山苦瓜對apoE剔除鼠脂質代謝之影響

Abstract

代謝症候群是指胰島素抗性所引起的葡萄糖不耐症、腹部肥胖、高TG、低HDL與高血壓等症狀，而最終將有可能會轉變為心血管疾病，對健康造成更大的傷害。在印度、中國及拉丁美洲地區，苦瓜被用做改善糖尿病的藥物已有很長久的歷史，但苦瓜對脂質代謝影響的研究則是近幾年才開始發展。本研究以血脂異常且容易產生動脈粥狀硬化之缺乏apoE小鼠為模式，探討苦瓜改善脂質代謝情形。實驗一、18週大缺乏apoE小鼠分為6組，給予不同飼料如下：C組(n = 5)為一般chow diet、HF組(n = 10)含20% fat、BGP組(n = 10)含20% fat加5%山苦瓜凍乾粉末、EAE組(n = 10)含20% fat加1%山苦瓜乙酸乙酯萃物、CF組(n = 5)含20%fat加0.5%clofibrate、TZD組(n = 5)含20%fat加0.00123% rosiglitazone，共餵養18週後犧牲，其間於第4、9、17週時採眼窩血測量血脂變化，並於犧牲後取組織器官進行後續分析。實驗結果以單因子變異數分析及Tukey事後分析進行組間比較。結果BGP組第9及17週血液TC顯著較HF組低25及39% (p<0.05)、第17週血液TG較HF組低38% ( p<0.05)、HDL-C較HF組高55%( p<0.05)，EAE組則使血液HDL-C高於HF組39%但未達顯著差異，肝臟脂質各組間無顯著差異。實驗二、改用較年輕缺乏apoE小鼠，並重新萃取山苦瓜乙酸乙酯萃物，分為3組：HF組(n = 11)、BGP組(n = 9)、EAE組(n = 10)，飼料成分同前述，餵食8週後，BGP組TC較HF組低28%( p<0.05)、TG下降幅度顯著高於HF組( p<0.05)、血液HDL-C高於HF組25%，但未達顯著差異。血液adiponectin、leptin濃度、肝臟PPAR-α、MTP mRNA表現量，各組間無顯著差異。本研究結果顯示，山苦瓜凍乾粉末對apo E剔除小鼠具有改善血脂功效，可研發為降血脂保健食品。The apolipoprotein E knockout (apoE-/-) mice are hyperlipidemic and a good model to study atherosclerosis. In order to know the effects of wild bitter gourd on lipid metabolism, we conducted two experiments in apoE-/- mice. In experiment 1, 18-wk-old apoE-/- mice were assigned to 6 groups and fed different diets as follows: the high fat (20%, w/w) diet (HF, n = 10), HF with 5%wild bitter ground powder (BGP, n = 10), HF with 1% ethyl acetate extract of bitter gourd (EAE, n = 10), HF with 0.5% clofibrate (CF, n = 5), HF with 0.00123% rosiglitazone (TZD, n = 5) and chow diet (C, n = 5). Serum total cholesterol (TC) and triglyceride (TG) concentrations were measured at the end of wk 4, 9 and 17. After 18 wk of feeding, the mice were sacrified. Liver and blood samples were obtained to determine hepatic TC, TG and serum HDL-C concentrations. Data were analyzed by one-way analysis of variance and the Tukey post hoc. The BGP group had a lower level of serum total cholesterol in week 9 and 17 (25& 39% reduction, respectively, p<0.05), a lower level of serum triglyceride in week 17 (38% reduction, p<0.05) and a higher level of HDL-C in wk 18 (55% increase, p<0.05) than the HF group. The EAE group had a 39% higher level of HDL-C than the HF group in week 18, but it was not statistically significant. Levels of hepatic TC and TG were not significantly different among all groups. In experiment 2, young (6-10 wk-old) apoE-/- mice were assigned to 3 groups and fed the HF diet (n = 11), the BGPdiet (n = 9) and the EAE diet (n = 10), respectively, for 8 wk. After feeding trials, the BGP group had a lower level of serum total cholesterol (28% reduction, p<0.05), and a larger decrease in level of serum triglyceride in wk 8 (p<0.05) than the HF group. The BGP group also had a 25% higher level of HDL-C than HF group, but it was not statistically significant. There were no significant difference in serum adiponectin, serum leptin, liver PPAR-αmRNA expression and liver MTP mRNA expression among HF、BGP and EAE groups. In conclusion, this study shows that wild bitter gourd powder can be a potent blood lipid-lowering health food.