氚β射线出生前照射致大鼠大脑甘氨酸含量改变的相对生物效应研究

STUDY ON RBE FOR THE CHANGES OF CEREBRAL AMINO ACID CONTENTS IN RATS PRENATALLY EXPOSED TO TRITIUM β-RAYS

对2组妊娠11 d 的大鼠分别注入氚水(HTO)和用^(137)Cs γ射线照射,以仔鼠出生后18 d 时大脑甘氨酸含量的改变为生物学终点,观察两种辐射的剂量效应曲线,并将两者比较,求出氚的 RBE值。结果表明,仔鼠受氚β射线和^(137)Cs γ射线照射,吸收剂量范围分别为0.0038—1.9 Gy 和0.07—2.68 Gy,仔鼠大脑甘氨酸含量皆随剂量的增加而增加(P<0.01);大脑甘氨酸含量增加的百分数 Y 与剂量 D(Gy)可拟合成对数直线回归方程(?)_β=113.9+30.1 lgD 和(?)_γ=86.2+49.7 lgD。氚β射线的 RBE 值在吸收剂量1.9—0.19 Gy 时为2.8—6.08。

Pregnant rats were divided in two groups and exposed to tritiated water(HTO)β-rays by single injection of HTO at llth day of gestation and to ^(137)Cs γ-rays from 11th dayto 19th day of gestation,respectively.The changes in cerebral amino acid content of their18-day-old off springs were used as the biological end piont.The dose-effect relationships forboth radiations were observed and the RBE values for tritium β-rays were calculated.The re-sults show that under both conditions of exposure,the cerebral amino acid content in youngrats increased with the doses of HTO or ^(137)Cs γ-rays. The data of the percentage(Y,%)in-crease of cerebral amino acid content and the logarithm of absorbed dose(D,Gy)gave agood fit to linear regression eguation.For HTO β-rays in range of the doese from 0.0038—1.9 Gy,it was (?)_β=113.9+30.1 lgD and for ^(137)Cs γ-rays in range of the doese from 0.07—2.68 Gy, it was (?)_γ=86.2+49.7 lgD.The RBE values for tritium β-rays increased with de-crease of absorbed doese and in dose range from 1.9 to 0.19 Gy, they changed from 6.8 to2.8.