Effect Of Pioglitazone On Renal And P38MAPK Expression In Type2Diabetic Rats

Objective To observe the effect of pioglitzone (PIO) on renal function and constitution,the renal expression of P38MAPK and investigate its possible renoprotectivemechanisms in type2diabetic (T2DM) rats.Method35healthy male SD rats of clean grade were chosen.10of them wererandomly selected as normal control group (group NC) which were fed with normal diet,while the others were established as T2DM rat model by using high-sucrose-high-fatdiet and injecting low dose Streptozotocin. The model of the rats were randomly dividedinto diabetic (group DM) and pioglitazone (group PIO), and were still fed withhigh-sucrose-high-fat food. Then treated with pioglitazone intervention in group PIO.The group PIO was treated with pioglitazone10mg/Kg.d via intragastric administration,the group DM and NC were treated with corresponding sodium chloride. The level ofserum fasting insulin (FINS),triglyceride (TG),cholesterol (TC), fasting peripheralblood glucose(FBG),glycosylated hemoglobin A1c(HbA1c), urinary albumin/creatinineratio(ACR) and urinary retinol binding-protein(URBP) were tested after8weeks’medical intervention. Meanwhile the renal tissues of all rats were obtained partly forevaluating kidney/body weight ratio, partly for examining the expression of P38MAPKand P-P38MAPK protein by histochemical staining,partly for examining the expressionof P38MAPK mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR),partly for observing pathologic changes via light microscope and electron microscope. .Results1. The levels of FBG and HbA1c in group DM and group PIO were significantly highercompared with those of group NC(P<0.01),however there were no statisticaldifferences between group DM and group PIO (P>0.05);Level of FINS in group PIOwas significantly lower than those in the DM group（P<0.05);but there was nosignificant difference between in the PIO group and NC group（P>0.05). TC and TGlevel in groups DM and group PIO increased significantly compared with those ingroup NC (P<0.01).Treatment with pioglitazone significantly reduced the TC and TG(P<0.01).2. ACR,URBP excretion rate and kidney/body weight ratio in groups DM and groupPIO increased significantly compared with those in group NC (P<0.01). Treatmentwith pioglitazone also significantly reduced ACR, URBP excretion rate as well askidney/body weight ratio (P<0.01).3. The light microscopes results showed that there’s no pathological lesion of kidneyfound in group NC. Pathological changes were much more obvious in group DM. Itwas clear that the glomerular capillary loops were tumbling, lumens blocked,mesangial region widened, basal lamina thickened, mesenterium base increased, thevolume of glomerulus became larger and the cell population increased significantly.It also can be observed that the renal tubule was vacuolization and the renalinterstitium wasinfiltrated by lots of lymphocytes and emononuclear macrophages.Pathological changes in group PIO were lighter, it can be observed that glomerularcapillary lumen was constrictive slightly and few lymphocyte infiltrated.4. After8weeks’ medical intervention,the electron microscopes results showed that thestructure and width of glomerular basement membrane (GBM), epithelial footprocesses (FP) as well as the mesangial region were normal in group NC at the8thweek. In group DM, the FP fusion rate was approximately70percent and thethickening of GBM were observed. it was noted that some FP were destroyed, even vanished, the ultrastructure of GBM became ambiguous, the mesangial cells swelledand the extracellular matrix accumulated which caused mesangial region to expandintensively. After the treatment of pioglitazone, the thickness of GBM in group PIOdecreased markedly compared with that in group DM. It was clear that theultrastructure of GBM was relatively regular, only25percent of the epithelial footprocesses fused and the expansion of the mesangial region was unconspicuous.5. After8weeks’ medical intervention,the expression level of P38MAPK andP-P38MAPK protein in glomcrulus and nephric tubule in group DM and group PIOwas significantly higher (P<0.01)than those in group NC, pioglitazone can inhibit theexpression of P38MAPK and P-P38MAPK protein(P<0.01).6. After8weeks’ medical intervention,compared with group NC the expression ofP38MAPK mRNA was markedly up-regulated in group DM and group PIO (P<0.01),and pioglitazone could decrease the expression of P38MAPK mRNA in the renaltissue (P<0.05).7. The expression of P38MAPK、P-P38MAPK protein and P38MAPK mRNA showedpositive correlations with ACR, URBP excretion rate and kidney/body weight ratio inthe renal tissue (P<0.01).Conclusion Pioglitazone can definitely protect type2diabetic kidney function andconstitution, and reduce ACR, URBP excretion rate, kidney/body weight ratio,inflammation and renal fibrosis.The mechanisms may be associated with itsinhibition effect on P38MAPK expression and its activation.