中文摘要
綠茶是唲茶素一種天然的酚類及抗氧化劑。近年來有報導指出含有唲茶素的綠茶萃取物有助於維持心血管健康、減少癌症風險及體重下降。特別是EGCG藉由對於減少脂肪生成、脂肪分化及前脂肪生長來促進體重下降、脂肪分解和產熱。我們已知綠茶唲茶素會顯著抑制3T3-L1白色前脂肪的訊息傳導機制，但是對於棕色前脂肪的訊息傳導機制仍未知。因此我們使用小鼠HIB1B棕色前脂肪細胞作為研究素材，透過細胞學以及生化學的角度，來了解綠茶對棕色前脂肪生長的影響。我們發現綠茶唲茶素減少棕色前脂肪的生長，從EGCG時間和濃度依賴正相關減少細胞數、BrdU試驗、細胞存活率我們看到EGCG 比其他綠茶唲茶素對棕色脂肪有更好的抑制效果。這是因結構依賴姓影響不同綠茶唲茶素，像是EC、EGC、ECG。另外，我們也發現EGCG影響棕色脂肪效果沒有比白色脂肪顯著，我們可以從細胞數實驗上看到。再進一步我們從蛋白質分析中看到EGCG傾向時間依賴性增加p-ERKs和p-AMPK蛋白。從這些觀察中可以看出EGCG抑制棕色前脂肪不同於3T3-L1白色前脂肪。這些結果得出在EGCG處理下確實對ERKs有依賴性作用，以及EGCG對棕色及白色前脂肪細胞的生長可能有不同的作用。

Abstract
Green tea catechins (GTCs) are a type of natural phenol and antioxidants. They are associated with a variety of health benefits, including the maintenance of cardiovascular health, the reduction of cancer risk, and weight loss. In particular, epigallocatechin gallate (EGCG) was found to reduce the fat synthesis, adipogenic differentiation and preadipocyte growth, while it induced weight loss, lipolysis, and thermogenesis. Although GTCs selectively inhibited the growth of 3T3-L1 white preadipocytes, the exact mechanism of their actions on brown preadipocyte growth is still unknown. Using HIB1B brown preadipocytes, we found that GTCs decreased the growth of brown preadipocytes. EGCG time- or dose-dependently decreased levels of the cell number, BrdU incorporation, and cell viability. EGCG was more effective in inhibiting growth of brown preadipocytes than other green tea catechins, such as epicatechin, epicatechin gallate, and epigallocatechin. This suggests the structure type-dependent effect of green tea. In addition, the potency of EGCG to reduce the growth on brown preadipocytes was greater than that on white preadipocytes, as indicated by changes in cell number. Further Western blotting analysis indicated that EGCG tended to time-dependently increase the phosphorylation of ERKs and AMPK proteins. These observations were different from those reported for EGCG inhibition of ERKs phosphorylation in 3T3-L1 white preadipocytes. These results suggest the ERK-dependent effect of EGCG on preadipocyte mitogenesis, as well as the possible different role of ERKs proteins in mediating the effect of EGCG on the growth between brown and white preadipocytes.

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