Effect of Dietary Omega-3 and Omega-6 Fatty Acids on IOP Elevation, Electroretinographic Changes and Retinal Ganglion Cell Loss in a Laser-Induced Rat Model of Glaucoma

Abstract

Purpose: : To test the efficacy of dietary omega-3 and omega-6 fatty acids in a rat model of glaucoma induced by laser photocoagulation.

Methods: : Male Sprague Dawley rats were fed for 3 months with a diet containing either: 1) 17% of omega-3 fatty acids (10% EPA + 7% DHA), 2) 10% of omega-6 fatty acids (as GLA), or 3) a combination of both omega-3 and omega-6 fatty acids (10% EPA + 7% DHA + 10% GLA), by comparison with a control group of animals fed with a standard diet deprived of EPA, DHA and GLA (n=10 in each group). After 3 months of diet, glaucoma was induced in one eye of each animal by laser photocoagulation (532nm) of the episcleral veins, the trabeculum and the limbal veins. During the 3 following months, the animals were fed on the same diets, IOP was regularly measured and the retinal function was evaluated by electroretinography (ERG). At the end of the experiment, the loss of the retinal ganglion cells in both operated and fellow eyes was evaluated after retrolabelling using Fluorogold.

Results: : A significant increase of IOP was observed in the laser treated-eyes: 49±16 mmHg compared to11±1.2 mmHg in the fellow eyes, during the first two weeks after photocoagulation. IOP elevation was similar in each group.The ERG b-wave amplitude was significantly reduced by approximately 70% 8 and 12 weeks after photocoagulation in the laser treated-eyes in the animals fed with the control and the omega-3 diets. Interestingly, both diets containing omega-6 lowered the reduction of the ERG b-wave amplitude in the laser treated-eyes. The number of retinal ganglion cells was reduced by 70% in the laser-treated eyes. None of the diets efficiently prevented the loss of the retinal ganglion cells.

Conclusions: : Neither dietary omega-6 nor omega-3 fatty acids efficiently prevented the development of glaucoma in our rat model using laser photocoagulation, as illustrated by the absence of effects against IOP elevation and loss of retinal ganglion cells. Further works are warranted to decipher the mechanisms and consequences of the effects of omega-6 fatty acids on the retinal function as assessed by ERG

Keywords: electroretinography: non-clinical • ganglion cells • lipids