全脑缺血-再灌注损伤后大鼠海马齿状回神经元发生的研究

目的：观察脑缺血－再灌注损伤后大鼠海马齿状回神经元发生的时间规律，探讨缺血性脑损伤后神经元发生的机制。方法 采用4血管闭塞法建立大鼠全脑缺血模型。使用5－溴脱氧尿核苷（5-bromodeoxyuridine,BrdU)标记有丝分裂和免疫组织化学方法观察大鼠海马齿状回的神经元发生，并采用荧光组织化学方法和激光共 焦显微镜确定新生细胞类型。结果 缺血性脑损伤可促进成年大鼠齿状回的细胞增殖。与对照组相比，大鼠全脑缺血－再灌注损伤后3d时，齿状回BrdU阳性数据胞数目没有显著性增加（P＞0．05），此后，齿状回BrdU阳性细胞数目开始显著增加，并于全脑缺血再灌注损伤后第14日时达到峰值。此时，齿状回BrdU标记阳性细胞数量是对照组的7倍。对新生细胞的分化过程进行观察后发现齿状回BrdU标记阳性细胞大部分可以分化为神经元。结论 缺血性脑损伤可诱导海马齿状回神经元发生水平在一定时间窗内上调，其机制可能与缺血引起脑组织激素水平、神经递质、神经营养因子浓度发生变化以及齿状回局部微环境改变有关。

Study of neurogenesis in dentate gyrus after global ischemia reperfusion in rats

AIM To investigate the tempo-spatial characteristics of neurogenesis in dentate gyrus (DG) of rats after global ischemia reperfusion and to explore the possible mechanisms of neurogenesis. METHODS Male mature Spraque Dawley rats were subjected to a 4-vessel occlusion (4-VO) model. Bromodeoxyuridine (BrdU) labelling method was used to observe the neurogenesis in the DG of rats and double-immunostaining with laser confocal microscopy was used to determine the cell phenotype. RESULTS Ischemia enhanced cell proliferation in DG of adult rats. The number of BrdU immunoreactive cells in DG did not significantly increase during the first 3 days after the global ischemia. Thereafter, cell proliferation increased markedly and reached the peak on the 14th day after ischemia. Compared with the control rats, the quantity of BrdU immunoreactive cells in the DG of rats after global ischemia had a 7-fold increase. The result obtained by observing the differentiation of newborn cells showed that many of the BrdU immunoreactive cells in DG had become neurons. CONCLUSION Neurogenesis in DG could be induced to increase at a certain time window after global ischemia reperfusion. The accommodational mechanisms of neurogenesis were possibly related to the changes of hormones, neurotransmitters, neurotrophic factors and the micro-circumstances of the dentate gyrus after ischemia.