Effect of matrix metalloproteinase inhibitor GM6001 on blood-retina barrier permeability in diabetic rats

Background Studies showed that some members of matrix metalloproteinases (MMPs) play an important role in the pathogenesis of diabetic retinopathy (DR).However,whether MMPs inhibitor can deter blood retinal barrier (BRB) from damage is below understood.Objective This study was to investigate the effects of GM6001,a MMPs inhibitor,on BRB permeability.Methods Twenty-four adult clean SD rats were randomized to the control group,diabetic group and diabetes+GM6001 group according to randomized number table.Diabetic models were induced by the intraperitoneal injection of streptozotocin in the rats of the diabetic group and the diabetes + GM6001 group,and equal volume of citrate buffer was used in the same way in the rats of the control group.GM6001 10 μ1 (100 μ mol/L) was intravitreously injected in the third and fourteenth day after modeling in the diabetes+ GM6001 group,and equal volume of normal saline solution was injected in the same way in the control group and the diabetic group.The rats were sacrificed and eyeballs were extracted 1 month after injection,and the relative expressions of MMP-2 mRNA and MMP-9 mRNA in rat retinas were detected by reverse transcription PCR (RT-PCR).Evens blue (EB) was infused via the right jugular vein,and paraformaldehyde solution 1％ was then infused via left ventricle at the perfusion pressure 120 mmHg.The eyeballs were extracted 2 minutes later,and the leakage of EB in rat retinas was examined.Results RT-PCR electrophoresis exhibited the response bands of MMP-2 mRNA,and MMP-9 mRNA and GAPDH,with the gene size of 436,536 and 484 bp,respectively.The difference of the MMP2 mRNA and MMP-9 mRNA was statisticaly significant (F =20.336,P =0.000 ; F =8.742,P =0.002) ; and the relative expressions of MMP-2 mRNA and MMP-9 mRNA were significantly higher in the diabetic group and diabetes +GM6001 group than those in the control group (all at P＜0.01),and the relative expressions of MMP-2 mRNA and MMP-9 mRNA in the diabetes+GM6001 group was significantly reduced in comparison with the diabetic group(both P=0.01,P=0.02).The standardized EB content in the retinas of the control group,diabetic group and diabetes+ GM6001 group was (12.60±3.50) ng/mg,(26.52±7.14) ng/mg and (17.55±2.65) ng/mg,showing a significant difference (F=17.032,P＜0.01),and EB content in rat retinas in the diabetic group was higher than that in the control group (P=0.003),and that in the diabetes+GM6001 group was lower in comparison with the diabetic group (P=0.020).Conclusions Intravitreal injection of GM6001 can down-regulate the expression of MMP-2 mRNA and MMP-9 mRNA in diabetic rats and therefore protect BRB. Key words: Metalloendopeptidase/antagonist and inhibitor;  Diabetes/complications;  Retina;  Bloodretinal barrier;  Permeability;  Disease model, animal;  Rat/Sprague-Dawley