高脂饮食诱导幼鼠脂肪肝模型的建立及其相关代谢研究

目的 通过高脂饮食诱导幼龄大鼠建立非酒精性脂肪性肝病(NAFLD)模型.方法 3周龄刚离乳SD大鼠30只,雌雄各半,随机分为正常(N)组、20%高脂饮食组(HFI组)、30%高脂饮食组(HF2组).无特定病原环境下饲养6周,第6周末处死大鼠,分别进行如下检测:(1)身长、体质量、肝脏质量测量,计算肝指数;(2)采血测空腹ALT、AST、甘油三酯(TG)、总胆固醇(TC)、胰岛素、血糖水平,计算HOMA胰岛素抵抗指数;(3)肝组织匀浆,检测肝脏TG水平;(4)肝组织切片苏木素-伊红染色观察肝组织病理形态,油红O染色显示脂质沉积;(5)免疫组织化学EnVision法染色,显示肝组织固醇调节元件结合蛋白-1、瘦素的表达.组间均数比较采用One-way ANOVA、两两比较采用LSD方法进行统计学分析.结果 病理结果显示模型组大鼠肝脏符合典型的NAFLD病理特征,HF2组内各标本脂肪变性程度较均匀,无动物死亡现象发生;与N组相比,HF2组血清TC显著升高(2.50±0.39)mmol/L对比(1.82±0.43)mmol/L,P<0.01],肝脏TG含量显著升高(25.38±13.29)mmol/L对比(12.09±9.59)mmol/L,P<0.01],血清ALT显著升高(69.80±18.22)U/L对比(48.00±10.45)U/L,P<0.01];与N组相比,HF1组血清TG显著下降(0.17±0.10)mmol/L对比(0.32±0.12)mmol/L,P<0.05];血糖水平显著升高(12.33±3.48)mmol/L对比(8.13±2.53)mmol/L,P<0.05];各组血清AST、胰岛素、及HOMA胰岛素抵抗指数差异无统计学意义;模型组肝组织固醇调节元件结合蛋白-1、瘦素表达增加.结论 30%高脂饲料饲养6周,可以诱导幼龄大鼠建立NAFLD模型,高脂饮食导致幼鼠肝脏固醇调节元件结合蛋白-1表达增加,脂肪合成增加,瘦素表达增加.

Metabolic characteristics of a fatty liver disease model induced by high-fat feeding in young rats

Objective To establish nonalchoholic fatty liver disease (NAFLD) in young rats, and to investigate the metabolic characteristics of these rats. Methods Fifteen male and fifteen female SD rats of 3 weeks old were randomly divided into three groups, normal group (N), 20% high fat group (HF1) and 30% high fat group (HF2). All the rats were fed under Specefic pathogen Free (SPF) condition for 6 weeks and executed at the end of the 6th week. Body length and weight of each rat as well as their liver weight were measured for calculating Liver Index (LI). ALT, AST, TG, TC, INS, Glu and HOMA-IR in the blood were mearsured. Liver tissue homogenate was prepared for detecting TG level. The liver section was stained with HE and oil red. The expression of SPEBP-1 and leptin in liver was detected by immunostaining. Results The typical pathological change of NAFLD was found in the rats of HF groups. In HF2 group, no rats died during the experiment and the degree of fat degeneration is homogeneous. Comparing with those in N group, TC (retool/L), liver TG (mmol/L) and ALT levels in HF2 group were significantly elevated (2.50±0.39 vs 1.82± 0.43, P < 0.01; 25.38±13.29 vs 12.09±9.59, P < 0.01 and 69.80±18.22 vs 48.00±10.45, P < 0.01, respectively). Comparing with those in N group, TG level in HF1 group was significantly decreased (0.17± 0.10 vs 0.32±0.12, P < 0.05), Glu level in HF1 group was significantly elevated (12.33±3.48 vs 8.13± 2.53, P < 0.05). There were no significant difference between the results of AST, INS and HOMA-IR among the groups. The expression level of SREBP-1 and leptin increased in HF groups. Conclusion NAFLD can be induced by 30% high-fat feeding for 6 weeks in young rats, high-fat feeding induces the expression of SREBP-1 and leptin expression and fat synthesis.