内毒素血症时大鼠心肌细胞凋亡与血管紧张素受体表达关系的研究

Study on the realation between expression of angiotonin Ⅱ receptor and apoptosis in myocardium in rats of endotoxemia

目的:对脂多糖诱导大鼠内毒素血症时心肌细胞凋亡与血管紧张素II受体AT1、AT2表达变化进行分析。方法:Wistar大鼠随机分为3组(n=10):空白组、脂多糖(LPS)干预2 h(L2)组、LPS干预6 h(L6)组。根据分组情况经腹腔注射LPS(10 mg/kg)制备内毒素血症模型,对照组给予等体积生理盐水腹腔注射。应用免疫组织化学法检测凋亡相关因子Bcl-2和Bax蛋白表达,并通过TUNEL法检测心肌细胞凋亡变化,并采用免疫组织化学、RT-PCR方法观察了大鼠心肌AT1、AT2受体表达变化,电镜观察心肌组织病理变化。结果:LPS干预2 h后Bcl-2阳性细胞表达开始明显上调,之后开始下降,但仍高于对照组(P<0.05)。Bax的表达随着干预时间的延长不断增加,6 h后表达与对照组相比,有显著的统计学差异(P<0.01)。Bcl-2/Bax的比率在干预开始2 h时升高,随后开始下降,心肌细胞凋亡增加。随着LPS干预的时间延长,AT1受体、AT2受体蛋白、mRNA表达水平呈下降趋势,6 h后表达与对照组相比,有显著的统计学差异(P<0.01)。结论:大鼠经LPS干预后随时间延长Bcl-2/Bax的比率呈下降趋势,心肌细胞凋亡增加,与AT1受体、AT2受体表达水平下降呈负相关,说明血管紧张素受体表达下调可能与内毒素血症时大鼠心脏功能损伤有关,为临床预防及治疗全身炎症反应所致心功能损伤提供一条新的思路以及实验室理论基础。

Objeelive： To analyze the expression of angiotonin Ⅱ （ANG Ⅱ） receptor and apoptosis in myocardium in rats of endotoxemia. Methods： Model of endotoxemia was induced by intraperitoneal injection with lipopolysaccaride（LPS） 10 mg/kg in male Wistar rats and saline was injected into control group. The rats were killed at 2 h or 6 h after saline （control） or LPS . Expression of the correlation factors releatod to apoptosis of Bcl-2, Bax, AT1 and AT2 receptor in myocardial tissue were detected with immunohistochemisty（IHC）, and changes of my- ocardial cells apoptosis was detected by me methord of TUNEL. The gene expression of AT1 and AT2 receptor was examined by RT-PCR. The pathological changes of myocardial tissue were observed by electron microscope. Results： Compared with control group , the expression of AT1 and AT2 receptor were significantly decreased, especially in 6 h group; and the expression of Bcl-2 and Bax were decreased, the ratio of Bel- 2/Bax had the downtrend as well as the apoptosis of myocardial cells. Conclusion： Imerfered by LPS, the down regulation of AT1 and AT2 re- ceptor expression has the negative realation with apoptosis of myocardial cells, this result indicated that down regulation of AT1 and AT2 recep- tor expression maybe related to cardic functional impairment, which maybe help us to find a new protective path to prevent myocardial damage induced by systemic inflammatomme.