Abstract
Purpose: :
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.
Methods: :
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 assayed.
Results: :
Antioxidant Capacity, (AC), (0.97 ± 0.1μM/mg prot) and glutathione concentration (GSH) (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); DHA administration normalized these alterations (1.41 ± 0.16 μM/mg prot (AC) and 0.51 ± 0.07 μmol/mg prot (GSH)). Moreover, the total nitrites (TN) and malondialdehyde (MDA) concentrations were significantly elevated in G group (1.09 ± 0.35 μmol/mg prot and 0.59 ± 0.16 μmol of MDA/mg prot respectively) when compared to the C group (0.53 ± 0.08 μmol/mg prot and 0.25 ± 0.05 μmol of MDA/mg prot), and DHA administration again normalized these alterations to normal values (0.49 ± 0.12 μmol/mg prot and 0.30 ± 0.03 μmol of MDA/mg prot; p<0,05). In addition, hydroxynonenal (HNE) and Pigment Epithelial Derived Factor (PEDF) immunohistochemical studies were performed. DHA restores HNE-positive cell density in GDHA group (42.59 ± 7.53 HNE-positive cells/total cells) when compared with G group (76.77 ± 12.7; p<0,05 ). Moreover, PEDF-positive cell number in GDHA group increased significantly (48.54 ± 12.53 PEDF-positive cells/total cells) when compared to G group (28.71 ± 7.73 PEDF-positive cells/total cells; p< 0,05).
Conclusions: :
These data further support previous findings that suggest that DHA might be useful in protecting diabetic retina.
Keywords: antioxidants • retinal pigment epithelium • diabetic retinopathy