The Effect Of Administration Of Iodine And Selenium On The Antioxidation And Apoptosis With Autoimmune Thyroiditis

Objective To study the influence of trace element iodine and selenium on the level of autoantibodies and the antioxidative capacity with autoimmune thyroiditis; to investigate the effect of iodine and selenium on the expression of apoptosis proteins with autoimmune thyroiditis; to explore and test an brief and effective approach of setting experimental autoimmune thyroiditis (EAT) model.Method 1.Rats were randomized to groups Control and Model, rats in group Model were injected with 0.8 mg porcine thyroglobulin for 3 times in a 2 weeks interval. Executed the rats and drew the relative materials for detection after the third immunization. Detected the level of autoantibodies TGAb and TMAb, observed the pathological changes of thyroid and evaluated the effect of the model. 2. Different dose of iodine were administered orally to groups of EAT rats by feed at total doses of 0.90 mg I/kg (group M), 18 mg I/kg (group M+I⁺) and <0.02 mg I/kg (group M+I^-). Then collected tissues and serum for the detection of the fluctuation of autoantibodies, antioxidation status in liver and brain and the expression of apoptosis proteins in thyroid. 3. Different doses of selenium were administered orally to groups by feed at total doses of 0.20 mg/kg (group M and C), 2.00 mg/kg (group Se⁺ +M) and 0.02mg/kg (group Se^- +M). Injected antigen to set EAT model 2 weeks later. The daily intake of selenium approximate 4μg (group M and C), 40μg (group Se⁺ +M), 0.4μg (group Se^- +M) respectively. Then collected relative samples for the detection of the change of autoantibodies, antioxidation and apoptosis protein. 4. The EAT rats were administered different dose of iodine and selenium for a certain period. The rats were randomized into 6 groups as M+I⁺Se⁺, M+I⁺Se, M+I⁺Se^-, M+I^-Se⁺, M+I^-Se and M+I^-Se^-. The doses of iodine and selenium were I⁺, 18 mg I/kg; I^-, <0.02 mg I/kg; Se, 0.20 mg Se/kg; Se⁺, 2.00 mg Se/kg; Se^-, 0.02 mg Se/kg, respectively. Then detected the changes of of autoantibodies, antioxidation status in liver and brain and apoptosis protein in thyroid. Analyzed the main effect and the interaction between iodine and selenium.Result 1. The thyroid tissue presented apparent pathological changes after immunization. The level of autoantibodies TGAb and TMAb elevated significantly. It demonstrated that this method can successfully generate EAT model and the rate of success is 100%. 2. The levels of autoantibodies of EAT rats which with different dose of iodine were significantly high but without difference between EAT groups (F1=0.716, P=0.501; F2=0.716, P=0.50l). The activity of EAT rats' liver GPx and SOD in groups M and M+I⁺ was higher than group M+I^- (F1=20.82, P=0.000; F2=4.05, P=0.035). However, the activity of liver GPx and SOD of group M+I⁺ presented slight decrease compared with group M. Brain GPx activity of group M and M+I^- enhanced more than group M+I⁺ (F=10.82, P＜0.001). But there was no distinguished variance of brain SOD among the EAT groups. For the apoptosis proteins, the expression of FasL and Bcl-2 in groups M+I⁺ and M+I⁺ was significantly elevated (F₁=l14.78, P₁=0.000; F₂=5.67, P₂=0.006). The TRAIL of group M+I^- was upregulated than group M (F=55.45, P=0.000) and the Caspase-3 was higher than group M+I⁺ (F=16.46, P=0.000). 3. There existed a decreased trend of the titers of TGAb and TMAb as the selenium supplementation, although the difference was not significant. For the activity of GPx, compared with group M, it increased in group Se⁺ +M and decreased in group Se^- +M significantly (P<0.05). We didn't detect a conspicuous difference of the activity of SOD among groups. 4. It had no interaction of the component administeration between trace elements, iodine and selenium, and the autoantibodies. Iodine had a main effect on the activity of liver SOD (F=47.26, P=0.000), and iodine and selenium had interaction on the liver GPx, the supplementation of selenium benefited the raise of liver GPx's activity (F=9.26, P=0.000). In brain, iodine and selenium made the same effect on the GPx but had no evident effect on the SOD. As the result of factor analysis about the expression of apoptosis protein, iodine mainly contributed to the expression of FasL, selenium impacted Bcl-2 strikingly. Additionally, iodine and selenium had a interaction on the TRAIL and Caspase-3.Conclusion 1. This study took the heterogeneic Tg as the immunogen to built the EAT model, this method performed easily and had a good reliability. 2. Both the excess and deficiency of iodine intake can intensify the apoptosis of thyroid follicle with EAT, they also can promote the pathological changes and cause the inhibition to the capacity of antioxidation. The deficiency of iodine makes disease more serious among the total. 3. Sufficient selenium intake is of benefit to degrade the titer of TGAb and TMAb, enhance the activity of GPx, reinforce the capacity of antioxidation against inflammantory. What is more, adequat selenium intake can modulate the expression of some apoptosis proteins. 5. selenium Supply can potentize the capacity of antioxidation effectively both in iodine excess and deficiency, which works better of iodine excess. Selenium supplementation has different effect on different apoptosis proteins. In brief, the risk of apoptosis can be cut down with adequate selenium intake.