星形胶质细胞和神经元凋亡的细胞周期时相分布特征

目的 通过测定星形胶质细胞和神经元各自细胞凋亡的细胞周期特异性分布规律,以进一步探讨两种细胞不同的凋亡发生机制. 方法 建立大脑中动脉阻塞再灌注模型并取损伤后3 d的脑组织进行分析,缺血再灌注3 d后取脑,采用BrdU方法标记S期的细胞;再利用流式细胞分选技术特异性的将星形胶质细胞和神经元分选出来,采用BrdU标记并结合TUNEL方法,分析星形胶质细胞和神经元凋亡的细胞周期定位. 结果 与正常组比较,缺血再灌注组中缺血侧大脑皮层可见BrdU标记阳性细胞和TUNEL标记阳性细胞均明显增多,并可见TUNEL阳性和BrdU阳性双重标记的细胞.星形胶质细胞凋亡可以发生在细胞周期的各个时相,大多发生在G0/G1期,比神经元在G0/G1期的细胞凋亡率显著增高(P＜0.01);神经元进入S期的细胞凋亡率显著高于星形胶质细胞(P＜0.01). 结论 星形胶质细胞和神经元的细胞凋亡是多点启动的,脑缺血后两种细胞的凋亡具有不一致的细胞周期时相性分布特征.

Characteristics of apoptosis during different phases of cell cycle between astrocytes and neurons

Objective To investigate the different characteristics of apoptosis during the different phases of cell cycle between astrocytes and neurons, so as to explore the apoptosis mechanism of the 2 kinds of cells. Methods Ischemia/reperfusion injury was induced by temporary middle cerebral artery occlusion (MCAO). And the brain was taken 3 d after injury. Thymidine analogues such as bromodeoxyuridine (BrdU) was used to incorporate during the S phase of the cell cycle, and the combined visualization of BrdU labeling and Tdt-mediated dUTP-biotin nick end labeling was performed to investigate the apoptosis in the adult rat brain in vivo. Then the apoptosis during the different phases of cell cycle between astrocytes and neurons was detected by flow cytometry (FCM) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) methods. Results Compared to the normal controls, BrdU or TUNEL positive cells were increased in injury group, and a few of of BrdU and TUNEL double positive cells were found. The most apoptotic neurons and astrocytes were in G0/G1 phase, and the apoptotic neurons were less than astrocytes in G0/G1 phase (P＜0.01), but the apoptotic neurons were more than astrocytes in S phase (P＜0.01). Conclusions Astrocytes and neurons may have the different characteristics of apoptosis during the different phases of cell cycle, which is induced at different check-points.