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本研究用1.5月龄的雄性Wistar大鼠600只,随机分为实验组和对照组,每组50只动物。实验组动物一次腹腔注射不同放射性强度的~(125)I或~(131)I溶液后观察2年。活存的动物用乙醚麻醉,心脏取血收集血清并解剖取甲状腺称重。以血清中T_3、T_4、r-TSH水平,相对甲状腺重量比较~(125)I和~(131)I的生物效应。结果表明,相对甲状腺重量减至对照的80％和60％时,~(125)I和~(131)I的等效剂量比值分别为1.5和1.2,若以血清中T_3、T_4和r-TSH的相对含量进行比较,其等效剂量的最大估计比值分别为2.1,19和4.5。 总之,~(125)I和~(131)I导致同样或类似的生物效应,所需~(125)I的剂量比~(131)I剂量高1.2—19倍,其结果因观察指标不同而异。本研究获得的资料,可供内照射剂量控制限定和防护标准的修订以及评价放射性碘进入体内后危险度做参考。
In this study, 600 male Wistar rats of 1.5 months old were randomly divided into experimental group and control group with 50 animals in each group. The experimental animals were intraperitoneally injected with ~ (125) I or ~ (131) I solution with different radioactive intensity for 2 years. Live animals were anesthetized with ether, blood was collected from the heart and dissected to take thyroid grafts. The biological effects of ~ (125) I and ~ (131) I were compared with the levels of T_3, T_4 and r-TSH in serum and relative thyroid weight. The results showed that the equivalent doses of ~ (125) I and ~ (131) I were 1.5 and 1.2, respectively, when the relative thyroid weight was reduced to 80% and 60% of the control. The T_3, T_4 and r-TSH Of the relative content of the comparison, the equivalent dose of the maximum estimated ratio were 2.1,19 and 4.5. In summary, ~ (125) I and ~ (131) I lead to the same or similar biological effects, requiring ~ 125 I I to dose 1.2 ~ 1.9 times higher than ~ 131 I doses. different. The information obtained in this study is available for internal control of dose limits and revision of standards of protection and for evaluation of the risk of radioiodine entering the body for reference.