The Effect Of Netrin-1on The Retinal Vascular Permeability In Early Diabetic Retinopathy Rats

Objective To observe the effect of netrin-1on blood-retinal barrier permeability in diabetic rats and analysis the mechanism.Methods One hundred adult clean SD rats were randomly divided into normal group(10rats), normal+BSS group(10rats) and diabetes mellitus(DM) group (80rats). DM rats were induced by intraperitoneal injection of STZ (60mg/kg).3months after intraperitoneal injection, we randomly sacrificed3rats every month. When the HE staining showed the early diabetic retinopathy, we injected5ul different concentrate netrin-1into the DM rats. The rats were randomly divided into DR+netrin-1(10μg/ml) group, DR+netrin-1(50μg/ml) group, DR+netrin-1(100μg/ml) group and DR+BSS group. The control group was injected with BSS. All rats were sacrificed at1month after intravitreal injection. Retinal vascular permeability was measured by Evans blue. The expression level of GFAP was determined by immunohistochemistry and the level of occludin mRNA were analysis by Real-time fluorescence quantitative reverse transcription polymerase chain reaction (RT-PCR).Results Staining of GFAP in retina was limited to ganglion cells and nerve fiber layer in normal rats, but in DR control group, the color of staining positive of GFAP was deepen and enlarged. However, DR+netrin-1group GFAP staining was lighter and more reduced, and it show some relationship with the dose of netrin-1. compared the low netrin-1dose with DR+BSS group, there was significant difference. There was significant difference between high dose group and normal group. the result of examination the retinal vascular permeability:There was statistically significant differences between DR group and normal control group (P<0.05). The netrin-1can reduce the permeability of retinal vascular, and this function have relationship with the concentration of netrin-1(P<0.05). However, it can not reduce the permeability to normal level. The expression of occludin mRNA in DR group was lower than the normal control group (P<0.05).When we injected netrin-1into the vitreous,the occludin mRNA increased, but it can not return to normal level, there was significant differences between the DR control group with DR+netrin-1group(P<0.05)Conclusion1.3months after intraperitoneal injection of STZ, the retina show early diabetic retinopathy.2. The blood-retinal barrierpermeability of diabetic rats is higher than normal rats’, and the occludin have relationship with the permeability of retinal vascular.3. Changes of glial cell activity can influence the retinal vascular permeability, which may be caused though influencing the expression of occludin.4. Netrin-1can protect the blood-retinal barrier, the more concentration, the more protection, but it can not decrease the retinal vascular permeability to normal level.5. Netrin-1may decrease BRB leakage in DR rats by inhibiting the activity of glial cell, which may be regulation by influencing the expression of occludin.