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.
Animals ; Diabetic Nephropathies ; metabolism ; pathology ; Intracellular Signaling Peptides and Proteins ; metabolism ; Male ; Membrane Proteins ; metabolism ; Podocytes ; metabolism ; pathology ; ultrastructure ; Proteinuria ; pathology ; Rats ; Rats, Wistar

The renal glomeruli of 12 male Osborne-Mendel (OM) rats 3 to 24 weeks old were examined by electron microscopy. Effacement of podocyte foot processes (FPs) developed at 3 weeks of age and became progressively worse over time. Loss or dislocation of the slit membrane was also found. Vacuoles and osmiophilic lysosomes appeared in the podocytes starting at 6 weeks of age. Podocyte detachment from the glomerular basement membrane (GBM) was apparent at 18 weeks of age. Laminated GBM was occasionally observed in all animals. These features might lead to the development of spontaneous proteinuria and glomerulosclerosis in OM rats.
Animals ; Animals, Outbred Strains ; Glomerular Basement Membrane/*pathology/ultrastructure ; Kidney Diseases/complications/etiology/*pathology ; Male ; Microscopy, Electron, Transmission ; Nephrosclerosis/etiology/pathology ; Nephrosis/complications/pathology ; Podocytes/*pathology/ultrastructure ; Proteinuria/etiology/pathology ; Rats

OBJECTIVETo investigate the morphological changes and expressions of desmin and podocin in podocytes of rats with diabetic nephropathy (DN) rats and renal protection mechanism of Shenkangwan.

METHODSDN model was established in rats by a single injection of streptozotocin. The rats were then randomly divided into model group, Shenkangwan treatment group, irbesartan treatment group, and Shenkangwan plus irbesartan treatment group, with normal rats as the control group. All the rats received daily gavage for 8 weeks. The urinary protein quantity in 24 h were detected, and the morphological changes of the kidneys were observed with optic and transmission electron microscopes. The expressions of desmin and podocin in the podocytes were detected by immunohistochemistry.

RESULTSShenkangwan and irbesartan reduced the urinary protein quantity in 24 h and alleviated the renal damage in DN rats, and the expression of desmin was significantly attenuated while podocin expression increased in the podocytes.

CONCLUSIONSShenkangwan can provide renal protection against DN in rats and alleviate the structural and functional damages of podocytes possibly by reducing desmin expression and increasing podocin expression in the podocytes.

Animals ; Desmin ; biosynthesis ; Diabetic Nephropathies ; drug therapy ; pathology ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Immunohistochemistry ; Kidney ; drug effects ; pathology ; ultrastructure ; Male ; Microscopy, Electron, Transmission ; Phytotherapy ; Podocytes ; drug effects ; metabolism ; pathology ; Random Allocation ; Rats ; Rats, Sprague-Dawley

AIMTo investigate the effect and mechanism of ascorbic acid on podocyte, last barrier of glomerular filtration, in diabetic rats.

METHODSDiabetic rats induced by streptozotocin injection intraperitoneally were treated by ascorbic acid for 5 weeks. The levels of blood glucose (BG), HbA1c, urinary albumin excretion rate (UAER) and superoxide diamutase (SOD), catalase (CAT) and malondialdehyde (MDA) in renal cortex were measured. The podocyte ultrastructure was observed while the expression of desmin protein, a marker of podocyte injury, was examined.

RESULTSCompared with control group, BG and HbA1c were increased markedly in diabetic group. The activities of SOD and CAT were decreased and the concentrations of MDA were increased significantly in diabetic renal cortex. There were the increased proteinic expression of desmin, foot process effacement in podocytes and UAER markedly in diabetic rats. Compared with diabetic rats, foot process effacement and the changes of UAER were ameliorated markedly while the activities of SOD were increased, the levels of MDA and proteinic expression of desmin were decreased markedly although BG, HbA1c and the activities of CAT were no significant difference in the diabetic rats by ascorbic acid treatment.

CONCLUSIONThe findings suggest that there are marked injury in podocyte, last barrier of glomerular filtration, in diabetic rats and administration of ascorbic acid can protect podocyte by increasing antioxidative capacity and ameliorating the renal oxidative stress.

Animals ; Ascorbic Acid ; pharmacology ; Catalase ; metabolism ; Desmin ; metabolism ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; physiopathology ; Diabetic Nephropathies ; metabolism ; pathology ; physiopathology ; Male ; Oxidative Stress ; drug effects ; Podocytes ; drug effects ; metabolism ; ultrastructure ; Random Allocation ; Rats ; Rats, Wistar ; Superoxide Dismutase ; metabolism

OBJECTIVETo evaluate the effect of bone morphogenic protein 7 (BMP-7) on nephrin expression and distribution in diabetic rat kidneys.

METHODSTwenty rats with diabetes mellitus (DM) induced by streptozotocin (STZ) injection were randomly divided into DM model group and BMP-7 treatment group, with another 10 normal rats serving as the normal control group. The rats in BMP-7 group received intraperitoneal human recombinant BMP-7 injections at 30 microg/kg twice a week for 24 consecutive weeks, while normal saline was administered in rats of the other two groups. Blood glucose and 24 hour urinary protein and creatinine (Ccr) were measured at 8, 16 and 24 weeks, and the rats were sacrificed at 24 weeks to obtain the renal tissues for detecting the expression and distribution of nephrin using immunofluorescence assay and RT-PCR and for examining the expressions of transforming growth factor-beta1 (TGF-beta1) and WT1 using immunohistochemistry.

RESULTSCompared with the normal control group, the DM model group showed significantly increased 24 hour urinary protein, kidney to body weight ratio and TGF-beta1 expression, but had lowered Ccr, glomerular podocyte number and nephrin expression. The linear distribution of nephrin along the capillary loops as found in the normal control group became granular in the kidney of diabetic rats. The rats in BMP-7 group showed less urinary protein excretion, lower TGF-beta1 expression and greater glomerular podocyte number than those in the DM group, and the expression and distribution of nephrin remained normal in the kidney.

CONCLUSIONAdministration of BMP-7 can significantly suppress the down-regulation of nephrin expression and maintain its normal distribution in the podocytes in diabetic rats possibly in association with a direct suppression of TGF-betasignaling.

Animals ; Blood Glucose ; metabolism ; Body Weight ; drug effects ; Bone Morphogenetic Protein 7 ; pharmacology ; Cell Count ; Diabetes Mellitus ; genetics ; metabolism ; pathology ; Gene Expression Regulation ; drug effects ; Humans ; Kidney ; drug effects ; metabolism ; pathology ; ultrastructure ; Male ; Membrane Proteins ; genetics ; metabolism ; Microscopy, Electron, Transmission ; Organ Size ; drug effects ; Podocytes ; drug effects ; pathology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Transforming Growth Factor beta1 ; metabolism