Effects of etanercept on the apoptosis of ganglion cells and expression of Fas, TNF-α, caspase-8 in the retina of diabetic rats

AIM: To evaluate the effects of etanercept on the expression of Fas, tumor necrosis factor-alpha (TNF-α) and caspase-8 in the early stage of the apoptotic pathway in diabetic rats, and to explore the therapeutic effect of etanercept on diabetic retinopathy. METHODS: A total of 60 Sprague-Dawley (SD) rats were randomly and evenly divided into 3 groups with 20 rats each, including control group, and diabetic groups with or without treatment. Streptozotocin (STZ)-induced diabetic rats were established for diabetic groups. Blood glucose and body weight were measured weekly. All the rats were sacrificed at the 12wk after treatment. The expressions of Fas, TNF-α and caspase-8 in rat retina were quantitatively detected by PCR and Western blot. The leakage of Evan blue was adopted to measure the retinal vascular leakage quantitatively, and to compare it among different groups. TUNEL method was used to compare the amount of apoptotic bodies quantitatively in rat retina ganglion cells under electron microscope. RESULTS: The expressions of Fas, TNF-α and caspase-8 in each group were compared via PCR and Western blot, in which the diabetic group with treatment was lower than those without treatment (P<0.01), but all the diabetic groups were higher than the control group (P<0.01). Evans blue leakage in the diabetic treatment group was lower than those without treatment (P<0.01), but those in the control group was the lowest compared with the other two groups (P<0.01). TUNEL method showed that the apoptotic bodies of retina in the diabetic treatment group was lower than those without treatment (P<0.01), while those in the control group was the lowest compared with the other two groups (P<0.01). CONCLUSION: Etanercept can effectively reduce the expression of Fas, TNF-α and caspase-8, as well as the retinal leakage and retinal cell apoptosis in diabetic rats.     

【In Press】Infliximab relieves blood retinal barrier breakdown through the p38 MAPK pathway in a diabetic rat model

AIM: To clarify the mechanism of infliximab treatment in diabetic macular edema (DME) and to provide a new alternative therapy for DME. METHODS: Rats were randomly divided into the control group, the model group and the treatment group. A diabetic rat model was created. The concentration of TNF-α in the vitreous body was detected by ELISA. The expressions of B-Raf, p38, claudin-1 and occludin in the retina were detected by Western blot. The integrity of the blood retinal barrier (BRB) was measured using Evan’s blue as a tracer. RESULTS: After three months and six months of the diabetes model, the vitreous TNF-α level in the model group was higher in models than that of the control. It was also higher in treated group than that of the control but was lower than that of the model group. The differences among the three groups were statistically significant (at 3mon, F=857.098, P<0.001; 6mon, F=1261.897, P<0.001). The expression of B-Raf and p38 in the retina of the model group was higher than that of the control group. The expression of B-Raf and p38 in the treatment group was higher than that of the control group but was lower than that of the model group. The differences among the three groups were statistically significant (B-Raf at 3mon, F=106.596, P<0.001 and at 6mon, F=200.681, P<0.001; p38 at 3mon, F=41.662, P<0.001 and at 6mon, F=67.979, P<0.001). The expression of claudin-1 and occludin in the retina of the model group was lower than that of the control group. The expression of claudin-1 and occludin in the treatment group was lower than that of the control group but was higher than that of the model group. The differences among three groups were statistically significant (claudin-1 at 3mon, F=139.088, P<0.001 and at 6mon, F=128.415, P<0.001; occludin at 3mon, F=92.733, P<0.001 and at 6mon, F=104.478, P<0.001). The retinal Evans blue leakage in the model group was higher than that in the control group. The retinal Evans blue leakage in the treatment group was higher than that in the control group but was lower than that in the model group. The differences among the three groups were statistically significant (at 3mon, F=447.946, P<0.001; at 6mon, F=1610.732, P<0.001). CONCLUSION: In a diabetic rat model, infliximab may relieve TNF-α induced BRB breakdown via the B-Raf and p38 signaling pathway.     

Infliximab relieves blood retinal barrier breakdown through the p38 MAPK pathway in a diabetic rat model

AIM: To clarify the mechanism of infliximab treatment in diabetic macular edema (DME) and to provide a new alternative therapy for DME. METHODS: Rats were randomly divided into the control group, the model group and the infliximab treatment group. A diabetic rat model was created. The concentration of TNF-α in the vitreous body was detected by ELISA. The expressions of B-Raf, p38, claudin-1 and occludin in the retina were detected by Western blot. The integrity of the blood retinal barrier (BRB) was measured using Evan’s blue as a tracer. RESULTS: After three months and six months of the diabetes model, the vitreous TNF-α level in the model group was higher than that of the control group. It was also higher in treated group than that of the control group but was lower than that of the model group. The differences among the three groups were statistically significant (at 3mo, F=857.098, P<0.001; 6mo, F=1261.897, P<0.001). The retina B-Raf and p38 levels in the model group were higher than that of the control group. They were also higher in treated group than that of the control group but were lower than that of the model group. The differences among the three groups were statistically significant (B-Raf at 3mo, F=106.596, P<0.001 and at 6mo, F=200.681, P<0.001; p38 at 3mo, F=41.662, P<0.001 and at 6mo, F=67.979, P<0.001). The retina claudin-1 and occludin levels in the model group were lower than that of the control group. They were also lower in treated group than that of the control group but were higher than that of the model group. The differences among three groups were statistically significant (claudin-1 at 3mo, F=139.088, P<0.001 and at 6mo, F=128.415, P<0.001; occludin at 3mo, F=92.733, P<0.001 and at 6mo, F=104.478, P<0.001). The retinal Evans blue leakage in the model group was higher than that of the control group. It was also higher in treated group than that of the control group but was lower than that of the model group. The differences among the three groups were statistically significant (at 3mo, F=447.946, P<0.001; at 6mo, F=1610.732, P<0.001). CONCLUSION: In a diabetic rat model, infliximab may relieve TNF-α induced BRB breakdown via the B-Raf and p38 signaling pathway.     

Protective effects of a novel drug RC28-E blocking both VEGF and FGF2 on early diabetic rat retina

AIM: To investigate protective effects of a novel recombinant decoy receptor drug RC28-E on retinal damage in early diabetic rats. METHODS: The streptozotocin (STZ)-induced diabetic rats were randomly divided into 6 groups: diabetes mellitus (DM) group (saline, 3 μL/eye); RC28-E at low (0.33 μg/μL, 3 μL), medium (1 μg/μL, 3 μL), and high (3 μg/μL, 3 μL) dose groups; vascular endothelial growth factor (VEGF) Trap group (1 μg/μL, 3 μL); fibroblast growth factor (FGF) Trap group (1 μg/μL, 3 μL). Normal control group was included. At week 1 and 4 following diabetic induction, the rats were intravitreally injected with the corresponding solutions. At week 6 following the induction, apoptosis in retinal vessels was detected by TUNEL staining. Glial fibrillary acidic protein (GFAP) expression was examined by immunofluorescence. Blood-retinal barrier (BRB) breakdown was assessed by Evans blue assay. Ultrastructural changes in choroidal and retinal vessels were analyzed by transmission electron microscopy (TEM). Content of VEGF and FGF proteins in retina was measured by enzyme linked immunosorbent assay (ELISA). The retinal expression of intercellular cell adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), VEGF and FGF genes was examined by quantitative polymerase chain reaction (qPCR). RESULTS: TUNEL staining showed that the aberrantly increased apoptotic cells death in diabetic retinal vascular network was significantly reduced by treatments of medium and high dose RC28-E, VEGF Trap, and FGF Trap (all P<0.05), the effects of medium and high dose RC28-E or FGF Trap were greater than VEGF Trap (P<0.01). GFAP staining suggested that reactive gliosis was substantially inhibited in all RC28-E and VEGF Trap groups, but the inhibition in FGF Trap group was not as prominent. Evans blue assay demonstrated that only high dose RC28-E could significantly reduce vascular leakage in early diabetic retina (P<0.01). TEM revealed that the ultrastructures in choroidal and retinal vessels were damaged in early diabetic retina, which was ameliorated to differential extents by each drug. The expression of VEGF and FGF2 proteins was significantly upregulated in early diabetic retina, and normalized by RC28-E at all dosages and by the corresponding Traps. The upregulation of ICAM-1 and TNF-α in diabetic retina was substantially suppressed by RC28-E and positive control drugs. CONCLUSION: Dual blockade of VEGF and FGF2 by RC28-E generates remarkable protective effects, including anti-apoptosis, anti-gliosis, anti-leakage, and improving ultrastructures and proinflammatory microenvironment, in early diabetic retina, thereby supporting further development of RC28-E into a novel and effective drug to diabetic retinopathy (DR).     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

胰岛素对链脲佐菌素诱导的糖尿病大鼠视网膜血管内皮生长因子表达的影响

Objective To investigate if insulin can affect the expression of vascular endothelial growth factor (VEGF) in the retina of streptozotocin-induced diabetic rats. Methods A total of 60 male Sprague-Dawley rats were randomly divided into sodium citrate buffer control group (CIT-CON, n= 30) and STZ-induced diabetic group (STZ-DM, n=30). At the 16th week, 24 rats from CIT-CON group at random were randomly divided to group A (sodium citrate buffer control group, n = 12) and group B (sodium citrate buffer plus insulin group, n= 12). The remaining 6 rats from as CIT-CON group served as negative control. At the same time, 24 rats from STZ-DM group at random were randomly divided to group C (STZ-induced diabetic group, n= 12) and group D (STZ-induced diabetic plus insulin group, n= 12). The remaining 6 rats from STZ-DM group also served as negative control. 4 IU of insulin was injected subcutaneously to rats of group B and D. Immunohistochemistry, Western blot and Real-time polymerase chain reaction (RT-PCR) were used to measure the expression level of VEGF protein and mRNA respectively. RESULTS Insulin significantly increased the VEGF mRNA (7.71 ± 0.25 vs 5.36 ±0. 37, t test P< 0. 05) and protein expression (0. 4925 ± 0. 0122 vs 0. 4272 ± 0. 0110, t test P< 0. 05) in the retina of CIT-CON rats.However, in retina of STZ-DM rats, insulin had no effect on VEGF mRNA (8. 92±0. 27 vs 9. 05±0. 28, t test, P>0. 05) and protein expression (0. 5152±0. 0109 vs 0. 5099±0. 0100, t test P>0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.     

Effect of geniposide on retinal microangiogenesis in rats with diabetic retinopathy and its mechanism北大核心

Objective To investigate the effect of geniposide (Gen) on retinal microangiogenesis in rats with diabetic retinopathy (DR) and its mechanism. Methods Fifty 6-week-old SPF male Wistar rats with normal eyes were randomly divided into the normal group, model group, low-dose Gen group, high-dose Gen group, and calcium dobesilate group, with 10 rats in each group. Except for the normal group, rats in the other groups were fed high-sugar and high-fat diets and induced by streptozotocin to establish the DR rat models. After modeling, drug intervention was carried out immediately. Rats in the low- and high-dose Gen groups were given 25 mg·kg-1 and 100 mg·kg-1 Gen intragastrically, rats in the calcium dobesilate group were given 5.8 mg·kg-1 calcium dobesilate intragastrically, while rats in the normal and model groups were given the same amount of solvent intragastrically, once a day for 4 weeks. During the drug administration period, rats in the normal group continued to be fed normal diets, and rats in the other groups continued to be fed high-sugar and high-fat diets. Levels of vascular endothelial growth factor (VEGF) and soluble VEGF receptor 1 (sFlt-1) in serum were measured by the enzyme-linked immunosorbent assay. Retinal pathological changes were exhibited by hematoxylin-eosin staining. Retinal microangiogenesis was revealed by periodic acid-Schiff staining. The expression levels of VEGF, hypoxia-inducible factor-1α (HIF-1α), intercellular adhesion molecule-1 (ICAM-1), and sFlt-1 in the retina were measured by Western blot. Results At the end of drug intervention (week 4), serum VEGF level in the model group was higher than that in the normal group, while sFlt-1 level was lower than that in the normal group (both P<0.001); serum VEGF level in the high-dose Gen and calcium dobesilate groups was lower than that in the model group, while sFlt-1 level was higher than that in the model group (all P<0.001); there were no significant differences in the above indexes between the low-dose Gen group and the model group (all P>0.05). At the end of drug intervention (week 4), the retinal morphology of rats in the normal group was normal, and the cells in the inner and outer nuclear layers were arranged neatly; cells in the inner and outer nuclear layers were arranged loosely, ganglion cells were reduced, and capillary congestion was observed in the model and low-dose Gen groups; the arrangement of cells in the inner and outer nuclear layers in the high-dose Gen and calcium dobesilate groups tended to be normal, and ganglion cells increased compared with the model group. At the end of drug intervention (week 4), the retinal vascular diameter in the model group was uneven, with segmental enlargement, and retinal microangiogenesis was more significant than that in the normal group (P<0.001); retinal microangiogenesis in the high-dose Gen and calcium dobesilate groups was less significant than that in the model group (both P<0.001); there was no significant difference in retinal microangiogenesis between the low-dose Gen group and the model group (P>0.05). At the end of drug intervention (week 4), the relative expression levels of VEGF, HIF-1α and ICAM-1 proteins in the model group were higher than those in the normal group, while the relative expression level of sFlt-1 protein was lower than that in the normal group (all P<0.001); the relative expression levels of VEGF, HIF-1α and ICAM-1 proteins in the high-dose Gen and calcium dobesilate groups were lower than those in the model group, while the relative expression level of sFlt-1 protein was higher than that in the model group (all P<0.001); there were no significant differences in the above indexes between the low-dose Gen group and the model group (all P>0.05). Conclusion Gen can inhibit the expression of VEGF and promote the expression of sFlt-1, which in turn reduces retinal microangiogenesis in DR rats to treat DR. © The Author(s) 2023.     

Effect of light-emitting diodes with different color rendering indexes on the ocular tissues of rat

AIM: To compare the damage of light-emitting diodes (LEDs) with different color rendering indexes (CRIs) to the ocular surface and retina of rats. METHODS: Totally 20 Sprague-Dawley (SD) rats were randomly divided into four groups: the first group was normal control group without any intervention, other three groups were exposed by LEDs with low (LED-L), medium (LED-M), and high (LED-H) CRI respectively for 12h a day, continuously for 4wk. The changes in tear secretion (Schirmer I test, SIt), tear film break-up time (BUT), and corneal fluorescein sodium staining (CFS) scores were compared at different times (1d before experiment, 2 and 4wk after the experiment). The histopathological changes of rat lacrimal gland and retina were observed at 4wk, and the expressions of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in lacrimal gland were detected by immunofluorescence method. RESULTS: With the increase of light exposed time, the CFS value of each light exposed group continued to increase, and the BUT and SIt scores continued to decrease, which were different from the control group, and the differences between the light exposed groups were statistically significant. Hematoxylin-eosin (HE) results showed that the lacrimal glands of each exposed group were seen varying degrees of acinar atrophy, vacuole distribution, increasing of eosinophil granules, etc.; the retina showed obvious reduction of photoreceptor cell layer and changes in retinal thickness; LED-L group has the most significant change in all tests. Immunofluorescence suggested that the positive expressions of TNF-α and IL-6 in the lacrimal glands of each exposed group were higher than those of the control group. CONCLUSION: LED exposure for 4wk can cause the pathological changes of lacrimal gland and retina of rats, and increase the expression of TNF-α and IL-6 in lacrimal gland, the degree of damage is negatively correlated with the CRI.     

Inhibition effect of interfering RNA targeting hypoxia inducible factor-1α on vascular endothelial growth factor mRNA expression in the retina of diabetic rats

Objective To observe the inhibition effect of the hypoxia inducible factor-1α(HIF-1α)specific siRNA on the expression of vascular endothelial growth factor(VEGF)mRNA in retinal tissues in diabetic rat.Methods This is a randomized controlled study.HIF-1α specific siRNA recombinant plasmid was built in pSilencer2.1-U6neo vector.Fifty-four healthy Sprague Dawley(SD)rats were divided into control group(15 rats)and experimental group(39 rats).The experimental rats were induced with streptozotocin injection for diabetic retinopathy model,and then randomly divided into diabetic retinopathy (DR)group(15 rats),vector group(12 rats)and gene therapy group(12 rats).LipofectamineTM2000mixed with pSilencer2.1-U6neo plasmid or HiF-1α siRNA plasmid were injected into the vitreous in the vector group and gene therapy group respectively.Nothing was transfected into DR and control group.The expression of VEGF mRNA in retinas was measured by real-time RT-PCR.The inhibition efficiency of VEGFmRNA was calculated at 24,48,72 hours and 1 week after injection respectively.Significant differences between groups were evaluated by one-way analysis and LSD-t analysis.Results HIF-1 α siRNA recombinant plasmid was confirmed by enzyme digestion and sequence analysis.Real-time RT-PCR revealed that the expression of VEGFmRNA was faint in the control group.increased obviously in the DR and vector group,decreased in the gene therapy group.There was no statistically significant between DR and vector group(t=0.669,0.142,0.151,0.025;P=0.514,0.889,0.882,0.980).The expression of VEGFmRNA in the gene therapy group were obviously decreased compared with DR and vector group(t=8.768,13.695,11.285,8.253;P=0.000).The inhibition efficiency of VEGFmRNA was 32.76% ,43.60% ,47.70% ,50.86% at 24,48,72 hours and 1 week after injection.Conclusions The expression of VEGFmRNA can be efficiently inhibited by HIF-1α siRNA recombinant plasmid.     

Inhibition effect of interfering RNA targeting hypoxia inducible factor-1α on vascular endothelial growth factor mRNA expression in the retina of diabetic rats

Objective To observe the inhibition effect of the hypoxia inducible factor-1α(HIF-1α)specific siRNA on the expression of vascular endothelial growth factor(VEGF)mRNA in retinal tissues in diabetic rat.Methods This is a randomized controlled study.HIF-1α specific siRNA recombinant plasmid was built in pSilencer2.1-U6neo vector.Fifty-four healthy Sprague Dawley(SD)rats were divided into control group(15 rats)and experimental group(39 rats).The experimental rats were induced with streptozotocin injection for diabetic retinopathy model,and then randomly divided into diabetic retinopathy (DR)group(15 rats),vector group(12 rats)and gene therapy group(12 rats).LipofectamineTM2000mixed with pSilencer2.1-U6neo plasmid or HiF-1α siRNA plasmid were injected into the vitreous in the vector group and gene therapy group respectively.Nothing was transfected into DR and control group.The expression of VEGF mRNA in retinas was measured by real-time RT-PCR.The inhibition efficiency of VEGFmRNA was calculated at 24,48,72 hours and 1 week after injection respectively.Significant differences between groups were evaluated by one-way analysis and LSD-t analysis.Results HIF-1 α siRNA recombinant plasmid was confirmed by enzyme digestion and sequence analysis.Real-time RT-PCR revealed that the expression of VEGFmRNA was faint in the control group.increased obviously in the DR and vector group,decreased in the gene therapy group.There was no statistically significant between DR and vector group(t=0.669,0.142,0.151,0.025;P=0.514,0.889,0.882,0.980).The expression of VEGFmRNA in the gene therapy group were obviously decreased compared with DR and vector group(t=8.768,13.695,11.285,8.253;P=0.000).The inhibition efficiency of VEGFmRNA was 32.76% ,43.60% ,47.70% ,50.86% at 24,48,72 hours and 1 week after injection.Conclusions The expression of VEGFmRNA can be efficiently inhibited by HIF-1α siRNA recombinant plasmid.     

Inhibition of β-elemene on the expressions of HIF-lα, VEGF and iNOS in diabetic rats model

AIM: To evaluate the effect of β-elemene on the expressions of hypoxia-inducible factor (HIF)-lα, vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS) in a streptozotocin (STZ) induced diabetic Sprague-Dawley (SD) rat model. METHODS: SD rats were administered an abdominal injection of STZ and induced to a diabetic model. After 6wk course of diabetes, the treatment groups were given β-elemene through periocular and intravitreous injection separately and the control groups were given blank emulsion injection. HE staining was used to observe the morphology of retina. The mRNA expressions of HIF-1α, VEGF and iNOS was assayed by real-time polymerase chain reaction (PCR) and the protein expression was measured by Western blot and immunocytochemistry methods. RESULTS: The results indicated that the protein and mRNA expressions of HIF-1α, VEGF and iNOS after treated by β-elemene periocularly and intravitreally injections were all found to be reduced compared with the levels in the diabetic rats group (P<0.05). The inhibitory effect of intravitreal injection was more remarkable. CONCLUSION: The results show β-elemene protect the retina of diabetic rats from high glucose damage by downregulating the expression of HIF-1α, VEGF and iNOS.