替米沙坦对非酒精性脂肪性肝炎大鼠的保护作用及其机制

Effects of telmisartan on nonalcoholic steatohepatitis rat model by activating peroxisome proliferator-activated receptor

目的观察替米沙坦通过激活过氧化物酶体增殖因子活化受体γ（PPARγ）对非酒精性脂肪性肝炎大鼠的保护作用。方法将30只雄性SD大鼠随机分为对照组、模型组和干预组，每组10只。模型组和干预组给予高脂饲料喂养16周诱发脂肪性肝炎，其中干预组于高脂喂养12周后，给予替米沙坦（5mg·kg^-1·d^-1）灌胃治疗4周。16周末处死大鼠，分别进行如下检测：（1）光学显微镜下观察肝脏病理变化；（2）检测血清ALT、AST、空腹胰岛素（FINS）、空腹血糖（FBG）、肿瘤坏死因子α（TNFα）和脂联素水平，计算稳态模型的胰岛素抵抗指数（HOMA—IR）；（3）用半定量逆转录-聚合酶链反应和Western blot检测肝组织过氧化物酶体增殖物激活受体γ（PPARγ）mRNA和蛋白的表达水平。用SPSS13．0统计软件处理，计量资料以均数±标准差（x^-±s）表示，多组间比较用单因素方差分析，组间比较用Student-Newman-Keuls q检验，等级资料组间比较用秩和检验，脂联素、TNFα与HOMA-IR的关联性用直线相关分析。结果（1）模型组大鼠造模均成功，根据肝细胞脂肪变性占所获肝组织标本量的范围分为4度（F0～4），其中模型组大鼠肝细胞脂肪变程度达F3、F4的分别有1、9只。干预组脂肪变性程度达F1、F2、F3的大鼠分别有1、6、3只。对照组大鼠肝组织炎症活动度积分为0。模型组大鼠肝组织炎症活动度积分为2．67±0．27，与对照组比较，U=15，P〈0．01，差异有统计学意义。干预组炎症活动度积分为1．36±0．12，与模型组比较，U=24，P〈0．05，差异有统计学意义。（2）对照组ALT、AST、FBG、FINS、HOMA—IR、TNFα分别为（48．20±10．99）U／L、（153．00±45．06）U／L、（4．58±1．00）mmol／L、（10．48±1．46）μU／ml、2．13±0．29、（1．38±0．75）μg／L，模型组分别为（114．00±19．7）U／L、（265．33±52．10）U／L、（6．58±0．86）mmol／L、（20．73±0．91）μU／ml、6．23±0．10、（3．47±0．19）μg／L，干预组分别为（78．80±15．64）U／L、（211．83±65．51）U／L、（5．38±0．88）mmol／L、（15．02±1．22）μU／ml、3．59±0．29、（1．58±0．13）μg／L，与对照组比较，模型组血清ALT、AST、FINS、FBG、HOMA—IR、TNFα升高，q值分别为13．130、6．472、6．909、26．619、49．683、14．591，P值均〈0．01，差异有统计学意义。与模型组比较，干预组血清ALT、FINS、FBG、HOMA—IR、TNFα降低，q值分别为7．024、4．145、14．829、31．991、13．195，P值均〈0．01，差异有统计学意义。（3）对照组血清脂联素、肝组织PPARγ mRNA和蛋白的表达分别为（8．93±0．44）mg／L、1．19±0．35、0．93±0．44，干预组分别为（7．12±1．00）mg／L、0．79±0．15、0．58±1．00，模型组分别为（6．09±0．96）mg／L、0．57±0．09、0．36±0．96。对照组与模型组比较，q值分别为10．696、8．679、16．762，P值均〈0．05，差异均有统计学意义；干预组与模型组比较，q值分别为3．879、3．079、6．400，P值均〈0．05，差异均有统计学意义。相关分析显示，脂联素水平与HOMA-IR呈负相关（r-=-0．891，P〈0．01），TNFα水平与HOMA—IR呈正相关（r=0．927，P〈0．01）。结论替米沙坦可能通过促进PPARγ的表达对NASH大鼠产生保护作用。

Objectives To investigate the effects of telmisartan on steatohepatitis （NASH） in rats by activating peroxisome proliferator-activated receptor γ Methods Thirty male SD rats were randomized into normal control group, NASH control group and telmisartan prevention group. Normal control group was given standard food and the other two groups were given high fat diet for 16 weeks to induce NASH. Prevention group was given telmisartan （5 mg.kg^-1.d%-1） for 4 weeks by intragastric adminstration after 12 weeks. At the end of the 16th week, all the rats were sacrificed. Pathological changes of liver were observed by optical microscopy. Serum alanine aminotransferase（ALT）, aspartate aminotransferase（AST）, fasting blood glucose（FBG）, fasting insulin（FINS）, HOMA-IR（homeostasis model assessment insulin resistance）, Serum TNF- α and adiponectin were detected and analyzed.Western blot and RT-PCR were used to detect PPAR γ, expression in hepatic tissues on protein and mRNA levels. Results （1） Rats were successfully modeled. The liver tissue samples were divided into 4 degrees （F0 - 4） based on total fatty degeneration of liver cells.There was one rat reached F3 and nine rats reached F4 in NASH group, one rat reached F1, six rats reached F2 and three rats reached F3 in prevention group. Inflammatory activity scores of hepatic tissues in the model group were 2.67 ± 0.25, while that in the control group was 0 （ U= 15 andP 〈 0.01）, in the prevention group were 2.67 ± 0.25 and 1.36 ± 0.12（ U= 24 and P 〈 0.05 ）. （2） The levels of serum ALT, AST, FBG, FINS, TNF α and HOMA-IR in the model group were increased than those in the control group（ the vaules ofq were 13.130, 6.472, 6.909, 26.619, 14.591 and 49.683 respectively, P 〈0.01）. The levels of serum ALT, FINS, FBG, TNF α and HOMA-IR in the prevention group were decreased as compared to the model group （ the vaules ofq were 7.024, 4.145, 14.829, 13.195 and 31.991 respectively, P 〈0.01 ）. （3） The serum adiponectin, PPAR γ mRNA and protein in liver tissues of the model group were lower than those in the control group （ q values were 10.696, 8.679 and 16.762 respectively, P 〈0.05 ）.The data in the prevention group were higher as compared to the model group（q values were 3.879,3.079,6.400,P 〈0.05 respectively）. HOMA-IR was positively correlated with the expression ofTNF a but negatively correlated with the expression of adiponectin（r = 0.927, P 〈 0.01 ;r = -0.891, P 〈 0.01,respectively）. Conclusion Telmisartan may has preventive effect on rats with steatohepatitis （NASH） by a mechanism of activating peroxisome proliferator-activated receptor γ.