镧示踪法观察常规分割外照射后血脑屏障的超微结构改变

目的 观察Sprague-Dawley(SD)大鼠全脑常规外照射后血脑屏障(BBB)的超微结构变化特点及其规律。方法 SD大鼠20只,分为5个实验组,60Coγ射线全脑常规分割外照射,各组受照后16h以硝酸镧为示踪剂,用透射电镜观察BBB超微结构变化。结果 对照组镧颗粒分布在血管腔内,BBB结构完整;10Gy组少量镧颗粒通过开放的毛细血管内皮细胞间的紧密连接,沉积于基底膜,但未入脑组织;20Gy组见大部分紧密连接开放,镧颗粒弥漫性分布于神经细胞间隙,细胞内无镧颗粒沉积;30Gy神经细胞质内见大量、核内见少量镧颗粒沉积;40Gy组部分毛细血管内皮细胞及神经细胞失去正常形态,结构破坏,大量镧颗粒沉积在细胞核内、外。结论 放射线具有降低及破坏BBB功能的作用,且与照射剂量呈正相关;30Gy后BBB完全开放,此时进行化疗为最佳时机;照射40Gy后不易再全脑追加剂量,否则会导致不可逆性放射性脑损伤。

Changes of ultrastructure of blood-brain barrier after whole brain irradiation treatment in rats with lanthanum

Objective A pilot study of ultrastructure of blood-brain barrier (BBB) after whole brain irradiation treatment in rats. Methods Twenty Sprague-Dawley rats were derided into 5 groups, To observe the changes of ultrastructure of BBB in 16 h after whole brain irradiation with 60Coγ ray in rats,using lanthanum trace labeling with electron microscopy. Results 1.The lanthanum was only seen in the lumens of capillaries but not in the extravessels to the rats of unirradiation. 2.A few tight junctions of capillaries endothelial cell opened through which the lanthanum entering the outside of capillaries but not in the extravessels after irradiation 10Gy. 3.Most tight junctions of endothelial cell opened through which the lanthanum entering the extra cellular space but not enter into the neurons in 20Gy group. 4. The lanthanum through tight junctions of capillary vessel and basement membrane entered the plasma, mitochondria and endoplasmic reticulum of neurons after irradiation treatment 30Gy. 5.To the 40Gy group, Lanthanum nitrate particles existed in the brain tissue diffusely and a few endothelial cells and neurons lost normal configuration. Conclusions 1.The effect that radiation can directly damage the function and structure of BBB were enhanced proportionally with irradiation doses. 2.It is optimum time of chemotherapy after the whole brain irradiation in 30 gray. 3.The whole brain radiotherapy could not more than 40Gy, or it result in irreversible brain injure.