[Changes of podocyte ultrastructure and expression of podocyte-associated molecules in rats with diabetic nephropathy].

OBJECTIVE: To investigate the effect of podocyte ultrastructure and changes of nephrin and the podocin expression on the pathogenesis of diabetic nephropathy (DN) in rats. METHODS: Twenty Wistar rats were divided into 2 groups: a normal control group and a DN model group.We determined the 24h proteinuria and other biochemical indexes, measured the ultrastructures of podocytes with electronic microscope, and detected the expression of nephrin and podocin with immunohistochemical technique and RT-PCR at the 4th and 8th weeks. RESULTS: The 24h proteinuria increased in the DN group; the number of podocytes was significantly lower; and the foot process width (FPW) obviously increased in the DN group compared with the normal group (P<0.01). The protein and mRNA expressions of nephrin and podocin reduced in the DN group.There was a negative correlation between the proteinuria and the protein expression of nephrin and podocin (P<0.01). CONCLUSION: The reduction in glomerular podocyte number,the increased FPW, and the down-regulated expression of nephrin and podocin appear at the early stage of DN and become more serious with the disease progression.The podocyte lesion not only is associated with the degree of proteinuria,but also correlates with the development of glomerulosclerosis and damage of renal function.