桑叶提取物对食源性肥胖大鼠的减肥作用及机制研究

Effects of Mori Folium extract on diet-induced obesity mechanism in rats

研究桑叶提取物对食源性肥胖(diet induced obesity,DIO)大鼠的减肥作用及初步作用机制。采用高糖高脂饲料喂养制备DIO模型大鼠,造模8周后,连续13周灌胃给予桑叶提取物高、低剂量(10,5 mg·kg-1)。末次给药后,测定大鼠体重、24h摄食量、饮水量、Lee's指数、肝体比、脂体比;酶联免疫法检测睾周脂肪脂蛋白脂肪酶(LPL)、CCAAT增强子结合蛋白α(C/EBPα)、过氧化物酶体增殖物激活受体γ(PPARγ);蛋白质印迹法(Western blot)检测睾周脂肪磷酸化腺苷酸活化蛋白激酶α(p-AMPKα),C/EBPα及PPARγ表达;苏木精-伊红染色法(HE)观察睾周脂肪组织病理学改变。结果表明桑叶提取物高、低剂量组均能降低DIO大鼠体重、Lee's指数、肾脂体比及睾脂体比;其中高剂量组能降低总脂体比;2个剂量组对摄食量、饮水量均无明显作用;但可以减少脂肪LPL水平;降低C/EBPα,PPARγ蛋白表达;同时升高脂肪p-AMPKα蛋白表达,减小脂肪细胞体积。提示桑叶提取物对DIO大鼠有减肥作用,其作用机制可能是通过上调脂肪p-AMPKα表达,下调PPARγ,C/EBPα及LPL表达,抑制前脂肪细胞分化为成熟脂肪细胞,减小脂肪细胞体积。

To study the anti-obesity effect of Mori Folium extract on diet-induced obesity（ DIO） and to explore the preliminary mechanism in rats. DIO rat models were established by high glucose and high fat diet for 8 weeks. Then high（10 mg·kg-1） and low（5 mg·kg-1） does Mori Folium extracts were given by intragastric administration for 13 weeks. After the last administration,their body weight,24 h food intake,water intake,Lee＇s index,liver/body mass index,and fat/body mass index were determined. The levels of lipoprotein lipase（ LPL）,CCAAT/enhancer-binding protein alpha（ C/EBPα） and peroxisome proliferator-activated receptor gamma（ PPARγ） were measured by enzyme-linked immunosorbent assay（ ELISA）. Phosphorylated AMP-activated protein kinase alpha（p-AMPKα）,C/EBPα and PPARγ expression levels in adipose tissues were detected by Western blot. The hematoxylin-eosin staining（HE） was used to observe the histopathological changes of adipose tissues. The results showed that both high dose and low dose Mori Folium extract can decrease body weight,Lee＇s index,renal fat/body mass ratio and testicle fat/body mass ratio,and the high dose group could decrease the total fat/body mass ratio. Both high dose and low dose groups had no significant effect on the food intake and water intake; however,they could decrease levels of LPL in fat,up-regulate p-AMPKα protein expression,down-regulate C/EBPα and PPARγ protein expression,and reduce fat cell volume. In conclusion,Mori Folium extract had a slimming effect on DIO rats,and its mechanism may be associated with up-regulating the expression of p-AMPKα,down-regulating the expression of PPARγ,C/EBPα and LPL,inhibiting the differentiation of preadipocytes into mature fat cells,and reducing the volume of fat cells.