Valsarta Influence On Kidney And C-jun N-terminal Kinase Signaling Pathway In Diabetic Rat

Objective: Diabetic nephropathy(DN) is one of the most common and most serious complications of diabetes. c-Jun N-terminal Kinase(JNK) signaling pathway can be activated by many excitant signals, such as growth factor, environmental stress and so on. JNK signaling pathways involved in the various life process, such as cell differentiation, cell apoptosis and etc. Recent researches discover that many factors including Abnormal glucose metabolism, kinds of cytokines factors and changes of glomerular hemodynamics can activate and change the signal transductions in the kidney cells, thus it takes part in the occurrence and development of DN in diabetes state. The studies show that the rennin-angiotensin system, particularly angiotensin II in the occurrence and progression of DN play an important role. In this study, through animal experiment, firstly we detect the expressions of MKK7, JNK, c-Jun and p-JNK and apoptosis of renal tissue in diabetic rats. Secondly, to investigate the role of JNK signaling pathways on renal tissue of diabetic rats. Thirdly, to investigate the role of JNK signal transduction pathway on renal tissue of diabetic rats. Lastly,to study the effects of valsartan on renal tissue of diabetic rats and the Possible mechanism.Methods: Clean male 45 wistar rats were randomly divided into 3 groups: normal control group(NC group,n=10), diabetic model group(DM group)and diabetic model group with valsartan treatment(Val group). DM group and Val group after 12 hours of fasting, were given STZ (STZ dissolved in 0.1mol/L citrate buffer to made into 6g/L and pH value of 4.5) according to 35mg/kg by intraperitoneal injection, and NC group were injected the same amount of citric acid buffer. Diabetic model wasconsidered to be successful when the blood glucose was≥16.7mmol/L after 72 hours of the injection. The total of 34 DM rats, the failure of one rat was discarded, were divided into two groups(n=17). Val group were given valsartan (10mg/kg/d) by irrigation stomach, and DM group and NC group were fed with the same amount of drinking water. Rats were treated for 8-week. All rats were allowed free access to food and water,and not feeded other drugs. The weight of the rats and weight of the kidneys were measured and ratio of kidney weight/body weight (KW/BW) were calculated. The levels of blood glucose(BG), albumin(ALB),triglyceride,(TG),total cholesterol (CHO),high density lipoprotein(HDL), Low Density Lipoprotein(LDL),serum creatinine(Cr), urea nitrogen (BUN), uric acid (UA)and 24-hour urine protein excretion were measured by Biochemistry. The protein expressions of JNK, P-JNK and c-Jun in renal tissue were detected by immunohistochemistry. Western blotting were employed to determine the expressions of MKK7, JNK, P-JNK and c-Jun in renal tissue. The apoptosis of renal tissue were evaluated by Flow Cytometry(FCM). The experimental data was demonstrated in mean±standard deviation.The analysis of variance were used to the significance test(p<0.05)and the relation about the data was measured with linear correlation by SPSS13.0, a statistic software.Results:1 The results of BG, weight of the rats, weight of the kidneys,KW/BW and the urinary protein excretion.Compared with the NC group, the urinary protein excretion,the levels of BG, weight of the rats, weight of the kidneys and KW/BW and were increased significantly in DM group and Val group(P<0.05). Compared with the DM group, the urinary protein excretion was reduced in Val group(P<0.05).2 The results of immunohistochemistry stainingJNK, c-Jun and p-JNK in glomerular, tubular and renal interstitial of the rats had a small amount of expression at 4-week and 8-week. Compared with the NC group,the expression of the three indexs was increased,especially in renal tubule cytoplasm and renal interstitial of the DM group rats at 4-week,and it was increased significantly in renal tubule cytoplasm,renal interstitial and part of the glomerular in the DM group rats at 8-week (P<0.05). Compared with the DM group, there was no statistically significant at 4-week,and the expression of the three indexs was reduced at 8-week in Val group(P<0.05).3 The results of Western blottingIn the DM group ,the expression of MKK7,JNK,c-Jun and p-JNK were higher at 8-week than those at 4-week(P<0.05). Compared with 4-week, the expression of p-JNK were incraesed at 8-week in Val group(P<0.05). Compared with DM group, the expression of the three indexs was reduced at 8-week in Val group(P<0.05).4 Aapoptosis index and correlation analysisThe apoptosis index of DM group was significantly higher than the NC group,and that of Val group was significantly lower than the DM group. Renal tissues The expression of JNK, MKK7, c-Jun and p-JNK and the apoptosis index of renal tissue were positively correlated.Conelusion: The protein expression of MKK7, JNK, p-JNK and c-jun were increased significantly, which prompted that JNK signaling pathways was activated in the renal tissue of diabetes and a series of reaction,such as apoptosis,were happened. Then it involved in the occurrence and development of DN. Valsartan can reduce proteinuria and improve renal pathological damageThe mchanism may be related to inhibition of JNK signaling pathway.