氚水β射线宫内照射对仔鼠脑发育和学习记忆能力的影响

Effects of prenatal exposure to tritiated water β rays in uterus on brain development and learning and memory of rat offsprings

目的探讨氚水β射线宫内照射对Wistar种大鼠脑发育和学习记忆能力的影响。方法用注射器将2ml蒸馏水或1-3ml不同浓度氚水经腹腔注入妊娠11d龄的母鼠体内，使得实验组母鼠体水氚放射性浓度在0-3．7GBq／L范围内。对宫内受照过的38d龄仔鼠进行条件饮水反应测试，实验结束脱颈椎处死仔鼠。开颅取出大脑，左半球脑组织进行常规组织化学分析，右半球脑组织用于脑内游离氨基酸含量的HPLC测定。结果随着母鼠体内注入氚水浓度的逐渐增加，其所产仔鼠大脑纵向长度、大脑皮层第V层锥体细胞数、海马CA3区细胞数及海马游离氨基酸含量逐步降低，相应地，仔鼠38-42d条件饮水测试成绩逐渐降低。且仔鼠大脑纵向长度缩短百分率、大脑皮层第V层锥体细胞数、海马CA3区细胞数减少百分率及海马游离羟脯氨酸含量增加百分率与仔鼠吸收剂量之间均可拟合成直线回归方程：Y=A＋BlgD。结论在0．0038-1．9Gy吸收剂量范围内，宫内受照仔鼠学习记忆能力明显受损。

Objective To invesigate the effects of prenatal exposure to tritiated water β rays in uterus on brain development and learning and memory of the Wistar rat offsprings. Methods Pregnant female rats on the 11 th day were divided into control group and four experiment groups. 2 ml distilled water and different concentrations of tritiated water（HTO） were peritoneally injected into different groups by syringe and the radiation concentration of tritium in water of the pregnant rat bodies in experiment groups were made to 0 - 3.7 GBq/ml. The conditional drink- ing behaviour test was performed on the offsprings exposed to tritiated water β rays in uterus on the 38th day after their birth. After test completion, the offsprings were executed by cervical vertebrae dislocation and cerebra were taken out,left cerebral hemisphere tissue was analyzed by conventional histochemical technique and right cerebral hemisphere tissue was used to determine the concentration of free amino acids by HPLC. Results With the increase of the concentration of HTO injected into pregnant female rat bodies, the cerebral portrait length, the number of pyramidal cells in cerebral cortex V stratum,cone cells in CA3 section of cerebral hippocampus and the concentration of free hydroxyproline in cerebral hippocampus of the offsprings gradully decreased. The rate of conditional drinking response also decreased step by step. Besides, the relationship between the above five indexes and abosorbed close in the offspring bodies all featured linear regression equation ： Y = A ＋ B lgD. Conclusion In the range of 0. 003 8 - 1.9 Gy absobed dose, the learning and memory ability of offsprings prenatally exposed to HTO β rays was significantly impaired, compared with the control.