| 摘要: | 飲食不均衡是目前常見的營養問題，尤其是攝取過多精緻化醣類食品與含糖飲品，研究指出改變飼料中的碳水化合物成份、增加比例或給予高蔗糖水均會誘發大鼠代謝上的改變，產生類似代謝症候群（metabolic syndrome）症狀。本實驗「以含糖飲料取代水」的飲食模式，利用30%蔗糖水誘發大鼠高脂血症，並給予高營養密度之辣木葉（Moringa oleifera leaves），目的在研究添加辣木葉粉末是否有降血脂或降體脂與增強抗氧化能力的效應，並探討其可能機轉。將三週齡Wistar 品系公鼠依體重隨機分成三組，包括正常組 (N組)、糖水組 (30% 蔗糖水，S組) 與辣木糖水組 (30% 蔗糖水+飼料含6% 辣木粉，MS組)，每組為 6～11隻，飼料均為AIN-93G正常飼料，N 組全程供應去離子水， S 與 MS 組供應 30% 蔗糖水，水、糖水與飼料均令其自由食用，飼養 8 週後，隔夜禁食犧牲，取血液、肝臟、脂肪組織，並收集犧牲前三天之糞便，進行相關分析。
結果顯示糖水效應方面（S 組與 N 組比較），糖水餵食顯著降低飼料攝取量（p<0.05），升高血清中 TG 與膽固醇濃度，分別為 N 組的 1.57倍與1.32 倍（p<0.05），顯著誘發大鼠高脂血症；抗氧化系統中，顯著降低血漿、紅血球與肝臟的 α-tocopherol 濃度，增加紅血球中 GSH 濃度為 N 組的1.21 倍（p<0.05），顯著降低肝臟中的 GSH 濃度、SOD 與 GPx 活性（p<0.05）；體脂方面，顯著增加肝臟與腹膜後脂肪（RE）中TG及膽固醇濃度。表示糖水餵食顯著誘發高脂血症、增加肝臟與腹膜後脂質濃度，肝臟之抗氧化分子與酵素均有減少的現象，推測未來將有肝臟氧化損傷之虞。
辣木葉效應（MS 組與 S 組比較），辣木葉餵食顯著降低飼料攝取量與體重增加量（p<0.05）；抗氧化系統方面，紅血球 GSH 含量與肝臟 GR 酵素活性顯著升高（p<0.05）；辣木餵食有減緩糖水誘發血清中 TG 及膽固醇升高的趨勢，顯著降低肝臟之 TG 和膽固醇之含量（p<0.05），增加糞便膽固醇量排出量。脂質合成相關轉錄因子 ChREBP、SREBP-1c、LXR-α mRNA 表現量均有顯著降低之現象（p<0.05）。雖然轉錄因子的mRNA量並不代表其活化程度，仍可推測辣木葉可能藉由降低LXR與ChREBP和SREBP-1c等轉錄因子活化達到降低高糖誘導高血脂症及脂質生合成效應。
綜合上述結果得知：餵食蔗糖水連續 8 週，會顯著誘發大鼠高脂血症、體脂堆積，補充辣木葉顯著降低肝臟之 TG 和膽固醇之含量，膽固醇經由糞便中排泄量顯著增高，推測辣木葉可能藉由提高膽固醇排出量與降低脂質合成相關轉錄因子mRNA表現，達到降體脂功效。
In modern human life, a global health problem is the unbalanced diet, such as excess consumption of refined sugar and sugar-sweetened beverages. Several studies had shown that consumption of high sucrose or fructose facilitated metabolic disorders but the mechanisms involved were unclear. In this study, we used sucrose water (30%) to induced hyperlipidemia in rats. To examine the effect of Moringa oleifera on sucrose water-induced lipid metabolism and antioxidative changes in rats. 3-week-old male Wistar rats (n = 6~11 rats/group) were divided into 3 groups, AIN-93G diets plus plain water (group N), AIN-93G diets plus 30% sucrose water (group S)、AIN-93G diets supplemented with 6% M. oleifera leaves powder plus 30% sucrose water (group MS). All rats were free access to food, drinking water or 30% sucrose water. At the end of 8 weeks, the rats were killed and collected blood、liver and fat for the analysis of lipid or antioxidative parameters.
Integration the effects of sucrose water (S versus N, p<0.05), rats fed sucrose water caused a significant increase in serum TG and cholesterol concentrations, lowered the α-tocopherol/TG ratio in serum and liver. In the liver, S group caused a decrease in the content of GSH and SOD、GPx activities. In body fat , S group increased TG and cholesterol in liver and retroperitoneal fat (RE) as compared with N group. Results showed that rat fed sucrose water induced significantly hyperlipidemia, increased the lipid content in liver and retroperitoneal fat, and decreased the antioxidative moleculars and antioxidative enzymes. We suggested that rats had detrimental effects on lipid metabolism and antioxidant defense system by drinking sucrose water.
Integration the effects of M. oleifera leaves (MS versus S, p<0.05), it was found that decreased food intake and total caloric intake significantly and body weight gain. In MS group, higher GSH in red blood cells and GR activities in liver were found. MS group decreased TG and cholesterol content in serum and liver, but caused a increase in fecal cholesterol excretion as compared with S group. The expression of lipogenesis-associated transcription factors, hepatic ChREBP, SREBP-1c and LXR-α mRNA were decreased significantly in MS group as compared with S group. Those results showed that M. oleifera leaves had a alleviative effect on high sucrose water-induced hyperlipidemia, and lowering effects of tissue lipid contents might be due to decreasing LXR-α, ChREBP and SREBP-1c expression. |
