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Antioxidant treatment of experimental diabetic retinopathy in rats with nicanartine
H P Hammes1, A Bartmann, L Engel
1III Department of Internal Medicine, Justus-Liebig-University, Giessen, Germany.
Abstract:
In order to study the contribution of oxidant stress to the pathogenesis of experimental diabetic retinopathy, male streptozotocin diabetic Lewis rats were treated with the antioxidant and lipid-lowering compound nicanartine (80 mg/kg; n = 8, blood glucose level 16.7 +/- 3.9 mmol/l; HbA1 11.8 +/- 1.6%) by oral supplementation for 6 months and compared with untreated diabetic (n = 6; blood glucose 18.1 +/- 1.4 mmol/l; HbA1 11.5 +/- 1.5%) and untreated, non-diabetic rats (n = 8; blood glucose 4.0 +/- 0.6 mmol/l; HbA1 4.8 +/- 0.9%). Diabetic retinopathy was evaluated by computer-assisted quantitative morphometry including measurement of autofluorescent advanced glycated end-products and immunohistochemistry for heme oxygenase I. Antioxidant treatment did not inhibit the 3.1-fold increase of retinal advanced glycation end products, while the expression of heme oxygenase I in both vascular and glial structures was markedly reduced. Chronic hyperglycaemia led to a 37.3% increase in endothelial cells (p < 0.001 vs normal controls) and a 26.6% reduction in pericyte numbers (p < 0.001 vs controls). Both abnormalities were significantly ameliorated by nicanartine (p < 0.001 vs diabetic controls). No effect was observed on the formation of acellular capillaries or microaneurysms. These data indicate that antioxidant therapy with nicanartine is of limited benefit in diabetic retinopathy, at least in the rodent model of streptozotocin-induced diabetes.
Insights
Antioxidant therapy with nicanartine showed limited benefit for experimental diabetic retinopathy in rats. While it improved some cellular changes, it did not prevent advanced glycation end-product accumulation or capillary damage.
Area of Science:
- Ophthalmology
- Endocrinology
- Pharmacology
Background:
- Oxidative stress is implicated in diabetic retinopathy pathogenesis.
- Experimental models are crucial for understanding disease mechanisms and testing interventions.
- Diabetic retinopathy is a leading cause of vision loss, necessitating effective treatments.
Purpose of the Study:
- To investigate the role of oxidative stress in experimental diabetic retinopathy.
- To evaluate the efficacy of the antioxidant nicanartine in mitigating diabetic retinopathy.
- To assess the impact of nicanartine on specific pathological markers in the retina.
Main Methods:
- Male streptozotocin-induced diabetic Lewis rats were treated with nicanartine for 6 months.
- Quantitative morphometry was used to measure advanced glycation end-products (AGEs) and heme oxygenase I (HO-1) expression.
- Retinal vascular and glial cell changes, including endothelial cells and pericytes, were analyzed.
Main Results:
- Nicanartine did not prevent the increase in retinal AGEs.
- HO-1 expression was significantly reduced by nicanartine treatment.
- Nicanartine ameliorated hyperglycemia-induced increases in endothelial cells and reductions in pericytes, but not acellular capillaries or microaneurysms.
Conclusions:
- Antioxidant therapy with nicanartine has limited efficacy in this rodent model of diabetic retinopathy.
- The study suggests that targeting oxidative stress alone may not be sufficient for comprehensive treatment.
- Further research is needed to explore alternative or combination therapies for diabetic retinopathy.