Intermedin attenuates renal interstitial fibrosis through inhibiting oxidative stress in rats with unilateral ureteral obstruction

Abstract

Objective To explore if intermedin (IMD) could reduce renal interstitial fibrosis through inhibiting reactive oxygen species (ROS) in rats with unilateral ureteral obstruction (UUO). Methods Healthy male Wistar rats were randomly divided into sham-operation group (n=24), UUO group (n=24), UUO+ IMD-pcDNA3.1 group (n=24), UUO+ IMDshRNA group (n=24), and UUO+ pcDNA3.1 group (n=24). Plasmid transfection was induced 7 days before UUO operation. Groups of 6 animals were killed at 1 d, 3 d, 7 d and 14 d after operation, respectively. The obstructed kidneys were harvested for further analysis. For analyzing the degree of tubulointerstitial collagen deposition, sections were stained with Masson trichrome. ROS content in the obstructed kidney was measured by chemiluminescence. Renal superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were evaluated by colorimetry. Expression of heme oxygenase-1 (HO-1) was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical staining, respectively. Results Masson trichrome showed no obvious fibrosis at each time point in kidneys of sham-operation rats. With the time of obstruction, the degree of renal interstitial fibrosis increased in the UUO group (P 0.05). At each time point, the ROS activity and MDA content increased obviously in the UUO group compared with the sham controls (P 0.05). SOD activity and HO-1 expression increased significantly at d1 after UUO in the UUO group, and then gradually declined. The SOD activity was lower than that of the sham controls at d3, d7, d14 after UUO, while HO-1 expressions of mRNA and protein were higher than those of the sham controls at each time point (P 0.05). Conclusion IMD attenuated renal fibrosis induced in the UUO rats through inhibiting oxidative stress. Key words: Renal fibrosis; Intermedin; Reactive oxygen species