香椿萃取物改善胰島素阻抗及抑制脂肪細胞內單房大油滴形成之作用機轉探討

Effects and mechanisms of the Toona sinensis extract on improving insulin resistance and inhibiting unilocular lipid droplet formation in adipocytes

康銘仁(Ming-Ren Kang)

指導教授 ： 謝翠娟

高雄醫學大學/醫學院/基因體醫學科研究所/碩士(2014年)

https://doi.org/10.6832/KMU.2014.00048

摘要

肥胖與第二型糖尿病是全世界及台灣正在面臨的一個重要的健康問題。香椿萃取物在過去的研究中已證實具有改善糖尿病的功用，但大多都侷限於中高極性的香椿萃取物，對於低極性香椿萃取物之藥理作用很少有這方面的研究。因此我們想探討超臨界萃取技術萃取的低極性香椿萃取物是否能有效改善胰島素阻抗與抑制脂肪細胞內單房大油滴的形成，及探討低極性香椿萃取物是否能將白色脂肪組織轉分化成類棕色脂肪細胞，並探討其中的分子藥理作用機轉。
在細胞實驗，我們給予低極性香椿萃取物在已分化的3T3-L1脂肪細胞；利用6-NBDG螢光染色觀察細胞內葡萄糖的吸收及油紅染色法觀察細胞型態，在基因的表現則利用DNA微矩陣去分析並使用RT-PCR與Western blotting去驗證。在動物實驗，我們利用口服葡萄糖耐受性試驗觀察血糖變化，及利用酵素連結免疫吸附分析法分析血液中胰島素與RBP4蛋白質濃度與免疫組織化學染色法觀察脂肪細胞型態，並觀察脂肪細胞分化成棕色脂肪細胞的主要因子PRDM16及PGC-1α蛋白的表現，與觀察低極性香椿萃取物是否能促進腎上腺訊號傳遞路徑ADRβ3蛋白的表現及棕色脂肪細胞標的蛋白UCP-1的表現。
我們的實驗證實低極性香椿萃取物能改善胰島素阻抗，及抑制脂肪細胞內單房大油滴的形成，而其主要分子機轉是提升胰島素訊息傳遞路徑的敏感性，及降低細胞內CIDEC與Plin1的表現，進而抑制脂肪油滴的生成。並發現低極性香椿萃取物或許能將白色脂肪細胞轉分化成類棕色脂肪細胞透過腎上腺訊號傳遞路徑促進產熱蛋白UCP-1的表現。因此低極性香椿萃取物在未來有潛力發展成新一代的抗糖尿病藥物。

關鍵字

香椿 ； 胰島素阻抗 ； 單房油滴

並列摘要

Obesity and type II diabetes are growing health issue and life threatening event worldwide, including Taiwan. Toona sinensis Roem leaf (TSL) has been used as nutritious food and been suggested for several medical applications. In the past studies, TSL extracts could improve hyperglycemia that had been confirmed. However the reported TSL compounds are from high to mid-high polar extracts. Therefore, we use
supercritical-CO2 fluid extraction to obtain the non-polar constituents of the T. sinensis
leave extract (TS-SCF) and we want to know whether the TS-SCF could improve insulin resistance and inhibit unilocular lipid droplet formation in adipocytes. And we investigate whether the TS-SCF could transdifferentiate the white adipocyte to brite adipocyte.
We treated differentiated 3T3-L1 with the TSL extracts. Then, we used 6-NBDG fluorescence to observe glucose uptake in 3T3-L1. And we used microscope and oil red stain to observe morphology of adipocyte and lipid droplets. The gene expression was analyzed by DNA microarray and confirmed by real-time PCR and western blotting. In animal model, hematoxylin and eosin stain was used to observe adipocyte size in subcutaneous and visceral fat tissue. We measured blood glucose level by OGTT and used ELISA to measured RBP4 and insulin concentration in serum. Then, we observed brown adipocyte differentiated factors PRDM16, PGC-1α, thermogenesis protein UCP-1 expression and adrenergic signaling ADRβ3 expression.
Our results demonstrated that TSL treatment increased glucose uptake and improve insulin sensitivity in the adipocytes. TSL treatment significantly prevented the formation of large unilocular LD by inhibiting FSP27 and Plin1 expression. In our studies, TS-SCF maybe could induce transdifferentiation of white adipocytes into brite adipocytes by increasing adrenergic signaling ADRβ3 expression.

並列關鍵字

Toona sinensis ； insulin resistance ； unilocular lipid droplet

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