Effects Of Administration Of Selenium And Iodine On Liver And Brain Deiodinase And Thyroid Cytokines Of EAT Rats

Objective To study the effect of selenium and iodine on thyroid morphology, the level of thyroid hormones and autoantibodies, the activity of liver and brain deiodinase enzymes, and the expression of thyroid cytokines of Experiment autoimmune thyroiditis(EAT) rats. To explore the effect of selenium and iodine on development of EAT through metabolism and immune aspects.Method 1.48 female Lewis rats were divided into 4 groups:C, M, M+I+, M+I". Immuned with pTg and CFA. Intervented with different iodine animal feeds. Killed all rats 16 weeks later. Observed the pathological changes of thyroid, detected the levels of T3, T4, TGAb and TMAb, the capacity of liver and brain deiodinase enzymes, and the expression of thyroid cytokines.2. Female Lewis rats were divided into:C, M, M+Se+, M+Se". Intervented M, M+Se+ and M+Se- groups with different levels of selenium feeds for two weeks, then immuned with. pTg and CFA. Observed the pathological changes of thyroid, detected the levels of T3, T4, TGAb and TMAb, the capacity of liver and brain deiodinase enzymes, and the expression of thyroid cytokines.3. Female Lewis rats were divided into 8 groups:C, M, M+I+Se+, M+I+Se, M+I+Se-, M+I-Se+, M+I-Se, M+I-Se-. Immuned with pTg and CFA to each group except C. At the same time, intervented with different levels of iodine feeds for four weeks, then with the association of different levels of selenium and iodine for twelve weeks. Observed the pathological changes of thyroid, detected the levels of T3, T4, TGAb and TMAb, the capacity of liver and brain deiodinase enzymes, and the expression of thyroid cytokines and analysised the interaction and the main effect of selenium and iodine.Results 1. The levels of T3, T4, TGAb, TMAb in immuned groups were significantly higher than C (P＜0.05); T4 in M+I+was much higher than M and M+I" group(P<0.05); the concentration of T3 in M+I- group was much higher than M group and M+I+ group (P＜0.05); the levels of TGAb and TMAb in M+I+ group was higher than M group and M+I- group (P＜0.05); in M group, the capacity of DII was lower than C group(P<0.05); in M+I" group, the capacity of D I and DII were much higher than M and M+I+ group(P<0.05), and in M+I+ group, it was lower than M group; compared with C, the expression of Thl cytokines, TNF-a and IL-2 were much higher in M group; Th2 cytokines, such as IL-4 and IL-10, were decreased; the expression of cytokines was the highest in M+I- group.2. Compared within EAT groups, DⅠand DⅡin M+Se+ group was higher than M group, and the capacity of DⅠin M+Se- group was lower than M group(P＜0.05); compared among EAT groups, the expression of IL-2 was increased along with the the level of selenium intake, but TNF-a had the opposite tendency. The expression of IL-4 and IL-10 were increased along with the increas uptake of Se.3. It had no interaction and main effects of the component administeration between iodine and selenium on T3, T4, TGAb and TMAb. Iodine had a main effect on activity of DⅠand DⅡ; there was interaction on the expression of cytokines. In iodine overdose groups, the expression of TNF-a in high and low selenium groups were both increased, IL-4 and IL-6 was decreased along with the increase uptake of selenium; among low iodine groups, the expression of TNF-a,IL-2,IL-10,IL-6 in M+I-Se+ group were much higher than M+I-Se- group.Conclusion 1. The destruction of thyroid follicular of EAT rats could be increased by iodine overdose, and iodine deficiency could lead to hyperplasy of follicular epithelial cells. Whether in iodine overdose or iodine deficiency condition, selenium supplement could release the destruction of thyroid follicular, and selenium deficiency would increase it.2. The capacity of DⅠand DⅡof EAT rats could affect by the level of selenium and iodine. Iodine overdose could decrease the activity of DⅠand DⅡof EAT rats, iodine deficiency and selenium supplement could increase them. Selenium deficiency could decrease the activity of DⅠmerely, it maybe the "significance priority principle" of biosystem. Iodine had the main effect on the activity of DⅠand DⅡwhen intervented with combination of selenium and iodine.3. The expression of Thl cytokines had an dominant position in EAT rats. Iodine deficiency could increase the expression of cytokines; selenium could affect the development of EAT by the expression of cytokines. Selenium and iodine had interaction effects on the expression of cytokines of EAT rats.