Abstract
Purpose: :
The high levels of circulating glucose in diabetics lead to diabetic retinopathy and eventually blindness. Controlling blood glucose in diabetics reduces significantly the incidence of retinopathy. High glucose levels damage retinal vessels leading to plasma leakage and retinal damage. Using a retina organ culture system we established, we have examined the effects of high glucose levels on the cells of the neural retina.
Methods: :
Adult bovine retinas were isolated soon postmortem and cultured in static culture for 3 days in the presence of normal glucose levels (5,5 mM D-glucose) or elevated levels of glucose (25 mM D-glucose). After 3 days in culture, the retinas were fixed, embedded in paraffin and stained with H&E for morphological evaluation. The density of the ganglion cell nuclei was measured and subjected to statistical analysis using analysis of variance (one way ANOVA). Using immunohistochemistry the retinas were also analyzed for vimentin expression as an indicator of cytoskeletal and cell shape alterations and glial fibrillary acidic protein (GFAP) as an indicator of astrocyte and glial cells.
Results: :
A significant loss of cell nuclei was observed in the high glucose cultures compared to the retinas cultured in normal glucose both in the inner nuclear layer (48.9 ± 7.6 cells /100µm vs. 37.1± 8.1 cells /100µm, p=0,003) and outer nuclear layer (197.9 ± 24 cells /100µm vs. 132.9 ± 17.6 cells /100µm, p<0,001). In addition in the retinas cultured in high glucose there was evidence of significant photoreceptor outer segment degeneration. Immunohistochemical analysis revealed upregulation of GFAP in the retinas cultured in high glucose, but no change was observed in the staining pattern or intensity for vimentin.
Conclusions: :
The changes we have observed in retinas cultured in the presence of high glucose indicate that glucose in high concentration has significant toxic effects for specific neural retinal cells. The organotypic retina cultures described here should prove useful as a model to examine the role of high glucose without the complications of other factors that play a role in the development of diabetic retinopathy in vivo.
Keywords: diabetic retinopathy