- 學位論文
二十二碳六烯酸在脂肪組織中參與脂質代謝之角色
The role of lipid metabolism by docosahexaenoic acid in adipose tissue
摘要
近年來由於食物取得容易與飲食中脂肪酸攝取比重之改變，使肥胖發生率日益增加，進而引發高血脂，第二型糖尿病等代謝性症候群。其中，脂肪組織除了作為累積能量之主要部位，也分泌脂肪激素參與調節體內代謝，因此若能了解脂肪組織中其代謝機制將可有效改善脂肪組織發育之調控。近年研究顯示日糧中n-3多元不飽和脂肪酸可降低血液中三酸甘油酯，以改善肥胖與代謝性症候群之併發症，但在脂肪中之調節機制尚無定論，因此本研究目的將探討不同脂肪酸飼糧在豬隻脂肪組織之調控。本研究利用8周齡之藍瑞斯 x 約克夏 x 杜洛克三品種豬在飼糧中提供 2%不同種類之脂肪酸包含大豆油(SBO)、二十二碳六烯酸(DHA)或牛油(BT)餵飼30天。相較於BT處理組，DHA處理組中顯著降低血液中三酸甘油酯，而作為脂解指標的甘油含量，BT處理組顯著高於其他兩組。為避免體內代謝所造成的影響，利用初代豬隻脂肪細胞分別處理亞麻油酸、DHA與油酸，以對應到SBO、DHA與BT飼糧中主要脂肪酸成分。在BT處理組之皮下脂肪組織，與初代脂肪細胞處理油酸中三酸甘油脂解酶 (adipose trigylceride lipase)與激素敏感脂解酶 (hormone sensitive lipase) 表現顯著提高。在DHA處理組當中，脂肪細胞大小與脂質合成基因包括脂肪分化相關蛋白 (Adipose differentiated related protein)、二醯基甘油醯基轉移酶1 (diacylglycerol acyltransferase 1) 皆顯著較其他組別提高。除此之外，蛋白激酶 A (protein kinase A)在皮下脂肪組織的活性也顯著較高。皮下脂肪組織之脂質氧化相關基因，乙醯化輔酶A氧化酶 (acyl-coenzyme A oxidase)相較於SBO處理組，DHA也有較高之表現量。這些結果顯示攝取DHA可能透過增加脂肪組織之脂質合成，並增加β-氧化以降低血液中三酸甘油酯的含量。
並列摘要
The incidence of obesity and its comorbidities such as insulin resistance and type II diabetes are increasing dramatically, perhaps caused by the change of fatty acid composition in habitual diets. Adipose tissue plays a role as the major energy reservoir in the body, and it also maintains homeostasis by adipokine production. The beneficial effects of n-3 PUFA may provide a more effective therapy to cope with the incidence of obesity and its comorbidities. Hence, the aim of this study was to elucidate the benefits of docosahexaenocic acid (DHA) on adipocyte lipid metabolism. We hypothesized that one of the benefits of ω-3 PUFA, particularly DHA is to lower plasma TAG, involving an effect on adipocyte lipid metabolism. Eight-week-old Landrace x Yorkshire x Duroc pigs were fed a diet with 2% dietary fat (as-fed basis) in experimental diets from either soybean oil (SBO), DHA or beef tallow (BT) for 30 days. Plasma TAG concentration was lower in DHA-fed than BT-fed pigs, and the products by lipolysis, plasma level of glycerol was greater in BT-fed pigs than the other groups. Primary pig adipocytes were treated with linoleic acid, DHA or oleic acid to represent the majority fatty acids compositions of SBO-, DHA- and BT- fed groups. Expression of lipolytic genes including adipose triglyceride lipase (ATGL) and hormone sensitive lipase were higher in the subcutaneous adipose tissues (SCAT) of BT-fed pigs and adipocytes treated with oleic acid. Adipocyte sizes and lipogenic-related gene expressions, adipose differentiated related protein, diacylglycerol acyltransferase 1 were elevated by DHA in vivo and in vitro. Furthermore, a higher level of protein kinase A phosphorylation was observed in the SCAT of DHA-fed pigs. Expression of acyl-coenzyme A oxidase, implicated in fatty acid oxidation, was higher in DHA-fed pigs as compared to SBO-fed pigs in SCAT. These results suggest that consumption of DHA leads to lower plasma TAG through the effect of DHA on increasing lipid accumulation in adipose tissue by increasing the expression of lipogenic genes.
參考文獻
延伸閱讀
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