BackgroundAstragalus root is a commonly used herb in traditional Chinese medicine. Although renoprotective effects have been reported in some clinical and experimental studies, the details remain unknown.MethodsWe used 5/6 nephrectomized rats as chronic kidney disease (CKD) models. At 10 weeks, they were divided into four groups, namely, CKD, low-dose astragalus (AR400), high-dose astragalus (AR800), and sham groups. At 14 weeks, they were sacrificed for the evaluation of blood, urine, mRNA expression in the kidney, and renal histopathology.ResultsKidney dysfunction was significantly improved following astragalus administration (creatinine clearance: sham group; 3.8 ± 0.3 mL/min, CKD group; 1.5 ± 0.1 mL/min, AR400 group; 2.5 ± 0.3 mL/min, AR800 group; 2.7 ± 0.1 mL/min). Blood pressure, urinary albumin, and urinary NGAL levels were significantly lower in the astragalus-treated groups than those in the CKD group. Excretion of urinary 8-OHdG, an oxidative stress marker, and intrarenal oxidative stress were lower in the astragalus-treated groups than those in the CKD group. Furthermore, the mRNA expression of NADPH p22 phox, NADPH p47 phox, Nox4, renin, angiotensin II type 1 receptor, and angiotensinogen in the kidney was lower in the astragalus-treated groups compared with the CKD group.ConclusionThis study suggests that astragalus root slowed CKD progression, possibly through the suppression of oxidative stress and the renin–angiotensin system.