Overexpression Of Facilitated Glucose Protein 2 In Renal Proximal Tubules Of Early Diabetic Rats

objective: the present study was designed to investigate the expression of renal facilitated glucose protein 2 in early diabetic rats, to explore whether the expression of GLUT2 protein is correlated with diabetic nephrothy in early stage. Methods: Male Sprague-Dawley rats were randomly divided to normal groups and diabetes mellitus group ,each group were 10 respectively. Male Sorague-dawley rats were injection intraperitioneally with streptozocin (STZ,60mg/kg).After 48h injection , blood samples were collected from the tail vein of the rats. Blood glucose levels were determined by using glucose oxidase method. Both kidneys of each rat were isolated after 1 week,2 weeks,4 weeks, 6 weeks, Respectively. of them ,one kidney of each rat was as a source of HE staining sample for demonstrating pathologic changes in kidney, and a source for evaluating the expression and location of GLUT2 protein using immunohistochemistry peroxides legation method and image analysis method; and the other kidneys were promptly transferred into liquid nitrogen for 2-3 min, then stored in -80°C. Differential centrifugation was employed to isolated cortical brush-border membrane vesicles and its concentration was further estimated by using BCA method. GLUT2 protein was identified by SDS-PAGE and Western blot with image analysis method. Results: Each rat was injected with STZ after fasting for 12h. Blood glucose levels were more than 16.7mmol/L and maintained at such high level without spontaneous remission. In addition, the classic symptoms of polyphonic, polydipsia, hyperdiuresis, together with depressed spirit, gloomy in color, slow in moving, loss in weight were indications for successful establishment of DM rat model. 2. The expression levels of GLUT2 protein in proximal tubule estimated by immunohistochemistry method, were on the increase in DM model and differences were obvious when compared with control, the levels of GLUT2 protein in 1-week groups were statistically higher (p<0.05) . the levels of GLUT2 protein in 2-weeks,4-weeks and 6 weeks groups were statistically higher (p<0.01) when compared with control. In comparison with 1-week,2-weeks, the levels of GLUT2 protein in 4-weeks groups were statistically higher (p<0.05). In comparison with 4-weeks, the levels of GLUT2 protein in 6-weeks groups were statistically decreased (p< 0.05),but In comparison with 2-weeks and 1week the levels of GLUT2 protein in 6-weeks groups were no difference(p>0.05) 3.Western blot revealed that GLUT2 protein in cortical brush-border membrane vesicles increased significantly in DM model groups. In comparison with control group, the levels of GLUT2 protein in 1-weeks,2-and 4-weeks and 6 weeks groups were statistically higher (p<0.01). In comparison with 1-week and 2-weeks, the levels of GLUT2 protein in 4-weeks groups were statistically higher (p<0.05). In comparison with 4-weeks, the levels of GLUT2 protein in 6-weeks groups were statistically decreased (p<0.05),but In comparison with 2-weeks and 1week the levels of GLUT2 protein in 6-weeks groups were no difference.the gray value GLUT2 protein in DM groups with the levels of insulin are positive correlation(r=0.982),with the levels of blood glucose are inverse correlation(r=-0.871).Conclusion: Overexpression of Facilitated glucose protein 2 in proximal Tubules of early Diabetic Rats, the pathogenesis of diabetic nephropathy contains the overexpression of GLUT2 protein . The expression of GLUT2 protein in kidney is probable time-dependent in Type 1 DM rat model, and its level is on the increase after 1 week and can last to the 6th week, suggesting the reserved compensation ability of kidney in some degree. Besides, the levels of GLUT2 protein in DM groups with the levels of insulin are inverse correlation,with the levels of blood glucose are positive correlation.