抵抗素在肝脏胰岛素抵抗中的作用及其机制

Role of resistin in hepatic insulin resistance and the underlying mechanism

目的:探讨抵抗素在肝脏胰岛素抵抗中的作用及其可能的机制。方法:将载有抵抗素基因的重组腺病毒经尾静脉注射构建高抵抗素血症小鼠模型,同时设正常对照组及病毒对照组,取肝脏组织切片行PAS糖原染色半定量观察肝糖代谢的变化;以Western blotting检测肝腺苷酸活化蛋白激酶(AMPK)的磷酸化,以磷酸化AMPK/总AMPK的比值代表AMPK激活程度;以实时PCR检测肝组织糖异生关键酶葡萄糖6磷酸酶(G6Pase)和磷酸烯醇式丙酮酸羧激酶(PEPCK)mRNA表达水平的变化。结果:重组腺病毒注射第5 d,获得血中抵抗素高表达构建了高抵抗素血症动物模型,糖原染色示高抵抗素血症小鼠肝糖原含量较正常对照及病毒对照组降低,分别为0.78±0.06vs0.93±0.13、0.89±0.05(P<0.05);高抵抗素血症组肝AMPK磷酸化水平较正常对照及病毒对照组下降,磷酸化AMPK/总AMPK比值分别为0.78±0.06vs0.93±0.13、0.89±0.05(P<0.05)。高抵抗素血症小鼠G6Pase和PEPCK的mRNA表达升高,高抵抗素血症组、对照组及空载病毒组G6Pase分别为2.136±0.857vs1.353±0.490、1.250±0.770(P<0.05);高抵抗素血症组、对照组及空载病毒组PEPCK分别为3.54±0.90vs2.75±0.78、2.63±0.67(P<0.05)。结论:抵抗素可能通过抑制肝脏AMPK活性,增加肝糖异生关键酶的表达而影响机体肝糖代谢,降低肝糖储量,参与肝脏胰岛素抵抗的形成。

AIM： To investigate the role of resistin in hepatic insulin resistance and its mechanism. METHODS： A mouse model of hyperresistinemia in C57BL/6 mice was established by intravenous administration of the recombi- nant adenovirus encoding mouse resistin. Using periodic acid - Schiff staining we observed the effects of resistin on hepatic glycogen storage. Western blotting was used to measure AMPK - α protein and phosphrylated AMPK - α （Thr172） protein. mRNA levels of phosphoenolpyruvate carboxykinase gene and glucose - 6 - phosphatase gene were measured by real - time PCR. RESULTS： On day 5 after Adv injection, the concentration of plasma resistin was much higher in Adv - resis- tin - EGFP - treated mice than that in saline - or Adv - EGFP - treated mice. Semiquantitation of hepatic glucogen storage by PAS showed that the mice with hyperresistinemia had decreased glycogen particles compared to normal control and Adv -EGFP groups. The ratio of phosphorylated AMPK （Thr172） -α to total AMPK-α was used to evaluate hepatic AMPK activation. Compared with normal control and Adv - EGFP groups, the Adv - resistin - EGFP - treated mice had significandy lower ratio of p - AMPK/AMPK, and higher expression levels of G6Pase and PEPCK mRNA in liver. CONCLUSION： Resistin may decrease AMPK activation with downregulating expression of gluconeogenic enzymes, resulting in increased glucose production and decreased hepatic glycogen storage. Resistin may play an important role in hepatic insulin resistance.