| Objective To observe the effect of exogenous Insulin on the serum Nuclear factor-κB (NF-κB) and monocyte chemoattractant protein-1(MCP-1) level, MCP-1 excretion in urine, the renal expression of NF-κB and MCP-1 and the effect on renal constitution and function which prompts the investigation of its possible renoprotective mechanisms in type 2 diabetic (T2DM) rats.Method 40 healthy male SD rats of clean grade were chosen. 10 of them were randomly selected as normal control group (group A) which were fed with normal diet while the others were established as T2DM rat model by using high-sucrose-high-fat diet and injecting low dose Streptozotocin. These rats were then randomly divided into T2DM rats (group B), diabetic rats treated with glibenclamide (group C) and insulinize treated rats (group D), and were still fed with high-sucrose-high-fat food. The group C was treated with glibenclamide (5mg.kg-1.day-1) via intragastric administration. Group A, B and D were treated with equivalent sodium chloride and group D were injected with protamine zinc insulin (2-8U/kg) with the dosage adjusted according to the glycemia. After 8 weeks' medical intervention, 12 hours'urine was collected and all the rats were then put to death. The level of serum monocyte chemoattractant protein-1, Nuclear factor-κB, glycosylated hemoglobin A1c (HbA1c), fasting peripheral blood glucose (FBG), fasting insulin (FINS), triglyceride (TG), cholesterol (TC) as well as urinary monocyte chemoattractant protein-1 (MCP-1 ) excretion rate, urinary albumin/creatinine ratio (ACR) and urinary retinol binding-protein (URBP) excretion rate were tested. Besides, the renal tissues of all rats were obtained for evaluating kidney/body weight ratio, partly for examining the expression of NF-κB and MCP-1 protein by histochemical staining, partly for observing pathologic changes via light microscope and electron microscope.Results1. After 8 weeks' medical intervention, the levels of FBG and HbA1c in group B, group C and group D were significantly higher than those of group A. The levels of FBG and HbA1c in group C and group D were decreased compared to group B(P<0.05) but there were no statistical differences between that of group C and group D(P>0.05). TC and TG level in groups B, group C and group D increased significantly compared with those in group A (P<0.05) but there were no statistical differences among group B, group C and group D (P>0.05).2. After 8 weeks' medical intervention, ACR, URBP excretion rate,serum NF-κB and sMCP-1 level ,UMCP-1 excretion rate in group B, group C and group D increased significantly compared with those in group A (P<0.05); Kidney/body weight ratio in groups B and group C were higher than those in the group A. Compared with group B and group C, each above-mentioned index of group D were obviously descended (P<0.05). In the meantime, compared with group B, each mentioned index of group C were decrease but the discrepancy have no statistics meaning (P>0.05). In addition, Serum NF-κB and sMCP-1 level ,UMCP-1 excretion rate showed positive correlations between FBG, HbA1c,ACR, URBP excretion rate and kidney/body weight ratio (P<0.01).3. After 8 weeks' medical intervention, the light microscopes results showed that there was no obvious transformation of kidney in group A. Pathological changes were much more obvious in group B. It was clear that: the glomerulus became larger, glomerular capillary loops were tumbling, lumens were blocked, basal lamina was thickened, mesenterium base increased, the renal interstitium was infiltrated by lots of inflammatory cells. Compared with group B, the pathological change of group C has been slightly improved but the glomerulus size was larger, mesenterium base increased, mesangial region widened, basal lamina thickened. The pathological changes in group D were obviously lighter than those of group B and group C.4. After 8 weeks' medical intervention, the electron microscopes results showed that the ultra microstructure was clear. In group B, the thickness of glomerular basement membrane (GBM) increased distinctively and the structure was fussy. It was noted that some foot processes (FP) thickened, even vanished, ruptured, mesangial matrix accumulated, mesangial cells proliferation. Group C has little improvement compared with group B. The thickness of GBM increased and FP were destroyed and fused. The thickness of GBM in group D decreased remarkably compared with that in group B and group C. The ultra microstructure was relatively regular with a few FP fused.5. After 8 weeks' medical intervention, the expression level of MCP-1,NF-κB protein in glomcrulus and nephric tubule in group B, group C and group D was significantly higher than that in group A (P <0.05). Compared with group B, the coloration of kidney organization of group C have slightly relieved but the discrepancy have no statistics meaning (P>0.05). At the same time the expression of MCP-1, NF-κB protein in group D were obviously weaken than group B and group C.Conclusion1. Treatment with exogenous insulin can reduce ACR, URBP excretion rate as well as kidney/body weight ratio and lessen pathological lesion of diabetic nephropathy in T2DM rats.2. Exogenous insulin which can reduce glucose will at the same time lower the expression and generation of inflammation factor. It is anti-inflammatory and can definitely protect diabetic nephropathy. The mechanisms may have some relation 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-1.3. Glibenclamide plays a part in reducing glucose but has no evident effect on reducing the expression of inflammation factors or protecting the kidney.
|
PDF Full Text Request