TY - JOUR
T1 - Retinal pigment epithelium pigment granules stimulate the photo- oxidation of unsaturated fatty acids
AU - Dontsov, Alexander E.
AU - Glickman, Randolph D.
AU - Ostrovsky, Mikhail A.
N1 - Funding Information:
Dr. A. E. Dontsov was a Research to Prevent Blindness International Scholar at the UTHSCSA during the performance of this research. Additional research support was provided by AFOSR grant F49629-95-1-0332 (to R.D.G.), grant No. 96-04-49819 from the Russian Foundation for Basic Research (to MAO), the San Antonio Area Foundation, the Helen Freeborn Kerr Foundation, an Enrichment Subgrant from the Howard Hughes Medical Institute Research Resources Program grant to the UTHSCSA, and an unrestricted grant from Research to Prevent Blindness (RPB) to the Department of Ophthalmology of the UTHSCSA. We thank Ms. Neeru Kumar and Mr. Steven Stubblefield for technical assistance during this project.
PY - 1999/6
Y1 - 1999/6
N2 - The cellular pigments of the retinal pigment epithelium (RPE) have been shown to catalyze free radical activity, especially when illuminated with visible or ultraviolet light. This activity is sufficient to cause photooxidation of several major cellular components. The present investigation determined the relative ability of melanin, lipofuscin, and melanolipofuscin granules isolated from human and bovine eyes to oxidize polyunsaturated fatty acids, specifically linoleic and docosahexaenoic acids. The dark reactivity as well as the light-stimulated reactions were determined. The production of hydroperoxide derivatives of the linoleic and docosahexaenoic acids were determined by NADPH oxidation coupled to the activity of glutathione peroxidase, and also by production of thiobarbituric acid reactive substances. All RPE pigment granules stimulated fatty acid oxidation when irradiated with short wavelength (<550 nm) visible light, with the melanosomes exhibiting the greatest light-induced activity. Only lipofuscin granules, however, caused peroxidation of fatty acids in the dark. These findings provide additional support for the role of RPE pigments in 'blue light toxicity' as well as indicating that accumulation of lipofuscin may contribute to increased photooxidation in the aging RPE.
AB - The cellular pigments of the retinal pigment epithelium (RPE) have been shown to catalyze free radical activity, especially when illuminated with visible or ultraviolet light. This activity is sufficient to cause photooxidation of several major cellular components. The present investigation determined the relative ability of melanin, lipofuscin, and melanolipofuscin granules isolated from human and bovine eyes to oxidize polyunsaturated fatty acids, specifically linoleic and docosahexaenoic acids. The dark reactivity as well as the light-stimulated reactions were determined. The production of hydroperoxide derivatives of the linoleic and docosahexaenoic acids were determined by NADPH oxidation coupled to the activity of glutathione peroxidase, and also by production of thiobarbituric acid reactive substances. All RPE pigment granules stimulated fatty acid oxidation when irradiated with short wavelength (<550 nm) visible light, with the melanosomes exhibiting the greatest light-induced activity. Only lipofuscin granules, however, caused peroxidation of fatty acids in the dark. These findings provide additional support for the role of RPE pigments in 'blue light toxicity' as well as indicating that accumulation of lipofuscin may contribute to increased photooxidation in the aging RPE.
KW - Free radicals
KW - Lipofuscin
KW - Melanin
KW - Melanolipofuscin
KW - Photooxidative stress
KW - Polyunsaturated fatty acids
KW - Retinal degeneration
KW - Retinal pigment epithelium
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U2 - 10.1016/S0891-5849(99)00003-9
DO - 10.1016/S0891-5849(99)00003-9
M3 - Article
C2 - 10401607
AN - SCOPUS:0033007242
VL - 26
SP - 1436
EP - 1446
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
SN - 0891-5849
IS - 11-12
ER -