Rapamycin保护大鼠缺血性脑损伤和特定脑区神经新生有关

目的:探讨缺血前给予自噬诱导剂对脑缺血损伤的保护效应及可能机制。方法:双侧颈总动脉结扎建立全脑缺血模型,再灌注后24 h,评价动物神经行为功能,连续脑切片,采用Nissl染色定量检测皮层及海马CA1区细胞密度;通过免疫荧光技术检测Caspase-3阳性神经元,计数皮层及海马CA1凋亡细胞数量;激光共聚焦显微镜观察并计数海马齿状回颗粒下层内呈Ki67阳性、GFAP(胶质纤维酸性蛋白)阴性(Ki67+/GFAP-)细胞的数量。结果:Rapamycin术前预处理可以改善缺血导致的神经功能缺陷(P<0.05)。Nissl染色结果表明Ra-pamincy术前1 h给药可以减轻缺血导致的皮层(P<0.01)及海马CA1区(P<0.01)细胞丢失。同时,Rapamycin术前给药也显著减少了缺血导致的皮层及海马CA1区内Caspase-3阳性细胞的数量,组间比较有显著性差异(P<0.05)。Rapamycin术前1 h给药增加了海马齿状回内Ki67+/GFAP-细胞的数量,和缺血组比较差异有显著性(P<0.05)。结论:在全脑缺血模型上,通过自噬活化途径的缺血预处理可以保护缺血性脑损伤,这一作用和Rapamycin减少凋亡、增加新生神经细胞的数量有关。

Role of rapamycin in protection against cerebral ischemia-induced brain injury is related to neurogenesis in discrete brain regions in rat

Objective: To explore the protective effects and the related mechanism of pre-administered rapamycin in rat after cerebral ischemia.Methods: Global cerebral ischemia was made by occlusion of bilateral common carotid artery,and the neurological deficit score were assessed after perfusion for 24 hours.The cell density in the cortex and CA1 of hippocampus was measured on serial sections by Nissl staining.Apoptotic cells in cortex and CA1 of hippocampus were detected by immunofluorescence of Caspase-3.Ki67-positive but GFAP(glial fibrillary acidic protein)-negative cells in dentate gyrus were observed and counted with confocal microscopy.Results: Pre-administration of rapamycin reduced the neurological deficit(P<0.05),and alleviated cell loss in cortex(P<0.01) and CA1 of hippocampus(P<0.01) in cerebral ischemic rats,as was revealed by Nissl staining on brain sections of the animals receiving rapamycin administration 1 h before surgery.Consistently,number of Caspase-3 positive cells in cortex and CA1 of hippocampus decreased significantly in rapamycin-treated group compared with the untreated group in ischemic rats(P<0.05).Further study indicated that the Ki67-positive/GFAP-negative cells in dentate gyrus in rats of pre-administration of rapamycin increased 1 h before surgery showed significant difference when compared with untreated rats following cerebral ischemia(P<0.05).Conclusion:Pre-treatment via activation of autophagy could protect brain against ischemia-induced injuny on rats of global ischenia model,which may be related to the role of rapamycin reducing the number of apoptosis cells and producing new neurons.