Effect of aldose reductase inhibitors on the progression of retinopathy in galactose-fed dogs.

The onset and progression of diabetic-like retinopathy has been investigated in age-matched male beagle dogs fed a 30% galactose diet. Examination of the intact retinal vessels, isolated by gentle trypsin digestion, reveals that the destruction of pericytes to form pericyte ghosts is the earliest observable retinal vessel change. This results in an irregular distribution of endothelial cell nuclei near pericyte ghosts and the subsequent formation of acellular capillaries containing neither endothelial cells or pericytes. This was followed by the histological appearance of microaneurysms and later, by the funduscopic appearance of intraretinal hemorrhages. Studies in similar galactose-fed dogs treated with aldose reductase inhibitors indicate that all of these changes are linked to the initial aldose reductase associated destruction of pericytes.