2-Deoxy-D-glucose uptake in the inner retina: An in vivo study in the normal rat and following photoreceptor degeneration

Purpose: To evaluate, in vivo, at the cellular level, glucose metabolism in the rat inner retina, and to determine how inner retinal glucose metabolism is affected by photoreceptor degeneration. Methods: Glucose metabolism was evaluated using the 2-deoxyglucose technique. This is an autoradiographic technique that permits evaluation of glucose uptake at the cellular level. The three experimental groups consisted of normal rats (n=13), dystrophic Royal College of Surgeons rats (n=3), and rats previously treated with argon green photocoagulation (n=5). Results: Deoxyglucose uptake in the normal rat was not uniform across the inner retina. Uptake was greatest at the junction of the outer plexiform and inner nuclear layers, and in the inner plexiform layer. Following focal or diffuse photoreceptor loss, there was a marked decrease in the amount of deoxyglucose uptake at the junction of the outer plexiform and inner nuclear layers. Conclusion: The pattern of uptake of deoxyglucose in the inner retina is consistent with abundant uptake of deoxyglucose by Müller cells and at sites of synaptic transmission. The decline in deoxyglucose uptake following diffuse or focal photoreceptor loss indicates that there is diminished inner retinal glucose uptake following photoreceptor loss. This change in inner retinal glucose metabolism following photoreceptor loss may help to explain the inner retinal vascular changes observed following photocoagulation and in retinal dystrophies.