Oxidative Injury by Oxygen and Nitrogen Radicals in Diabetic Retinopathy in the BBZ/WOR Rat: CytoChemical and ImmunoCytochemical Studies

Abstract

Previous studies have documented NADH oxidase as a source of the oxygen radicals, superoxide (O2) and hydrogen peroxide (H2O2), at sites of disruption of the blood retinal barrier (BRB) in a rat model of noninsulin dependent diabetes (NIDDM). Excess production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) has been implicated in the complications of diabetes. The effects of NO depend on its microenvironment and one mechanism for its role in complications of diabetes is interaction with oxygen radicals to form the toxic species, peroxynitrite (ONOO−). Since NO is a highly labile molecule, its potential localization is best achieved by immunocytochemical studies of NOS. The activity of iNOS can be detected by localization of nitrotyrosine, a marker indicative of the formation and activity of ONOO−.Colloidal gold labeled immunocytochemical studies of iNOS and nitrotyrosine were done on sections of neural retina in eyes of obese, NIDDM BBZ/Wor rats in which NADH oxidase had been localized with cerium perhydroxide. Disruption of the BRB was documented by immunocytochemical localization of extravasated endogenous serum albumin. Age matched, nondiabetic control retinas were from eyes from BBDR/Wor rats.