缺血预处理模型大鼠心肌组织小分子热休克蛋白的表达

背景：小分子热休克蛋白,尤其是热休克蛋白27和α-B晶体蛋白高表达量对于心肌组织缺血再灌注的保护作用已比较明确。但是在老龄大鼠中小分子热休克蛋白是否仍具有这种保护作用迄今仍无报道。 目的：观察热休克蛋白27和α-B晶体蛋白在青年及老年大鼠心肌缺血预处理时表达的变化。 方法：24月龄老龄大鼠及两三月龄青年大鼠在体心脏经缺血5 min、再灌注5 min(反复3次)预处理后,于0,5,15,45,60 min取左心室缺血的前壁与非缺血的后壁心肌组织分别匀浆,分离上清及沉淀蛋白,用Western Blot检测热休克蛋白27和α-B晶体蛋白在预处理不同时间可溶性蛋白及不溶性蛋白含量的改变;采用RT-PCR方法观察缺血预处理对青年及老龄大鼠热休克蛋白27和α-B晶体蛋白mRNA在不同时间点表达的改变情况,采用免疫荧光观察缺血预处理后不同时间点热休克蛋白27和α-B晶体蛋白的移位情况。 结果与结论：老龄大鼠在缺血预处理后热休克蛋白27和α-B 晶体蛋白表达量增加,表明老龄大鼠仍具有正常的基因转录及蛋白合成的能力;与青年大鼠比较,老龄大鼠缺血预处理后小分子热休克蛋白移位能力降低,从而减弱了与各相应蛋白结合的能力,限制其保护作用的发挥。提示老年大鼠心肌组织中小分子热休克蛋白丧失移位能力,可能是老年大鼠缺血预处理保护作用减弱的重要原因之一。

Expression of small heat shock proteins in rat myocardium damaged by ischemia-reperfusion

BACKGROUND:The protective effects of small heat shock proteins (sHSP), especially the highly expression of heat shock protein 27 (HSP27) and α-B crystalline on myocardium from ischemia-reperfusion (I/R)-induced damage have been confirmed. However, whether this protective effect happened in aged rats remains unclear. OBJECTIVE:To observe the expression changes of HSP27 and α-B crystalline in the myocardium from I/R-induced damage between aged and young rats. METHODS:24-month aged rats and 2 to 3-months young rats were induced I/R injury by 5 minutes ischemia and 5 minutes reperfusion. The anterior wall of the left ventricular ischemia and posterior wall of non-ischemia were obtained at 0, 5, 15, 45 and 60 minutes. RT-PCR and Western blot analysis were used to examine the expression of α-B crystalline and HSP27 mRNA and protein, respectively. Double immunofluorescence labeling-confocal microscopy was used to observe the translocation of α-B crystalline and HSP27 after I/R. RESULTS AND CONCLUSION:The expressions of α-B crystalline and HSP27 mRNA and protein did not decrease both in aging and young rats, but the abilty of translocation of α-B crystalline and HSP27 protein from the cytosol to sites of the myofibrillar system reduced in aging rats compared with young rats. The present results demonstrate that translocation ability of α-B crystalline and HSP27 in aging rat reduced, which may explain why aging rat heart partly loss the protection role of I/R.