小剂量γ射线全身照射对小鼠脑组织氨基酸类神经递质含量的影响

Influence of whole-body irradiation with low-dose γ-rays on amino acid neurotransmitter levels in mice brain tissue

目的 探讨小剂量γ射线全身照射后对小鼠中枢神经系统的影响。方法 将50只C57小鼠按随机表法分为健康对照组及0.5和1 Gy照射组。用60Co γ射线全身照射,吸收剂量为0.5和1 Gy,吸收剂量率为19.2 cGy/min,连续照射3 d,1次/d,照射后24和48 h取小鼠脑组织并匀浆,用高效液相色谱荧光法（HPLC）测定匀浆上清中氨基酸类神经递质（谷氨酸、天冬氨酸、γ-氨基丁酸及甘氨酸）含量。结果 与健康对照组相比,0.5 Gy γ射线照射后48 h以及1 Gy照射后24和48 h,小鼠脑内谷氨酸和天冬氨酸含量表达增高（t=-4.080、-3.935、-4.416、-3.630、-4.831和-4.656,P＜0.05）;而0.5 Gy γ射线照射后24 h小鼠脑内谷氨酸、天冬氨酸含量无明显改变。各照射组小鼠脑内γ-氨基丁酸和甘氨酸含量与健康对照组比较,差异无统计学意义。结论 小剂量γ射线短期全身照射对小鼠中枢神经系统具有轻度的兴奋作用。

Objective To investigate the biological effects of 12C heavy ions with different LETs,and to construct the dose-effect curves of chromosomal aberrations and micronucleus. Methods Human peripheral blood lymphocytes were irradiated with 0.5-5.0 Gy of 60Co γ-rays, 29 and 148 keV/μm 12C with a dose rate of 0.5 Gy/min, respectively. The colchicine method and cytokinesis-blocking method were applied to measure chromosome aberrations and micronuclei formation, respectively. Results The chromosomal aberrations induced by 29 and 148 keV/μm of 12C ion had a linear dose response,while the dose-response of micronucleus induction followed to a linear-quadratic model.Chromosome aberration and micronucleus frequency increased with the LET of 12C ions. However, the micronucleus frequency increased slowly when the radiation doses exceeded 3.0 Gy.Chromosomal aberrations induced by 148 keV/μm 12C ions increased significantly when the time of colchicine treatment was prolonged. Conclusions Chromosome aberration and micronucleus induced by 12C ions increased with the LET, and the micronucleus frequency increased with dose less than 3 Gy. The biological effects of 12C ions were stronger than those of low LET irradiation of γ-rays.