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Updated: Oct 1, 2026
An Immature Murine Model of Reversible Unilateral Ureteral Obstruction
Published on: April 4, 2025
Recovery from release of ureteral obstruction in the rat: relationship to nephrogenesis
Robert L Chevalier1, Barbara A Thornhill, Alice Y Chang
1Department of Pediatrics, University of Virginia, Charlottesville, Virginia 22908, USA. RLC2m@Virginia.edu
Insights
Temporary ureteral obstruction causes lasting kidney damage in neonatal rats, especially after kidney development. Prompt relief of obstruction is crucial to prevent severe, long-term renal insufficiency in infants.
Area of Science:
- Pediatric Nephrology
- Developmental Biology
- Urology
Background:
- Obstructive nephropathy is a leading cause of renal insufficiency in children.
- Unilateral ureteral obstruction (UUO) in neonatal rats impairs kidney growth and function.
- The timing of UUO relative to nephrogenesis impacts long-term renal recovery.
Purpose of the Study:
- To investigate if renal recovery from temporary UUO depends on the stage of kidney development (nephrogenesis) at the time of obstruction relief.
- To compare the long-term effects of UUO relieved during nephrogenesis versus after its completion.
Main Methods:
- Neonatal rats underwent a five-day UUO or sham operation during nephrogenesis (days 1-5) or after completion (days 14-19).
- Renal function, blood pressure, kidney weight, and histological parameters were assessed three months post-obstruction relief.
- Glomerular counts were also assessed in adult rats one month after a five-day UUO.
Main Results:
- Relief of UUO after nephrogenesis (days 14-19) resulted in greater renal growth impairment (50% reduction) compared to relief during nephrogenesis (30% reduction).
- Glomerular number decreased similarly regardless of timing, but glomerular size was reduced only when UUO occurred after nephrogenesis.
- Post-obstructed kidneys showed increased blood pressure and tubular atrophy, with decreased GFR, urine flow, and electrolyte excretion.
Conclusions:
- The developing kidney is highly susceptible to permanent injury from temporary UUO in the period immediately following nephrogenesis.
- Delaying the relief of significant ureteral obstruction diagnosed prenatally or neonatally should be avoided to prevent long-term kidney damage.
Background:
Obstructive nephropathy is a major cause of renal insufficiency in infants and children. Despite release of unilateral ureteral obstruction (UUO) in the first five days of life in the rat, renal growth is impaired, while glomerular filtration rate (GFR) is preserved at one month, but decreases markedly by one year. To test the hypothesis that renal recovery from UUO depends on the stage of nephrogenesis at the time of relief of obstruction, renal recovery from relief of five days UUO following completion of nephrogenesis (days 14 to 19) was compared with UUO during nephrogenesis (days 1 to 5).
Methods:
Rats underwent UUO or sham operation at one day of age, with relief five days later. In additional groups of neonatal rats, the operation was at 14 days, with relief at 19 days. Three months later, blood pressure, GFR, urine flow, sodium and potassium excretion, and kidney weight were measured. In addition, the number of glomeruli, glomerular maturation, glomerular diameter, tubular atrophy, and interstitial fibrosis were determined in each kidney. The effects of five-day UUO on number of glomeruli was determined also in adult rats one month following relief of obstruction.
Results:
Three months following relief of UUO during days 14 to 19, renal growth was decreased by 50%, compared to a 30% reduction following relief of UUO during days 1 to 5 (P < 0.05). The number of glomeruli was reduced by approximately 50% regardless of the timing of UUO, but glomerular size was reduced only in rats with UUO from days 14 to 19. Blood pressure and tubular atrophy were increased, and GFR, urine flow, sodium and potassium excretion were decreased in the postobstructed kidney of both neonatal groups. In the adult rat, the five-day UUO did not result in a decrease in the number of glomeruli.
Conclusions:
In the period immediately following nephrogenesis, the kidney is particularly susceptible to long-term injury from temporary UUO. This suggests that a delay in relief of significant ureteral obstruction should be avoided if diagnosed in the perinatal or neonatal period.
