| Objectives:1.To investigate the expression of pigment epithelium-derived factor(PEDF)in the renal tissue of diabetic rats induced by STZ.2.To detection the influence of(DPP-4)inhibitor Sitagliptin(SIT)on the expression of PEDF and MAPK / ERK signal pathway in diabetic rat kidney.Methods:60 Sprague Dawlry(SD)5 weeks old male rats were randomly selected as normal group(group A),the other 50 were used as the experimental group adaptive feeding after 1 weeks.The normal group was fed with standard feed,and the experimental group was fed with high sugar and high fat diet.4 weeks later weighing,tseting blood of biochemical index including glucose(FBG),insulin(FINS),triglyceride(TG),total cholesterol(TC),low density lipoprotein cholesterol(LDL-C),high density lipoprotein cholesterol(HDL-C),and then according to the HOMA index: HOMA-IR =(FBG * FINS)/22.5 evaluation of insulin resistance,to determine whether the formation of insulin resistance.Insulin resistance in rats with water but after 12 hours of fasting to streptozotocin(streptozocin,STZ)35mg/kg 72 hours after intraperitoneal injection,the rats were measured blood glucose,three consecutive random blood glucose(BS)for more than 16.7 mmol/L for the successful models(there are 3 no success,and died 1 rat).The successful modeling rats were randomly divided into 5 groups: sitagliptin 5mg/kg.d group(group B,n=9),sitagliptin 10mg/ kg.d group(group C,n=9),sitagliptin 5mg/ kg.d+MAPK/ERK 1mg/kg.d inhibitor PD98059 group(group D,n=9),sitagliptin 10mg/ kg.d+MAPK/ERK 1mg/kg.d group inhibitor PD98059(group E,n=9),non intervention group(group F,n=10);group A were given normal saline;Sitagliptin was given at 9 am daily by intragastric administration for 8 weeks.Tenth weeks later group D,E were given intraperitoneal injection of MAPK/ERK inhibitor 1mg/kg.d PD98059 for 2 weeks.After eleven weeks,weight the rats,test their urinary microalbumin by urine,and test FBG,triglyceride(TG),total cholesterol(TC),low density lipoprotein cholesterol(LDL-C),high density lipoprotein cholesterol(HDL-C),serum creatinine(SCr),blood urea nitrogen(BUN),C reactive protein(CRP)and other biochemical indicators by blood;Look into the species of kidneys after HE staining under 400 times light microscope,the expression of PEDF,ERK,TGFbeta 1 immunohistochemical staining were observed in renal tissue of rats,reverse transcription polymerase chain the reaction(RT-PCR)was used to detect the expression of PEDF m RNA.Results:1.4 weeks later,the weight of the model group was higher than the normal group,so as FBG,FINS,TG,TC,LDL-C,the difference was statistically significant(P < 0.05).2.12 weeks later,group B,C,D,E,F compared with group A,weight decreased,but FBG,TG,TC,LDL-C,24 h urinary protein,,SCr,BUN,CRP was degrees(P <0.05);compared with F,group B,C,D,E,TG,FBG rats,TC,LDL-C,SCr,BUN,24 h urinary protein,CRP decreased(P < 0.05);3.The histopathological examination of the rats in each group: Under the light microscope,the renal structure of rats in group A was normal,and the structure of kidney was not destroyed.Glomerular regularity,clear and tidy basement membrane,glomerular capillary cavity normal renal interstitial inflammatory cell infiltration.In group F,glomerular hypertrophy,thickening of basement membrane,narrowing of capillaries and even occlusion were observed.Infiltration of inflammatory cells such as lymphocytes and monocyte-macrophages was observed in renal interstitium.Compared with F group,the proliferation of glomerular mesangial cells in group B,C,D and E decreased gradually,the mesangial matrix lesions gradually decreased and the infiltration of inflammatory cells gradually decreased,The pathological changes of group C were obviously improved.4.Immunohistochemical results showed that Compared with group A,the renal levels of ERK,TGF-?1 by group B,C,D,E were increased(P<0.05),but PEDF was opposite(P<0.05).Compared with group C and group B,group D and group B,group E and group C,the renal levels of ERK,TGF-?1 by group B,C,D,E were decreased(P<0.05),but PEDF was opposite(P<0.05).5.Pearson correlation analysis showed that expression of PEDF in renal tissues of diabetic rats was negatively correlated with ERK and TGF-?1(r=-0.606,R2=0.368,P<0.05;r=-0.607,R2=0.368,P<0.05);expression of PEDF was positively correlated with that of ERK(r=0.991,R2=0.783,P<0.05).6.Compared with group A,the expression of PEDF m RNA in renal tissue of group B was significantly lower than that of group A(P <0.05);the expression of PEDF m RNA in group B,C,D and E was significantly lower than that in group B(P <0.05).The expression of PEDF m RNA in group C was higher than that in group B(P <0.05),and the expression of PEDF m RNA in group C was significantly higher than that in group B(P <0.05)The expression of PEDF m RNA in group D and group E was significantly higher than that in group B and C(P <0.05).Conclusion:1.The expression of ERK,TGF-?1 in the renal tissue of diabetic rats is increased induced by STZ and high sucrose-fat diets,but PEDF is opposite.It suggests that PEDF,ERK and TGF-?1 participate in inflammation of diabetic rats.2.Sitagliptin can relieve renal inflammation in diabetic rats,the mechanism may be through regulating the expression of PEDF,then down-regulation ERK expression in renal inflammation,thus inhibiting MAPK/ERK signaling pathway. |
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