title: Dynamic, in vivo, real-time detection of retinal oxidative status in a model of elevated intraocular pressure using a novel, reversibly responsive, profluorescent nitroxide probe.
abstract: Changes to the redox status of biological systems have been implicated in the pathogenesis of a wide variety of disorders including cancer, Ischemia-reperfusion (I/R) injury and neurodegeneration. In times of metabolic stress e.g. ischaemia/reperfusion, reactive oxygen species (ROS) production overwhelms the intrinsic antioxidant capacity of the cell, damaging vital cellular components. The ability to quantify ROS changes in vivo, is therefore essential to understanding their biological role. Here we evaluate the suitability of a novel reversible profluorescent probe containing a redox-sensitive nitroxide moiety (methyl ester tetraethylrhodamine nitroxide, ME-TRN), as an in vivo, real-time reporter of retinal oxidative status. The reversible nature of the probe's response offers the unique advantage of being able to monitor redox changes in both oxidizing and reducing directions in real time. After intravitreal administration of the ME-TRN probe, we induced ROS production in rat retina using an established model of complete, acute retinal ischaemia followed by reperfusion. After restoration of blood flow, retinas were imaged using a Micron III rodent fundus fluorescence imaging system, to quantify the redox-response of the probe. Fluorescent intensity declined during the first 60 min of reperfusion. The ROS-induced change in probe fluorescence was ameliorated with the retinal antioxidant, lutein. Fluorescence intensity in non-Ischemia eyes did not change significantly. This new probe and imaging technology provide a reversible and real-time response to oxidative changes and may allow the in vivo testing of antioxidant therapies of potential benefit to a range of diseases linked to oxidative stress.
authors.affiliation: Queensland Eye Institute, South Brisbane, Queensland, Australia.
authors.forename: Cassie L
authors.initials: CL
authors.lastname: Rayner
authors.affiliation: Department of Paediatrics & Child Health, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Glen A
authors.initials: GA
authors.lastname: Gole
authors.affiliation: ARC Centre of Excellence for Free Radical Chemistry School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Bottle
authors.affiliation: Queensland Eye Institute, South Brisbane, Queensland, Australia; The University of Queensland, UQ Centre for Clinical Research, Herston, Queensland, Australia; School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia. Electronic address: nigel.barnett@qei.org.au.
authors.forename: Nigel L
authors.initials: NL
authors.lastname: Barnett
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004596:Electroretinography; D005260:Female; D005456:Fluorescent Dyes; D005901:Glaucoma / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D007150:Immunohistochemistry; D007429:Intraocular Pressure / Q000502:physiology*; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020127:Recovery of Function; D012160:Retina / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology
chemical_list: D005456:Fluorescent Dyes; D017382:Reactive Oxygen Species
keywords: Fluorescent probe; Ischemia; Nitroxide; Oxidative stress; Reactive oxygen species; Reperfusion; Retina