白血病抑制因子在压力和容量负荷所致大鼠心衰模型心肌组织中的表达及其与心脏自主神经重塑的关系

Expression of LIF in the cardiac tissues of rat model with heart failure induced by pressure and volume overload and its relationship with cardiac autonomic nervous remodeling

【目的】观察白血病抑制因子(leukemia inhibitory factor,LIF)在压力超负荷和容量超负荷诱导的大鼠心衰模型心肌组织表达的变化,及其在大鼠心脏自主神经重塑中的作用。【方法】将15只成年雄性Wistar大鼠随机分为3组(n=5):正常组、压力负荷模型组(pressure overload,POL)和容量负荷模型组(volume overload,VOL)。分别通过腹主动脉缩窄术和腹主动脉腔静脉瘘术(aorta vena caval fistula,AVF)建立大鼠心脏POL模型和大鼠VOL模型。术后8周,经大鼠颈总动脉插管,多导生物记录仪测定大鼠心功能:左心室收缩压(left ventricular systolic pressure,LVSP)、左心室舒张末压(left ventricular end-diastolic pressure,LVEDP)、左心室压力变化最大速率(max maximal rate of rise of left ventricular pressure and max maximal rate of decline of left ventricular pressure,±dp/dtmax),并计算心脏质量指数。灌注大鼠后行左心室心肌组织切片,免疫组织化学方法分别检测交感神经、迷走神经标志物:酪氨酸羟化酶(tyrosine hydroxylase,TH)和乙酰胆碱转移酶(choline acetyl transferase,Ch AT)蛋白及白血病抑制因子(leukemia inhibitory factor,LIF)的表达,并比较左心室心肌组织中TH、Ch AT蛋白及LIF蛋白变化。同时观测左心室心肌细胞形态变化情况。【结果】POL、VOL二组大鼠LVSP较假手术对照组大鼠显著降低(P<0.05),LVEDP显著升高(P<0.05),±dp/dtmax明显降低(P<0.05),表明二种模型大鼠均发生心力衰竭,处于失代偿期。POL组大鼠心肌细胞长度和直径与对照组比较明显增加,VOL组大鼠心肌细胞长度显著增加。免疫组化检测,与对照组相比:(1)POL组表达心肌TH蛋白显著增加(P<0.05),VOL组表达显著减少(P<0.05)。(2)POL组表达心肌Ch AT蛋白明显减少(P<0.05),VOL组表达明显增加(P<0.05)。(3)POL、VOL组心肌LIF蛋白较手术对照组均表达增加(P<0.05),且VOL组LIF蛋白的表达增加显著高于POL组(P<0.05)。【结论】心脏超负荷诱导心力衰竭时心脏组织自主神经可发生交感神经重塑,且心肌组织中LIF参与了不同心肌细胞、间质重塑。提示心力衰竭时机体免疫系统激活和心脏自主神经重塑间可能存在密切关系。

【Objective】 To observe the expression of leukemia inhibitory factor（LIF） in the cardiac tissues of rat model with heart failure induced by pressure and volume overload and its effect on cardiac autonomic nervous remodeling.【Methods】A total of 15 male adult Wistar rats were randomly divided into 3 groups（n = 5）： sham-operation group, POL（pressure overload） group and VOL（volume overload） group. The POL model was established by constricting suprarenal abdominal aorta, while the VOL model was established by abdominal aorta vena caval fistula（AVF）. After 8 weeks, rat carotid artery was cannulated and cardiac functions（LVSP, LVEDP, ± dp/dtmax） were recorded by multi-channel biological recorder including left ventricular systolic pressure（LVSP）, left ventricular end-diastolicpressure（LVEDP） and max maximal rate of rise of left ventricular pressure and max maximal rate of decline of left ventricular pressure（±dp/dtmax）, as well as the index of heart weight was evaluated. Then the myocardial tissue sections of left ventricular were removed.The expressions of sympathetic and vagus markers were detected by immunohistochemical methods including tyrosine hydroxylase（TH）,choline acetyl transferase（Ch AT）. The expression of LIF was also determined in this way. In addition, the changes of cardiac TH, Ch AT and LIF were compared. Furthermore, the myocardial morphology of left ventricular was observed.【Results】Compared with the results in the sham-operation group, the LVSP in POL and VOL groups markedly decreased（P〈0.05）, the LVEDP significantly increased（P〈0.05）, and the ±dp/dtmax markedly decreased（P〈0.05）. These data indicated that the two rat models of heart failure decompensated.Compared with those in the sham-operation group, the length and diameter of myocardial cells in the POL group markedly increased（P〈0.05）, and the length of myocardial cells in the VOL group significantly increased（P〈0.05）. The immunohistochemical results showed that：（1） the expression of cardiac TH protein in the POL group significantly increased（P〈0.05）, while that in the VOL group significantly decreased（P〈0.05）;（2） the expression of cardiac Ch AT protein in the POL group significantly decreased（P〈0.05）, while that in the VOL group significantly increased（P〈0.05）;（3） the expression of cardiac LIF protein in both POL group and VOL group markedly increased（P〈0.05）, and the LIF expression in the VOL group was significantly more than that in the POL group（P〈0.05）.【Conclusions】The sympathetic-nerve remodeling will occur in overload-induced heart failure. The expression of LIF protein plays an important role in the remodeling of myocardial cells and interstitial tissues. Thus, the immune system activation is closely related with the cardiac autonomic nervous remodeling in heart failure.