新生大鼠脑白质损害时神经细胞凋亡及bcl-2蛋白的表达变化

Expression of bcl-2 protein and apoptosis of neurocytes in neonatal rats with brain white matter damage

目的研究表明脑白质损害与少突胶质前体细胞凋亡密切相关,bcl-2蛋白作为抗凋亡蛋白与新生大鼠脑白质损害(WMD)的关系较少报道。该文探讨bcl-2蛋白在新生大鼠脑白质损害(WMD)时的表达变化及意义。方法将2日龄SD大鼠(n=90),随机分为两组,实验组(缺氧缺血)45只,对照组(假手术)45只,制成WMD模型;采用TUNEL法测定神经细胞凋亡及免疫组化(SP)法检测bcl-2蛋白在脑室周围白质区不同时间点的表达变化。结果成功建立了WMD模型。实验组神经细胞凋亡在缺氧缺血后3 d达到高峰,凋亡指数脑白质为37.40±4.26,胼胝体为29.84±1.11,与对照组比较,在4 h,12 h,24 h,3 d,7 d有统计学意义(P<0.05)。实验组bcl-2蛋白表达在WMD后1 h就上升,12 h达高峰,平均灰度值脑白质为124.96±0.27,胼胝体为130.09±0.77),在1 h,4 h,12 h,24 h,3 d的表达与对照组相比,差异有统计学意义(P<0.05)。结论新生大鼠脑白质损害时,bcl-2蛋白早期表达增高,而神经细胞凋亡高峰滞后,二者具有明显时序性,这种时序变化提示bcl-2蛋白可能对神经细胞具有一定保护作用。

Objective Some research has shown that the brain white matter damage is closely related to apoptosis of pre-oligodendrocytes. The relationship of hcl-2 protein, a protein of anti-apoptosis, with brain white matter damage in neonatal rats is rarely reported. This study examined the changes of bcl-2 protein expression following brain white matter damage in neonatal rats. Methods Ninety 2-day-old Sprague-Dawley （SD） rats were randomly divided into 2 groups： experimental group （n =45） and control group （n =45 ）. Brain white matter damage was induced by ligation of the right common artery, followed by 6% hypoxia exposure in the rats from the experimental group. The rats of the control group were sham-operated, without hypoxia-ischemia treatment. The expression of hcl-2 protein in the periventricular white matter and the callositas was detected by immunohistochemical technique. Apoptosis of neurocytes in these tissues was detected by TUNEL. Results The apoptosis index of neurocytes in the experimental group was up-regulated at 4, 12 and 24 hrs and at 3 and 7 days, peaking at 3 days after white matter damage, compared with the control group （ P 〈 0.05 ）. The expression of bcl-2 protein in the experimental group began to increase at 1 hr, reached a peak at 12 hrs and remained a higher level until 3 days after white matter damage compared with that observed in the control group （ P 〈 0.05 ）. Conclusions The expression of bcl-2 protein increased at the early stage of white matter damage in neonatal rats. The peak of apoptosis lagged behind that of the bcl-2 protein expression, which suggests that bcl-2 protein may have protective effects against neuronal apoptosis.