Changes in Expression of the Vascular Endothelial Growth Factor in the Kidneys of Diabetic Rats During Aging

Abstract

Background. Diabetic nephropathy is the leading cause of end-stage renal disease (ESRD) in most developed countries. A number of specific factors may contribute to the onset and progression of diabetic nephropathy. One of those specific factors is vascular endothelial growth factor (VEGF). We studied the expression of VEGF in the kidneys of diabetic rats during aging. Methods. Male Sprague-Dawley rats were injected with 55mg/kg streptozotocin (STZ) (DM group) or with citrate buffer (control group). Kidneys were collected after 2 weeks, 2 months, 6 months and 12 months, and were analyzed in three different kidney structures: glomeruli, proximal (PCT) and distal convoluted tubules (DCT). Sections were stained immunohistochemically, using VEGF.Results. Significant differences in marker expression were observed after 2 months, with higher VEGF expression in diabetic rats. Positive VEGF cells were detected exclusively in the glomeruli of diabetic rats after 2 months. After 2 weeks of DM onset, high VEGF expression was demonstrated in the distal tubules of diabetic rats, as well as a complete absence of VEGF expression in the distal tubules of the control group. Conclusions. The major change in expression of VEGF occurs after 2 months of DM onset, particularly in the DTC, implying an early onset of pathophysiological changes in diabetic kidneys, which would usually occur with aging. These findings help to contribute to our understanding of changes associated with DN and guide towards potentially appropriate treatment modalities.Key words: diabetes mellitus, kidneys, nephropathy, VEGF