背景:脑缺血再灌注后细胞周期蛋白的表达以其在凋亡机制中的作用为主,部分细胞凋亡是由于细胞增殖周期的异常调控所致. 目的:研究脑缺血再灌注后细胞周期蛋白 D1( cyclin D1)和周期蛋白依赖性蛋白激酶 4( cyclin dependent kinase,CDK4)基因表达及其与神经细胞凋亡的关系. 设计:随机对照的实验研究. 地点和材料:本实验在青岛大学医学院脑血管病研究所和山东省脑血管病防治重点实验室完成.成年健康雌性 SD大鼠 36只,体质量 230～ 270 g,清洁级,由中国科学院上海实验动物中心提供.将动物随机分为假手术组 4只和实验组 32只,实验组再进一步分为缺血 1.5 h再灌注 2, 6, 12 h, 1, 2, 3, 7和 14 d亚组,每组 4只. 方法:全部实验均由本文作者完成.具体方法:应用线栓法经左侧颈外-内动脉插线建立 SD大鼠大脑中动脉阻塞再灌注模型,原位末端标记法检测脑缺血再灌注后神经细胞凋亡的变化,原位杂交技术检测 cyclin D1 mRNA和 CDK4 mRNA的表达. 结果:脑缺血再灌注 2 h脑组织即开始出现凋亡神经细胞,并于 1 d和 2 d分别在皮质区和纹状体区达高峰(分别为 72.80± 4.66和 96.75 ± 4.37).神经细胞 cyclin D1 mRNA和 CDK4 mRNA的表达分别于再灌注 2 h和 6 h开始逐渐增强,并于 12 h和 1 d分别在皮质区和纹状体区达高峰(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),至再灌注 14 d降至假手术组水平. cyclin D1 mRNA和 CDK4 mRNA的表达与凋亡细胞的区域基本相同. 结论:脑缺血再灌注后皮层区较纹状体区对缺血更为敏感, cyclin D1 mRNA和 CDK4 mRNA表达可能是诱导细胞凋亡的重要因素之一.%BACKGROUND:The expressions of cyclins mainly play its apoptotic role after cerebral ischemia reperfusion and some apoptosis is caused by the abnormal regulation of cell proliferation cycle. OBJECTIVE:To investigate the relationship between the gene expressions of cyclin D1 and cyclin dependent kinase(CDK4) and neuronal apoptosis after focal cerebral ischemic reperfusion in rats. DESIGN:Randomized and controlled experimental research. SETTING and MATERIALS:This experiment was finished in the Institute of the Cerebrovascular Diseases,in Medical College of Qingdao University and the Key Laboratory of Cerebrovascular Diseases of Shandong Province.Thirty-six adult healthy female SD rats,with a body mass of 230 g to 270 g,of clearing grade,and purchased from Shanghai Experiment Animal Center of Chinese Science Academy.The animals were divided into sham-operated group(4 rats) and experiment groups(32 rats) which were further divided into ischemic 1.5 hours and reperfusion 2,6,12 hours,1,2,3,7 and 14 days subgroups,consisting of 4 rats each. METHODS: The experiment was performed by the authors.The model of focal ischemic reperfusion in rats was induced by occlusion of intraluminal middle cerebral artery with a nylon monofilament suture from left external internal carotid artery.The neuronal apoptosis was detected by terminal deoxynucleotidy1 transferase-mediated 5'-dUTP nick end- labeling(TUNEL)staining.Hybridization in situ was performed to examine the expressions of cyclin D1 mRNA and CDK4 mRNA. RESULTS: TUNEL positive neurons appeared from reperfusion 2 hours and peaked at 1 day and 2 days in cortex and striatum[(72.80± 4.66)and (96.75± 4.37) respectively].Cyclin D1 mRNA expression was detected in cortex and striatum of ischemic hemisphere as early as 2 hours after reperfusion while CDK4 mRNA was detected at 6 hours, and reached its highest levels at 12 hours and 1 day[in cortex(94.50± 2.75) and(85.75± 3.73)and in striatum(88.25± 5.06) and(89.80± 2.93) respectively],then decreased to sham-operated level at reperfusion 14 days.The expressions of cyclin D1 mRNA and CDK4 mRNA in the fields almost were the same as apoptosis. CONCLUSION:The cortex might be more sensitive to ischemia than striatum and the expressions of cyclin D1 and CDK4 mRNA might be one of the important factors inducing apoptosis in cerebral ischemia reperfusion.
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