不同剂量全脑放疗胶质瘤模型对血脑屏障紧密连接影响的研究

Effect of whole-brain irradiated with the different doses on study of the tight junction of blood-brain barrier in glioma models

目的:观察C6脑胶质瘤单次全脑放疗后早期血脑屏障(BBB)通透性的变化、超微结构特征及紧密连接蛋白Claudin-5的表达变化。方法:荷瘤鼠50只,随机分为假照射组和5、10、15、20Gy组各10只,行相应剂量全脑放射线单次照射,并于照射后24h处死,各5只分别行硝酸镧透射电镜示踪法观察肿瘤临近处(BAT)BBB通透性,免疫组化法测定Claudin-5的变化。结果:硝酸镧示踪电镜观察:假照射组、5Gy组荷瘤鼠BAT处见La3+渗出至局部基底膜,大部分分布在血管腔内;10Gy组BAT处可见La3+渗出至广泛基底膜及脑组织间隙,紧密连接开放;15、20Gy组BAT处均可见La3+渗出至基底膜、血管腔外、脑组织间隙内及细胞内。统计学分析硝酸镧渗出显示,20、15Gy>10Gy>5、0Gy,P<0.05。Clau-din-5表达变化:假照射组、5Gy组荷瘤鼠BAT处脑组织表达下降,仍呈中度表达;10Gy组BAT处可见较假照射组脑组织表达下降,呈轻中度表达,血管扭曲、变形与间断表达状态并存;15、20Gy组BAT处均可见较假照射组脑组织表达下降,呈轻度表达,沿血管间断表达,并见碎片状。统计学分析显示,20、15Gy>10Gy>5、0Gy,P<0.05。结论:荷瘤鼠全脑放疗后早期放射线损伤BBB的完整性发生在单次放疗剂量10～15Gy,且增加剂量BBB通透性无明显增加。

OBJECTIVE： To investigate the change in BBB permeability and ultrastructure of microvessle in C6 glioma and the tight junction protein expression of Claudin 5, after whole-brain irradiated with the single dose. METHODS： Fifty tumor-bearing rats were ran domly divided into sham irradiation group, 5 Gy, 10 Gy, 15 Gy and 20 Gy group. All groups were 10 rats sacrificed at 24 h after irradiation, 5 rats were using transmission electron microscopy of exogenous lanthanum nitrate（La^3＋ ） tracing to observe the BBB permeability of he tissues within 2 mm to the border of the tumor and using immuno histochemical method to detect the expression of Claudin 5, repec tively. RESULTS： Using TEM of exogenous La^3 -tracing to observe the BBB permeability. In BAT of 5 Gy group, La^3＋ exuded to the lo cal BM, most of which lied in endovascular. In BAT of 10 Gy group, La^3＋ exuded to a wide range of BM and the brain tissue space, and tight junctions were opened. In BAT of 15 Gy and 20 Gy group,La^3＋ seeped to the BM, extra-vascular, the space inside the brain tissue and cells. Statistical analysis showed that 20 Gy and 15 Gy〉 10 Gy 〉 5 Gy and 0 Gy （P〈0.05）. The expression of Claudin-5 in BAT of the tumor-bearing rats after irradiation with different doses was following up. Claudin 5 expression in BAT of 5 Gy Group was de creased than that in the control group brain tissue, showing moderate expression. Ten Gy group BAT Department could be seen moderate expression, combining with vascular distortion, deformation and continuous expression state. Fifty Gy, 20 Gy group could be seen mild expression in BAT, showing intermittent and debris like ex pression along the vessels. Statistical analysis showed that 20 Gy and 15 Gy〉 10 Gy〉 5 Gy and 0 Gy （P〈0.05）. CONCLUSION： With dose changes during whole-brain radiotherapy, BBB begin opening from 15 Gy to 20 Gy, and significantly after single irradiation 15 Gy, 20 Gy, in which the two doses have not differences.