The studies of Gelidium amansii on plasma lipids, glucose and obesity in animal models

• Main Authors: Yang, Tsung-Han, 楊宗翰
• Other Authors: Chiang, Meng-Tsan
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/vnww4c

博士 === 國立臺灣海洋大學 === 食品科學系 === 104 === Gelidium amansii (GA) is an edible red algae that is distributed mainly in northeastern Taiwan. GA is widely used in food and chemical fields. The metabolic syndrome has become one of the major public-health challenges worldwide and in Taiwan. Hyperglycaemia, dyslipidaemia, hypertension and obesity were main risk factors for metabolic syndrome. In this study, we investigated the effect of GA and Gelidium amansii hot-water extract (GHE) on the metabolic syndrome by the animal models such as type 2 diabetes mellitus, hyperlipidemia and obesity models, respectively. Experiment (1): Diabetes is the fifth among the top ten leading causes of death in Taiwan. In Taiwan, an estimate shows that about ten thousand people died with diabetes every year. Type 2 diabetes accounts for 90-95% of patients with diabetes. After streptozotocin-nicotinamide induced rats can develop symptoms similar to human with type 2 diabetes. The first study was designed to investigate the effects of GA on plasma glucose, lipids and adipocytokines in rats with streptozotocin-nicotinamide-induced diabetes. Streptozotocin-nicotinamide induced diabetic rats were fed with 5% GA for 11 weeks, significantly reduced the fasting blood glucose level and improved the insulin resistance index HOMA-IR (homeostatic model assessment- insulin resistance). GA feeding significantly reduced the total cholesterol and triglycerides both in the plasma and liver. Furthermore, feeding of 5% GA can also significantly increase the excretion of fecal lipids and reduced liver weight, triglycerides and total cholesterol. Diabetic rats fed with GA could induce the rate of lipolysis and thus lower adipose tissue weight and thus reducing the inflammatory factors such as TNFα (tumor necrosis factor alpha), IL-6 (interleukin-6) and PAI-1 (plasminogen activator inhibitor type 1) concentrations. The results suggest that GA feeding can regulate plasma glucose and lipid levels and prevent adipose tissue accumulation in rats with diabetes. Experiment (2): Type 2 diabetes often combined with hyperlipidemia. The first part of study results show that feeding GA improved hyperlipidemia in diabetic rats. Therefore, the purpose of second part study was to investigate the effects of Gelidium amansii hot-water extracts (GHE) on lipid metabolism in hyperlipidmia hamsters. GHE is rich in water-soluble fiber (68.6%). Hyperlipidmia hamsters fed 1.5% GHE had lower triglycerides and total cholesterol concentrations both in plasma and liver after 6 weeks of feeding period. In addition, GHE feeding significantly decreased body weight, liver weight, and adipose tissue (perirenal and paraepididymal) weight. GHE supplementation increased the phosphorylation of AMPK (AMP-activated protein kinase) and reduced SREBP1 (sterol regulatory element binding protein 1) and SREBP2 protein expression, and thus reduced lipid synthesis enzyme activity such as FAS (fattyacid synthase) and ACC (acetyl-CoA carboxylase) in the liver. In addition, intaking of GHE can also significantly increase the excretion of total cholesterol, triglyceride and cholic acid. These results suggest that GHE feeding ameliorate lipid meatabolism in hyperlipidemia hamsters. Experiment (3): In the type 2 diabetes and hyperlipidemia animal model, feeding GA or GHE can improve plasma and liver lipid metabolism and have reduced the white adipose tissue weight. Therefore, the purpose of third study was to investigate the mechanism of GHE on plasma, liver lipids, adipocytokines and adipose tissues in high-fat diet induced obese hamsters. Obese hamster supplementation with 3% GHE extract for 9 weeks had decreased concentrations of plasma and liver total cholesterol, triglyceride and weight of the adipose tissue (paraepididymal and perirenal). Furthermore, feeding of GHE can also significantly increase the excretion of fecal total cholesterol and triglyceride. In addition, supplementation of GHE significantly reduced plasma levels of TNFα and IL-6. However, GHE supplementation had no effect on plasma concentrations of GLP-1 and food intake. GHE supplementation increased the phosphorylation of AMPK protein expression and increased hepatic levels of PPARα (peroxisome proliferator activated receptor alpha) and UCP 2 (uncoupling protein). Moreover, GHE feeding had higher HSL (hormone sensitive lipase) and lower LPL (lipoprotein lipase) enzyme activities in both paraepididymal and perirenal adipose tissues thus had lower triglyceride content of adipose tissues. In addition, hamsters feeding with GHE had lower body weight and adipose tissue than guar gum (GG), which due to the higher fecal total cholesterol excretion and adipose tissue HSL activity. Results from the present study show that GA and GHE can reduce the risk factors of metabolic syndrome.