肝组织PREP活性在小鼠非酒精性单纯性脂肪肝转变为脂肪性肝炎中的作用研究

Study on the role of PREP activity in the transformation of nonalcoholic simple fatty liver into steatohepatitis in mice

目的研究肝组织脯氨酰内肽酶(PREP)活性在小鼠非酒精性单纯性脂肪肝(NASFL)转变为脂肪性肝炎中的作用。方法取32只C57BL/6J雄性小鼠,按照随机原则,将其分为对照组(给予常规饲料进行喂养)和观察组(给予高脂饮食诱导建立NASFL模型),分别于喂养4周与12周时,将小鼠处死。用HE染色观察两组小鼠喂养4周和12周时肝组织病理学改变情况,比较两组小鼠喂养4周和12周时体质量、睾脂指数、肝指数和血生化指标变化的差异,并同时采用免疫印迹法检测两组小鼠喂养4周和12周时PREP蛋白表达,用实时荧光定量PCR法检测小鼠PREP mRNA相对表达量,用Suc-Gly-Pro-AMC底物法对PREP活性水平进行检测。结果喂养4周时,两组小鼠体质量、肝指数和睾脂指数的比较,均无统计学意义(P> 0. 05);喂养12周时,观察组小鼠体质量、肝指数和睾脂指数较对照组均明显增大(P <0. 05)。喂养4、12周时,观察组小鼠空腹血糖(FBG)、总胆固醇(TC)、甘油三酯(TG)、天门冬氨酸氨基转移酶(AST)及谷氨酸转氨酶(ALT)较对照组均明显升高(P <0. 05)。喂养12周时,观察组小鼠PREP蛋白、PREP mRNA及PREP活性水平较喂养4周时均明显升高(P <0. 05),且较对照组喂养12周时的水平均明显升高(P <0. 05)。结论肝组织中PREP活性水平改变在小鼠NASFL转变为脂肪性肝炎中可能起到重要作用。

Objective To investigate the role of prolyl endopeptidase( PREP) activity in the transformation of nonalcoholic simple fatty liver( NASFL) into steatohepatitis in mice. Methods 32 C57 BL/6 J male mice were randomly divided into control group( fed with conventional diet) and observation group( fed with high-fat diet induction to establish NASFL model). The mice were killed at 4 and 12 weeks of feeding respectively. HE staining was used to observe the pathological changes of liver tissue in mice of the two groups at 4 and 12 weeks of feeding. The changes of body mass,testicular fat index,liver index and blood biochemical indexes were compared between the two groups at 4 and 12 weeks of feeding. The expression of PREP protein in mice of the two groups at 4 and 12 weeks of feeding was detected by immunoblotting,and the relative expression of PREP protein in mice was detected by real-time fluorescence quantitative PCR. The activity of PREP was detected by Suc-Gly-Pro-AMC substrate method. Results There was no significant difference in body mass,liver index and testicular fat index between the two groups at 4 weeks of feeding( P > 0. 05). At 12 weeks of feeding,the body mass,liver index and testicular fat index of the observation group were significantly higher than those of the control group( P < 0. 05). At 4 and 12 weeks of feeding,the fasting blood glucose( FBG),total cholesterol( TC),triglyceride( TG),aspartate aminotransferase( AST) and alanine transaminase( ALT) in the observation group were significantly higher than those in the control group( P < 0. 05). At 12 weeks of feeding,the PREP protein,PREP mRNA and PREP activity levels in the observation group were significantly higher than those at 4 weeks of feeding( P < 0. 05),and significantly higher than those in the control group at12 weeks of feeding( P < 0. 05). Conclusion The change of PREP activity in liver tissue may play an important role in the transformation of NASFL into steatohepatitis in mice.