Introduction & Objective: Comparative reductase inhibitors, such as simvastatin increase HDL-cholestrol and decrease serum triglyceride and cholesterol. It is widely recognized that statins have organ protective nature and most effective for organ damage progressing. Obstructive uropathy can be used to indicate any obstruction to urinary flow which causes a developing of hydronephrosis, tubular atrophy and associated renal impairment. The aim of this study was evaluation of the simvastatin effect on renal fibrosis after unilateral ureteral obstruction in rat.

Materials & Methods: In this experimental study, 50 adult male Sprague-Dawley rats were subjected to unilateral ureteral obstruction (UUO) and randomly divided into five groups (ten rats in each group) as follows: (1) control group (2) UUO (3) UUO/SIM (4) Sham-operated (5) Sham/SIM. Control animals received orally drug solvent by gavage for 15 days (started one day before operation). Unilateral ureteral obstruction was performed in groups 2 and 3 and sham operations were performed in groups 4 and 5. In group 2 animals received drug solvent and in group 3 animals received simvastatin (2 mg/kg/twice daily) for 15 days (started one day before operation). Rats were sacrificed either at day 14 for histopathological evaluation with H&E, masson-trichrome and PAS technique.

Results: In this investigation histopathologic evaluation approved that in UUO group, renal interstitial fibrosis, tubular epithelial necrosis, hemorrhage, interstitial infiltration of mononuclear cells, tubular atrophy, glumerular tufts expanding, periglomerular sclerosis, subcapsular fibrosis, glomerulosclerosis and peritubular capillaries edema were observed. But in simvastatin treated animals this histopatologic lesions and fibrosis significantly (p<0.05) decreased. There was no difference between control and sham groups.

Conclusion: In this investigation our results showed that ureteral obstruction increased renal fibrosis and caused sever deterioration in renal tissue but simvastatin administration improved renal fibrosis. It needs to be more investigation for approving of organ protective action of simvastatin in human renal disorders.