肝脏缺血-再灌注损伤对大鼠肝胰岛素信号转导分子的影响

Effects of hepatic ischemia-reperfusion injury on insulin signal transduction in rat liver

目的研究肝脏缺血-再灌注损伤(HIRI)大鼠肝细胞胰岛素信号转导过程中信号蛋白表达的改变,探讨引起HIRI后高血糖的机制。方法选用健康SD大鼠80只,随机分为对照组(C组)和缺血-再灌注组(IR组),每组40只。IR组建立HIRI大鼠模型(肝门阻断30min后再灌注2h),分别测定肝门阻断前(T1)及肝门阻断30min再灌注2h(T2)血糖(BG)、血胰岛素(Ins)的浓度。检测两组大鼠肝组织胰岛素受体β亚单位(IRβ)、胰岛素受体底物2(IRS2)及其酪氨酸磷酸化蛋白表达的改变。结果与T1比较,两组大鼠T2时BG均明显升高(P<0.01),但IR组更为明显(P<0.01)。与T1比较,IR组T2时Ins无明显变化,C组明显升高(P<0.05)。与C组比较,两组大鼠肝组织内IRβ、IRS2总蛋白表达无明显差异,但其酪氨酸磷酸化蛋白表达水平分别减少了32.2%(P<0.05)和47.7%(P<0.01)。结论HIRI导致肝胰岛素信号转导通路中IRβ、IRS2蛋白的酪氨酸磷酸化表达水平降低,从而影响葡萄糖代谢过程,这可能是HIRI后血糖升高的原因之一。

Objective To observe the changes of insulin signal protein （ISP） expression in rat hepatocytes after hepatic ischemia-reperfusion injury（HIRI）. Methods Eighty healthy SD rats were randomly divided into control group（C） and ischemia-reperfusion （IR）group with 40 rats each. Rat model was established by clamping the hepatic hilurn for 30 min and reperfusing for 2 h after release of the clamp in group IR. Blood samples were taken before hepatic ischemia （T1） and after reperfusion （T2） to determine the levels of plasma glucose and insulin. Liver tissues were used to measure the expressions of ISP and the levels of phosphotyrosine state of insulin receptorβ （IRβ）unit, insulin receptor substrate-2 （IRS2） were detected. Results The levels of plasma glucose in two groups were higher at T2 than those at T1 （P〈0.01）, but the increase in group IR was more obvious （P〈0. 01）. There was no any significant difference in the insulin concentration between T1 and T2 in group IR. The level of insulin in group C at T2 was higher than that at T1. Compared with those in group C, total protein expressions of IRβ, IRS2 in group IR were not significant. However, the levels phosphotyrosine state of these proteins were deceased by 32. 2% （P〈0.05） and 47.7% （P〈0.01）, respectively. Conclusion HIRI impacts glucose metabolism by decreasing the expressions of the phosphotyrosine state of insulin signal proteins such as IRβ, IRS2, which may be one of the reasons for the elevation of plasma glucose after HIRI.