Apoptosis in Renal Hypertrophy after Uninephrectomy in the Rats

ABSTRACT

BACKGROUND: Glomerular compensatory hypertrophy maintains decreased renal function after uninephrectomy (UNX). Proliferation and apoptosis of renal cells may be involved in hypertrophy. METHODS: In small and large male Sprague-Dawley rats, contralateral kidneys were harvested 1, 7, 14 and 30 days after UNX. Apoptosis was assessed by the Tdt-mediated dUTP-digoxigenin nick end labelling method. Proliferating cell nuclear antigen and Fas ligand (FasL) expression was determined by immunohistochemically. RESULTS: Morphometrically, glomerular hypertrophy was observed in both small and large rats after UNX, and it was more significant in the small rats. The glomerular proliferation index (PI) was gradually increased from day 7 but decreased on day 30 in the small rats. Glomerular PI was significantly increased from day 7 in large rats and peaked at day 14. Apoptotic cells in the glomeruli were slightly increased on day 1 and on day 7 in both groups of rats. The expression of FasL was gradually increased in the distal tubular epithelium in both groups. CONCLUSIONS: These results demonstrate different profiles regarding the compensatory growth of the kidney, cell proliferation, and apoptosis during the period of compensatory hypertrophy in uninephrectomized rats of different weight and age. Apoptosis may play a role in regressing a number of proliferated cells during renal compensatory hypertrophy.