脑过度灌注动物模型的血脑屏障超微结构研究

Ultramicrostructure of BBB in animal model of cerebral luxury perfusion

目的 从形态学基础探讨脑过度灌注的发生机理。方法 透射电镜下观察不同时相的脑盗血和脑过度灌注动物局部脑组织超微结构。结果 慢性脑盗血大鼠毛细血管周围星形胶质细胞足突层 (AsF)肿胀 ,胞浆稀疏呈空泡化 ,AsF层空泡化程度较急性、亚急性者严重 (P <0 0 1)。邻近的星形胶质细胞 (As)出现相似的空泡化等改变 ,神经元细胞 (NC)形态改变不如As明显。脑过度灌注发生后 ,慢性脑盗血区BBB结构完整性严重破坏。结论 在慢性脑盗血状态下 ,As最先发生形态学异常。BBB超微结构的改变以AsF层空泡化为特征 ,构成了脑过度灌注发生的形态学基础。当脑微血管网承受血流高灌注时 ,BBB进一步破坏 ,组织水肿形成。

Objective This study is to evaluate the BBB in adjacent brain parenchyma for any ultramicrostructural deficiencies that would predispose the brain to the postoperative formation of edema and hemorrhage, which was called cerebral luxury perfusion. Methods The pathological ultrasmicrostructural changes of BBB induced by cerebral steal in different time stages were assessed by light and transmission electron microscopic techniques. Results The transmission electron microscopy demonstrated the marked vacuolar degeneration of astrocytic endfeet (AsF) in the chronic stage team of cerebral steal model. The rats of other stage or control groups did not express such marked paramorphia (P<0 01). The adjacent astrocytes express the similar ultrastructural degeneration. The pathological abnormalities of neurons & endotheliocyte were not so significant as AsF. The tight junction between the endotheliocyte did open after the cerebral luxury perfusion occurred, which implied the BBB did not remain its integrity. Conclusions These astrocytes developed configurational abnormality as a result of neovascularization in response to chronic cerebral steal in the first. Marked vacuolar degeneration of AsF were the feature of structural alteration of BBB, which made up the morphologic foundation of cerebral luxury perfusion. It prone to mechanical weakness and instability following the increase in perfusion pressure that occurs follow blood redistribution. The authors believe that this study pinpoints a structural accompaniment to the hemodynamic changes that occur in brain tissue in the vicinity of cerebral GAVM. It predispose these areas to the formation of luxury perfusion after GAVM excision.