Expression Of Intermedin And Its Receptors In Renal Tissues Of Rats With Unilateral Ureteral Obstruction(UUO)

Objective:To investigate the expression changes of intermedin(IMD) and its receptor system, namely calcitonin receptor-like receptor(CRLR) and receptor activity-modifying proteins(RAMP1/2/3), in renal tissues of rats with unilateral ureteral obstruction(UUO).Methods:Forty-eight male Wistar rats were randomly divided into UUO group(n=24) and sham-operated group(n=24). UUO model was made by ligation of left ureter. For sham-operated group, rats were subjected to left flank incisions, and the kidney was exposed, but the ureter was not ligated. Groups of six animals each were killed at 1, 3,7, and 14 d after operation, respectively. Kidneys were harvested for further analysis.Paraffin-embedded transverse kidney slices were sectioned at 4 μm, and stained with hematoxylin and eosin. For analyzing the degree of tubulointerstitial collagen deposition, sections were stained with Masson trichrome. m RNA expression levels of IMD, CRLR and RAMPs were detected by real-time reverse transcription-polymerase chanin reaction(Real-Time RT-PCR). Protein expression levels of IMD, CRLR and RAMPs were detected by immunohistochemical staining. The variance analysis of factorial design was used for data analysis.Results:Renal morphology showed that no changes were detected in the sham-operated group. In the UUO group, there were significant pathological changes, and theinterstitial fibrosis gradually increased with time(P<0.05). Real-Time RT-PCR and immunohistochemical staining revealed that, after UUO operation, the m RNA and protein expression levels of IMD, CRLR, RAMP1, RAMP2 and RAMP3 increased from day 1(P<0.05, compared with sham group), and reached peak value at day 3(RAMP2 and RAMP3) or at day 7(IMD, CRLR and RAMP1), respectively, and then gradually declined.Conclusion:Our results indicated that IMD and its receptors were upregulated after UUO,which might play a role in renal fibrosis.