| 摘要: | 全球需面對的健康負擔之一是肥胖所引發的相關健康問題，如第二型糖尿病( type 2 diabetes mellitus，T2DM) 和非酒精性脂肪肝疾病 (nonalcoholic fatty liver disease; NAFLD)，胰島素阻抗會增加肝臟脂質形成並引發多種機制如發炎反應，導致肝脂肪變性。目前並無適當的藥物用於治療非酒精性脂肪肝疾病病人。因此，開發治療非酒精性脂肪肝疾病有效藥物是重要的必需進一步研究。錫蘭七指蕨 (Helminthostachys zeylanica， HZ) 在亞洲被廣泛用在緩解發燒症狀或發炎疾病中常見的中草藥。本研究中，我們評估了錫蘭七指蕨是否對於肥胖、非酒精性脂肪肝疾病及胰島素阻抗有治療的效果。本論文分成兩個部分，第一部分的研究中，我們將HZ萃取物加入游離脂肪酸誘導的人體 HuS-E/2 肝細胞脂肪病變模型及高脂飲食誘導非酒精性脂肪肝疾病小鼠模型中，用以評估HZ之生物活性。由高效液相層析法（High Performance Liquid Chromatography， HPLC）實驗檢測出HZ萃取物的主要成分是ugonin J和ugonin K。細胞實驗中，我們在人肝細胞HuS-E / 2細胞中加入用棕櫚酸會促進細胞脂質累積。而加入HZ萃取物後，HuS-E / 2細胞中的脂質累積有顯著降低。動物實驗中，在餵食高脂飲食混合HZ萃取物的小鼠12週後，高脂飲食小鼠可免受高脂血症和高血糖症的侵害。HZ萃取物可防止高脂飲食小鼠體重增加，脂肪組織擴張和脂肪細胞肥大。此外，減少了小鼠肝臟中的脂肪積累。進一步，評估胰島素功能的胰島素敏感性相關指數也得到了顯著恢復。這些結果顯示，HZ對高脂飲食誘導的肥胖，肝脂肪變性和胰島素阻抗具有良好的藥理作用，HZ具有臨床改善非酒精性脂肪肝疾病應用潛力。在第二部分的研究中，利用飲食誘導的肥胖小鼠實驗，我們發現錫蘭七指蕨萃取物ugonin J（UJ）可以有效控制新陳代謝失調和改善非酒精性脂肪肝疾病病理機制。在週齡5週大的C57BL / 6J小鼠，餵食高脂飲食（HFD）12週後評估其代謝相關生理機制。 在高脂飲食的小鼠中， 我們發現在ugonin J給予可減少脂肪在脂肪組織中的堆積，以及減少高脂飲食所引起的高脂血症和肝臟發炎，並且抑制高脂飲食引起的體重增加。 進一步，ugonin J明顯改善高脂飲食引起的葡萄糖耐受性和胰島素抗性。此外，我們也利用棕櫚酸誘發人肝细胞株HuS-E / 2脂肪堆積及利用高血糖刺激大鼠胰腺β-细胞株BRIN-BD11胰島素的分泌以探討ugonin J調控代謝的作用機制。在棕櫚酸所誘發人肝细胞株HuS-E / 2中，ugonin J可藉由上調pAMPK、pACC和CPT-1及下調SREBP-1c來清除脂肪堆積。在急性胰島素分泌試驗中，ugonin J增加了人肝細胞中的Akt活性並增加了β細胞的胰島素分泌，改善了脂肪細胞肥大，高胰島素血症，高血糖症，高脂血症和肝臟脂肪堆積。總結我們的研究證實HZ萃取物和ugonin J在治療非酒精性脂肪肝疾病和飲食引起的代謝失調方面具有潛力。
Both type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease (NAFLD) are common medical complications of obesity. Hepatic steatosis and its increased hepatic lipid are following a lot of mechanisms to insulin resistance and T2DM involving inflammatory signals. Although developing agent to treat NAFLD was urgent, it was still no effective drugs. Helminthostachys zeylanica (HZ) is one kind of common herbal medicine and in the past used widely to relieve inflammatory conditions and fever-associated symptoms in Asia. In our first part study, the HZ’s therapeutic effects on obesity were demonstrated, also on NAFLD and insulin resistance. Using cells model by free fatty acid-induced steatosis (in human HuS-E/2) and animal model by high-fat diet-induced NAFLD (in mice), the protective effects of HZ extract were examined and proved. Ugonin J and K are confirmed as the major components of the HZ extract by HPLC. By palmitate incubation model, human hepatocytes (HuS-E/2 cells) showed markedly increased accumulation of lipid and significantly decreased lipid deposition after treatment with the HZ extract. After 12 week’s treatment of high-fat diet and HZ extract, the HFD mice had got protective effects from both hyperlipidemia and hyperglycemia. Furthermore, HZ extract prevented HFD mice from increase of body weight, expansion of adipose tissue and adipocyte hypertrophy. We observed that in the mice livers fat accumulation was reduced. Moreover, the insulin function was greatly restored when evaluating by insulin sensitivity-associated index. Hence, all these facts of HZ’s reducing high-fat diet-induced obesity, preventing hepatic steatosis and improving insulin resistance contribute its potentials for pharmacological and clinical application. In the second part of the study, , we found that ugonin J from HZ is efficient in ameliorating metabolic disorder and NAFLD pathophysiology in the diet-induced obese mice study. The 5-week-old C57BL/6J mice was initially fed with a high-fat diet (HFD) for 12 weeks, and the later supplement of ugonin J treatment avoided HFD-induced body weight gain by lowering fat accumulation in adipose tissues. HFD-induced hyperlipidemia and hepatic inflammation dropped after supplement of ugonin J. Also, HFD-induced glucose tolerance and insulin resistance was better after supplement of ugonin J. Using cell modals of hepatocytes [palmitate (PA)-induced steatotic human HuS-E/2] and pancreatic β cells (hyperglycemia-simulating rat BRIN-BD11), the working mechanism of ugonin J was evaluated and proved to improve lipid clearance via pAMPK, pACC and CPT-1 upregulation and SREBP-1c downregulation. However, in acute insulin secretion tests, the Akt activity in hepatocytes was upregulated and insulin secretion from β cells was increased.
Therefore, all these facts of HZ extract and ugonin J preventing adipocyte from hypertrophy, and avoiding hyperinsulinemia, hyperglycemia, hyperlipidemia and fat deposition with modulating key metabolic regulators in fatty acid accumulation process contribute its potential application for the NAFLD and diet-induced metabolic disorders. |
