Objective: To observe the role of blood glucose control on morphology changes of retinal vessels and retinal vascular endothelial growth factor (VEGF) expression in early diabetic rats.
Methods: Diabetes was induced in 8-week-old male Wistar rats by a single intraperitoneal injection of Streptozotocin (STZ). After 3 weeks, the animals were randomly divided into four groups: (1) normal rats group, (2) diabetic rats group, (3) diabetic rats with glucose controlled group, received intensive insulin therapy for 20 days, and (4) diabetic rats with uncontrolled blood glucose group, received unregular insulin therapy, which caused the abrupt fluctuation of glucose. After the treatment period, the animals were perfused with 30 mg/ml Fluorescein isothiocyanate-dextran (FITC-Dextran). The eyes were enucleated and fixed in 4% paraformaldehyde immediately. Retinal flat mounts and paraffin sections were prepared. Morphology of impaired retinal vessels and retinal VEGF expression were assessed by immunofluorescence stain and image analysis.
Results: The flat-mounted retinas showed more FITC-Dextran aggregated locally at vessels and capillary meandered or dilated in STZ-diabetic rats with uncontrolled blood glucose than in STZ-diabetic rats with controlled blood glucose. Retinal VEGF expression decreased in group 3 compared with group 2 or with group 4. The statistical difference was significant (P < 0.05).
Conclusion: Strict control of blood glucose by insulin could decrease VEGF expression in retina and protect retinal vessels from impairing in early STZ-diabetic rats.