| Objective To observe the effect of Spironolactone on the serum Nuclear factorκB (NF-κB) and monocyte chemoattractant protein-1 (MCP-1)level, MCP-1 excretion in urine, the renal expression of NF-κB and MCP-1, renal constitution and function and investigate its possible renoprotective mechanisms in type 2 diabetic (T2DM) rats.Method The model of T2DM rat was established by fed with high-sucrose-high-fat diet and injected low dose Streptozotocin (STZ), will become the model of the rats were randomly divided into two groups: diabetes mellitus (group DM, n=10) and diabetic rats treated with Spironolactone (group SPI,n=10) .Each rat in group DM and SPI was fed with the high - sucrose - high - fat diet. Normal control rats (group NC,n=10) were fed with routin animal feeds. The group SPI was treated with Spironolactone (20mg.kg-1.day-1) via intragastric administration, the group DM and NC were treated with corresponding sodium chloride. Body mass (BM) and peripheral blood glucose of each group were tested weekly. The level of serum Nuclear factorκB and monocyte chemoattractant protein-1, glycosylated hemoglobin A1c(HbA1c), FBG, FINS, TG, TC as well as urinary albumin/creatinine ratio (ACR), urinary retinol binding-protein (URBP) excretion rate and urinary monocyte chemoattractant protein-1 (MCP-1)excretion rate were tested at the 8th week, and the renal tissues of all rats were obtained partly for evaluating kidney/body weight ratio, partly for examining the expression of NF-κB mRNA and MCP-1 mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR),observing pathologic changes via light microscope and electron microscope, partly for examining the expression of NF-κB and MCP-1 protein by histochemical staining. Results1. The levels of FBG and HbA1c at the 8th weeks in group DM and group SPI were significantly higher compared with those of group NC(P<0.01),and there were no statistical differences between group DM and group SPI (P>0.05); Level of FINS in group SPI and DM were significantly higher than those in the NC group(P<0.05);but there was no significant difference between in the SPI group and DM group(P>0.05).2. TC and TG level at 8th week in groups DM and group SPI increased significantly compared with those in group NC (P<0.01). and there were no statistical differences between group DM and group SPI (P>0.05)3. SNF-κB and SMCP-1 level ,UMCP-1 excretion rate, ACR , URBP excretion rate and kidney/body weight ratio at the 8th week in groups DM and group SPI increased significantly compared with those in group NC (P<0.01). Treatment with Spironolactone also significantly reduced SNF-κB and SMCP-1 level ,UMCP-1 excretion rate, ACR , URBP excretion rate as well as kidney/body weight ratio (P<0.01). In addition, UMCP-1 excretion rate showed positive correlations with ACR (r = 0.842, P<0.01), URBP excretion rate (r = 0.897, P<0.01) and kidney/body weight ratio (r=0.649,P<0.01) and SNF-κB and SMCP-1 level also showed positive correlations with ACR (r=0.824,0.795,P<0.01), URBP excretion rate (r=0.786,0.751, P<0.01) and kidney/body weight ratio (r=0.681,0.739, P<0.01).4. At the 8th week, the expression level of NF-κB and MCP-1 protein in glomcrulus and nephric tubule in group DM and group SPI was significantly higher than that in group NC, pioglitazone can inhibit the expression of NF-κB and MCP-1 protein.5. The light microscopes results showed that there's no pathological lesion of kidney found in group NC. Pathological changes were much more obvious in group DM. It was clear that the glomerular capillary loops were tumbling, lumens blocked, mesangial region widened, basal lamina thickened, mesenterium base increased, the volume of glomerulus became larger and the cell population increased significantly. It also can be observed that the renal tubule was vacuolization and the renal interstitium wasinfiltrated by lots of lymphocytes and emononuclear macrophages. Pathological changes in group SPI were lighter, it can be observed that glomerular capillary lumen was constrictive slightly and few lymphocyte infiltrated.6. The electron microscopes results showed that the structure and width of glomerular basement membrane (GBM), epithelial foot processes (FP) as well as the mesangial region were normal in group NC at the 8th week. In group DM, the FP fusion rate was approximately 80 percent and the thickening of GBM were observed. it was noted that some FP were destroyed, even vanished, the ultrastructure of GBM became ambiguous, the mesangial cells swelled and the extracellular matrix accumulated which caused mesangial region to expand intensively. After the treatment of pioglitazone, the thickness of GBM in group SPI decreased markedly compared with that in group DM. It was clear that the ultrastructure of GBM was relatively regular, only 35 percent of the epithelial foot processes fused and the expansion of the mesangial region was unconspicuous.7. Compared with group NC, the expression of NF-κB mRNA and MCP-1 mRNA was markedly up-regulated in group DM and group SPI (P<0.01), and spironolactone could decrease the expression of NF-κB mRNA and MCP-1 mRNA in the renal tissue (P<0.01).Conclusion Treatment with spironolactone can lessen pathological lesion of diabetic nephropathy in T2DM rats, which can definitely protect diabetic nephropathy, such as reduce ACR, URBP excretion rate as well as kidney/body weight ratio. The mechanisms may be associated with decreasing the expression of NF-κB and MCP-1 protein in renal tissue , reducing sNF-κB and sMCP-1 level and the urinary excretion of MCP-1.
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