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T.I. Dentchev, Y. Yao, D. Pratico, J.L. Dunaief; Isoprostane, a new marker of oxidative stress, increases following light damage to the mouse retina . Invest. Ophthalmol. Vis. Sci. 2004;45(13):758.
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Purpose: A number of studies have suggested that retinal light damage involves oxidative stress. These include demonstration of protection by antioxidants, immunohistochemical detection of oxidative stress markers, and upregulation of antioxidant enzymes. Recent work has developed a new specific marker of lipid peroxidation, the isoprostane 8,12–iso–iPF2α. This prostaglandin isomer is produced by non–enzymatic oxidation of membrane–linked arachidonic acid. Because it provides an unusually stable and specific measure of lipid peroxidation, we sought to determine whether its levels would increase following retinal light damage. Methods: Eight week old male Balb/c mice were dark adapted for 24 hrs and then exposed for 7 hrs to 10,000 lux cool white fluorescent light. The mice were euthanized 28 hrs after light damage and retinas were immediately collected for immunohistochemistry (IHC) and gas chromatography/mass spectrometry (GC/MS) to measure levels of 8,12–iso–iPF2α. The control group was dark adapted and but did not receive light damage. Results: IHC analysis of 8,12–iso–iPF2α showed increased levels throughout the retina in the group that underwent to light damage. Similarly, GC/MS demonstrated elevated levels of this isoprostane following light damage. TUNEL analysis demonstrated photoreceptor cell death after light exposure. Conclusion: Isoprostanes are prostaglandin isomers produced by free radical–catalyzed peroxidation of polyunsaturated fatty acids. Elevated levels of 8,12–iso–iPF2α , a stable, highly specific maker of lipid peroxidation confirm earlier reports of light–mediated retinal lipid peroxidation, potentially an important mechanism of retinal degeneration. Further, since levels of 8,12–iso–iPF2α are readily quantified by GC/MS, its measurement provides a new means to monitor retinal oxidative damage and test the efficacy of retinal antioxidants.
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