Glycine receptor is differentially expressed in the rat retina at early stages of streptozotocin-induced diabetes

Diabetes mellitus is a metabolic disease that leads to several complications which include retinopathy. Neuronal abnormalities have been reported to appear before microvasculature alterations. We analyzed the expression levels of GlyR subunits in the retina at 7, 20, and 45 days after streptozotocin-induced diabetes to gain insight into the pathogenesis of diabetic retinopathy. We determined the mRNA and protein expression by qPCR and western blot, respectively. The mRNA and protein expression of the alpha 1 subunit was not altered over the study period; however, they were slightly reduced in alpha 2 yet statistically significant. While protein expression of alpha 3 subunit was only reduced at 45 days diabetes. The mRNA and protein expression of the alpha 4 subunit was remarkably decreased since day 7 of diabetes, remaining only similar to 20% on day 45 of diabetes. Surprisingly, the mRNA of the beta subunit was highly increased, while its protein levels were not changed. The decrease in GlyR alpha subunits expression in the retina from diabetic animals suggest a perturbation in the inhibitory glycine signaling pathway, which might be related to the visual alterations observed in diabetes.