Renal fibrosis is an important pathologic change in chronic kidney disease. Unilateral ureteral obstruction (UUO) in the rodent is a model exhibiting interstitial inflammatory cell infiltration and tubular dilatation followed by tubulointerstitial fibrosis of the obstructed kidney. The blockade of the renin-angiotensin-aldosterone system with either angiotensin converting enzyme inhibitor, angiotensin receptor blocker or direct renin inhibitor has renoprotective effect in diabetic nephropathy. In this study, we investigate the effect of a therapy combined aliskiren with valsartan on UUO-induced renal fibrosis by the pathologic examination, Western blot and reverse transcriptase PCR. Point counting method was used for scores of interstitial volume, interstitial collagen deposition, interstitial α-SMA and tubular dilatation to evaluate degree of renal fibrosis. We observed that the combination therapy or each alone all significantly blunted the degree of hydronephrosis determined by the increase of weight and length of the obstructed kidney. Specially, the combination therapy has the best renoprotective effect. The combination therapy also attenuated UUO related increases on the scores of tubular dilatation, interstitial volume, interstitial collagen deposition, α-smooth
