Simvastatin ameliorates vascular endothelial growth factor overexpression in a rat model of diabetic retinopathy: a histological and immunohistochemical study

Background and objectives: Diabetic retinopathy (DR) is one of the main causes of vision loss. Treatment options during its early stages are not available. This study was designed to evaluate the potential protective effects of simvastatin on experimentally induced DR, with special emphasis on its possible modulatory effect on vascular endothelial growth factor (VEGF). Materials and methods: Thirty adult male albino rats were divided equally into three groups: group І (the control group), group II (the diabetic group), and group III (diabetic/simvastatintreated group). Diabetes was induced by intraperitoneal injection of streptozotocin at a dose of 50 mg/kg/rat in 20 adult male albino rats. Simvastatin was administered orally as 20 mg/kg/rat 48 h after streptozotocin injection. Blood glucose levels and body weight were measured. Retinal specimens were processed for hematoxylin and eosin staining and VEGF immunohistochemistry. Morphometric analysis included measurement of retinal thickness and area percentage of VEGF. All results were statistically analyzed using the Student t-test and analysis of variance test. Results: The untreated group showed histological features of DR and increased VEGF immunoreactivity compared with controls. The simvastatin-treated group showed improved features of DR and decreased VEGF immunoreactivity. Conclusion: These results suggest that simvastatin has protective effects against DR by eliminating VEGF overexpression and might be considered a promising therapeutic agent for it.