Chronic inhibition of NOS-2 ameliorates renal injury, as well as COX-2 and TGF-beta 1 overexpression in 5/6 nephrectomized rats

• Published in: Nephrology, dialysis, transplantation dialysis, transplantation, 2006-11, Vol.21 (11), p.3074-3081
• Main Authors: Bautista-García, Pablo, Sánchez-Lozada, Laura Gabriela, Cristóbal-García, Magdalena, Tapia, Edilia, Soto, Virgilia, Avila-Casado, Ma Carmen, Márquez-Velasco, Ricardo, Bojalil, Rafael, Franco, Martha, Herrera-Acosta, Jaime
• Format: Article
• Language: English
• Subjects: Animals; Cyclooxygenase 2 - biosynthesis; Cyclooxygenase 2 - genetics; Kidney Cortex - blood supply; Kidney Cortex - enzymology; Kidney Cortex - metabolism; Kidney Cortex - pathology; Ligation; Male; Nephrectomy; Nitric Oxide - physiology; Nitric Oxide Synthase Type II - antagonists & inhibitors; Rats; Rats, Sprague-Dawley; Renal Artery - surgery; Transforming Growth Factor beta1 - biosynthesis; Transforming Growth Factor beta1 - genetics
• ISSN: 0931-0509
• DOI: 10.1093/ndt/gfl444

Chronic renal damage is associated with inflammatory infiltration, fibrosis and vascular lesion, coupled with increased expression of cyclo-oxygenase 2 (COX-2) and transforming growth factor-beta1 (TGF-beta1). However, the role of inducible nitric oxide synthase (NOS-2) is still controversial. Thus, we studied the contribution of NOS-2 to the expression levels of COX-2 and TGF-beta1, as well as the structural renal injury in rats with subtotal renal ablation (5/6 Nx). Four groups of rats were studied: sham, 5/6 Nx, 5/6 Nx+aminoguanidine (AG) and 5/6 NX+L-NIL (L-N6-iminoethyl-lysine). Systolic blood pressure (SBP), proteinuria and creatinine (Cr) clearance were measured. NOS-2, COX-2 and TGF-beta1 gene expression was determined by real-time reverse transcription-polymerase-chain reaction. Protein expression was evaluated by western blot and ELISA (TGF-beta1). Immunohistochemistry and morphometry were performed for NOS-2, microvascular thickening and fibrosis. Systemic hypertension and marked proteinuria, increased expression of NOS-2, COX-2 and TGF-beta1, thickening of arteriolar wall and tubulointerstitial fibrosis were produced in 5/6 Nx rats. Chronic inhibition of NOS-2 did not prevent arterial hypertension or the fall in Cr clearance, but partially reduced proteinuria. Nevertheless, AG and L-NIL preserved arteriolar morphology and the administration of both selective inhibitors of inducible NOS (AG and L-NIL) prevented NOS-2 overexpression. This study shows that NOS-2 was markedly enhanced in renal tissue of 5/6 Nx rats. Moreover, treatment with AG and L-NIL prevented the morpho-functional changes induced by subtotal renal ablation, despite persistence of systemic hypertension, suggesting that high concentrations of nitric oxide produced by NOS-2 could act as a positive modulator of the proinflammatory and profibrotic pathways involved in the progression of renal disease.