The Effect Of Benazepril On The Renal MCP-1 Expression In The Diabetic Nephropathy

Diabetic nephropathy(DN)is one of the most common chronic complications of Diabetes mellitus(DM). It is also the important cause of death. With the rising incidence of DM, DN has become the increasingly important cause of chronic renal failure in China. In recent years, many studies have shown that the occurrence of inflammation plays an important role in the development of DN. MCP-1 is the specific inflammatory chemokine and has a strong role on the chemoattractant of monocyte/macrophage. Also can mediate the accumulation and activation of monocyte/macrophage cells in the renal. MCP-1 may have a vital role on the occurrence and development of DN.Objective: To investigate the expression of MCP-1 on kidney tissue and excretion of urinary MCP-1 in early diabetic rats, and observe the effect of benazepril on early diabetic nephropathy and renal MCP-1 expression in diabetic rats for provided clues for provention and cure for DN.The experiment included two parts:Part I1. Modeling and Administration WayAdult male Wistar rats weighing 200g to 260g were studied,and randomly divided into two groups: 1.normal control group(Group NC,n=10); 2.DM model group(Group DM,n=20);DM group were induced by STZ,55mg/Kg,intr- aperitoneal injection one time. Blood glucose from caudal vein were measured after 48 hours.Rats in DM groups whose random blood glucose was at least 16.7mmol/L were regard as sucessful models. Once the models were sucessfully established, randomly divided DM group into two groups:1.model group(Group DN,n=10);2.benazepril-treated group(Group DN+ACEI,n=10). Benazepril was given to Group DN+ACEI,10mg/Kg/d,by intragastric admini- stration,distilled water to Group NC and DN.2. Sample collectionAfter 4 weeks of the experiment, body weight and blood glucose from caudal vein were measured. And urinary production was collected exactly for quantity of 24 hour urinary protein before sacrificed. All the rats were sacrificed in the experimental period of the 4th week. blood was gotten from heart, then serum was stored below -70℃, then biochemical indicators were examined, After sacrificed, right kidneys were taken out and weighed.Renal tissues were imbedded by paraffin,cut sections of 2μm,then stained with PAS, MCP-1 expression were assessed by immunohistochemistry.PartⅡMesangial cell culture: cells were devided into three groups:(1)Normal control group:(NC,5.6mmol/L D-glucose);(2)High glucose group (HG,30 mmol/L,D-glucose);(3)High glucose + Benazepril group (HG+ACEI,30 mmol/L,D-glucose+10umol/L,Benazepril). And then cultural cells were taken out for RT-PCR to detect MCP-1 expression. Statistical analysisData was presented as Mean±SD, statistical analysis was performed using t test, P value <0.05 or P value <0.01 was considered significantly. ResultAfter 4 weeks, BG level of Group DN and DN+ACEI was evidently increased and maintained at a very high level compared with Group NC (P<0.01). The BW grew rapidly in Group NC, however slowly in Group DN and DN+ACEI(P<0.01). The levels of kidney weight and KHI in Group DN were significantly higher than Group NC(P<0.01), and the level of kidney weight was lowerer obviously than Group DN(P<0.01), the level of KHI was lowerer than Group DN(P<0.05). The levers of urinary MCP-1/Ucr and UAlb/Ucr in Group DN were significantly higher than Group NC(P<0.01), and Group DN+ACEI was lowerer than Group DN(P<0.01). Renal pathological sections showed that renal glomeruli size was larger in group DN and group DN+ACEI than their controls.and also the mesangial matrix. Above-mentioned changes of Group DN+ACEI were lighter than Group DN, mesangial matrix lightly increased. Immunohistochemistry technique showed that the expression of MCP-1 in Group DN was much more than Group NC, but MCP-1 expression in Group DN+ACEI was decreased compared with Group DN.Cells experiment showed that MCP-1expression of Mesangial cells increased significantly after 120 h in high glucose environment, and benazepril could decrease MCP-1 expression of mesangial cells in high glucose environment.Conclusions:MCP-1 plays an important role in the development of early DN. The MCP-1 protein expression of mesangial cells increases markly under the stimulation of HG environment. Benazepril has little influence on blood glucose, but decreases MCP-1 protein expression and decreases the excretion of early DN protein and KHI, then protects the kidney function. The protection of Benazepril to the kidney, through the effect of independent hemodynamics changes, one of the effect mechanisms is decreasing angiotensin II and III by redusing MCP-1, repressing the infilitration and aggregation of mononuclear macrophage, and then lightering Inflammatory reaction of renal. Urinary MCP-1 may become the anticipation index of early DN. It is effective to through intervening the MCP-1 protine expression in the early stage, lighter inflammatory reaction of renal, relieve the damage in the early stage of DN and delay its advancement.