摘要
目的观察高脂饮食诱导的非酒精性脂肪性肝病(NAFLD)小鼠肝脏脯氨酰内肽酶(PREP)蛋白水平及活性的变化。方法随机将40只雄性C57BL/6J小鼠分成普通饲料和高脂饲料喂养组,分别在喂养4 w和16 w处死小鼠。检测血生化指标,观察肝组织病理学变化并计算NAFLD活动度积分(NAS);采用荧光定量PCR法、Western blot法和Suc-Gly-Pro-AMC底物法分别检测肝组织PREP m RNA、蛋白水平和活性变化。结果在高脂饮食喂养4 w,模型组小鼠肝细胞出现轻度脂肪变,NAS积分为(3.43±0.79),较对照组显著升高;在高脂饮食喂养16w,模型组小鼠体质量、肝指数、ALT、甘油三脂、总胆固醇和空腹血糖分别为(32.93±2.72)g、(4.64±0.46)%、(53.64±22.01)IU/L、(1.18±0.17)mmol/L、(4.34±0.44)mmol/L和(5.67±0.87)mmol/L,显著高于对照组【分别为(28.19±1.23)g、(4.02±0.11)%、(28.60±4.01)IU/L、(0.99±0.15)mmol/L、(2.94±0.18)mmol/L和(4.26±0.65)mmol/L,P<0.05】;模型组肝组织NAS积分为(5.60±1.43),显著高于对照组【(0.40±0.70),P<0.01】;PREP蛋白水平与对照组相比无显著性差异,但PREP m RNA水平和酶活性分别为对照组的(1.81±0.34)倍(P<0.01)和(1.36±1.78)倍(P<0.05)。结论小鼠肝组织PREP活性变化可能参与了小鼠非酒精性单纯性脂肪肝向脂肪性肝炎的转变。
Objective To investigate the dynamic changes of expression and activity of prolyl endopeptidase(PREP) in the liver tissues of mice with non-alcoholic fatty liver disease(NAFLD). Methods 40 male C57 BL/6 J mice were randomly divided into standard diet-fed and high fat diet-fed group. The animals were scarified at the end of 4 weeks and 16 weeks. The levels of serum biochemical index were measured by biochemical analyzer. Hematoxylin-easin staining,real-time polymerase chain reaction,western blot or Suc-Gly-Pro-AMC substrate method were applied to determinate the liver histological alterations,m RNA levels,protein expressions and activity of PREP,respectively. Results At the end of 4 weeks,the body weight,liver weight,alanine aminotransferase(ALT),triglyceride(TG),total cholesterol(TC) and fasting blood glucose(FBG) in mice in model group were similar with those in the control group; the liver tissues in model group showed mild steatosis with increased NAFLD activity score(NAS) of(3.43±0.79) as compared with that in the control group; relative levels of PREP m RNA,protein and activity had no statistical significance as compared with those in the control group;at the end of 16 weeks,the body weight,liver weight,ALT,TG,TC and FBG in model group were(32.93±2.72) g,(4.64±0.46) %,(53.64±22.01) IU/L,(1.18±0.17) mmol/L,(4.34±0.44) mmol/L and(5.67±0.87) mmol/L,respectively,significantly higher than those in the control group [(28.19±1.23) g,(4.02±0.11) %,(28.60±4.01) IU/L,(0.99±0.15) mmol/L,(2.94±0.18) mmol/L and(4.26±0.65) mmol/L,respectively,P<0.05];the NAS score in the model group was(5.60±1.43),significantly higher than that in the control group [(0.40±0.70),P<0.01];although the hepatic PREP protein expression was not statistically elevated both at 4 and 16 weeks, the relative levels of PREP m RNA and activity of the enzyme in the liver tissues of model group were increased to(1.81 ±0.34)-and(1.36±1.78)-fold of those in the control group at 4 and 16 weeks, respectively. Conclusion The dynamic changes of PREP activity in the mouse liver might participate in the progression from non-alcoholic fatty liver to non-alcoholic steatohepatitis.
引文
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