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目的探讨放射线全脑常规外照射后对血脑屏障通透性的影响,为临床颅内肿瘤放化疗的序贯性和最佳化疗时机提供理论基础。方法100只正常成熟Sprague Dawley大鼠被随机分为0、10、20、30、40Gy组,每组20只。采用60Coγ线进行全脑常规分割外照射,2Gy/次,1个野/d,5次/周。各组完成计划照射剂量后16h经尾静脉注射氨甲蝶呤(MTX)25mg/kg,2h后采集静脉血及脑脊液,用RP HPLC法监测其中的MTX浓度。结果对照组、10、20、30、40Gy组脑脊液中MTX平均浓度分别为0.07、0.08、0.12、0.24、0.23mg/L。经秩变换检验方差分析,10Gy组与对照组、30Gy与40Gy组脑脊液中MTX浓度比较差异无统计学意义(P>0.05),其余各组间两两比较差异均有统计学意义(P值均<0.05)。血液中MTX平均浓度各组比较均无统计学意义(P>0.05)结论放射线具有降低血脑屏障功能的作用,照射20～30Gy其通透性明显增加,故20～30Gy时为化疗最佳时机。
Objective To investigate the influence of radiation on the permeability of the blood-brain barrier after routine external irradiation and to provide a theoretical basis for the consistency and optimal timing of chemotherapy and radiotherapy in clinical intracranial tumors. Methods 100 normal mature Sprague Dawley rats were randomly divided into 0, 10, 20, 30 and 40 Gy groups, with 20 rats in each group. The 60Coγ line was used to divide the whole brain by conventional external irradiation, 2Gy / time, 1 wild / d, 5 times / week. Methotrexate (MTX) 25mg / kg was injected into the caudal vein 16 hours after the completion of the planned irradiation dose. Venous blood and cerebrospinal fluid were collected after 2 hours and MTX concentration was monitored by RP-HPLC. Results The mean concentrations of MTX in cerebrospinal fluid of 10,20,30,40 Gy group were 0.07,0.08,0.12,0.24,0.23mg / L respectively. There was no significant difference in MTX concentration in cerebrospinal fluid between 10Gy group and control group, 30Gy group and 40Gy group (P> 0.05). There was significant difference between the other groups (P> 0.05) <0.05). The average concentration of MTX in blood was not significantly different between groups (P> 0.05) .Conclusion Radiation has the function of lowering the blood-brain barrier function, and the permeability of 20-30 Gy is obviously increased at 20-30 Gy. .