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目的观察脑缺血后细胞周期蛋白(cyclin)D1和它的酶CDK4基因表达,以及这种表达的改变是否影响神经细胞凋亡。方法成年雄性SD大鼠32只随机分为假手术组(n=4)和实验组(n=28),实验组再进一步分为7个亚组(再灌注2h,6 h,12 h,1 d,3 d,7 d和14 d,每组n=4)。应用线栓法建立SD大鼠大脑中动脉阻塞/再灌注模型,TUNEL法检测神经细胞凋亡,原位杂交检测cyclin D1和CDK4 mRNA的表达。结果Cyclin D1 mRNA和CDK4 mRNA的表达与凋亡细胞的区域基本相同。再灌注2h脑组织即开始出现神经细胞凋亡,并于1d分别在皮层区和纹状体区达高峰(分别为72.80±4.66和87.75±0.85)。神经细胞cyclin D1 mRNA和CDK4 mRNA的表达分别于再灌注2h和6h开始逐渐增强,并于12h和1d达高峰(皮质区分别为94.50±2.75和85.75±3.73,纹状体区分别为88.25±5.06和89.80±2.93)。结论Cyclin D1和CDK4选择性地在形态学完整或已经有改变的缺血侧神经元和少突胶质细胞内表达。Cyclin D1/CDK4 mRNA表达可能是诱导细胞凋亡的重要因素之一。
Objective To observe the expression of cyclin D1 and its enzyme CDK4 after cerebral ischemia, and whether the change of expression affects neuronal apoptosis. Methods Thirty-two adult male Sprague-Dawley rats were randomly divided into sham operation group (n = 4) and experimental group (n = 28). The experimental group was further divided into 7 subgroups (2h, 6h, 12h, d, 3 d, 7 d and 14 d, n = 4 for each group). The model of middle cerebral artery occlusion / reperfusion in SD rats was established by thread occlusion method. The neuronal apoptosis was detected by TUNEL method. The expressions of cyclin D1 and CDK4 mRNA were detected by in situ hybridization. Results The expression of Cyclin D1 mRNA and CDK4 mRNA were basically the same as that of apoptotic cells. Neuronal apoptosis began to occur 2h after reperfusion and peaked in the cortex and striatum at 1d (72.80 ± 4.66 and 87.75 ± 0.85, respectively). The expression of cyclin D1 mRNA and CDK4 mRNA increased gradually at 2h and 6h after reperfusion, reaching the peak at 12h and 1d (cortex 94.50 ± 2.75 and 85.75 ± 3.73 respectively, striatum 88.25 ± 5.06 And 89.80 ± 2.93). Conclusions Cyclin D1 and CDK4 are selectively expressed in ischemic and oligodendrocytes with morphologically intact or altered morphology. Cyclin D1 / CDK4 mRNA expression may be one of the important factors in inducing apoptosis.