非诺贝特对非酒精性脂肪性肝病大鼠肝细胞凋亡的影响

Effects of fenofibrate on hepatocyte apoptosis in nonalcoholic fatty liver

目的 通过高脂饲料喂养SD大鼠建立非酒精性脂肪性肝病（NAFLD）模型,观察过氧化物酶体增殖物激活受体（PPAR）激动剂非诺贝特对NAFLD大鼠肝脂肪变的影响并探讨可能的机制.方法 将66只雄性SD大鼠适应性喂养1周后,随机分为3组：对照组（C组,n=18）、模型组（M组,n=24）和非诺贝特组（F组,n=24）.在实验的第4、6、8周时,分别处死1/3的各组大鼠,观察各组大鼠肝脏脂肪变性及炎症程度,观察肝细胞凋亡程度;检测肝组织中PPAR-αmRNA相对表达量及Bcl-2、Bax和Caspase-3 mRNA和蛋白的表达.多组间比较采用单因素方差分析（one-way ANOVA）法;等级资料采用Kruskal-Wallis H非参数检验进行分析;相关性分析采用Pearson相关分析和spearman秩相关分析两种方法.结果 与C组大鼠相比,随造模时间的延长,M组大鼠肝细胞脂肪变加重;炎症活动度计分升高（1.62±0.92对比0,P＜0.01）;肝细胞凋亡指数升高（58.86±13.59对比39.55±3.99,P＜0.05）,差异均有统计学意义.与C组大鼠比较,M组大鼠PPAR mRNA相对表达量降低（0.366±0.068对比0.570±0.061）,Bcl-2 mRNA和蛋白的表达均减低（0.234±0.099对比0.437±0.053和0.0098±0.0002对比0.0155±0.0004）,P值均＜0.01,差异均有统计学意义;Bax、Caspase-3 mRNA相对表达量（0.368±0.064对比0.230±0.052和0.363±0.058对比0.218±0.031）和蛋白表达（0.1311±0.0050对比0.0947±0.0139和0.1297±0.0065对比0.0794±0.0038）均明显增高,P值均＜0.01,差异均有统计学意义.F组大鼠肝细胞凋亡指数降低,肝组织PPAR mRNA和Bcl-2 mRNA和蛋白的相对表达量分别为0.510±0.109、0.425±0.042、0.0148±0.0004,与M组大鼠比较,P值均＜0.01,差异均有统计学意义;Bax、CaspaSe-3 mRNA和蛋白相对表达量为0.249±0.034、0.226±0.055、0.0966±0.0069和0.0911±0.0136,与M组大鼠比较,P值均＜ 0.01,差异均有统计学意义. 结论 非诺贝特可减轻NAFLD大鼠肝脂肪变性,其机制可能与抑制NAFLD大鼠肝细胞凋亡有关.

Objective To use a rat model of nonalcoholic liver disease （NAFLD） to observe effects of the peroxisome proliferator-activated receptor-α （PPAR-α） agonist fenofibrate on hepatic steatosis in nonalcoholic fatty liver and to investigate the underlying mechanism.Methods Sixty-six SpragueDawley rats were given adaptive feeding for 1 week and then randomly allocated into the following three groups：unmodeled control （group C,n =18）,untreated NAFLD model （group M,n =24）,and fenofibratetreated NAFLD model （group F,n =24）.Group C rats were given a normal diet,while group M and group F rats were given a high-fat diet.After model establishment,the group F rats were treated with fenofibrate （10 mg/kg/d,intraperitoneal） and the group C and group M rats were given sham-treatment with cosolvent （5 mL/kg/d,intraperitoneal）.At the end of treatment weeks 4,6 and 8,one-third of rats in each group were euthanized.Liver tissues were assessed by hematoxylin-eosin （HE） staining to determine level of steatosis and inflammaion activity,and by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling to measure changes in hepatocyte apoptosis index.Changes in expression levels of the PPAR-α receptor and apoptosis factors （bcl-2,bax and caspase-3） were assessed by reverse transcription-PCR and immunohistochemistry.Results The NAFLD modeled rats showed appropriate induction of hepatic steatosis,hepatic inflammation,and hepatocyte apoptosis.Compared to the group M rats,the group F rats showed lower expression of PPAR-and bcl-2 and higher expression of bax and caspase-3 at both the mRNA and protein level.Conclusion Fenofibrate can ameliorate hepatic steatosis in an experimental rat model of NAFLD,and the mechanism may be associated with inhibition of hepatocyte apoptosis.