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目的:研究桑叶对L-谷氨酸钠(MSG)诱导的肥胖大鼠脂代谢作用的机制。方法:乳鼠连续7 d皮下注射4 g·kg-1·d-1L-谷氨酸钠,断乳后高脂喂养,复制MSG肥胖型大鼠模型。随机分为模型组,罗格列酮组(5 mg·kg-1·d-1),非诺贝特组(100 mg·kg-1·d-1),桑叶总多糖高、低剂量组(625,312.5 mg·kg-1·d-1),总黄酮高、低剂量组(80,40 mg·kg-1·d-1),总生物碱高、低剂量组(5 000,2 500 mg·kg-1·d-1)共9组;另取正常组大鼠8只,雌雄各半,每日上午ig给药。连续给药8周后,分别检测MSG大鼠血清、肝脏和骨骼肌中总胆固醇(TC),甘油三酯(TG),和血清中游离脂肪酸(NEFA)含量;实时定量PCR检测肝脏和骨骼肌中过氧化物酶体增殖物激活受体α(PPARα),肉毒碱棕榈酰转移酶-Ⅰ(CPTⅠ)和脂酰辅酶A氧化酶(ACOX1)的基因表达水平。结果:与正常组相比,模型组大鼠血清、肝脏以及肌肉中脂质水平均显著升高(P<0.01),肝脏和骨骼肌中PPARα,CPTⅠ和ACOX1的基因相对表达量均明显下调(P<0.01,P<0.05);与模型组相比,各给药组对MSG大鼠血清、肝脏和骨骼肌中TC和TG含量有一定调节作用(P<0.01,P<0.05);另外对血清中游离脂肪酸也具有一定的降低作用。桑叶提取物对MSG大鼠肝脏和骨骼肌中PPARα,CPTⅠ和ACOX1的基因相对表达量均有上调作用(P<0.01,P<0.05)。结论:桑叶可以通过激活PPARα受体,调节脂肪酸氧化过程来达到改善MSG肥胖大鼠脂代谢紊乱的作用。
Objective: To study the mechanism of mulberry leaf on the lipid metabolism of obese rats induced by L-glutamate (MSG). Methods: The suckling rats were injected subcutaneously with 4 g · kg -1 · d -1 L-glutamate for 7 days continuously. After weaning, the rats were fed with high fat diet and MSG obese rats were duplicated. Randomly divided into model group, rosiglitazone group (5 mg · kg -1 · d -1), fenofibrate group (100 mg · kg -1 · d -1), mulberry leaf total polysaccharide high and low dose Group (625,312.5 mg · kg-1 · d-1), total flavonoids high and low dose group (80,40 mg · kg-1 · d-1), total alkaloid high and low dose group mg · kg-1 · d-1) were divided into 9 groups. Another 8 rats in normal group were divided into male and female rats, and were given ig daily morning. After continuous administration for 8 weeks, the content of total cholesterol (TC), triglyceride (TG) and free fatty acid (NEFA) in serum, liver and skeletal muscle of MSG rats were detected respectively; liver and skeletal muscle (PPARalpha), carnitine palmitoyltransferase-I (CPTI), and acyl-CoA oxidase (ACOX1) were measured by flow cytometry. Results: Compared with the normal group, the lipid levels in the serum, liver and muscle of the model group were significantly increased (P <0.01), and the relative gene expression of PPARα, CPT Ⅰ and ACOX1 in the liver and skeletal muscle were significantly decreased P <0.01, P <0.05). Compared with the model group, the content of TC and TG in the serum, liver and skeletal muscle of MSG rats were significantly increased (P <0.01, P <0.05) Serum free fatty acids also have a certain role in reducing. The mulberry leaf extract up-regulated the gene expression of PPARα, CPTⅠ and ACOX1 in liver and skeletal muscle of MSG rats (P <0.01, P <0.05). CONCLUSION: Mulberry leaves can improve the lipid metabolism disorders of MSG obese rats by activating PPARα receptor and regulating fatty acid oxidation process.