| Object:To observe the influence of pioglitazone on the oxidative stress and the activity of protein kinase C in diabetic rats,and investigate the protection mechanism of pioglitazone for kidney of diabetic rats.Methods:The diabetic model was induced by streptozotocin.40 male rats in good health were randomly divided into four groups of 10 rats each,normal control group(NC group),diabetic group(DM group),diabetic group treated with low dose pioglitazone(3mg.kg-1.d-1,DP1 group), and diabetic group treated with high dose pioglitazone(9mg.kg-1.d-1,DP2 group).12 weeks later, each group left the blood preparation,urine aliquot and nephridial tissue sample.Ratio of kidney weight to body weight(KW/BW) was calculated.Blood glucose,blood cholesterol (TC),triglyeride(TG),blood insulin,blood C-peptide,blood urea nitrogen(BUN),serum creatinine(Scr),and 24-hour urinary protein were measured.The activities of Cu-Zn superoxide dismutase(Cu-ZnSOD),catalase(CAT),and malondialdehyde(MDA) in nephridial tissue were measured by chromatometry.The activity of protein kinase C in renal cortex was measured by PepTag Assay for Non-Radioactive Detection.In addition,the renal tissue was observed by light microscope and electron microscope.Results:①12 weeks later 2 rats were dead of infestation in DM group;1 rat was dead of intragastric administration in DP2 group,and there was no diabetes natual relief during the experiment process.②Comparing with the rats of NC group,there's significant increasing of the serum glucose,TC,TG,LDL-c in the rats of group DM,DP1 & DP2,and obvious decreasing of HDL-c,blood insulin and blood C-peptide;thers is no statistic difference among the data of group DM,DP1 & DP2(p＞0.05).③Compared with NC group,the level of BUN,Scr,KW/BW, 24-hour urinary protein in DM group were significant increasing(P＜0.01).Compared with DM group,there was no difference in BUN and Scr between DP1 & DP2 group.However,the level of KW/BW,24-hour urinary protein both in DP1 & DP2 group were much lower than DM group(P＜0.05).There were statistic differences between DP1 & DP2 group(P＜0.05).④Compared with NC group,the level of MDA in DM group increased significantly,but the activities of Cu-Zn SOD and CAT decreased(P＜0.05).However,the level of MDA decreased, the activities of Cu-Zn SOD and CAT increased significantly both in DP1 group and DP2 group. There were statistic differences between DP1 & DP2 group(P＜0.05).⑤The activity of cytolymph protein kinase C decreased significantly in DM group but the activity of cell membrane protein kinase C increased significantly(P＜0.05).Compared with DM group,The activity of cytolymph protein kinase C wad much higher and the activity of cell membrane protein kinase C was much lower both in DP1 group & DP2 group(P＜0.05).In addition,there were differences between DP1 group & DP2 group(P＜0.05).⑥There is inverse correlation between Cu,Zn-SOD, KW/BW and 24-hour urinary protein,positive correlation between MDA and KW/BW,24-hour urinary protein in rats' kidney.There is positive correlation between the activity of cytolymph protein kinase C and KW/BW,24-hour urinary protein in rats' nephridial tissue cellular membrane;but negative correlation between the activity of cytolymph protein kinase C and KW/BW,24-hour urinary protein in rats' cytolymph.There is negative correlation between Cu, Zn-SOD,CAT and the activity of cytolymph protein kinase C in rats' nephridial tissue of all groups;but positive correlation between MDA and the activity of cytolymph protein kinase C in cellular membrane(P＜0.05).⑦12 weeks later Glomerulus volume and cell population increasing of group rats can be ovserved by HE dyeing;Glomerular filtration membrane structure is obviously abnormal ovserved by electron microscope,endotheliocyte arrangeschaoticly and desquamate,with integrality demolition,foot process and basal lamina thickening and syzygium obviously;there's contaminate existing in glomerular filtration membrane structure in DM group;but in DP1 & DP2 group foot process is thickening but line up in order,confluence decreasing,basal lamina thickening under extenuation,filter membrane structure keeping integrated,but getting more improving than DM group.Conclusion:It's obvious that oxidative stress reaction exists in kidney of diabetic rats. Pioglitazone could have the specific antioxidation which is independent of its glucose-lowering action and blood fat-regulating action.However,pioglitazone can lower KW/BW,urine microcontent albumin and activity of protein kinase C,it also has dose dependent,so that it could protect kidney and postpone effectiveness of diabetic nephropathy. |
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