Abstract
Abstract: :
Purpose: There is increasing evidence for neuronal anomalies early in diabetes. In this ongoing longitudinal study, we examined whether dietary supplementation of omega–3 fatty acids ameliorates retinal dysfunction in the streptozotocin (STZ)–diabetic rat model using the electroretinogram (ERG). Methods: Two groups of diabetic Sprague–Dawley rats (D), were supplemented with either an omega–3 sufficient diet (fish oil; DFO=16) or an omega–3 deficient diet (safflower oil; DSO=16). Sprague–Dawley rats supplemented with fish oil were used as controls (CFO=16). Dietary supplementation was commenced during gestation on pregnant dams and was continued following weaning to facilitate neural incorporation of omega–3 substrates. ERGs were measured over a 24–week period following STZ injection (53mg/kg at 8–weeks of age). Diabetes was confirmed through blood glucose levels and HbA1c and animals were administered 2 units insulin daily. Following dark adaptation (>12hrs) and anesthesia (ketamine & xylazine 60:5 mg/kg im), rod and cone responses were isolated over a 2.0 log cd/m2 range intensity series. Photoreceptoral responses were modeled on known phototransduction processes and inner retinal responses were extracted. Retinal phospholipids were extracted and methyl esters identified using gas chromatography. Results: No differences in blood glucose levels were observed between DFO and DSO groups. Fish oil supplementation prevented ERG amplitude losses for photoreceptoral and inner retinal responses for the diabetic group (DFO vs. CFO). However, diabetic animals raised in the absence of fish oil (DSO) displayed amplitude reductions for both photoreceptoral (–18%) and inner retinal responses (–25%) after 24–weeks of diabetes. Conclusions: Our findings provide evidence for a protective role of dietary fish oil on diabetic retinal function.
Keywords: diabetic retinopathy • electroretinography: non–clinical • retina