Increased cell proliferation of urothelium in rat bladder following unilateral nephrectomy

The aim of this study is to investigate the effect of unilateral nephrectomy on cell proliferation of normal urinary bladder epithelium in adult rats.

Following unilateral nephrectomy or sham operation 5 rats for each time point were sacrificed and their bladders were removed at 6 and 12 hours and also on 1, 2, 4, 7, 14, 28, and 56 days. Another 5 rats were not operated and served as the control. The percent number of proliferating cell nuclear antigen (PCNA) positive cells and the number of argyrophilic nucleolar organizer regions (AgNORs) were determined for each bladder.

In the nephrectomized groups, a significant increase of PCNA expression in urothelial cells of the bladder was found at each sacrifice time with the exception of 28 and 56 days when compared with that of the control and corresponding sham-operated groups. Percent PCNA labeling index (PCNA-LI) reached a peak value of approximately 9.1% on day 2 post operation. From day 4 post nephrectomy, however, PCNA-LI decreased gradually reaching control levels by day 28. No significant difference was found between the control and sham-operated groups. The mean number of AgNOR dots in nephrectomized rats sacrificed on day 1, 2, 4, 7 and 14 post operation was significantly larger than that of the control and corresponding sham-operated groups.

The results suggest that unilateral nephrectomy temporarily enhances normal urothelial cell proliferation in adult rat bladder.