Histologic and molecular evidence of obstructive uropathy in rats with hereditary congenital hydronephrosis

Partial obstruction of the upper urinary tract, a frequent challenge for th e pediatric urologist, leads to renal damage, if deobstruction is delayed. Several but sometimes unsatisfactory animal models have been developed to s tudy this phenomenon. Obstruction created by surgical manipulation lacks ad equate correlation with a developing congenital obstruction. In some animal s with congenital hydronephrosis, evidence of renal obstruction is absent. A study of the renal morphology of rats with hereditary unilateral hydronep hrosis has exhibited clear evidence of renal obstruction distinguishable fr om renal dilation. The renal mRNA expression of renin and transforming-grow th factor-beta(1) (TGF-beta(1)) was measured by a semiquantitative RT-PCR t echnique. In hydronephrotic kidneys, a marked loss of parenchyma, atrophy a nd dilation of tubuli and collecting ducts and interstitial fibrosis was ob served. The mRNA expression of renin was increased significantly in compari son to controls, whereas the contralateral kidneys showed renin activity be low control levels. TGF-beta(1) expression was markedly increased in hydron ephrotic kidneys, whereas contralateral kidneys did not differ significantl y from control values. These data suggest the presence of renal obstruction and not only renal dilatation in these rats with congenital hydronephrosis . This colony seems to be a representative animal model to study congenital renal obstruction even in the fetal period without the need of surgical ma nipulation.