低剂量辐射预处理对放射性脑损伤自由基的影响

目的通过研究低剂量辐射（low does radiation，LDR）预处理对放射性脑损伤自由基的影响，验证低剂量辐射预处理是否在急性放射性脑损伤中具有保护作用。方法预照射剂量为100mGy，攻击性照射剂量为25Gy。30只SD大鼠随机分为单纯照射组、间隔6h预照射组、间隔24h预照射组。攻击性照射后6h，脑组织匀浆后检测预照射对超氧化物歧化酶（SOD）、丙二醛（MDA）含量的影响。结果与单纯照射组相比．预照射组在25Gy照射后6h可提高照射后脑组织SOD活力、减少MDA含量。6h预照射组SOD及MDA变化与24h预照射组比较，差别无统计学意义。结论在实验观察的时间范围内，低剂量辐射预处理可促使脑内SOD升高和MDA下降，对大鼠急性早期放射性脑损伤有一定的保护作用。

Effects of Low Dose Radiation Pretreatment on Radiation Injuried Brain's Free Radicle

Objective To investigate the effect of low dose radiation pretreatment on radiation injuried brain's free radicle to provide some useful data of brain radiation injury protection.Methods One hundred mGy was selected as the pretreatment does,25 Gy was selected as the challenge does.Experiment rats were divided into three groups randomly,group one as simple group:the group irradiated without exposing to preirradiation;group two as 6 h-group:the group irradiated with LDR pretreatment 6 h before exposing to 25 Gy irradiation;group three as 24 h-group:the group irradiated with LDR pretreatment 24 h before 25 Gy irradiation.The observation was done 6 hours after irradiation,the effect of LDR pretreatment on increasing activity of the superoxide dismutase(SOD)and the content of malondialdehyde(MDA) after the brain tissue homogenate were detected.Results Compared with the simple group,the group with LDR pretreatment showed increasing of SOD and decreasing of MDA at the 6th hour after 25Gy irradiation.In addition,there was no difference between the 6 h-group and the 24 h-group.Conclusion LDR pretreatment can increase SOD and decrease MDA in some period.It could infer that the suitable LDR pretreatment could play a protective role in the brain radiation injury.