Objective: To investigate the effects of nonselective endothelin receptor antagonist bosentan on the progression of renal interstitial fibrosis following unilateral ureteral obstruction (UUO).
Methods: Eighteen female SD rats were randomly divided into 3 groups: intervention group (administered with bosentan for 7 days after left ureter ligation), animal model group (administered with solution of Arabic gum for 7 days left ureter ligation) and sham operation group (administered with Arabic gum for 7 days after sham operation). Seven days after the operation the rats were killed and their left kidneys were harvested. The mRNA expressions of preproendothelin-1 (prepro ET-1), type I collagen (ColI), transforming growth factor beta1 (TGF-beta1), tissue inhibitors of metalloproteinase-1 (TIMP-1) and type 1 plasminogen activator inhibitor (PAI-1) were detected semiquantitatively with reverse transcription-polymerase chain reaction (RT-PCR). The protein expressions of endothelin-1 (ET-1), ColI, TGF-beta1, TIMP-1 and PAI-1were determined semiquantitatively by immunohistochemical staining assay.
Results: The mRNA expressions of prepro ET-1, ColI, TGF-beta1, TIMP-1 and PAI-1 were significantly upregulated in obstructed renal tissue compared to those in sham operation group (all P < 0.05). The positive staining areas of ET-1, ColI, TGF-beta1, TIMP-1 and PAI-1 in tubulointerstitium were markedly enhanced in the animal model group in comparison with those in the sham operation group (all P < 0.05). The mRNA expressions of ColI, TGF-beta1 and TIMP-1 in renal tissue subjected to ureter ligation were significantly lower in the bosentan group then in the animal model group (all P < 0.05). The positive staining areas of ColI, TGF-beta1 and TIMP-1 in the tubulointerstitium were significantly smaller in bosentan group than in the animal model group (all P < 0.05). However, there was no significant difference in the mRNA expression of PAI-1 and in the positive staining area between the animal model group and bosentan group (both P > 0.05).
Conclusion: ET-1 may be involved in the progression of renal interstitial fibrosis following unilateral ureter ligation and blockage of its receptors with bosentan attenuates the fibroticlesion to a certain extent by possibly inhibiting TGF-beta1 and TIMP-1.