Experimental Study Of Iodine Excess On The Morphology Of Cerebral Cortex And Hippocampus In Adult Rats

ObjectivesTo observe the morphological changes of the pyramidal cells in internalpyramidal layer of cerebral cortex motor area, and of the neurons and the astrocytes in hippocampus in adult Wistar rats after fed with different concentration iodine water for 3 months and 6 months. To study the effects of iodine excess on the functions of cerebral cortex and hippocampus .MethodsTwo months Wistar rats weighted 80-100 grams, half of male and female,were divided into six groups randomly: low iodine group (LI group), normal iodine group (NI group), 5, 10, 50 and 100 folds of normal iodine intake groups (5HI, 10HI, 50HI and 100HI groups). The animals of LI group were fed with diet derived from endemic goiter area containing iodine of 50μg/kg, and drank deironized water. The other rats were fed with standard diet containing iodine of 300μg/kg. The rats NI group drank tap water containing iodine of 5μg/kg, and the rats of 5HI, 10HI, 50HI and 100HI groups drank different concentration KI tap water respectively. According to intake of the water and the diet everyday, the iodine intake of 5HI, 10HI, 50HI and 100HI groups is 5, 10, 50 and 100 folds of that of NI group respectively. All rats were sacrificed at 3 month and 6 month respectively. 10 rats from each group were selected randomly to observe the morphological changes of cerebral cortex and hippocampus. The whole brains were weighed. The expressions of NSE in the pyramidal cells of cerebral cortex motor area and in the neurons of hippocampus, the expressions of GFAP in the astrocytes of hippocampus were examined by immunohistochemistry, and volume density (Vv), numerical density on area (Na) and the average of gray scale were measured. The pyramidal cells of cerebral cortex motor area were also examined by silver impregnation technique, and the dendrites arising from basal portions of the pyramidal cells were counted.Results1. Compared with NI group, the weights of brains in LI group decreased. But thechanges in brain weights were insignificant in all iodine excess groups.