The role of 131I on apoptosis of thyrocytes in patients with Graves' disease

Abstract

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Objectives: To investigate the changes of the apoptotic protein Fas, FasL and the anti-apoptotic protein Bcl-2 of thyrocytes in GD pts before and after 131I administration. Methods: Thyroid tissue was obtained from 22 pts (F9, M13, mean age 35.2±8.67 yrs) with GD by histological biopsy before and 2 weeks after 131I treatment, and were examined by immunohistochemical method for the expression of Fas, FasL and Bcl-2. Quantitative analysis was performed by Mias 2000 pathological image system. And the serum FT3,FT4 and sTSH concentration were detected at the 3rd month after treatment. All pts were divided into two groups: hypothyroid (G1) and non-hypothyroid (G2). For G1, the FT3, FT4 were lower and sTSH were higher than normal.For G2,the FT3, FT4 and sTSH were normal or FT3, FT4 were higher and sTSH were lower than normal. Results: 1. The PU of Fas in thyrocytes before and after treatment were 12.93±1.80, 23.43±6.60 respectively,p<0.02. FasL, 14.56±4.06, 20.4±6.46,p<0.002; Bcl-2, 15.22±5.94, 21.68±7.83,p<0.005. 2. For G1, the PU of Fas before and after treatment were 17.82±9.18, 29.17±9.76 respectively, p<0.05, and the FasL, 17.82±9.18, 29.17±9.76,p<0.05, but for the Bcl-2, 16.85±7.06, 21.39±10.41,p>0.05. For G2, the PU of Fas before and after treatment were 16.20±6.05, 18.10±3.89 respectively,p>0.05, the FasL, 15.71±4.98, 17.92±4.27,p>0.05, but for the Bcl-2 , 15.2±5.86, 21.80±7.69,p<0.05. Conclusions: 1. 131I can induce thyrocytes to express the apoptotic protein Fas, FasL and the anti-apoptotic protein Bcl-2 of thyrocytes in pts with GD, but can promote apoptosis. 2. It may be due to increased expression of Fas and FasL in thyrocytes of hypothyroid after 131I administration.