全脑放疗对大鼠血-脑脊液屏障功能的影响

目的通过检测顺铂在脑组织中的浓度变化,观察全脑常规分割外照射对血-脑脊液屏障通透性的影响。方法将Wistar大鼠50只随机分为0、10、20、30、40Gy组,每组10只,用6MV的X线加1.0cm厚组织补偿进行全脑常规分割外照射,每次2Gy,每天照射1次,每周照射5d。各组大鼠完成既定照射总量后16h经腹腔注射顺铂（1.0mg/kg）,20min后采集静脉血及脑组织,采用高效液相色谱法测定血清和脑组织中顺铂的浓度。结果各组大鼠血清中顺铂浓度比较差异无统计学意义（F=0.16,P〉0.05）。大鼠脑组织中顺铂的浓度随照射剂量的增加而逐渐增高,各组间比较差异有显著性（F=63.12,q=2.231～18.005,P〈0.05、0.01）。结论放射治疗可增加血-脑脊液屏障通透性,全脑放疗20～30Gy时为加用化疗的最佳时机。

THE EFFECT OF WHOLE BRAIN IRRADIATION ON BLOOD-BRAIN BARRIER PERMEABILITY IN RATS

Objective To investigate the effect of whole brain conventional fractionation irradiation on permeability of blood-brain barrier （BBB） in rat through measuring cisplatin concentration （DDP） in brain tissue. Methods Fifty adult Wistar rats were randomized to five groups based on different irradiation doses： 0 Gy; 10 Gy; 20 Gy; 30 Gy; and 40 Gy-groups. A 1.0 am-thick tissue compensator was utilized, then all rats were exposed to conventional fractionation （2 Gy/d, 5 d/w） with 6 MV X ray. DDP （1.0 mg/kg） was injected into the abdominal cavity 16 hours after the irradiation. Brain tissue and blood were collected 20 minutes later. The samples were used to assay DDP concentration using HPLC. Results The average serum concentrations of DDP in different groups were not significantly different （F= 0.16,P〉0. 05）. While the average concentrations of DDP of brain tissues increased along with increase of the irradiation doses, the differences among the groups were significant （F= 63. 12;q = 2.231-18.005;P〈0.05,0.01）. Conclusion Irradiation can increase the permeability of BBB. The whole brain irradiation ranges from 20 Gy to 30 Gy would be considered as the optimum for chemotherapy.