Immunohistochemical Distribution of Inducible Nitric Oxide Synthase Enzyme (iNOS) in the Renal Cortex of Control and Diabetic Adult Male Albino Rats and the Effect of iNOS Inhibition by Aminoguanidine

Background: Inducible nitric oxide synthase (iNOS) enzyme endogenously synthesizes nitric oxide molecule involved in regulation of renal function. Conflicting reports exist regarding immunohistochemical localization of iNOS in the kidney and its role in diabetes. Aim of the Work: Investigation of immunohistochemical distribution of iNOS in renal cortex of control and diabetic rats and effect of iNOS inhibition by aminoguanidine. Materials and Methods: Forty adult albino male rats were used. Rats were divided into; group I (negative control animals), group II positive control rats (receiving aminoguanidine), group III included diabetic rats (diabetes was induced by streptozotocine drug), group IV (diabetic rats receiving aminoguanidine). The animals were sacrificed after1 month. Kidneys were prepared for histological study and immunohistochemical localization of iNOS in renal cortex. Results: In control (Group I II) rats, collecting tubules revealed a positive immune reaction of iNOS, while renal glomeruli were negative. Diabetic (Group III) animals showed structural changes 1 month after induction of diabetes in the form of enlarged renal corpuscles, degenerated renal tubules and interstitial leukocytic infiltration, with a positive immune-reaction of iNOS in those structures. In diabetic (Group IV) animals, more diabetic changes were found after iNOS inhibition by aminoguanidine. Conclusion: The iNOS was expressed in collecting tubules of control rat kidney and in renal corpuscles of early diabetic rats. The inhibition of iNOS promoted more diabetic changes, indicating a possible protective role of iNOS against progression of diabetic nephropathy.