Influence Of Different Dosage Of KIO₃ On The Function Of Reproduction In Rasts And The Development Of Cerebellum And Cerebrum In Their Filial Generations

Objectives:To study the effect of different dosage of KIO3 upon the function of reproduction in Wistar rats and the development on the cerebrum and cerebellum in their filial generations of 1-day, 20-day and 60-day. Methods:One month Wistar rats weighted 120¹40gram, half of male and female, were divided into six groups randomly and given by different dosage of KIO₃ which were low iodine(LI),normal iodine(NI),5 fold high-iodine(5HI),10 fold high-iodine (10HI),50 fold high-iodine(50HI),100 fold high-iodine(100HI). After three months, the rats mated and their filial generations of 1 -day, 20-day and 60-day were observed. The changes of cerebral and cerebellar development were observed. All rats were sacrificed at 1, 20 and 60 days respectively, and 10 filial generations of rats from each group were selected randomly to observe the morphological changes of cerebrum and cerebellum. The whole brains were weighed. After fixation in suffer cushion of formalin solution, the cerebrum and cerebellum were stained with HE, Spoerrl, meliorated Golgi silver impregnation and immunohistochemistry. The density and distributional types of spinal processes in pyramidal cells, the exponent, the maximum cross section area, the mean volume and surface of cortex pyramidal cells were counted. The expressions of NSE in the neurons of hippocampus, the expressions of GFAP and MBP in the astrocytes of hippocampus were examined by immunohistochemistry, and volume density (V_v), numerical density on area (N_a) and the average of gray scale were measured. The pyramidal cells of cerebral cortexmotor area were also examined by silver impregnation technique, and the dendrites arising from basal portions of the pyramidal cells were counted, and the cross section area, the exponent, density and distributional types of spinal processes in cerebellum Purkinje cells were counted. Results:1. The conception rate and the number of filial generation in iodine deficiency was lower than the normal.The death rate was increased and the development of filial generation was later than the normal.In iodine excess, The death rate of female and filial generation were higher than the normal.2. Cerebral cortex motor area: In filial generations of 1-day, the density and distributional types of spinal processes in pyramidal cells, the exponent, the maximum cross section area, the mean volume and surface of cortex pyramidal cells were no remarkably change among different groups. The cerebral development of filial generations of 20-day and 60-day were later than the normal, especially in LI and 1OOHI groups.3. Hippocampus: In filial generations of 1-day, the changes of Vv and NA of neurons in CA3 region were insignificant in all iodine excess groups. But in 20-day and 60-day the expressions of NSE^GFAP and MBP were different. In contrast to NI group, the averages of gray scale of the neurons were lower in LI and 100HI groups;the changes of Vv, Na and the averages of gray scale of the astrocytes in CA1 region were significant decreased in LI and 100HI groups.4. cerebellum: In filial generations of 1-day, the cross section area , the exponent ,density and distributional types of spinal processes in cerebellum Purkinje cells were no remarkably change among different groups. With the prolong of drinking KIO3 water, the cerebellum development of filial generations of 20-day and 60-day were later than the normal.Conclusions:1. Hypothyroidism was observed both in iodine deficient and iodine excessrats,and then affected the reproduction function in female rats and the physical development in their filial generation,but more obvious in iodine deficiency rather than iodine excess.2. Both iodine deficiency and the dosage of KIO3 more than 50 times of normal iodine intake can affect on the development of the pyramidal cells of cerebral cortex motor area and the neurons in hippocampus cerebellar Purkinje cells.3. Iodine excess would affect the development of the the cerebrum and cerebellum in the filial generations, and the mechanism perhaps has relative with hypothyroidism induced by iodine excess. Wistar rats have high endurance to high doses of iodine, so iodine intaking within 50HI has no effect on their development of the the cerebrum and cerebellum in the filial generations.4. These findings above demonstrated that KIO3 in appropriate dosage was safe and effective for correction of iodine deficiency. No side effect was found in 5 and 10 fold of normal iodine intake. It showed that the safety range of iodine intake was wide, and 5 fold of normal iodine intake maybe the upper bound dosage.