ERK对缺血缺氧性脑损伤后神经元凋亡的影响

目的研究在缺血缺氧性脑损伤后细胞外信号调节激酶(ERKs)对神经元凋亡的影响。方法建立光化学法诱导大鼠局灶性脑缺血模型,随机分为脑缺血组(缺血组和干预组)和假手术组,干预组于缺血前30min尾静脉注入U0126溶液,缺血组尾静脉注入相同体积不含U0126的DMSO稀释溶液;2,3,5-氯化(或溴化)三苯四氮唑(TTC)染色显示梗死灶;应用免疫组织荧光化学法检测梗死灶周围神经元核心抗原(NeuN)的表达及通过TUNEL方法检测神经元凋亡,并做NeuN与TUNEL的双标;用免疫印迹(Westernblot)方法观察损伤侧皮层NeuN、细胞周期蛋白D1(CyclinD1)和细胞周期蛋白E(CyclinE)蛋白的表达。结果缺血组的梗死体积明显大于干预组,在假手术组未见梗死灶;缺血组大鼠NeuN阳性细胞数和NeuN蛋白表达明显少于假手术组,TUNEL阳性细胞数和CyclinD1和CyclinE蛋白表达明显高于假手术组(P<0.05)。干预组NeuN阳性细胞数和NeuN蛋白表达亦少于假手术组,但多于缺血组,TUNEL阳性细胞数和CyclinD1及CyclinE蛋白表达亦多于假手术组,但少于缺血组(P<0.05)。结论ERK可通过对细胞周期的调控而对神经元凋亡产生影响,抑制脑缺血引起的pERK1/2磷酸化可部分抑制神经元凋亡,减少缺血梗死灶,对缺血性脑损伤起一定的保护作用。

Effect of extracellular signal-regulated kinase (ERK) on neuron apoptosis in brain injury after cerebral ischemia in rats

Objective To investigate the effect of extracellular signal-regulated kinase(ERK)on neuron apoptosis in brain injury after cerebral ischemia.Methods Ischemic model of rats was induced by photochemistry.The rats were randomly divided into cerebral ischemia group(control and intervention)and sham-operation group.U0126 solution was injected through vena caudalis at 30 min.pre-ischemia in the intervention group,and identical volume of DMSO-attenuating solution without U0126 was given in the control group.The foci of infarct were detected using 2,3,5-chloride three benzene tetrazolium(TTC).Neuronal core antigen(NeuN)in the boundary zone of infarct was detected with immunohistofluorescence chemical method,neuron apoptosis was examined by TUNEL;and double immunofluorescence staining for the neuronal marker,NeuN and TUNEL,was finished.The protein expression of NeuN,CyclinD1 and CyclinE in the ischemic side of the cortex was detected by western blot.Results There was no infarct focus in the sham group.TTC staining showed significant reduction of infarct volume after ischemia in intervention group.Significant reduction(P<0.05)of NeuN-postitive cells was observed in ischemia group,compared with intervention and sham group.TUNEL-positive cells in ischemia group showed significant stronger expression,compared with that in intervention and sham group.Western blot showed significant reduction of the protein expression of CyclinD1 and CyclinE in intervention group,compared with ischemia group.Conclusions ERK may have the effect on neuron apoptosis by regulating cell cycle and providing protection of brain injury after ischemia.Neuron apoptosis could be partially supressed through inhibiting ERK1/2 phosphorylation induced by cerebral ischemia.