Experiment studies on renal damage, tubular-interstitial fibrosis and the expression of related factors in rats' aristolochic acid nephropathy / 解放军医学杂志

ABSTRACT

Objective To study the tissue pathology and the expression of related factors during renal tubular-interstitial fibrosis in aristolochic acid (AA) nephropathy in rat. Methods 46 male Wistar rats were randomly divided into 2 groups. The test group consisted of 26 rats which were gavaged with the extract of Caulis Aristolochiae Manshuriensis (CAM) (AA 20mg?kg -1 ?d -1 ); the control group consisted of 20 rats which were given with equal volume of potable water. At the end of 4th, 8th, 12th week, the kidneys of each rat were separately harvested. The HE, PAS and Masson staining were used to analyze the degree of tubular damage and interstitial fibrosis, and immunohistochemical method was applied to assess the protein expression of proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), transforming growth factor-?_1 (TGF-?_1) in the renal specimens. The mRNA expression of VEGF, endothelin-1 (ET-1), bone morphogenetic protein-7 (BMP-7) in renal tissue were determined by RT-PCR respectively. Results A severe renal tubular-interstitial damage and an early fibrosis were observed at the end of 12th week, and the interstitial fibrotic area was 31.36%. The protein expression of PCNA was increased at 4th week, but down-regulated after 8th week; the expression of TGF-?_1 and VEGF was increased at 4th week, while TGF-?_1 was maintatined on a high level with passage of time, but VEGF decreased gradually. The mRNA expression of VEGF and ET-1 increased notably at 4th week, slightly decreased after 8th week, but maintained at a high level. The BMP-7 declined slowly with the progression of pathological changes, reaching its lowest level at 12th week. Conclusion The mechanism of the rapid progression of fibrosis in AAN might be the renal result of severe impairment of regeneration of epithelial cells, lowering of expression of factors of promoting repair and inhibiting fibrosis, while the expression of factors of promoting fibrosis was maintained at a highlevel.