第2型糖尿病患者血糖控制不良時,會造成全身性高血糖,而長期高血糖會促使過多的葡萄糖走向多元醇路徑來代謝,增加糖化終產物的堆積,導致組織的傷害。香瓜茄為茄科茄屬植物,台灣產地大多位於澎湖,本實驗室先前以BALB/c小鼠誘發成第2型糖尿病,已發現香瓜茄對第2型糖尿病具有延緩體內傷害及多元醇路徑之影響。因此本實驗室更進一步利用leptin receptor基因變異的db/db老鼠,觀察香瓜茄對第2型糖尿病的影響。db/db小鼠分別餵食1%和2%香瓜茄水萃物八週,取血液、肝臟、腎臟、胰臟等臟器進行實驗分析。結果顯示db/db小鼠餵食不同劑量的香瓜茄水萃物八週後,胰島素阻抗性有顯著的改善;在血脂方面,血清中cholesterol、TG、free fatty acid顯著下降,肝臟DGAT-2和副睪脂肪DGAT-1基因表現也顯著下降;在抗氧化方面,肝臟、腎臟、胰臟及坐骨神經也都有顯著上升;在多元醇路徑方面,腎臟、胰臟、紅血球及坐骨神經的多元醇路徑關鍵酵素Aldose reductase比活性和終產物Fructose的堆積有下降的情形;在發炎方面,腎臟TGF-β1基因表現量與纖維網狀蛋白含量都有減;在組織切片方面,腎臟及坐骨神經有保護作用。因此根據本研究顯示香瓜茄水萃物可降低db/db小鼠體內氧化壓力及糖化作用,進而可以延緩第2型糖尿病的併發症發生。
Solanum muricatum Ait (pepino) is a popular plant food in Penghu island, Taiwan. Our previous study has reported that the aqueous extract from pepino was able to improve antioxidant defense and polyol pathway in streptozotocin induced type 2 diabetic BALB/c mice. Therefore, we further use the leptin receptor gene mutated db/db mice to investigate the effects of pepino aqueous extract on type 2 diabetes. Db/db mice were fed by 1 or 2% aqueous pepino for eight weeks. The serum and tissues were collected to analyze. Results showed that pepino intake improved insulin resistance and decreased resistin gene expression. This extract inhibited DGAT-2 gene expression in liver, DGAT-1 gene expression in adipose tissue, reduced lipid synthesis, lowered serum cholesterol, triglyceride and free fatty acids. In addition, this extract also reduced malondialdehyde (MDA); retained glutathione (GSH), glutathione peroxidase (GPx) in liver, kidney, pancreas and sciatic nerve, attenuated oxidative damage. The activity of aldose reductase, a key enzyme in polyol pathway, decreased in kidney, pancreas, erythrocyte and sciatic nerve. Also, the fructose and N-ε-carboxymethyl-lysine (CML) levels were lowered in these organs. On the other hand, this extract inhibited TGF-β1 gene expression and reduced fibronectin level in kidney, and decreased inflammatory stress. These results suggest that pepino aqueous extract could delay progression of type 2 diabetic complications by decreasing oxidative stress, glycosylation and inflammatory response.