| 摘要: | 肥胖一般皆伴隨著白色脂肪組織的過度擴張，此過程包含前脂肪細胞經分化使細胞數目增加、體積擴張並改變細胞特性。十字花科蔬菜衍生物indole-3-carbinol (I3C)，已被指出具抗肥胖的活性，但其對脂肪細胞相關探討仍有限。本研究以3T3-L1脂肪細胞分化模式，探討I3C對脂肪分化過程的影響。小鼠3T3-L1前脂肪細胞與0.5-10 μM I3C先培養於含3-isobutyl-1-methylxanthine、dexamethasone、insulin (MDI)之脂肪細胞分化培養液，再以含insulin之培養液與I3C培養，使完全分化為成熟的脂肪細胞後，以油紅染色定性與定量分析I3C添加之有無對細胞內脂質累積程度之影響，同步分析細胞內三酸甘油酯 (TG)含量；偵測脂質合成關鍵酵素glycerol-3-phosphate dehydrogenase (GPDH)活性，以釐清I3C對於脂肪細胞TG合成之調控作用；此外，也分析培養基中甘油與游離脂肪酸釋出量，以了解I3C對於脂解作用的影響；為釐清I3C對於脂肪細胞分化的可能調控機轉，亦分析參與該路徑相關轉錄因子、脂質合成或脂解作用關鍵酵素之蛋白質表現量作分析；且偵測脂肪細胞之adiponectin製造量，以了解I3C對促脂質累積之adipokine製造量的影響。結果顯示，5-10 μM I3C可顯著降低脂肪分化前期細胞生存率，於0.5-10 μM I3C可顯著降低細胞內油紅之染色，且細胞內TG含量亦呈相似結果。此外分化第四天時，5、10 μM I3C甘油釋出量顯著上升，但於第六天顯著下降，而游離脂肪酸釋出量則無顯著差異，然而I3C對脂質合成與脂解作用之關鍵酵素 hormone-sensitive lipase (HSL)及GPDH的蛋白質表現量無顯著影響，但發現1 μM I3C可顯著降低peroxisome proliferator- activated receptor gamma (PPAR-γ)蛋白質表現量，且GPDH酵素活性也顯著下降。對於脂肪細胞分泌之adiponectin製造量，有隨濃度降低的趨勢。總言之，I3C可藉由影響脂肪分化前期之細胞生存率、降低TG累積量與增加甘油釋出量進而抑制脂肪細胞分化，且此過程伴隨著GPDH酵素活性下降與PPAR-γ蛋白質表現量的下降。
The etiology of obesity is mainly due to the imbalance between energy intake and energy expenditure. The excessed energy is stored in adipocytes resulting in expansion of adipose tissue. Indole-3-carbinol (I3C) is a bioactive component present in cruciferous vegetables, It has multiple functions, including anticarcinogenic and anti-obesity properties. However, the potential mechanisms of I3C on anti-obesity is not clear. Therefore, the aim of this study was to investigate the effect of I3C on 3T3-L1 preadipocytes proliferation and differentiation. The cells were culturated and differentiated in DMEM supplemented with 3-isobutyl-1-methyl-xanthine, dexamethasone, insulin (MDI) and 10 % of newborn calf serum for 6 days. To examine the effect of I3C on cell proliferation, the preadipocyte and differentiating adipocytes were treated with I3C for 24 hr, 2 days, 3 days and 4 days respectively. The results indicate that I3C suppresed the differentiating adipocytes proliferation at 5 μM I3C on the second and third day of differentiation time. Besides, to examine the effect of I3C on adipocyte differentiation, differentiating adipocytes were treated with I3C for 6 days, and shown that 1 to 10 μM of I3C reduced TG accumulation in differentiated adipocytes. And the results indicate that I3C increased lipolysis as measured by glycerol release but the increment was only observed at the 4th day of differentiation. On the other hand, I3C decreased the glycerol-3-phosphate dehydrogenase (GPDH) activity, the key enzyme of lipogenesis during the adipocyte differentiation, although no significance was observed on the expression of hormone-sensitive lipase and GPDH proteins, as well as adiponectin production. In conclusion, I3C decrease cell proliferation of differentiating adipocytes, and such effect was associated with decreased TG accumulation, decreased lipogenic GPDH enzyme activity, and decreased PPAR-γ protein expression. |
