Photo-oxidative stress in the eye: role of retinal pigment epithelial pigments

Randolph D. Glickman, Alexander E. Dontsov, Mikhail A. Ostrovsky, Neeru Kumar, Meena Vendal, Mary Ann Gonzales

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

The pigments of the retinal pigment epithelium, i.e. the intracellular granules of melanin, lipofuscin, and melanolipofuscin, have been shown to catalyze free radical activity, especially when illuminated with visible or ultraviolet light. An important question is whether these reactions are sufficient to produce oxidative damage in the eye. To address this question, the relative photoreactivity of isolated RPE pigment granules towards polyunsaturated fatty acids has been determined, including the dark as well as the light-stimulated reactions. Hydroperoxide derivatives of docosahexaenoic acid were produced by irradiation with short wavelength (<550 nm) visible light when RPE pigments were present. Although melanosomes exhibited the greatest light-induced activity in these reactions, lipofuscin granules induced peroxidation of fatty acids in the dark. In intact, cultured RPE cells, the existence of pigment-mediated photo-reactions were demonstrated with a fluorescent indicator probe of oxidation, 2′,7′-dichlorofluorescein, that was photooxidized in probe-labeled cells in a wavelength dependent fashion with peak activity in the 450 to 500 nm region. This behavior resembled the action spectrum for melanin reactivity. These findings support the hypotheses that the RPE pigments contribute to general photooxidative stress in ocular tissue, and that accumulation of lipofuscin pigment contributes to age-related oxidative stress in the RPE.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Pages428-438
Number of pages11
Volume3863
StatePublished - 1999
EventProceedings of the 1999 International Conference on Biomedical Optics (BMO'99) - Wuhan, China
Duration: Oct 25 1999Oct 27 1999

Other

OtherProceedings of the 1999 International Conference on Biomedical Optics (BMO'99)
CityWuhan, China
Period10/25/9910/27/99

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

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