In vitro retinal and erythrocyte polyol pathway regulation by hormones and an aldose reductase inhibitor

Abstract

The effects of a high-glucose medium, insulin, and an aldose reductase inhibitor (ONO-2235) on sorbitol accumulation were compared in the human erythrocyte and the rabbit retina, while the effects of epinephrine on in vitro sorbitol accumulation were investigated in the human and rabbit retina. In both erythrocytes and the retina, linear increments of sorbitol accumulation were observed in a dose-dependent manner with 5 to 50 mM glucose. These increments were markedly inhibited by 100 microM ONO-2235 but not by insulin (400 microU/ml). In the presence of 5 mM glucose, a dose-dependent increase of the sorbitol content of the rabbit retina was seen following epinephrine stimulation (0.4-4.0 microM and this was markedly reduced by 100 microM ONO-2235. Moreover, both 50 mM glucose and 4.0 microM epinephrine increased the sorbitol content of the retina from a diabetic patient, and the glucose-induced increment in sorbitol was significantly reduced by 100 microM ONO-2235. Our data suggested that aldose reductase inhibitors might be useful for the treatment of diabetic retinopathy, since the polyol pathway appears to be an important factor in its pathogenesis, and that catecholamines might have some role in the activation of the retinal polyol pathway.