RESUMEN
Objective To observe the changes of VEGF and Ang-2 expression in streptozotocin(STZ)-induced diabetic rat retina after insulin therapy and explore possible roles of insulin in the development of diabetic retinopathy. Methods Diabetes was induced in 8-week-old male wistar rats by a single intraperitoneal injection of STZ. After three weeks,animals were randomly divided into four groups:(1)diabetic rats received intensive insulin therapy for 20 days;(2)diabetic rats received unregular insulin therapy,which caused the abrupt fluctuation of glycemic level;(3)diabetic control rats; and (4)normal control rats. After treatment,the animals were sacrificed with an overdose of anesthesia,and the eyes were enucleated and fixed in 4% paraformaldehyde immediately. Paraffin sections of retina were prepared.Expression of VEGF and Ang-2 was assessed by immunofluorescence stain and images analysis. Results Quantitative analysis showed VEGF and Ang-2 protein expression was increased by 2.38-fold and 2.41-fold in diabetic rats retinas as compared to non-diabetic rats retinas respectively (P0.05). Conclusion Intensive insulin therapy could decrease VEGF and Ang-2 expression in retina and has protective effect on diabetic retinopathy in STZ-diabetic rats.