Background: This study investigated the effects of losartan intervention on the expressions of hypoxia-inducible factor-1α (HIF-1α), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in renal fibrosis in rats with 5/6 nephrectomy. Methods: Sprague Dawley rats were randomly divided into three groups. Rats in the losartan group were gavaged with losartan (33.3 mg/kg/day) from 1 week after 5/6 nephrectomy, and those in the sham group and the model group only received an equal volume of saline solution by gavage. Rats were sacrificed at the ends of the 4, 8 and 12 weeks, respectively. Urinary N-acetyl-glucosaminidase (NAG), 24-h urinary protein, serum cystatin C, blood urea nitrogen (BUN), and serum creatinine (Scr) levels were assessed. Kidney tissues were observed under light and electron microscope. The expressions of HIF-1α, transforming growth factor-β1 (TGF-β1), MMP-9, and TIMP-1 were determined by immunohistochemistry and Western blotting. Results: Twenty-four hour urinary protein, urinary NAG, serum cystatin C, BUN, and Scr levels in the model group were significantly higher than those in the sham group (p < 0.05), but losartan treatment improved these changes. The apparent glomerular sclerosis and tubulointerstitial fibrosis were also found in the model group, which were ameliorated by losartan. The expressions of HIF-1α, TGF-β1, MMP-9, and TIMP-1 were elevated and MMp-9/TIMP-1 ratio was lowered in the model group (p < 0.05), but losartan increased the expression of MMP-9 and MMp-9/TIMP-1 ratio (p < 0.05) and lessened the expressions of HIF-1α, TGF-β1, and TIMP-1 (p < 0.05). Conclusion: Losartan may ameliorate renal fibrosis partly by down-regulating HIF-1α and up-regulating MMP-9/TIMP-1 in rats with 5/6 nephrectomy.
