Alteration of renal cyclooxygenase expression due to partial unilateral ureteral obstruction in neonatal

Abstract

E150Cite as: Can Urol Assoc J 2013;7:E150-E155. http://dx.doi.org/10.5489/cuaj.11163. Epub 2012 March 2. AbstractIntroduction: Impaired renal water handling in response to neonatally-induced partial unilateral ureteral obstruction (PUUO) may be associated with altered expression of cyclooxygenase (COX). The purpose of the present study was to examine whether long-term PUUO induced at birth was associated with changes of COX-2. Methods: Rats were subjected to PUUO (n = 14) or a sham operation (n = 12) within the first 48 hours of life. The rats were divided into 4 groups: (1) PUUO at 9 weeks (n = 7); (2) the sham operation at 9 weeks (n = 6); (3) PUUO at 15 weeks (n = 7); and (4) the sham operation at 15 weeks (n = 6). Urine and blood samples were collected before sacrificing the animals. Plasma potassium, creatinine and urea, as well as the osmolality and sodium of plasma and urine were tested in each sample. The expression of renal COX-1 and COX-2 was examined at 9 and 15 weeks in rats with neonatallyinduced PUUO within the first 48 hours of life by immunoblotting and immunocytochemistry. Results: PUUO caused a marked decrease in urine osmolality and a significant increase in urinary sodium of the obstructed kidney compared with the sham-operated kidney at 9 and 15 weeks. Immunoblotting analysis showed that an abundance of COX-2 in the obstructed kidney significantly increased compared with the non-obstructed kidney and sham-operated kidney at 9 weeks (p < 0.05) and 15 weeks (p < 0.05) in rats with PUUO. In contrast, COX-1 abundance in the obstructed kidney was similar to that in the non-obstructed kidney. Immunocytochemistry confirmed these findings. Conclusion: Renal COX-2 expression in the obstructed kidney is significantly altered in response to neonatally-induced PUUO. A marked increase in COX-2 indicates that it may be an important factor in reducing renal handling of sodium and water in response to PUUO. IntroductionCongenital obstructive nephropathy is the primary cause of renal insufficiency in children.1 Congenital ureteral obstruction is distinguished by the profound impairment of kidney functions.2 Previous studies have shown that unilateral ureteral complete obstruction in adult rats caused impairment of urinary concentrating ability.3,4 However, neonatal partial unilateral ureteral obstruction (PUUO) as an experimental model for congenital obstructive nephropathy is clinically much more common than complete obstruction. Wen and colleagues demonstrated that PUUO induced neonatally in rats was associated with the development of progressive hydronephrosis. 5 The rat was chosen because obstruction induced shortly after birth simulates obstruction in the last trimester in humans. In the pediatric population, obstruction at the pelvic-ureteral junction is mostly partial and congenital. Furthermore, with rats, we can obtain a sufficient number of obstructed animals to cover the large variety of responses to obstruction seen in clinical and experimental materials with respect to severity and changes in re...

Glomerular filtration rate and urine osmolality in unilateral ureteropelvic junction obstruction

“…[ 21 ] While acute short-term unilateral obstruction in rats has not changed the permeability to water and reabsorptive capacity of terminal collecting duct, prolonged unilateral obstruction has resulted in increased cyclooxygenase and decreased permeability to water and urinary sodium excretion in obstructed kidney. [ 22 23 ] Since we calculated GFR based on Schwarz formula and selected unilateral obstruction, comparing GFRs in 2 kidneys (obstructed and nonobstructed) was unfeasible. However, we demonstrated that GFR after 72 h of releasing the obstruction increased significantly comparing with the previous stages.…”