ABSTRACT
Objectives To study the expression features of C-type natriuretic peptide (CNP)/natriuretic peptide receptor-B (NPR-B) axis and two parallel elimination pathways, natriuretic peptide receptor-C (NPR-C) and neutral endopeptidase (NEP) in unilateral ureteral obstruction (UUO) rats. Methods CNP, NPR-B, NPR-C, NEP, Col-IV and type IV collagen (Col-IV) mRNA and proteins were determined by in situ hybridization, real-time PCR, immunohistochemistry and western blot in UUO rats at 24h, 72h, 1w, 2w, 3w, 1m, 2m and 3m. Results CNP expression tended to be higher immediately after ligation and de-clined along with the progression of disease, occurring predominantly in tubular epithelial cells. A high-level CNP may attribute to the elevated expression of NPR-B in the early phase of UUO. Conclusions NEP and NPR participate in the regulation of CNP expression in tubulointerstitial fibrosis. The gradual increased expression of NPR-C and NEP may cause the subsequent de-cline of CNP.