OBJECTIVETo study the effect of different selenium intake on the expression of apoptosis protein Fas/FasL in experimental autoimmune thyroiditis (EAT) rats' thyroid with adequate iodine.

METHODSThirty-two female lewis rats were divided stochastically into 4 groups as C group, M group, Se(+) + M group, Se(-) + M group, respectively, and pretreated with feedstuffs containing different concentrations of selenium (Se(+) + M group 2 mg/kg, C and M group 0.20 mg/kg, Se(-) + M group 0.02 mg/kg, respectively) for two weeks, and immunized the rats with porcine thyroglobulin (pTg) to establish an EAT model. The thyroid gland was sampled, embedded in mineral wax and sliced, and the expression of Fas/FasL was measured with immunohistochemistry.

RESULTSBoth the expressions of Fas and FasL of EAT rats were significantly increased as compared with control group. The expression of Fas in rats' thyroid follicular cells with EAT was down-regulated as the increased selenium intake (optical density: 0.059 +/- 0.006), the expression of Fas of Se(+) + M group (0.036 +/- 0.004) was significantly inhibited (q = 11.591, P = 0.000), and expression of Fas was lower in the Se(+) + M group than Se(-) + M group (0.050 +/- 0.005) (q = 7.055 , P = 0.000). Effect of selenium on FasL was not identified.

CONCLUSIONIncreasing the intake of selenium might decrease the expression of Fas on thyroid follicular cells and restrain the development of EAT.