^(137)Csγ射线慢性照射诱导大鼠血MDM2基因表达改变研究

Study on expression changes of MDM2 gene in SD rats' blood after chronic ^(137)Csγ ray irradiation

目的探讨长期慢性137Csγ射线照射对大鼠血中MDM2基因表达改变的影响。方法无特定病原体级雄性SD大鼠120只,随机分成1个对照组,11个剂量组,每组均为10只,各剂量组137Csγ射线慢性累积照射分别为0.05、0.10、0.20、0.40、0.60、0.80、1.00、2.00、3.00、4.00、5.00 Gy,对照组不予照射。照射完成后采腹主动脉血,利用实时荧光定量聚合酶链反应法检测各组血中MDM2基因表达的剂量-效应关系。结果各剂量组和对照组比较,血中MDM2基因的表达量均发生变化,从整体水平看随受照剂量的增加,基因表达量先上升后下降。其中,0.05、0.10 Gy剂量组中的基因表达量升高,其后0.20~1.00 Gy剂量范围MDM2基因的相对表达量出现一定程度回落,以0.20 Gy剂量组中的基因表达量降至最低点;0.20~2.00 Gy剂量范围随着照射剂量增大,MDM2基因的相对表达量呈线性关系升高,2.00 Gy剂量组的MDM2基因表达量最高;其后随着剂量的增加,MDM2基因的相对表达量再次出现下降趋势。拟合建立了0.20~2.00 Gy剂量范围内MDM2基因表达量与照射剂量之间的回归方程为^y=1.918 9 x+0.386 0,决定系数=0.99,P<0.01。结论慢性累积照射可诱导大鼠血中MDM2基因表达发生改变,其总体表达趋势是先上升后下降,其中0.20~2.00 Gy剂量内MDM2基因表达量与照射剂量有较好的剂量-效应关系。

Objective To explore the changes ofMDM2 gene expression in SD rats＇ blood induced by chronic 137Cs γray irradiation. Methods 120 SPF SD rats were randomly divided into 11 dose groups and 1 control group, with 10 rats in each group. 11 dose groups were respectively exposed toγ ray of 137Cs with the chronic accumulated irradiation doses at 0. 05, 0. 10, 0. 20, 0. 40, 0. 60, 0. 80, 1.00, 2. 00, 3.00, 4. 00, 5.00 Gy, while control group was not exposed. The changes of MDM2 gene in peripheral blood were detected by real-time PCR. Results After irradiation, the expression of MDM2 gene in rats＇ peripheral blood up-regulated generally then decreased compared with that in the control group. Spe- cifically, from 0. 10 Gy to 0. 20 Gy, the expression of MDM2 gene decreased with the increase of irradiation dose. Then, from 0.20 Gy to 2.00 Gy, the expression of MDM2 gene increased gradually compared with that of the control. At the dose range of 0. 20 - 2. 00 Gy a linear regression equation （ y = 1. 918 9 x ＋ 0. 386 0, determination coefficient = 0.99, P 〈 0. 01 ） was obtained using statistics regression analysis method. After 2. 00 Gy of exposure the expression of MDM2 gene decreased gradually. Conclusion 137 Cs γray chronic irradiation can induce the changes of MDM2 gene expression in pe- ripheral blood of rats, and the gene expression level was first up-regulated then decreased, there was good dose-effect rela- tionship in gene expression with the exposure of 0. 20 - 2. 00 Gy of irradiation.