γ刀单次大剂量(200Gy)照射所致脑损伤的病理研究

PATHOLOGICAL STUDY ON RATS BRAIN INJURY INDUCED BY A SINGLE DOSE OF 200Gy γ RAY IRRADIATION

采用普通病理检查、原位杂交、透射电镜方法 ,观察了使用旋转式头部γ刀以 4mm直径准直器单次 2 0 0Gy剂量定点照射正常大鼠右侧尾状核头部后长达 1年的不同时间点的靶区和靶周围区的病理改变。结果表明 ,γ刀照射后脑损伤病变经历 4个阶段 :1.急性水肿阶段 (照射后即刻至 14d) ,2 .坏死形成阶段 (2 1d至 2个月 ) ,3.吸收阶段 (3至 6个月 ) ,4 .增生阶段 (9至 12个月 ) ;照射后 2h血脑屏障通透性即开始增加 ,其程度在一定时间内与照射后生存时间呈正相关 ;血管内皮细胞和胶质细胞超微结构的改变先于神经元 ;照射引起TNF -α、IL - 1βmRNA表达增加 。

In order to improve the treatment of functional disorders with result from the clinical radiotherapy of encephalic diseases with rotate head γ knife, the pathological changes and expression of TNF-α and IL-1β mRNA in the right caudate nucleus of the rat brain irradiated locally with a single dose of 200Gy γ rays were studied by general and electron microscopical observation and in situ hybridization respectively. The results showed that the pathological changes develop through 4 stages: (1) cerebral edema (0-14 days after irradiation); (2) necrosis of the injured tissue (21d-2 months); (3) scavenging of the necrotic tissue (3-6 months) and (4) hyperplasia stage (9-12 months). It was also found that the permeability of the blood-brain barrier began to increase 2 hours after irradiation, and the degree of increase showed a positive correlation with the survival period of the animals. The ultrastructural changes in endotheliocytes and the gliocytes occurred prior to that of neurons. In this study, the expression of TNF-α and IL-1β mRNA was found increased in irradiated brain tissue, and treatment of rats with dexamethasone before irradiation could inhibit this expression.