Abstract
Purpose::
vascular pathology in the retina is one of the hallmark changes during diabetes. It is commonly perceived that these vascular changes are the result of retinal hypoxia, which leads to the expression of vascular endothelial growth factor (VEGF). In this study, the role of dietary fish oil on retinal hypoxia and VEGF expression in the diabetic retina was examined.
Methods::
Sprague-Dawley rats were fed either a diet supplemented with or without fish oil. The diets were commenced at birth through to adulthood, where animals where then assigned to either control or diabetic groups (n=12 for each group). Diabetes was induced through streptozotocin (STZ) administration (50mg/kg) and followed for 13 weeks on their respective diets. VEGF ELISA and PCR were measured on retinal tissue at 13 weeks of diabetes. HypoxyProbe (Chemicon) immunoreactivity was assessed in vertical retinal sections (fixed in 4% paraformaldehyde for 30 mins) to examine hypoxic changes.
Results::
Diabetic animals bereft of dietary fish oil showed increases in VEGF protein and mRNA. However, fish oil supplementation was found to reduce the VEGF expression. HypoxyProbe immunofluorescence indicated the presence of hypoxia in the inner retina of diabetic animals. Fish oil supplementation did not prevent the presence of hypoxia in diabetic retina, however, there was a significant reduction in the number of inner retinal neurons undergoing hypoxic change.
Conclusions::
Dietary supplementation with fish oil was found to reduce the expression of VEGF in the diabetic retina. This indicates the possible benefit of dietary fish oil in improving the outcome of diabetic retinopathy as VEGF is one of the major growth factors involved in vascular change during diabetes.
Keywords: diabetes • hypoxia • retina