初探山苦瓜萃物對3T3-L1脂肪細胞褐化及粒線體增生相關基因表現之影響

An initial approach to explore the effects of Momordica charantia L. extracts on the mRNA expression of browning and mitochondria biogenesis related genes in 3T3-L1 adipocytes

王思文(Si-Wen Wang)

指導教授 ： 黃青真

國立臺灣大學/生命科學院/生化科技學系/碩士(2013年)

https://doi.org/10.6342/NTU.2013.00662

摘要

近年臺灣地區由於西方飲食的盛行及體能活動量不足，過重及肥胖盛行率在不同性別及年齡層逐年增加。肥胖防治的主要策略是降低能量攝取、增加能量消耗。最近研究顯示，刺激白色脂肪「褐化」可消耗熱量，抑制脂肪組織累積，防止肥胖。本實驗室先前研究，小鼠攝食山苦瓜飲食可促進白色脂肪中「棕色脂肪」及粒線體相關基因mRNA表現，並增加能量代謝速率。本研究擬建立3T3-L1脂肪細胞培養為試驗平台，觀察苦瓜萃物於培養之白色脂肪細胞是否能誘發褐化及粒線體增生的特徵，並進一步觀察比較不同山苦瓜萃物/區分物對脂肪細胞褐化及增加粒線體相關基因的活性。
首先以5 μM troglitazone處理，分別比較兩種分化法以及在3種處理時間，對於成熟脂肪細胞褐化及粒線體增生相關基因表現的影響。根據實驗結果，選擇「分化成熟前四天，樣品處理四天」，並以「分化法1」的脂肪細胞模式進行後續實驗。試驗樣品包括：山苦瓜乙酸乙酯萃物 (EAE) 、皂化物 (S) 、不皂化物 (NS) 、山苦瓜水萃物 (WE) 、經納豆菌作用後之水萃物 (WEn) 與自苦瓜純化分離的化合物 (CLN、 phytol和leutin) 。結果顯示，低濃度的EAE、S及NS處理下，能觀察到棕色脂肪相關基因表現增加；而EAE也能增加脂肪細胞檸檬酸合成酶 (citrate synthase, CS) 的活性。而苦瓜中活化PPARγ的活性成分也能刺激脂肪細胞的褐化。
綜合上述，3T3-L1脂肪細胞可作為觀察褐化現象的試驗模式。而山苦瓜能活化PPARγ之區分物/化合物，皆可使脂肪細胞表現褐化相關基因，與文獻中PPARγ agonist可使白色脂肪細胞表現「褐化」之現象相符。

關鍵字

肥胖 ； 山苦瓜 ； 脂肪細胞 ； 褐化 ； 粒線體

並列摘要

Due to westernized diet and insufficient physical activities, the prevalence of overweight and obesity have been increased Taiwan and other parts of the world. Managing energy balance is the principle of obesity prevention/treatment. Recent studies demonstrated that “browning”of white adipose tissue (WAT) might increase energy expenditure and prevent obesity. Previous study of our lab showed that mice fed the wild bitter gourd (Momordica charantia.L, WBG) diet had higher metabolic rate and some characteristics of “browning” WAT, i.e., higher expressions of brown-fat-selective and mitochondria biogensis genes. This study thus aimed to develop a cell model using cultured 3T3-L1 adipocytes for the examination of mRNA expressions of brown-fat-selective and mitochondria biogensis genes as affected by various WBG extracts/fractions and compounds.
Two differentiation protocols and three treating stage/times were compared using 5 μM troglitazone as the positive control. The differentiation protocol 1 and treatment during the last 4 days of differentiation showed the best results. Ethyl acetate extract (EAE), its saponifable (S) and non-saponifable fraction (NS), water extract without (WE) or with pretreatment (WEn) as well as 3 PPAR active compounds of WBG were then tested in the system. Low concentrations of EAE、S and NS did induce brown-fat gene expression in 3T3-L1 adipocytes (p<0.05), and EAE can also increase the citrate synthase activity (p<0.05). The induction of brown-fat gene expressions were also observed in cells treated with the 3 PPAR active compounds of WBG (conjugated linolenic acid, phytol and leutin), implying the involvement of WBG PPARγ activity in the “browning” effect.
In conclusion, 3T3-L1 adipocytes can be used as a model to investigate “browning” effect of WBG. The PPARγ active fractions and compounds of WBG induced mRNA expressions of brown-fat-selective genes in this cell model.

並列關鍵字

obesity ； Momordica charantia ； adipocytes ； browning ； mitochondira

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