To investigate the protective effects of eplerenone on adriamycin-induced renal injury and the possible mechanisms involved,36 male Sprague-Dawley rats were randomly divided into control group,adriamycin nephropathy (AN) group and eplerenone-treated group (100 mg·kg-1·d-1 eplerenone).Blood pressure,24-h urinary protein,serum potassium,sodium and creatinine were measured 28 days after adriamycin injection (a single tail intravenous injection of 6.5 mg/kg adriamycin).The morphological changes of renal tissues were observed by light and electron microscopy.lmmunohistochemistry and West blotting were performed to examine the expression of TGF-β1 and desmin in renal cortex.The results showed that 28 days after adriamycin injection,there were no significant changes in the level of serum potassium,sodium,creatinine concentrations and blood pressure values in the rats of the three groups.Meanwhile,the 24-h proteinuria excretion in the AN group was significantly higher than that in the control group (P＜0.01),but that in the eplerenone-treated group was substantially reduced when compared with that in the AN group (P＜0.05).Mild mesangial cell proliferation and matrix expansion,diffuse deformation and confluence of foot processes in podocytes were found in the AN group.By contrast,rats in the eplerenone-treated group exhibited obvious attenuation of these morphological lesions.The protein expression of TGF-β1 and desmin in the AN group was markedly up-regulated in contrast to that in the control group (P＜0.01),whereas that in the eplerenone-treated group was much lower than in the AN group (P＜0.05).It was concluded that eplerenone may ameliorate the proteinuria and the development of pathological alteration in adriamycin-induced nephropathy presumably via the inhibition of cytokine release,and restore the morphology of podocytes independent of its blood pressure-lowing effects.