- 學位論文
保健食品改善代謝症候群 小鼠評估模式之建立
To Develop a Mice Model for Evaluating the Effect of Functional Foods on Metabolic Syndrome
摘要
代謝症候群與心血管疾病發生的危險因子，包括胰島素阻抗、肥胖、高血壓、和涉及糖尿病型動脈粥狀硬化的一些危險因子（如血脂與脂蛋白異常、血管內皮功能異常、和發炎相關細胞激素分泌上升等）具高度相關。而在疾病防治上，若無即時治療，代謝症候群的嚴重性是其終將造成第二型糖尿病和心血管疾病，且第二型糖尿病會加速動脈粥狀硬化之進程。 本篇將實驗分成三大部分，第一部分以TXAS基因剔除小鼠與正常小鼠測試Streptozotocin （STZ）的最佳注射濃度，分別用高濃度，以20 mg/kg STZ注射一天，隔天再以100 mg/kg STZ注射；以及低濃度，以55 mg/kg STZ連續注射五天。結果發現以低濃度注射較為適當。 第二部分利用先前測試的低劑量STZ（55 mg/kg）連續施打五天，之後給予小鼠高脂質飼料混合以大豆、紅麴、苦瓜、綠藻、甘草等具降血糖、血壓、血脂之五種食材的粉末餵食，觀察十二週後，發現以大豆、紅麴、苦瓜、綠藻、甘草等食材混合的飼料在血壓、血脂、血糖等皆沒有顯著的功效。 第三部分改利用 ApoE 基因剔除小鼠，配合低劑量STZ連續注射五天，適當破壞小鼠胰臟的 β-細胞，誘導其具糖尿病病徵，再配合高脂質的飼料餵食，連續觀察十二週，發現小鼠血糖上升速度增快、造成高密度脂蛋白膽固醇偏低、三酸甘油酯偏高、甚至產生動脈粥狀硬化症狀，和代謝症候群的五大臨床診斷標準極具相關，以作為代謝症候群的小鼠動物模式。再者，以紅麴、兒茶素、豆豉、鰹魚等能夠降血壓、血脂、血糖等的健康食材做為複方食材去餵食小鼠，評估上列食材的療效為何。而研究結果發現，以紅麴、兒茶素、豆豉、鰹魚等食材餵食的小鼠，其血糖在第二週起即有開始下降的趨勢；在膽固醇方面除了第六週有上升，其他皆較對照組為低；三酸甘油酯方面，餵食健康食材的小鼠呈現穩定平緩的曲線，而未餵食健康食材的小鼠則呈持續上升的趨勢，且在第六週後急遽的攀升，到第十週時具顯著差異。 實驗推論，以紅麴、兒茶素、豆豉、鰹魚等食材混合的飼料餵食小鼠具有降低血壓、血糖、膽固醇、三酸甘油酯的功效，且以ApoE 基因剔除小鼠，配合低劑量之STZ連續注射合併高脂餵食的方式，將可以作為未來研究代謝症候群的實驗用小鼠動物模式。
並列摘要
Metabolic syndromes, cardiovascular diseases and diabetic atherosclerosis have common risk factors such as insulin resistance, obesity, and hypertension. However, diabetic atherosclerosis solely manifests endothelial dysfunction, lipid and lipoprotein anomalies. If not prevented, metabolic syndrome could lead to type II diabetes and cardiovascular diseases. Furthermore, the type II diabetes would accelerate atherosclerosis. This research was divided into three experimental approaches. The first experiment was to determine the optimum concentration of Streptozotocin (STZ) that would induce type II diabetes. Two groups of mice were used: TXAS -/- and control group. A set (of high concentration STZ) comprising the two groups were initially injected with 20 mg/kg STZ and 100 mg/kg STZ on the first and second day, respectively. On the other hand, another set (of low concentration STZ) comprising of both groups was injected with 55 mg/kg STZ for five successive days. Based from the two different sets (of high and low concentration STZ), low concentration STZ was more appropriate in inducing type II diabetes. On the second experiment, low concentration STZ was injected to TXAS-/- and normal mice for five consecutive days. Two different groups of mice were fed separately with high-fat diet only; and high-fat diet plus remixed powder, containing soy bean, red rice, balsam pear, green algae, liquorice, which functions to decrease plasma glucose, blood pressure, total cholesterol and triacylglycerol. After twelve weeks, results showed that there was no significant effect on the decrease plasma glucose, blood pressure and total cholesterol. The final experiment used ApoE+/- mice and STZ to aggravate the risks of metabolic syndrome. Low concentration STZ was injected for five consecutive days in order to destroy the β- cells of pancreas of mice effectively. When the characteristics of diabetes were induced, mice were fed separately with high-fat diet only and high-fat diet plus remixed powder and observed for twelve weeks. ApoE+/- mice injected with STZ and fed with high-fat diet can make the plasma glucose rise easier and faster, and lower high density lipoprotein (HDL) cholesterol which could lead to higher triacylglycerol levels that can cause atherosclerosis and metabolic syndrome. These five clinical diagnostic approaches are in high relation to an average metabolic syndrome in humans as depicted in our mouse model. Moreover, healthy food which consists of red rice, Catechins, soy bean and Katsuobushi, are effective in decreasing plasma glucose, blood pressure, total cholesterol and triacylglycerol as alternative way of feeding mice for its curative effect. According to the research result, it was found that mice fed with remixed powder consists of red rice, Catechins, soy bean and Katsuobushi showed decrease in blood glucose on the second week. On the other hand, cholesterol levels were lower than other control group, except on the sixth week; while triacylglycerol levels were stable on the mice that were fed of healthy food. Oppositely, triacylglycerol levels of the mice that were not fed of healthy food keep on rising and a sharp increase on the sixth week and have significant difference on the tenth week. Based on these experiments, red rice, cathechins, soy beans, and katsuobushis reduce blood pressure, plasma glucose, triglycerol, and cholesterol content in mice. Intraperitoneal injection of low concentration STZ into ApoE-/- mice in combination with high-fat diet could be a candidate mice model for people interested in research regarding metabolic syndrome.