[Effect of protamine on VEGF expression in vitreous and serum of rats with diabetic].

Objective: To study the effect of protamine on vascular endothelial growth factor (VEGF) expression in vitreous and serum of rats with diabetic.

Methods: 110 rats were included in the study, with 10 rats for normal control and the other 100 for diabetic models that induced by Streptozocin intraperitoneal injection. Then 80 rats with diabetic were used as eight groups: three groups (T1, T2 and T3) for intravitreal injection of protamine (50 microg protamine in 5 microL), and the other five groups were used as control. After 3 months, the T1, T2 and T3 group received the first injection; after 4 months, the T2 and T3 group received the second injection; after 5 months, the T3 group received the third injection. The rats were executed one week after their last injection, the retinae of the rats were taken for HE staining, and expression of VEGF in the serum and vitreous were measured by ELISA.

Results: As diabetic developed, VEGF expression in both serum and vitreous rised (P < 0.05); after the second protamine injection, VEGF expression in vitreous began to decrease obviously (P < 0.05); but VEGF expression in the serum didn't change by protamine. Rat retinal HE staining for the diabetic model group revealed retinal thickening, local interrupt, inner and outer nuclear layer cell derangement and vascular proliferation, which were significantly improved for the treatment groups.

Conclusion: Intravitreal injection of protamine reduced VEGF expression in vitreous of rats with diabetic, and protamine might be a new treatment for diabetic retinopathy, especially for retinal neovascularization.