Effect Of Different Dosages X-ray Irradiation On Developing Filial Mice

OBJECTIVE:To explore the synthetical effect on developing mammal,provide a basis for developmental biology,clinical cure of irradiation damnification and prevention of irradiation. Body weight,growth of skin,activities of antioxidant-enzyme in many important tissue,histological structure and expression of c-Fos and KGF in cutis of developing filial mice after irradiation with different dosages of X-ray were determined.METHODS:Age of 5-7 days filial mice were chosed and divided into six groups (32 per group).The six groups irradiated by different dosages(0.0,0.5,2.0,3.5,5.0,6.5 Gy) X-rays respective every day and persisted three days. Changes of Body weight and skin of filial mice were observed before and after the irradiation on schedule(0,2,5,10,20 d). Eight filial mice of every group were killed (1,5,10,20 d) after irradiation, and effect on activity and content of Superoxide dismutase(SOD),Catalase (CAT),and Maleic dialdehyde (MDA) in liver and kidney were determined after this tissue be skived from this filial mice and confect to liquid supernatant. Changes of histological structure were observed by histological methods and thickness of pellicle,derma and cutis were measured. Expression of c-Fos and KGF in skin of filial mice were observed by immunohistochemistry methods. The expression intensity of them was analyzed by IPP.RESULT:1. X-ray irradiation affected body weight of filial mice. Body weight of filial mice increased after irradiation with 0.5 Gy X-ray. In other groups,body weight decreased firstly and then increased slowly,but it was always lower than the control group.2. X-ray irradiation affected the growth of skin of filial mice. Skin started to be denuded of hairs at 3 d and end at 7 d after irradiation with 3.5,5.0 and 6.5 Gy of X-ray. But the new hairs resurged at 10 d and it comeback to the normal level approximatively at 20 d. Purple spot appeared in the skin of 6.5 Gy group filial mice.3. Activities of antioxidant-enzyme in liver and kidney of filial mice changed after X-ray irradiation. SOD activity in liver and kidney in 0.5 Gy group filial mice increased in the early time after irradiation,subsequently decreased to the normal level gradually. In other groups,SOD activity decreased firstly and then increased slowly,but it was always lower than the control group. MDA content in liver and kidney in 0.5 Gy group filial mice decreased in the early time,then increased to the normal level slowly. In other groups,it obviously increased firstly and then decreased slowly, but always higher than the control group. CAT activity in liver and kidney in 0.5,2.0 Gy groups filial mice decreased in the early time,then increased. However,in other groups the activity increased in the early time and decreased in the following days. There was a trend that the activity and content of target enzyme in liver and kidney recovered slowly to the normal level after irradiation,but the time and extent of the changes in this two tissue were different.4. X-ray irradiation affected the histological structure of skin of filial mice. There was not visible changes in histological structure of skin in filial mice after irradiation with 0.5,2.0 Gy X-ray. But the different changes appeard in histological structure of skin in filial mice of other groups. Thickness of pellicle,derma and cutis in filial mice decreased except 0.5 and 2.0 Gy groups. It recovered to the normal level period of time after irradiation.5. Expression of c-Fos and KGF in skin of filial mice influenced by X-ray irradiation. There c-Fos and KGF immunoreaction appeared in skin of filial mice, and the intensity of the immunoreaction was increased with augmentation of dosages. Expression of c-Fos increased in the early time and decreased in the following days; Expression of KGF increased in the beginning and than decreased,but increased later, and comeback to normal level finally.CONCULSION:High dosages irradiation will cause serious damage to alimentary tract, especially to the epithelia of small intestine which have high sensitivity to radiation. So it may be the main reason why the body weight of the filial mice decreased after X-ray radiation. Capillary vessel in skin have very high sensitivity to radiation. Irradiation can lead abnormity in capillary vessel of skin. So injection and purple spot appeared in the skin after large dosages X-ray irradiation. Large dosage of irradiation can also cause the keratinization of hair follicle and damage on epithelial cells,make the hair loose and desquamate finally. Free radical produce by low dosage X-ray could activate the immune activity and improve antioxidant-capability of tissue. So the activities of antioxidant-enzyme in tissue of the filial mice increased and content of lipid decreased after the irradiation. Free radical which produce by large dosage X-ray and could not be eliminate timely will assault cell and cause damage to tissue and activities of antioxidant-enzyme decreased. There are high radiation sensitivity on skin which is the first barrier to external radiation enter into organism. So it suffer from serious damnification. Histological structure of skin of the filial mice obviously changed after large dosage irradiation. Radiation can induce expression of c-Fos and KGF in skin of filial mice. Intensity of the expression relate to dosage and time of radiation and the radiation sensitivity of tissue. There was a trend that the body weight,growth of skin,activity of target enzyme,expression of c-Fos and KGF and histological structure recovered slowly to the normal level after irradiation. The irradiation of X-rays affects the weight,growth of skin,activity of target enzyme,expression of c-Fos and KGF and histological structure of developing filial mice significantly. And the dosages contributed more to the damage effect than treatment time. In short,large dosages of irradiation would cause disadvantageous effect on developing filial mice,but the organism also have enginery to resist the radiation.