The Expression Of GLUT1 And Angiopoietin-1 In Diabetic Rats' Retina

Objectives:Glucose is an essential metabolic substrate for retinal metabolism, and its transport from blood to retina is tightly coupled with retinal glucose utilization. The disorder of glucose metabolism plays an essential role in the occurance and development of diabetic retinopathy. Glucose entry into the endothelial cells of the inner BRB is mediated by a saturable, facilitated transport process involving GLUT1, a member of a family of sodium-independent glucose transporter proteins. The expression of GLUT1 is regulated by many factors. It is reported that Akt mediates a step in the activation of GLUT1 gene expression. Ang1 is an angiogenic growth factor, playing an essential role in retinal vascularization. Studies have suggested that Ang1 could regulate Akt pathway through phosphorylation of Ser473 and Thr308 in Akt. But whether Angl could regulate the expression of GLUT1 in the retina of diabetic rats via the regulation of Akt is still unknown. Our study aims to use diabetic rats to explore expression of GLUT1 and the content of Angl mRNA in diabetic retina, and further to evaluate the correlation between Angl and the expression of GLUT1 in diabetic retinas. Materials and Methods:A total of 40 healthy male wistar rats weighting 180-220g were used, 10 rats were randomly chosen to be normal control group (group NC), the rest 30 rats were induced to be diabetes mellitus by STZ which was injected into the abdomens and only 20 rats became diabetes finally. After the diabetic model was successfullyestablished, the 20 rats were randomly divided into 2 groups: diabetic group without blood glucose control (group DM1), diabetic rats treated with insulin (group DM2). The DM2 group were treated with protamine zinc insulin(PZI))to control their blood glucose levels to<14mmol/L. After three months the HbAlc of three groups were measured, then all rats were decapitated and their retinas were dissected. The immunhistochemistry method was used to measure the expression GLUT1 and reverse transcription-polymerase chain reaction (RT-PCR) was used to measure the content of Angl mRNA.Datas were analysed using the Statistical Package of the SPSS 11.0. Discriptive data were given as means±SD. Continuous variables were tested by analysis oft-test and the relations between the variables were tested by linear correlation. The p-values are two-tailed and a p-value of less than 0.05 being considered to be significant.Results:1. During the experiment the weights of DM1 and DM2 groups were lower than the control group, but the blood glucose and HbAlc were much higher than the control group.2. Immunohistochemistry method showed that the positive stained granules of GLUT1 protein in BRB were found in NC group. In DM1 and DM2 group the positive stained granules of GLUT1 protein increased markedly, especially in DM1 group. The differences were significant (P