低剂量辐射对小鼠下丘脑神经元信号传递的影响

目的：探讨低剂量辐射对小鼠下丘脑神经元信号传递的影响。方法：应用竞争蛋白结合分析，放射免疫分析，原位杂交和免疫组化方法观察75mGy X射线全身照射对小鼠下丘脑神经元cAMP和cGMP含量及c-fos mRNA,FOs蛋白和前阿黑皮素（POMC）mRNA表达的影响。结果：照射后15min小鼠下丘脑cAMP含量立刻明显增高并达峰值，1h回复接近假照组水平，cGMP含量的变化与cAMP含量的变化基本相反，而cAMP/cGMP比值的变化与cAMP含量的变化基本一致，照后15min下丘脑神经元出现c-fos mRNA表达，照后8h FOs蛋白表达峰值。POMC mRNA表达在照后1h明显降低，结论：低剂量辐射可激活小鼠下丘脑神经元，促进其信号传递，以及下调下丘脑－垂体－肾上腺皮质轴的功能。

Effects of low dose radiation on signal transduction of neurons in mouse hypothalamus

Objective\ Effects of low dose radiation on signal transduction of neurons in mouse hypothalamus were investigated. Methods\ In the present study competitive protein binding assay,radioimmunoassay, in situ hybridization and immunohistochemistry were used to observe the effects of whole\|body irradiation with 75 mGy X\|rays on the contents of cAMP and cGMP and the expressions of c\|fos mRNA,Fos protein and proopiomelanocortin (POMC) mRNA in neurons of mouse hypothalamus. Results\ The results showed that cAMP content in mouse hypothalamus immediately increased significantly and reached the peak value at 15 min after irradiation,and then returned to near the sham\|irradiation level 1 h after irradiation;the changes of cGMP content were basically opposite to those of cAMP content,while the changes of cAMP/cGMP ratio were basically consistent with those of cAMP content.The expression of c\|fos mRNA in the neurons of hypothalamus appeared 15 min after irradiation;The expression of Fos protein reached its peak value 8 h after irradiation.The expression of POMC mRNA decreased significantly 1 h after irradiation. Conclusion\ These findings implicate that low dose radiation may potentiate the activity of the neurons in mouse hypothalamus,expedite their signal transduction,and down\|regulate the functions of hypothalamus\|pituitary\|adrenocortical axis.