Effect of aldosterone on glomerular mesangial cells apoptosis bothin vivo and in vitro / 中华肾脏病杂志

ABSTRACT

Objective To evaluate the effect of aldosterone (Ald) on glomerular mesangial cells apoptosis and to explore the possible mechanisms.Methods Twenty-four Sprngue-Dawley rats were subcutaneously embedded with osmotic mini-pumps and randomly divided into 3 groups.Aldosterone (1.5 μg/h) was administrated subcutaneouly by osmotic mini-pumps in Ald group,eplerenone (Epl,100 mg·kg-1·d-1) and Ald (1.5 μg/h) was given to Epl group.And normal saline was used in control group (Con group).Systolic blood pressure and urinary albumin excretion rate (UAER) were detected on day 0,7,14,21,28.Blood and kidney samples were harvested on day 28.Plasma creatinine,potassium and aldosterone were measured.Renal paraffin sections were stained by PAS and the morphological changes were evaluated by light microscopy.Apoptosis index of mesangial cells were detected by TUNEL assay.The glomerular mesangial cells (MCs) were cultured in a DMEM-F12 media.MCs apoptosis was evaluated by staining cells with Annexin V and propidium iodide (PI) using flow cytometer.Expression of Bcl-2 and Bax mRNA was examined by RT-PCR.The protein level of Bad or phospho-Bad was measured by Western blotting.Results Ald-infused rats developed hyperaldosteronemia and hypokalemia.Rats in Ald group exhibited significant hypertension and marked albuminuria.Ald group rats showed increased number of TUNEL-positive mesangial cells when compared with control rats (P＜0.05).Aldosterone induced mesangial cells apoptosis in a time-dependent manner.Expression of Bcl-2 mRNA was decreased but Bax mRNA was increased in aldosterone treated MCs compared to that in Con group (P＜0.05).Aldosterone promoted dephosphorylation of cytosolic phospho-Bad compared with vehicle treated cells (P＜ 0.05).However,eplerenone attenuated these effects of aldosterone.Conclusion Aldosterone directly promotes mesangial cells apoptosis,and eplerenone can attenuate this effect of aldosterone.Dephosphorylation of cytosolic phospho-Bad may be the key role in the progression of mesangial cells apoptosis induced by aldosterone.