地塞米松给药及撤药后糖皮质激素受体的表达

目的 观察地塞米松对体外培养人皮肤角质形成细胞--HaCaT细胞糖皮质激素受体(glucocorticoid recep-tor,GR)α仅和β表达的调节以及撤药后GRα、GRβ基因表达的后续变化,并探讨其临床意义.方法 以含10-6mol/L地塞米松的DMEM(高糖)培养基孵育细胞,48 h后换不含地塞米松的培养摹继续孵育.在地塞米松给药后24、48 h以及撤药后24、48、72 h的不同时相点,采用RT-PCR和Western blot检测GRα、GRβ的表达变化,采用免疫荧光化学法观察GRα、GRβ的细胞内定位.结果 地塞米松给药后24、48 h,GRα的mRNA和蛋白质水平逐渐下降(P<0.05),呈时间依赖性,GRβ的mRNA和蛋白质水平均逐渐上升(P<0.05);撤药后24、48、72 h,GRα和GRβ的上述变化不同程度地向原有水平回复.结论 地塞米松下调GRα并上调GRβ,可部分解释持续外用糖皮质激素制剂后出现的激素耐受现象;下调的GRα和上调的GRβ在地塞米松撤药后呈现向其原有水平恢复的趋势,提示临床上外用激素治疗应避免长期使用.

Expression of glucocorticoid receptor in HaCaT cells under dexamethasone treatment or after withdrawal

Objective To investigate the expression of glucocorticoid receptor ( GR)α and β in cultured human keratinocytes (HaCaT cells) with treatment of dexamethasone (Dex) and after withdrawal. Methods The mRNA and protein expressions of GRα and GRβ in HaCaT cells after the treatment of Dex (10~(-6)mol/L) for 24 and 48 h and in 24, 48 and 72 h after withdrawal of Dex were detected by real-time PCR and Western blot analysis respectively. The intracellular distribution of GRα and β was examined by immunofluorescence. Results In 24 or 48 h after Dex treatment, the expressions of GRα at mRNA and protein levels were reduced in a time-dependent manner (P<0.05) , and those of GRβ were increased (P<0. 05) as shown by real-time PCR and Western blot analysis. However, in 24, 48 and 72 h after withdrawal of Dex, the above changes gra-dually recovered to their previous levels. Conclusion Dex down-regulates GRα but up-regulates GRβ, which may partly explain that the tachyphylaxisis correlated to persistent application of topical glucocorticoids. After Dex is removed, both GRα and GRβ could recover to their previous levels, suggesting long-term application of topical glucocorticoid should be avoided.