Effects Of Different Levels Of Iodine Intake On The Growth And The Development Of Brain In The Second Filial Generation Mice

Objective:To study the influence of different iodine intake upon the growth of the second filial generation Balb/c mice in 20-day, 40-day and the development of cerebral ,cerebellum cortex and hippocampus' morphous, further to approach the influence of iodine deficiency and iodine excess on the development of the second filial generation mice cerebral, cerebellum and their function.Methods:One month Balb/c mice weighted 16～20 gram, half of male and female, were divided into five groups randomly and given by different dosage of KI which were low iodine(LI), normal iodine(NI), 5 fold high iodine(5HI), 10 fold high iodine(10HI), 50 fold high iodine(50HI). Group LI were raised low iodine forage (containing iodine of less than 50μg/ kg), The other four groups were raised standard diet containing iodine of 300μg /kg. The two forages were containing the same match fare just different iodine. Group LI drank deionized water, and the other groups drank deionized water containing different KI concentration respectively. The concentrations of KI were 10μg/L(NI), 1200μg/L (5HI), 2700μg/L (10HI) and 14700μg/L (50HI) in the water. According to the intake of water and the diet everyday, the mice's iodine intake of the whole day were estimated as follows: <1μg/d(LI), 1.5μg/d(NI), 7.5μg/d (5HI), 15μg/d(10HI), 7.5μg/d (50HI). After three months, the mice mated and their second filial generaions of 20-day and 40-day were observed. The whole brains were weighed. After fixation in formalin and embedding, the cerebrum were stained with cresyl viollet and immunohistochemistry (NSE, GFAP, MBP). The morphology of cerebral cortex and the neuron, astrocyte, ligodendrocyte in hippocamp were observed. The expression of NSE in the neuron of hippocampus CA3 region, the expression of GFAP in the hippocampus CA1 region and the expression of MBP in hippocampus were examined by immunohistochemistry, and numerical density on area(N_A) and average optical were measured.The expressions of NSE in the neurons of the Purkinje layer, the expressions of GFAP and MBP in the glial cell in the cerebellum medulla were examined by immunohistochemistry, and volume density (Vv), numerical density on area (N_A) and average optical density were measured.Results:1 Growth and development of the second filial generation: In the second filial generation of 20-day, compared with group NI, the weight, brain weight, body length, hind limb length fell behind in group LI and group 50HI. In the second filial generation 40-day, condition was more serious.2 Cerebral cortex and Hippocampus: In the second filial generations of 20-day, 40-day, compared with group NI, the expression of NSE, GFAP , MBP, numerical density on area and the average optical density were decreased in group LI and group 50HI. The contrast was statistical significant.3 Cerebellum: In the second filial generations of 20-day, 40-day, compared with group NI, the expression of NSE, GFAP , MBP, Vv, Na, AOD were decreased in group LI and group 50HI. The contrast was statistically significant.Conclusions:1 In mice, iodine deficiency and excess can cause hypothyroidism, then affected the physical development, and condition was more serious in iodine deficiency group.2 In critical period of mice, iodine deficiency and severe iodine excess can both influence the development of cerebral,cerebellum cortex and hippocampus.