氚水照射对发育中的中枢神经系统影响——低水平氚剂量阈值研究

目的研究大、小鼠出生前受氚水照射对发育中的中枢神经系统影响的剂量阈值。方法选用孕龄１２５天和１３０天的Ｃ５７ＢＬ／６Ｊ小鼠和Ｗｉｓｔａｒ大鼠，每克体重注入氚水活度（×１０４Ｂｑ）分别为０００、２４０９、４８１８和１４４５４，观察仔代生长发育、神经行为、脑细胞学、脑神经肽含量、海马神经元和Ｃａ２＋电流幅度改变等５６项生物学指标与对照组比较出现显著差异的最低剂量。结果以大鼠和小鼠为实验对象，观察的５６项生物学指标中，氚的致畸阈值：８０４％的指标分布在００３０～００９２Ｇｙ范围内，有少数指标（１９６％）分布在００９３～０３００Ｇｙ范围内。结论通过上述研究结果证明低水平氚照射对发育中的中枢神经系统影响存在剂量阈值。

Threshold dose to developing central nerve system of rats and mice from prenatal exposure to tritiated water

Objectives To study the threshold dose to the developing central nerve system of rats and mice from prenatal exposure to tritiated water. Methods Pregnant adult C57BL/6J strain mice and Wistar strain rats were irradiated with betarays from HTO by a single intraperitoneal injection on the 125th and 13th days of gestation.The activities of HTO were 2409,4818 and 14454 (104Bq/g bw),respectively.Fiftysix parameters including postnatal growth,neurobehavior,pathology of brain,neuropeptide contents,changes of hippocampal neurons,Ca2 conductance of hippocampal neurons etc were used to test the teratogenic threshold dose (the lowest dose was different from that of the control). Results Of the observed 56 parameters of rats and mice 804% indicated that the threshold doses for prenatal HTO exposure ranged from 0030 Gy to 0092 Gy,and the other 196% showed the threshold doses from 0093 to 0300 Gy. Conclusions There exists threshold dose from the low level tritiated water irradiation of the developing central nerve system