Free insulin-like growth factor-1 and unilateral complete ureteral obstruction in the rat

Abstract

Objectives. To determine the effect of unilateral ureteral obstruction on renal free insulin-like growth factor-1 (IGF-1) content in the kidneys and the possible role of free IGF-1 in compensatory growth in the nonobstructed kidney in an experimental model. Methods. The content of free IGF-1 and total protein in the obstructed and nonobstructed kidneys were measured 7 days after unilateral ureteral obstruction. The weights of the kidneys were also determined. The results were compared with those of the sham-operated animals. Results. The mean renal free IGF-1 level of the obstructed kidneys was significantly lower than the mean renal free IGF-1 level of the sham-operated kidneys ( P = 0.03), and the mean renal free IGF-1 level of the nonobstructed kidneys was significantly higher than the mean renal free IGF-1 level of the sham-operated kidneys ( P <0.0001). The serum free IGF-1 levels in the two groups were not different. The mean weight of the obstructed and nonobstructed kidneys was significantly higher than those of the sham-operated kidneys (1.49 ± 0.09 and 1.03 ± 0.03 versus 0.88 ± 0.02 g, P <0.0001 and P = 0.006, respectively). The obstructed kidneys had significantly lower mean protein content than the nonobstructed kidneys and had significantly higher mean protein content than the sham-operated kidneys ( P <0.0001 and P = 0.0004, respectively). Conclusions. Our results reveal that compensatory renal growth is driven by a rise in the free IGF-1 concentration after unilateral ureteral obstruction.