脑缺血性半影区胶质细胞和神经元重组的形态学观察

Morphological Observation of Glial and Neuronal Reorganization in the Ischemic Penumbra of Rat Brains

【目的】观察大脑皮质缺血性半影区星形胶质细胞和小胶质细胞以及神经元的反应模式和时程以及相关蛋白表达概况 ,以探讨半影区胶质细胞之间以及与神经元之间及其与梗死灶修复之间的联系。【方法】采用大脑中动脉缺血模型和组化及免疫组化染色方法探查 2 4只成年雄性SD大鼠 (分成假手术对照、缺血 3d和 2周组 ,每组 8只 )脑梗死灶半影区的星形胶质细胞、小胶质细胞和神经元的形态学变化及其相关蛋白的表达。【结果】大脑皮质半影区的星形胶质细胞发生显著的形态学变化 :表现为胞体肥大、染色加深、突起增粗、变长 ,细胞的变化显示为明显的时间依赖性 ,脑缺血 3d时尤为显著。反应型星形胶质细胞的GFAP、巢蛋白 (nestin)和S10 0蛋白的反应性增强 ,在脑缺血 3d时尤为显著 (+++～ ++++)。半影区小胶质细胞也显示肥大和增生 ,在脑缺血 2周时更为显著 ,其补体 3型受体抗原和MHCⅡ类抗原呈渐进性高表达 ,脑缺血 2周时最显著 (+++～ ++++)。半影区神经元随缺血时间延长 ,由急性期损伤逐渐趋于稳定。脑缺血 3d时 ,半影区出现大量神经元死亡 ,神经纤维断裂 ,排列紊乱 ,密度下降 (+)。半影区神经元GAP43呈高表达 (++++)。脑缺血 2周时 ,半影区神经元的死亡减轻 ,神经纤维密度增加 (++) ,染色加深 ,GAP43表达减弱

To explore the astrocytic, microglial and neuronal reactive model, time course, and the profiles of associated protein expression in the ischemic penumbra, in order to inquire into the relationships between the astrocytes and microglia, and between the glial cells and neurons, and their relationships to recovery of ischemic foci. 24 adult male SD rats with middle cerebral artery occlusion were divided into sham operation control group, 3 d ischemic group and 2 week ischemic group. Astrocytic, microglial and neuronal morphological changes, and the profiles of associated protein expression in the ischemic penumbra were observed by histo and immunohisto chemical methods. (1) The morphological alterations occurred in astrocytes of penumbra with hypertrophic bodies and sturdy processes. The changes were most remarkable on day 3 post ischemia. Meanwhile, overexpression of GFAP, nestin and S100 proteins on astrocytes was found(+++～++++). (2) Microglial hypertrophy and proliferation in ischemic penumbra were observed, with most remarkable changes at 2 week postischemia. Meanwhile, gradual overexpressions of CR3 and MHC class Ⅱ antigens were found(+++～++++). (3) On 3 d postischemia, numerous neurons in the penumbra died and some of their fibers were broken, and disordered, and the density of fibers decreased(+). Overexpression of GAP 43(++++) on the neurons of penumbra was found. At 2 week postischemia, the died neurons became less, and the density of nervous fibers increased progressively, while GAP 43 expression on neurons in the penumbra decreased(++). [Conclusion] The astrocytes, microglia and neurons in the penumbra exhibit morphological and biochemical reorganization, which indicates that the process of active cerebral self recovery occurs in the ischemic penumbra.