Instability and remodeling of cerebral aneurysmal walls

1)未破裂和破裂的动脉瘤在手术或尸检时获得：尸检时对照脑动脉。用α-平滑肌肌动蛋白、巨噬细胞和基本转录调节元件结合蛋白2（BTEB 2）的抗体对标本进行化学染色。BTEB 2阳性巨噬细胞和平滑肌细胞被发现在大的和巨大的未破裂的动脉瘤的管腔层。这表明BTEB 2在动脉瘤壁中的表达可能在动脉瘤的生长中起作用，并可能防止其破裂。我们使用血管腐蚀模型，以检测早期超微结构的变化，发生在脑动脉分叉处的血流动力学应激反应，并导致脑动脉瘤形成的大鼠进行动脉瘤诱导结扎右侧颈总动脉和双侧后，肾动脉在20只手术大鼠中，11只（55%）发生了血管性变化;其中5只表现为内皮细胞印记的变化（I期）。另6只大鼠血管内皮细胞形态学改变与不同程度的动脉瘤扩张相关，2只大鼠动脉分叉处出现囊状扩张（III期），4只大鼠内膜垫隆起（II期）。卵巢切除大鼠动脉瘤形成的频率是未切除大鼠的3倍。用雌激素替代治疗的大鼠动脉瘤形成的频率降低到对照水平。提示雌激素在脑动脉瘤的发病中起重要作用。

1)Unruptured and ruptured aneurysms were obtained at surgery or autopsy : control cerebral arteries at autopsy. The specimens were stained immunohistochemically with antibodies to α-smooth muscle actin, macrophages, and basic transcription regulatory element binding protein 2 (BTEB2). BTEB2-positive macrophages and smooth muscle cells were found in the luminal layer of large and giant unruptured aneurysms. This suggests that BTEB2 expression in the aneurysmal wall may play a role in the growth of aneurysms and may protect against their rupture.2)We used vascular corrosion casts in order to detect early ultrastructural changes that occur at cerebral arterial bifurcations in response to hemodynamic stress and lead to cerebral aneurysms formation in rats subjected to aneurysm induction by ligation of the right common carotid artery and bilateral posterior renal arteries. Of the 20 operated rats, 11 (55%) developed aneurysmal changes ; 5 of these manifested changes of the endothelial cell imprints only (Stage I). In the other 6 rats, morphological changes of endothelial cells were associated with different grades of aneurysmal dilatation : 2 rats developed saccular dilatation of the arterial bifurcation (stage III) and 4 manifested intimal pad elevation (stage II).3)New experimental aneurysmal model was developed in female rats subjected to estrogen deficiency by adding oophorectomy. Frequency of aneurysm formation in oophorectomized rats was 3 times higher than that in rats without oophorectomy. Frequency of aneurysm formation in rats treated with estrogen replacement reduced to the control level. The findings suggest that estrogen play an important role in the pathogenesis of cerebral aneurysms.