葛根素对大鼠全脑缺血再灌注后学习记忆障碍保护作用及其机制的研究

目的 探讨葛根素对大鼠全脑缺血再灌注后学习记忆能力的影响及其机制。方法 采用四血管阻断法建立SD大鼠全脑缺血再灌注损伤模型，暗回避反应法测定学习记忆能力，并应用免疫组织化学法、原位末端标记法，检测大鼠全脑缺血再灌注海马CA，区的bcl-2阳性细胞数、凋亡细胞数的动态变化。结果 (1)与再灌注组相比，葛根素组大鼠潜伏期明显延长；(2)脑缺血再灌注后，海马CA1区bcl-2蛋白的表达随再灌注时间不同而变化，缺血20min后再灌注24h达高峰，葛根素组bcl2蛋白的表达于相应的时间点明显增多；(3)脑缺血再灌注后海马CA1区神经元凋亡损伤在再灌注72h损伤最重，葛根素组可减少相应时点神经细胞凋亡数。结论 葛根素对全脑缺血再灌注后大鼠学习记忆能力具有明显的改善作用，其作用机制可能与通过上调bcl-2基因表达从而抑制或延迟脑缺血再灌注后细胞凋亡有关。

The mechanism of protective effects of puerarin on learning-memory disorder after global cerebral ischemic reperfusive injury in rats

Objective To investigate the mechanism of protectiveeffects of puerarin on learning-memory disorder after global cerebral ischemic reperfusive injury in rats.Methods The global cerebral ischemia-reperfusion injury models was created by four-vessel occlusion in Sprague-Daewley rats.The learning-memory ability was evaluated by using passive avoidance test.The dynamic changes on the cell counts of bcl-2 and apoptosis in hippocampus CA 1 were determined by immunohistochemical method and TUNEL,respectively.. Results (1) As compared with the rats in reperfusive group,the performance on passive avoidance test of rats in puerarin group was improved significantly.(2) The level of positive expression of bcl-2 varied to the duration of reperfusion and the peak level was at 24h in the hippocampal CA 1 regionafter 15 minutes of global cerebrai ischemia, while in the puerarin group,expression of bcl-2 was upregulated at respective time after ischemia reperfusion.(3)The apoptotic neurons were injured most severely at 72h after global ischemia and reperfusion.While in the puerarin group,the number of neuronal apoptosis wasdecreased at respective time after schema reperfusion.Conclusion Puerarin could improve the learning-memory ability after 15 minutes of globalcerebral ischema in rats.The protective mechanism might be related to the effect of preventing apoptosis through unregulating expression of bcl-2.