Effects Of ～(60)Co Radiation On Hippocampal Function And Formation Lesion Of Rats

Objective:To estimate the neurobehavior and the Circulating endothelial cells(CECs)changes in the different time after the different doses ⁶⁰Co irradiation on the encephalon of rats;hippocamp ultrastructure and astrocyte change.Methods:One hundred and eight rats were randomly divided into 3 groups:control group,single-dose 10Gy ⁶⁰Co radiation group and single-dose 30Gy ⁶⁰Co radiation group,there were 36 rats in each group.The neurobehavioral changes were observed by Morris water labyrinth at 1 week,1 month and 3 months respectively after radiation to 9 rats from each group.The CECs taken from right ventricular blood were counted after Morris water mase test. hippocamp ultramicrostructure and GFAP positive cell were detected after perfusion of encephalon.Results:â‘ Neurobehavior chang There were no significant differences for 3 groups in terms of the swim lantency,the time of swim in the platform quadrant and the times of swim through the plateau region at 1 week after radiation.At 1 month and 3 months after radiation,the swim lantency was significantly prolonged(30Gy group＞10Gy group＞control group,p＜0.05),the time of swim in the platform quadrant was signicantly reduced(control group＞10Gy group＞30Gy group,p＜0.05)and the times of swim through the plateau region were significantly decreased(control group＞10Gy group＞30Gy group,p＜0.05).â‘¡CECs change At 1 week and 1 month after irradiation, the numbers of CECs were significantly increased(control group＞10Gy group＞30Gy group,p＜0.05),however,at 3 months,there was no significant differences for 3 groups.Good correlation between the numbers of CEC and the swim lantency was demonstrated in this study at 3 months for both group B and C(r_10Gy=0.97,r_30Gy=0.95).â‘¢Hippocamp dentate gyrus change There were no significant differences for 3 groups in terms of GFAP positive cell at 1 week,at and 1 month 3 months after irradiation,the numbers of GFAP were significantly increased(control group＞10Gy group＞30Gy group,p＜0.05).of ultrastructural changes were found under electronic microscope.Vascular endothelium became thinner,pinocytotic vacuole of endothelium increased significantly,and the tighe junctions that connect capillary endothelial cells were ruptured.The glial perivascular feet and astrocytes surrounding the basement membrance were swallon.Conclusions:The number of CECs was correlated to radiation-induced brain injury;more irradiation dose and long duration after irradiation there is more hippocamp lesion.