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Diabetic-like retinopathy in rats prevented with an aldose reductase inhibitor
W G Robison1, M Nagata, N Laver
1National Eye Institute, Bethesda, MD 20892.
Abstract:
The earliest histopathologic signs of diabetic retinopathy include selective loss of intramural pericytes and thickening of capillary basement membranes. Previous evidence from animal models indicated that aldose reductase inhibitors could prevent these capillary wall lesions, but only recently have aldose reductase inhibitors been tested for prevention of the subsequent retinal complications of diabetes, such as microaneurysms. In the present study, Sprague-Dawley rats were fed diets containing 50% galactose with or without an aldose reductase inhibitor (tolrestat). After 28 months of galactose feeding, the retinal capillaries in whole mounts exhibited a marked increase in periodic acid-Schiff (PAS) staining, extensive pericyte loss, endothelial cell proliferation, acellularity, diffuse dilation, occluded lumens, microaneurysms, and complex microvascular abnormalities including gross dilation and formation of multiple shunt networks. The PAS hyperchromaticity of basement membrane material and pericyte loss occurred throughout the retinal vasculature, while while the microaneurysms and complex lesions were limited to the capillaries of the central and paracentral retina. The changes were associated with both the arterial and venous portions of the capillary plexus. Treatment with orally administered tolrestat prevented essentially all of the vessel abnormalities. Thus, long-term galactose feeding of rats induced microvascular lesions simulating those occurring in background diabetic retinopathy in humans, and these lesions were prevented by treatment with an aldose reductase inhibitor.
Insights
Aldose reductase inhibitors prevent diabetic retinopathy complications. In rats, tolrestat treatment halted microvascular damage caused by galactose-induced diabetes, suggesting therapeutic potential for preventing vision loss.
Area of Science:
- Ophthalmology
- Diabetology
- Vascular Biology
Background:
- Diabetic retinopathy involves pericyte loss and basement membrane thickening.
- Aldose reductase inhibitors (ARIs) show promise in preventing early diabetic microvascular lesions.
- Previous studies focused on early lesions; this study investigates ARI efficacy against later complications like microaneurysms.
Purpose of the Study:
- To evaluate the efficacy of an aldose reductase inhibitor (tolrestat) in preventing galactose-induced retinal microvascular abnormalities in rats.
- To determine if ARIs can prevent advanced lesions resembling human diabetic retinopathy.
Main Methods:
- Sprague-Dawley rats were fed a 50% galactose diet for 28 months, with or without the ARI tolrestat.
- Retinal capillaries were analyzed using whole mounts for histopathologic changes.
- Key markers assessed included PAS staining, pericyte loss, microaneurysms, and vascular abnormalities.
Main Results:
- Galactose feeding induced significant retinal microvascular damage, including PAS hyperchromaticity, pericyte loss, endothelial proliferation, occluded lumens, microaneurysms, and shunt networks.
- These lesions mimicked human background diabetic retinopathy.
- Tolrestat treatment effectively prevented nearly all observed retinal vessel abnormalities.
Conclusions:
- Long-term galactose feeding in rats reliably replicates key microvascular lesions of diabetic retinopathy.
- Aldose reductase inhibition with tolrestat demonstrates significant efficacy in preventing these simulated diabetic microvascular complications.
- These findings support the therapeutic potential of aldose reductase inhibitors for managing diabetic retinopathy.