Expression of osteopontin in rat kidney with unilateral ureteral obstruction and the therapeutic effect of candesartan

Objective To explore the effect of osteopontin in the renal tubule on the process of renal interstitial fibrosis caused by unilateral ureteral obstruction (UUO) in rats, to examine the expression changes of osteopontin after candesartan intervention and to interpret the anti-fibrotic mechanism. Methods UUO model was established by ligating left ureter. Thirty-six healthy male Sprague-Dawley rats were randomly divided into three groups: sham operation group, UUO group and candesartant reated group. The rats in candesartant reated group were administered with candesartan ( 10 mg/kg every day), while those in UUO group and sham operation group with saline 10 ml/(kg·day). The rats were sacrificed at the 7th and 14th day after the surgery. The paraffin-embedded sections of the left kidney were stained with Masson Trichrome staining. The expression of osteopontin mRNA and protein was detected by reverse transcriptionpolymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. Results At the 7th and 14th day after the surgery, the percentage of green-stained region in sections of the left kidney by Masson Trichrome staining was 15.2％ and 24. 8％ in UUO group, and 10. 1％ and 18.5％ in candesartan-treated group, respectively. The expression levels of osteopontin mRNA and protein were higher in UUO group than in the sham-operated group (P<0. 01 ). As compared with UUO group, candesartan-treated group showed the significant attenuation of osteopontin in the left kidney, which was accompanied with the amelioration of renal interstitial fibrosis process ( P < 0. 05 ). Conclusion Osteopontin participated in the renal interstitial fibrosis. The effect of candesartan on reduction of the expression of osteopontin may be one of the strategies preventing renal interstitial fibrosis. Key words: Candesartan;  Unilateral ureteral obstruction;  Osteopontin