在低膳食纖維狀態下，不同直鏈澱粉含量的米對STZ誘發糖尿病大白鼠脂質代謝的影響

The Effects of various rice containing different amounts of amylose on lipid metabolism in STZ-induced diabetic rats in low dietary fiber level status

陳嘉文(Chia-Wen Chen)

指導教授 ： 鄭心嫻

臺北醫學大學/公共衛生暨營養學院/保健營養學研究所/碩士(2002年)

摘要

本研究目的在探討低膳食纖維含量下，不同直鏈澱粉含量的米對糖尿病大白鼠體內脂質代謝的影響。整個研究分為兩個實驗。採用腹腔注射 nicotinamide (200 mg/kg BW)、streptozotocin (STZ, 45~40 mg/kg BW) 兩階段誘發糖尿病的 16 週齡雄性 Wistar rats 進行四週實驗，以 AIN93M 為基準調配膳食纖維含量 5%、2.5% 的實驗飼料。實驗一分成正常大白鼠 (NC) 及糖尿病大白鼠 (DC) 兩組，皆餵食玉米澱粉調配膳食纖維含量 5% 的飼料，比較 STZ 誘發糖尿病後對大白鼠血脂狀態的影響。實驗二是糖尿病大白鼠餵食以秈米 (Indica rice)、粳米 (Japonica rice)、糯米 (Waxy rice) 配製膳食纖維含量 2.5% 且不同直鏈澱粉含量飼料，依序分成 DI、DJ、DW 三組。上述實驗飼料所使用的玉米澱粉、秈米、粳米、糯米皆先經過糊化、再乾燥磨粉後才配製飼料。兩實驗在實驗開始及第四週各進行一次腹腔注射葡萄糖耐受試驗與採取禁食血液樣本，實驗結束時犧牲大白鼠取副睪脂肪組織和肝臟。檢測項目包括：血糖、胰島素、血漿三酸甘油酯及膽固醇濃度、極低密度脂蛋白與低密度脂蛋白三酸甘油酯濃度、低密度脂蛋白與高密度脂蛋白膽固醇濃度、副睪脂肪組織和肝臟 fatty acid synthase 活性。 發現此次 STZ 誘發糖尿病模式，禁食血漿葡萄糖濃度平均值在190 mg/dL，禁食時能維持正常胰島素分泌，進行葡萄糖耐受試驗時，前 30 分鐘胰島素分泌有明顯減少甚至缺乏的現象。由實驗一的結果，顯示此次 STZ 誘發糖尿病模式未能引起糖尿病高脂血症或高膽固醇血症，也發現糖尿病大白鼠的肝臟 fatty acid synthase 活性顯著低於正常大白鼠，副睪脂肪組織 fatty acid synthase 活性則無差異。實驗二比較 DI、DJ、DW 三組結果，發現餵食較高直鏈澱粉含量飼料 (DI、DJ組) 的極低密度脂蛋白和血漿三酸甘油酯濃度比 DW 組明顯升高，在膽固醇濃度方面三組並無差異。肝臟 fatty acid synthase 活性則是 DI、DJ 兩組明顯比 DW 組高，而副睪脂肪組織 fatty acid synthase 活性是 DW 組明顯較高。 發現在飼料膳食纖維含量 2.5% 時，糖尿病大白鼠攝取較高直鏈澱粉含量的米，所配製高碳水化合物比例的飼料會促進肝臟 fatty acid synthase 活性升高，導致內生性極低密度脂蛋白和血漿三酸甘油酯濃度上升。

關鍵字

直鏈澱粉 ； STZ誘發糖尿病大白鼠 ； 秈米 ； 粳米 ； 糯米 ； 腹腔注射葡萄糖耐受試驗 ； 脂質代謝

並列摘要

The purpose of this study was to investigate the effects of various rice containing different amounts of amylose on lipid metabolism in STZ-induced diabetic rats given a low-dietary-fiber diet. This study was divided into two experiments. Both experiments used 16-week old male Wistar normal or diabetic rats as experimental animals for 4 weeks of experimental dietary feeding. Diabetes was induced by nicotinamide and streptozotocin injection. The formulas of these experimental diets were modified from the AIN93M formula. In experiment I, the experimental rats were divided into two groups: a normal rat group (NC) and a diabetic rat group (DC), each group with ten rats. Both groups were fed the experimental diets with 5% dietary fiber and gelatinized cornstarch as the carbohydrate source. The purpose of experiment I was to investigate differences in lipid metabolism between normal rats and diabetic rats. In experiment II, the rats were divided into three groups and fed three diets Indica rice (DI), Japonica rice (DJ), and Waxy rice (DW), each group with ten diabetic rats. All groups were fed the experimental diets with 2.5% dietary fiber and gelatinized Indica rice, Japonica rice or waxy rice as the carbohydrate source. The purpose of experiment II was to investigate differences in lipid metabolism in diabetic rats fed the three diets with 2.5% dietary fiber. Fasting blood sampling and an intraperitoneal glucose intolerance test (IPGTT) were conducted in the first week initially and the fourth week in both experiments. At the end of both experiments, all rats were sacrificed, and their livers and epididymal fat pads were collected. Results of experiment I showed those diabetic rats did not have hypercholestinemia or hypertriglyceridemia, and the normal rats had significantly higher activity of fatty acid synthase in the liver than did diabetic rats. Results of experiment II showed that rats eating the DI and DJ diets had significantly higher plasma TG and VLDL-TG concentrations, than did those on the DW diet. Fatty acid synthase activities of the liver in the DI and DJ diets were significant higher than that of the DW diet. But rats on the DW diet had significantly higher activity of fatty acid synthase in epididymal fat pads. In conclusion, hypertriglyceridemia was induced in diabetic rats by feeding an experimental diet with 2.5% dietary fiber and higher amylose rice as the carbohydrate source.

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