relative to total HSL protein levels compared with the olive oil group. However, the olive oil consisting of the high MUFA% with very low P/S ratio group significantly elevated hepatic FAS activities (de novo lipogenesis) compared with the high MUFA% with high P/S ratio oil group. Moreover, we found effects of body fat accumulation of P/S ratio were more important than those of MUFA/PUFA ratio in 3T3-L1 adipocyte, suggesting that SFA, MUFA and PUFA are needed to consist of the optimal dietary fat composition. In conclusion, 60% MUFA with P/S ratio=5 oil appeared to be beneficial in preventing white adipose tissue accumulation.

並列關鍵字

monounsaturated fatty acid ； polyunsaturated to saturated fatty acid ratio ； diet-induced obese ； peroxisome proliferator-activated receptors ； lipoprotein lipase ； hormone-sensitive lipase

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不同比例之不飽和脂肪酸組成對脂質代謝和體脂肪蓄積之影響

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