醛固酮抑制Akt活性诱导大鼠足细胞凋亡

目的 探讨醛固酮(ALD)能否诱导培养大鼠足细胞凋亡及Akt信号通路是否参与ALD诱导的足细胞凋亡。方法 体外培养并鉴定大鼠足细胞。无血清同步化处理24 h，分别给予终浓度为0(对照组)、10-9~10-5 mol/L ALD，伴或不伴螺内酯(10-7 mol/L)共孵育。流式细胞仪检测凋亡指数，Hoechst-33342染色检测足细胞凋亡。多聚酶链反应(RT-PCR)检测足细胞盐皮质激素受体(MR)和11β-羟类固醇脱氢酶2 (11β-HSD2) mRNA表达。Akt活性检测试剂盒检测Akt活性表达。结果 ALD以时间和剂量依赖方式诱导足细胞凋亡。螺内酯可明显抑制ALD诱导的足细胞凋亡[ALD+螺内酯组(5.61%±0.72%)比ALD组(15.10%±1.46%)，P < 0.05]。RT-PCR结果证实足细胞表达MR和11β-HSD2 mRNA。螺内酯可部分阻断ALD对Akt活性的抑制作用。ALD诱导的足细胞凋亡率与Akt活性呈明显负相关(r=-0.77， P < 0.05)。结论 ALD可诱导大鼠足细胞凋亡，Akt活性下降可能参与ALD诱导的足细胞凋亡。

Aldosterone inhibits Akt activation and induces apoptosis in rat podocytes

Objective To evaluate the effect of ALD on podocyte apoptosis and the possible roles of Akt in ALD-induced apoptosis. Methods The cultured rat podocytes were incubated with increasing concentrations of ALD (10-9~10-5 mol/L) for variable time periods. Apoptosis was evaluated by cell nucleus staining and flow cytometry. RT-PCR was used to examine the expression of mineralocorticoid receptor (MR)and 11 Beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2) mRNA in podocyte. Activation of Akt/PKB was evaluated by performing Akt kinase assay. Results ALD induced podocyte apoptosis in a dose- and time-dependent manner. The proapoptotic effect was attenuated by the presence of spironolactone (10-7mol/L). The expression of MR and 11β-HSD2 mRNA was demonstrated in the podocytes by RT-PCR. ALD also inhibited the activity of Akt in a dose-dependent manner， but the inhibitory effect was significantly ameliorated by the presence of spironolactone. The activity of Akt was negatively correlated with podocyte apoptosis. Conclusion ALD induces apoptosis in rat podocytes through the signaling mechanism by which Akt is inhibited.