甲状腺素对胰岛β细胞A20 mRNA表达作用的研究

Effects of A20 mRNA Expression Induced by Thyroxin on Pancreatic Islets β Cells

目的研究甲状腺素对胰岛β细胞A20 mRNA表达作用的影响,观察大鼠胰岛β细胞形态学变化。方法采用氧化酶法及放射免疫法测定大鼠血清葡萄糖和血清胰岛素的含量。大鼠胰岛β细胞总DNA琼脂糖凝胶电泳,检测凋亡条带的形成。RT-PCR检测胰岛细胞抗凋亡蛋白A20(TNF-induced protein 3)mRNA的表达。结果给予T4(600μg.kg-1.d-1)灌胃14d后,可使大鼠血清胰岛素水平明显降低(P<0.05),血糖水平则明显升高(P<0.01),并且大鼠胰岛β细胞总DNA琼脂糖凝胶电泳呈现典型凋亡梯状条带。而给予T4灌胃7d时,不发生上述改变。A20 mRNA在给予T4(600μg.kg-1.d-1)灌胃7d和14d组有表达,而且后者明显低于前者(P<0.01),但在对照组和给予T4灌胃21d组无表达。结论T4引起胰岛细胞的凋亡可能与抗凋亡蛋白A20在胰岛β细胞的非持续性表达有关。

Objective To probe the effect of A20 mRNA expression induced by Thyroxin on pancreatic islets β cells, and to observe the morphological change at the same time. Methods Serum Insulin was assayed using radioimmunoassay （RA） methods and fasting serum glucose （FSG） concentrations were determined by the glucose oxidase technique. The determination of DNA fragmentation extracted from β cells was analyzed by agarose gel electrophoresis. The total RNA extracted from them was used to RT-PCR to determine the expression of A20 mRNA. Results The serum level of insulin of the rats in the groups that T4-treated for 14d and 21 d were significantly decreased when compared with the controlled group（ P 〈 0.05） , while the serum level of FG of rats in both of the groups was significantly increased when compared with the controlled group（ P 〈 0.01 ）. Typical apoptosis ladder was observed in agarose gel electrophoresis of the DNA in the groups that T4-treated for 14d and 21d, but not in others. The level of A20 mRNA expression was significantly decreased in T4-treated group administered for 14d compared with that of 7d（ P 〈 0.01 ） ,but not found in other groups. Conclusion The mechanism of the apoptosis in pancreatic islets 13 cells induced by T4 maybe in connection with the incontinuous expression of anti-apoptosis protein A20 in it.