The effect of netrin-1 on the retinal vascular permeability in diabetes mellitus rats

Objective To observe the effect of different concentration netrin-1 on retinal vascular permeability in diabetes mellitus (DM) rats. Methods Eighty adult Sprague-Dawley rats were randomly divided into 8 groups, 10 rats in each group, including normal control group (group A), normal+ balanced salt solution (BSS) group (group B), normal+ netrin-1 (500 μg/ml) group (group C) and DM group (50 rats in 5 subgroups). DM rats were induced by intraperitoneal injection of streptozocin. Three months after intraperitoneal injection, 10 DM rats in the control group were injected with BSS (group D). Forty DM rats were injected with 5 μl of different concentrate netrin-1, and were divided into DM+netrin-1 10 μg/ml group (group E), DM+netrin-1 50 μg/ml group (group F), DM+ netrin-1 100 μg/ml group (group G), DM+ netrin-1 500 μg/ml group (group H) according to the different concentration. Non-DM rats in group C were injected with netrin-1 500 μg/ml. The expression of occludin was determined by immunohistochemistry for protein, and by real-time fluorescence quantitative reverse transcription polymerase chain reaction for mRNA level. Retinal vascular permeability was measured by Evans blue infusion. Results The expression of occludin protein and mRNA in group D were less than group A (t=27.71, 8.59; P=0.00, 0.00). However, the retinal vascular permeability increased in group D (t=-42.72, P=0.00). The expression of occluding protein, occludin mRNA and retinal vascular permeability showed significant differences between group D, E, F, G and H (F=146.31, 16.54, 67.77; P=0.00, 0.00, 0.00). Compared the group B with group C, there was no significant differences between the expression of occludin protein, occludin mRNA and the retinal vascular permeability (t=-1.13, 0.93, 1.04; P=0.27, 0.36, 0.31). The concentrate of netrin-1 showed a significant positive correlation to the expression level of occludin and occludin mRNA (r=0.73, 0.81; P=0.00, 0.00), but negative correlation to the vascular permeability (r=-0.61, P=0.00). Conclusion Netrin-1 can reduce the DM rats' retinal vascular permeability, which depended on the concentration of netrin-1. Key words: Diabetic retinopathy/physiopathology; Blood retinal barrier/physiopathology; Nerve growth factors; Animal experimentation