The Effects Of Telmisartan On Early Diabetic Retinopathy In STZ Induced Diabetic Mice

Objective To investigate the mechanism of telmisartan on diabetic retinopathy by intravitreous injection in mice.Methods One hundred healthy SPF grade 6-week male C57BL/6J mice were randomly divided into control group?n=15?,solvent control group?n=15?,and diabetic group?DM??n=70?.The DM group was established by injection of streptozotocin intraperitoneally?streptozotocin,STZ?.The solvent control group was injected with same dosage of sodium citrate buffer?vehicle?intraperitoneally.3 months after intraperitoneal injection,we randomly sacrificed 3 mice every month and used HE staing to determine the progression of retinopathy.When HE staining showed diabetic retinopathy,we injected different medicine into the left eyes of DM mice.Based on the medicine injected into the left eyes,the diabetic mice were divided into telmisartan group,compastep group,and the model control group.All mice were sacrificed at 1 month after intravitreal injection. Western blotting was used to detect the protein expression levels of VEGF-A and TNF-?,RAGE in the retina of mice.The histological protein localization expression of VEGF-A and TNF-?were obseverd under light microscopy by immunohistochemistry.The retinal blood perfusion status of each group was observed by fluorescence reperfusion angiography.Results 1.There was no significant difference in the expression of VEGF-A,RAGE and TNF-?protein between the blank control group and the solvent control group?P>0.05?. Immunohistochemistry of VEGF-A showed a small amount of brown-yellow particles and light color in layer of ganglion cells and nerve fiber layer,TNF-?showed a small amount of brown-yellow particles in the retina and extracellular matrix.Fluorescence vascular reperfusion angiography showed that the control group was uniformly filled and the retinal blood vessels interlaced in a reticular pattern.2.Compared with the control group,the expression of VEGF-A,RAGE and TNF-?protein in the model group was significantly increased?all P<0.05?.There was no significant difference in the protein expression of VEGF-A,RAGE and TNF-?between the left eyes and the right eyes of the model control group?all P>0.05?.Immunohistochemistry of VEGF-A showed that the color of original retinal nerve fiber layer,ganglion cell layer brown yellow particles deepened,the staining range expanded comparing with the control group,?t=8.991,P<0.001?,and the TNF-?showed that the color of original retinal layer and extracellular matrix brown-yellow particles were darkened,and the inner and outer nuclear layers showed brown-yellow particles comparing with the control group?t=12.46,P<0.0001?.In the model control group,the retinal blood flow perfusion was not uniform and the vascular morphology was tortuous.3.In Telmisartan group,the expression levels of VEGF-A,RAGE and TNF-?in the left eyes were significantly lowed than that in the right eyes?all P<0.001?.The results of immunohistochemistry showed that the retinal staining particles in the left eye was smaller than that in the right eye,and the color was lighter,and the difference was statistically significant(t_VEGF-A=4.701,P=0.003;t_TNF-?=3.951,P=0.00191).Fluorescence vascular reperfusion angiography showed that the left eyes of Telmisartan group improved significantly after treatment.4.In Compastep group,the expression levels of VEGF-A,RAGE and TNF-?in the left eyes were significantly lowed than that in the right eyes?all P<0.05?.The results of immunohistochemistry showed that the retinal staining particles in the left eye was smaller than that in the right eye,and the color was lighter,and the difference was statistically significant(t_VEGF-A=5.016,P_VEGF-A=0.0001;t_TNF-?=4.918,P_TNF-?=0.004).The results of fluorescence vascular reperfusion angiography in the left eye showed that no perfusion area is reduced,and the vascular morphology was relieved,and deep blood perfusion was visible.Conclusion 1.Diabetic retinopathy of diabetic mice induced by intraperitoneal injection of streptozotocin may be associated with up-regulation of VEGF-A,RAGE and TNF-?expression in the eye after 3 months; 2.Telmisartan can reduce the expression of VEGF-A,RAGE,TNF-?in retinal tissue,thereby delaying the occurrence of DR,which may be related to the inhibition of intraocular RAS system.