- 學位論文
Quercetin及其結構類似物在骨骼肌細胞中葡萄糖吸收及利用之影響
Effects of Quercetin and its analog on glucose uptake and utilization in C2C12 cell line
摘要
背景：糖尿病是一種常見的代謝疾病，影響全世界人口的健康。隨著罹患糖尿病的人數日益增加，尋找新的治療方式是必要的。AMPK是能量代謝的感應者，過去研究指出其在治療肥胖、第二型糖尿病及代謝症候群的發展上佔有重大角色。本篇實驗目的為尋找AMPK的活化劑，並比較quercetin及其結構相關化合物對AMPK活化的影響。 材料及方法：本實驗使用C2C12小鼠骨骼肌細胞株作為細胞模式，看quercetin及其結構相關的6種化合物對AMPK活性的影響，並進一步測試quercetin及RS-25兩藥物對葡萄糖吸收、肝醣合成，及對胰島素阻抗的改善作用。 結果：在測試7個化合物後，發現除了642C不會增加C2C12 myotubes的AMPK磷酸化外，642D、RS-25、RS-26、quercetin、RS-47、RS-59在不同濃度或時間下均可增加AMPK的磷酸化。雖然0.3 uM的quercetin有相當於10 uM RS-25的AMPK活化作用，但發現0.3 uM quercetin的葡萄糖吸收及肝醣合成作用較10uM RS-25強，推測可能與其有較強的Akt磷酸化有關。此外，發現quercetin及RS-25皆可使ATP含量降低，而quercetin可以改善高血糖或IL-6引起的胰島素阻抗。 結論：造成此兩種化合物作用上差異的機制，可能在於此兩種藥物活化Akt以及活化AMPK能力的差異。由於在刺激葡萄糖吸收的機制：一條經由胰島素依賴的phosphoinositide 3 kinase/Akt訊息路徑而另一條經由代謝的stress而活化的AMPK依賴的訊息傳遞，除了化合物對此兩種訊息路徑作用不同外，兩者作用之差異仍有待進一步的釐清。
並列摘要
Background: Diabetes mellitus is one of the most common metabolic disorders that disturbs lots of people’s life and heath all over the world. With the increase number of diabetic patients, the search for new agent in treatment of diabetes is needed. Recently, AMPK is known as an energy sensor and important target, its activation is reported to play an important role in regulation of obesity, type II diabetes, and metabolic syndrome. The present study was aimed to examine and compare the AMPK activating activities of quercetin and its chemical derivatives. Methods: C2C12 myotube was used as a cell model. The increase of AMPK phosphorylation after treatment with quercetin and its analogs was used as an index of AMPK activation. Further study of the effect of quercetin and RS-25 on glucose uptake, glycogen synthesis, and improvement of insulin resistance was examined and compared. Results: Among the seven compound examined, except 642C, all six other compounds(642D, RS-25, RS-26, quercetin, RS-47, RS-59) were found to activate AMPK phosphoryltaion at different time and concentration. Although 0.3 uM quercetin has comparable AMPK activating activity as 10 uM RS-25, 0.3 uM quercetin was found to have stronger activity than 10 uM RS-25 in increasing glucose uptake and glycogen content of C2C12 myotubes. The stronger activity of quercetin was correlated with the stronger stimulation of Akt phosphorylation in C2C12 myotubes. Besides, both quercetin and RS-25 were found to induce ATP depletion, and quercetin was found to improve high glucose or IL-6-induced insulin resistance. Conclusion: Most quercetin derivatives were found to have AMPK activating activities. Quercetin at 0.3 uM was found to exert stronger activity in stimulation of glucose uptake than 10 uM RS-25. The stronger activity of quercetin is related to its stronger stimulation of Akt phosphorylation. However, mechanism of quercetin to induce depletion of ATP is remained to be clarified.