肾素血管紧张素系统在非酒精性脂肪性肝病发病机制中的实验研究

Study on the role of renin angiotensin system in pathogenesis of nonalcoholic fatty liver disease

目的探讨肝组织肾素血管紧张素系统在非酒精性脂肪性肝病（NAFLD）发病机制中的作用。方法取Wistar大鼠24只均分为模型组和对照组。对照组予正常饮食，模型组予高脂饮食，8周后处死大鼠，测定血清肝功能、血脂、血糖和胰岛素，分别以HE染色和苦味酸一天狼星红染色进行肝组织病理学观察，ELISA法测定肝组织血管紧张素Ⅱ（AngII）浓度，免疫组织化学法测定肝组织转化生长因子（TGF）-β1表达水平。结果模型组大鼠高脂喂养8周后，体质量、肝指数、肝功能、血脂、血胰岛素显著高于对照组[体质量：（463．50±22．72）g比（405．12±10．32）g；肝指数：（3．75±0．21）比（2．66±0．15）；ALT：（79．8±8．6）U／L比（58．8±11．6）U／L；AST：（200．01士51．72）U／L比（150．30±37．27）U／L；胆固醇：（3．67±0．48）mmol／L比（1．50±0．23）mmol／L；三酰甘油：（2．06±0．40）mmol／L比（O．71±0．34）mmol／L；胰岛素：（17．37±2．89）pmol／L比（11．08±2．12）pmol／L]，差异均有统计学意义（均P〈0．01）。模型组大鼠病理组织学均出现明显的肝脂肪变性，且部分出现小叶内和汇管区炎性反应，部分肝组织出现明显的纤维化改变。模型组大鼠肝组织AngII[（32．80±2．81）pg／ml]较对照组[（22．83土1．75）pg／m1]高（t=9．559，P〈O．01）。免疫组织化学检测显示模型组TGF[31表达量明显高于对照组（Z=-2．540，P=0．011）。Spearman相关性分析显示，大鼠肝组织内AngⅡ浓度增加程度与肝脂肪变积分（r=0．644，P=0．002）和TGF-131表达量（r=0．470，P=0．037）均呈正相关。结论AngⅡ和TGF-β1在NAFLD模型大鼠的肝组织内浓度明显增加，肾素血管紧张素系统可能参与了NAFLD的发生和发展。

Objective To investigate the role of renin angiotensin system （RAS） in pathogenesis of nonalcoholic fatty liver disease （NAFLD）. Methods Twenty-four Wistar rats were evenly divided into control group and model group. The rats of control group were fed with normal diet, and model group were with high-fat diet. Rats were killed at the eighth week and serum liver function, blood lipid, glucose and insulin were tested. The liver tissues were stained with HE and Picro acid-Sirius red for pathological observation. The liver tissue concentration of angiotensin 11 was determined by ELISA method and the expression of TGF-β1 in liver tissue was examined by immunohistochemistry. Results After eight weeks high fat feeding, weight, liver index, liver function, blood lipids and serum insulin of model group were significantly higher than those of control group （weight.. （463. 50 ±22.72） gvs. （404.29±10.32） g; liver index： （3.75±0.21） gvs. （2.66±0.15） g; ALT： （79.8± 8.6） U/Lvs. （58.8±11.6） U/L; AST： （200. 012±51.72） U/L vs. （150. 302±37.27） U/L; total cholesterol： （3. 672±0.48） mmol/L vs. （1.50±0.23） mmol/L; triglycerides： （2. 062±0.40） mmol/L vs. （0.712±0.34） mmol/L; insulin： （17. 372±2. 89） pmol/L vs. （11.085±2.12） pmol/L）, and all the differences were statistically significant （P〈0.01）. The histopathologieal results of model group indicated liver steatosis, inflammatory reaction in part of lobule and portal area and significant fibrosis in part of liver tissue. The liver tissue angiotonin H concentration of model group [（32.80 ± 2.81） pg/ml] was higher than that of control group [（22.83 ± 1.75） pg/ml, t= 9. 559, P〈0.01]. The immunolistochemistry results showed that the expression of TGF-β1 of model group was obviously higher than that of control group （Z=- 2. 540, P = 0. 011）. Spearman correlation analysis revealed that the increasing degree of angiotensin II concentration was positively correlated with liver steatosis scores （r=0. 644,P=0. 002） and the expression of TGF-β1 （r=0. 470,P=0. 037）. Conclusion The concentration of angiotensin II and TGF-β1 increased in the livers of model rats, which indicated that RAS may participate in the pathogenesis and progress of NAFLD.