Beneficial effect of zeaxanthin on retinal metabolic abnormalities in diabetic rats.
OBJECTIVE
Oxidative damage and growth factors are implicated in the pathogenesis of retinopathy in diabetes. Recent studies have shown that two dietary carotenoids, lutein and zeaxanthin (Zx), that are specifically concentrated within ocular tissues, may play important roles in maintaining their integrity. This study is to evaluate the potential protective effects of Zx against retinal oxidative damage and growth factors in diabetes.


METHODS
A group of rats received normal powdered diet or powdered diet supplemented with 0.02% or 0.1% Zx soon after induction of diabetes. Age-matched normal rats served as control subjects. At 2 months of diabetes, oxidative stress, vascular endothelial cell growth factor (VEGF), and intercellular adhesion molecule (ICAM)-1 were quantified in the retina.


RESULTS
Zx supplementation prevented diabetes-induced increase in retinal damage, and increases in VEGF and ICAM-1. The levels of lipid peroxide, oxidatively modified DNA, electron transport complex III, nitrotyrosine, and mitochondrial superoxide dismutase were similar in the retinas of Zx-treated diabetic rats and normal control rats, and these values were significantly different from those obtained from diabetic rats without any supplementation. In the same rats, Zx also prevented diabetes-induced increases in retinal VEGF and ICAM-1. Both 0.02% and 0.1% Zx had similar effects on diabetes-induced retinal abnormalities, and these effects were achieved without ameliorating the severity of hyperglycemia. However, Zx administration failed to prevent a diabetes-induced decrease in retinal GSH levels.


CONCLUSIONS
Zx significantly inhibits diabetes-induced retinal oxidative damage and elevation in VEGF and adhesion molecule, all abnormalities that are associated with the pathogenesis of diabetic retinopathy. The results suggest that Zx supplementation has the potential to inhibit the development of retinopathy in diabetic patients.
Kowluru
Renu A
RA
Department of Ophthalmology, Kresge Eye Institute, Detroit, Michigan 48201, USA. rkowluru@med.wayne.edu
Menon
Bindu
B
Gierhart
Dennis L
DL
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000378:metabolism / Q000517:prevention & control*; D003930:Diabetic Retinopathy / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D004032:Diet; D014450:Electron Transport Complex III / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008297:Male; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D024341:Xanthophylls / Q000008:administration & dosage*; D065146:Zeaxanthins
D001786:Blood Glucose; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D024341:Xanthophylls; D065146:Zeaxanthins; C467498:vascular endothelial growth factor A, rat; D018799:Intercellular Adhesion Molecule-1; C002744:3-nitrotyrosine; D014443:Tyrosine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D013482:Superoxide Dismutase; D014450:Electron Transport Complex III; D003849:Deoxyguanosine