The goal of the proposed work is to define the molecular mechanisms underlying age pigment accumulation in the mammalian retinal pigment epithelium (RPE). This goal will be achieved by determining the chemical structures of the molecules responsible for age pigment autofluorescence. In addition, it will be determined whether experimental manipulations can affect composition and rates of autofluorescent pigment deposition in the RPE. The latter experiments will reveal the significance of various physiological factors in determining the extent of age pigment accumulation in the RPE. Chemical characterization of age pigment will be performed on pigment granules isolated from the RPE of human donor eyes. The fluorophores will be extracted from these granules, separated and purified by various chromatographic techniques, and structurally identified using standard analytical techniques including mass, nuclear magnetic resonance, uv-vis and ir absorbance and corrected fluorescence spectroscopic techniques. Spectral and chromatographic behaviors will be utilized in the development of qualitative and quantitative assays for specific fluorescent components of the lipofuscin granules. Animal experiments will be conducted to determine whether antioxidant nutrient status, vitamin A intake, light exposure, and phagocytosis influence the chemical composition and rates of deposition of lipofuscin in the RPE. The effects of the latter manipulations will be evaluated by quantitative microscopic and chemical assay procedures. It is possible that age pigment accumulation or the reactions leading to its formation may be detrimental to RPE function. Such effects may ultimately lead to senile macular degeneration. Understanding the mechanisms underlying age pigment accumulation may suggest means by which to prevent development of the latter disease.
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