EXPRESSION OF PAIRED BOX2 AND Α-SMOOTH MUSCLE ACTIN IN UNILATERAL URETERAL OBSTRUCTION IN RATS

[Objective] To evaluate the expression of Paired Box2(PAX2) andα-smooth muscle actin(α-SMA) in renal tissue of rats with unilateral ureteral obstruction(UUO),and initially to investigate the effects of PAX2 in renal tubulointerstitial fibrosis.[Methods] Twenty-four Wistar male rats(6-week-old) were randomly assigned into 2 groups,the control and model group.The mode group's left ureter was dissociated to be obstructed.The control group was only dissociated left ureter,and not to be obstructed.12 rats of both two group were killed at 21 th day after surgery respectively,then serum creatinine(Scr) and blood urea nitrogen(BUN) were measured.Histological changes of renal tubular interstitium were observed by HE and Masson staining to observe the renal interstial fibrosis index.The expression of PAX2 mRNA of the left renal cortex were assessed by real-time quantitative polymerase chain reaction,immunohistochemistry was performed on left renal tissue for assessing expression of PAX2 and α-smooth muscle actin(α-SMA).[Results] The fibrosis index in the model group were significantly increased as compared with control(P﹤0.01).Immunohistochemistry staining indicated that the expression of PAX2 and α-SMA in model group increased significantly compared with control group(P﹤0.01).Meanwhile,the expression lever of PAX2mRNA in model group was obviously higher than that in the control group.The expressions of PAX2 protein were significantly positive correlated with α-SMA protein,renal interstial fibrosis index,BUN and Scr(r= 0.882,0.899,0.731 and 0.933,respectively,all P﹤0.05).[Conclusion] The expression of PAX2 and α-SMA in model group increased significantly in unilateral ureteral obstruction in rats.Mayble PAX2 may play a role of tubular epithelial-myofibroblast transdifferentiation(TEMT) in unilateral ureteral obstruction in rats,as a result the number of the myofibroblast cell increased in renal interstitium,which resulted in large accumulation of Extracellular Matrix(ECM),then it may contribute to renal tubulointerstitial fibrosis.