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 SpragueDawley 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 STZDM group at random were randomly divided to group C (STZinduced 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 (7.71plusmn;0.25 vs 5.36plusmn;0.37, t test Plt;0.05) and protein expression (0.4925plusmn;0.0122 vs 0.4272plusmn;0.0110, t test Plt;0.05) in the retina of CITCON rats. However, in retina of STZDM rats, insulin had no effect on VEGF mRNA (8.92plusmn;0.27 vs 9.05plusmn;0.28, t test, Pgt;0.05) and protein expression (0.5152plusmn;0.0109 vs 0.5099plusmn;0.0100, t test Pgt;0.05). Conclusions Insulin had no effect on VEGF expression in the retina of STZ-DM rats.
Objective To observe the effect of celecoxib on the expression vascular endothelial growth factors (VEGF) in diabetic rats. Methods Thirty-six wistar rats were used to establish the diabetic models by intraperitoneal injection with streptozotocin. The diabetic rats were divided into 2 groups: diabetic group (n=18) and celecoxib group (n=18). Celecoxib (50 mg/kg) was administered orally to the rats in celecoxib group and the physiological saline with the same volume was given orally to the rats in diabetic group. Eighteen else rats were in normal control group. All of the rats were executed 3 months later. The expression of VEGF protein was detected by immunohistochemistry method. Reverse transcription-polymerase chain reaction（RT-PCR） analysis was used to examine the expression of retinal VEGF mRNA and cyclooxygenase-2 mRNA. Results Lower positive expression of VEGF mRNA and cyclooxygenase-2 mRNA, weakly positive action of immunohistochemistry of VEGF, and lower expression of VEGF protein were detected in normal control group; in the diabetic group, the expression of VEGF mRNA and cyclooxygenase-2 mRNA increased obviously comparing with which in the control group (Plt;0.05), and the bly positive action of immunohistochemistry of VEGF and increased expression of VEGF protein were detected (Plt;0.01); in celecoxib group, the expression of VEGF mRNA was lower than that in the diabetic group (Plt;0.05), the expression of cyclooxygenase-2 mRNA didnprime;t decrease much (Pgt;0.05), the positive action of immunohistochemistry of VEGF decreased, and the expression of VEGF protein decreased (Plt;0.01). Conclusion By inhibiting the activation of cyclooxygenase-2, celecoxib can inhibit the expression of retinal VEGF mRNA and protein in diabetic rats induced by streptozotocin. (Chin J Ocul Fundus Dis,2007,23:265-268)