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Siv Johnsen-Soriano, Emma Arnal, Miguel Flores-Bellver, Luis Bonet-Ponce, Francisco Javier Romero; DHA restores VEGF via Nrf2 protection pathway inhibiting oxidative damage in RPE at high glucose levels. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1793.
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© ARVO (1962-2015); The Authors (2016-present)
Diabetic retinopathy is a leading cause of visual loss and have been related to oxidative stress. The aim of the present study was to evaluate protective properties of Docosahexaenoic acid (DHA) at retinal pigment epithelial (RPE) cells exposed to high glucose levels.
Human RPE cells (ARPE-19) were cultured 4 days with normal blood glucose concentration, followed by ten days exposure to either normal or high D-glucose concentration. DHA was administered according to the following groups: control group (C), control+DHA group (CDHA), glucose group (G) and glucose+DHA group (GDHA). At the end of the experiment cells were washed, sonicated and lysed and the homogenates cryopreserved until biochemical assays. At this time point, cell population of different groups were fixed for electronic microscopy evaluation.
Antioxidant Capacity, (AC),(0,97± 0,1 μM/mg prot) and glutathione (GSH) concentration (0,25 ± 0,05 μmol/mg prot) in G group decreased significantly when compared to C group (1,52 ± 0,09 μM/mg prot and 0,61 ± 0,16 μmol/mg prot respectively) confirming the oxidative status in cells treated with glucose. DHA administration normalized these alterations (1,41 ± 0,16 μM/mg prot (AC) and 0,51 ± 0,07 μmol/mg prot (GSH)) in GDHA group. In addition, VEGF and Nrf2 immunohistochemical studies were performed. DHA restores VEGF to control values in GDHA group (61,82 ± 10,94 VEGF-positive cells/total cells) when compared with G group (89,46 ± 2,49; p<0,05 ). Moreover, Nrf2 expression in GDHA group increased significantly (58,38 ± 12,37 Nrf2-positive cells/total cells) when compared to C group (29,75 ± 1,51 Nrf2-positive cells/total cells; p< 0,05), showing a possible protection response via Nrf2 pathway. Finally, an electron microscopy study was done to establish possible alterations present in the ultrastructure of RPE diabetic cells.
These data further support previous findings that suggest that DHA might be useful in protecting diabetic retina.
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