Effects Of Gamma-irradiation On Serum Iron And Its Mechanisms And The Study Of Serum Iron-based Biodosimeter

Iron, an important trace element, is closely related with the generation of radiation biological effect.In this study, serum iron concentration of gamma-irradiated mice was detected using 5-Br-PADAP spectrophotometric method. The result shows that serum iron increased immediately after irradiation and was positively correlation with dose. Then, it fell on 0~7 days after irradiation and a recovery plateau observed during the 7th and 21 st day post-irradiation. Further more, the single variable method was used for analyzing mechanisms of the increased level of serum iron in 4 Gy gamma-irradiated mice. Thus, ferrous concentration, free radical, activity of ceruloplasmin, copper concentration and ferritin concentration in serum of irradiated mice were measured. Results show that :(1) serum ferrous concentration of irradiated mice was inversely correlation with dose;(2) serum iron concentration of irradiated mice pretreated by free radical scavenger was significant lower than irradiated group, ROS concentration of irradiated mice was increased immediately after irradiation and then fell to the normal level at the 7th day post-irradiation;(3) the ceruloplasmin activity of irradiated mice was increased, whereas the serum copper concentration decreased;(4) ferritin concentration in serum of irradiated mice was increased. Thus, main reasons of the increase in serum iron concentration in irradiated mice may be:(1) free radicals induced by irradiation can change ferrous ions to be ferric ions;(2) irradiation inducing the change of ceruloplasmin activity, the oxidizing effect of ceruloplasmin on ferrous irons was achieved by transfer of electrons from ferrous ions to cupric ions;(3) the damaged cells in tissues induced by irradiation would released a large amount of ferritin into blood, which could increase serum iron content. However, free radicals induced by irradiation and the ferritin released into blood can only affect the serum iron content of irradiated mice within 7 days post-irradiation, while the ceruloplasmin can influence the serum iron content until the 21 st day post-irradiation.In this study, serum iron of irradiated mice with the different dose was measured immediately and at the 7th day after irradiation. Two dose-response curves were obtained. One is a linear equation of y = 0.420x+2.08 for dose estimating during 0~6 days after irradiation. Another is a linear square equation of y = 0.01x2+0.204x+2.10 for dose estimating during 7~21 days post-irradiation. According to dose-response curves, double blind method was using for estimating the dose of irradiated mice. Results show that the biodosimetry based on serum iron in gamma-irradiated mice is simple, rapid and effective.This is the first time proposed the view that irradiation could induce the valence change of iron. The researches of effects and mechanisms of gamma-irradiation on serum iron can provide some basis for studying radiation biological effect in the future. In addition, the study of serum iron-based biodosimeter has great significance and effect to the development and application of biological dosimeter.