H Wan1, S L Gong, S Z Liu. 1. MH Radiobiology Research Unit, Jilin University, Changchun 130021, China.
Abstract
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 the neurons of mouse hypothalamus. RESULTS: The results showed that cAMP content in mouse hypothalamus immediately increased significantly and reached the peak value in 15 min after irradiation, and then returned to near sham-irradiation level 1 h after irradiation, followed by a small fluctuation of increase and decrease; 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, reached its peak value within 1 h, began to abate 2 h with its total disappearance 8 h after irradiation; the expression of Fos protein reached its peak value 8 h after irradiation, and then gradually returned to sham-irradiation level 48 h after irradiation; the expression of POMC mRNA decreased significantly 1 h after irradiation and remained at a lower level in the observation period of 12 h. 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.
OBJECTIVE: Effects of low dose radiation on signal transduction of neurons in mousehypothalamus 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 the neurons of mousehypothalamus. RESULTS: The results showed that cAMP content in mousehypothalamus immediately increased significantly and reached the peak value in 15 min after irradiation, and then returned to near sham-irradiation level 1 h after irradiation, followed by a small fluctuation of increase and decrease; 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, reached its peak value within 1 h, began to abate 2 h with its total disappearance 8 h after irradiation; the expression of Fos protein reached its peak value 8 h after irradiation, and then gradually returned to sham-irradiation level 48 h after irradiation; the expression of POMC mRNA decreased significantly 1 h after irradiation and remained at a lower level in the observation period of 12 h. CONCLUSION: These findings implicate that low dose radiation may potentiate the activity of the neurons in mousehypothalamus, expedite their signal transduction, and down-regulate the functions of hypothalamus-pituitary-adrenocortical axis.