Effects Of Total Glucosides Of Paeony On Oxidative Stress In The Kidney Of Diabetic Rats

Background and objective Diabetic nephropathy(DN) has become one of the main cause of end-stage renal disease(ESRD),but unfortunately the intimate mechanisms leading to the development and progression of renal injury are not yet fully known.The recent study in vivo and in vitro evidence demonstrated that oxidative stress play a major role in the development and progression of diabetic nephropathy,and that antioxidant treatment had significant protective effects on DN.Total glucosides of paeony(TGP) are active compounds extracted from the roots of the tradition herb Paeonia lactiflora Pall,its mainly composed of peoniflorin,hydroxide radical peoniflorin, peonin,albiflorin and benzoylpaeoniflorin.It possesses a variety of pharmacological functions,including anti-inflammation,anti-oxidative stress and immunoregulatory activity. The purpose of the present study was to investigate the effects of TGP on Oxidative stress in renal tissue of diabetic rats induced by STZ and explore the possible mechanism.Methods Fifty adult male Sprague-Dawley rats were separated into five groups at random.Control group(n=10),model group(n=10),model group treated with TGP 50 mg·kg^-1(n=10),model group treated with TGP 100 mg·kg^-1(n=10) and model group treated with TGP 200 mg·kg^-1(n=10).To induce an experimental model of diabetes, rats received a single intraperitoneal injection of STZ(60mg·kg^-1 d^-1).TGP was given by gavage.8 weeks after STZ injection,the following determinations were done in samples:(1) BG were determined according to standard methods;(2) Renal lesions were evaluated using PAS staining,the mean glomerular volume(V_G) and indices for tubulointerstitial injury(TII) were measured by using pathology image analysis system software;(3) Renal tissue T-AOC,GSH-PX,CAT,SOD were determined by spectrophotometric method;(4) Expression of nitrotyrosine(NT) was measured by Western blot analysis;(5) Expression of osteopontin(OPN) andα-smooth muscle actin (α-SMA) in renal tubulointerstitium were determined by immunohistochemistry method.Results 1.BG,Body weight(BW) ratio of KW to BW(KW/BW):8 weeks after STZ injection,there was a significant increase in BG(P＜0.01) and significantly decreased in BW(p＜0.01) in diabetic rats compared with control group.The BG level of TGP group(50mg,100mg and200mg·kg^-1) have no statistically significant difference compared with model group.KW/BW in TGP group(50mg,100mg and 200mg·kg^-1) was decreased compared with model group,but there have no statistically significant.2. Renal pathologic morphology:Compared with control group,V_G and TII in model group was significantly increased.V_G in TGP group(50mg·kg^-1) was significantly lower than model group(P＜0.05),TII in TGP group(50mg·kg^-1) was lower than model group,but there have no statistically significant.V_G and TII in TGP group(100,200mg·kg^-1) was significantly lower than model group(P＜0.05,P＜0.01).3.T-AOC,GSH-PX,CAT,SOD activities in renal tissue:The T-AOC,SOD and CAT activities in renal tissue of model group significantly decreased compared with that of control group(P＜0.01).TGP treatment with 200mg·kg^-1 increased the T-AOC,SOD and CAT activities(P＜0.01,P＜0.05).In addition,GSH-PX have no difference between control group,model group,and TGP group(50,100,200mg·kg^-1).4.NT expression in renal tissue:Western blot analysis noted that the expression of NT protein in ranal tissue of model group increased by 3.4 folds to that of control group,TGP treatment with 50,100 and 200mg.kg^-1 reduced the increased expression of NT protein by 41.2%,43.8%and 57.5%,respectively.5.OPN andα-SMA protein expression in renal tubulointerstitium:There was minimal immunohistohemistrical staining for OPN in renal tubulointerstitium of control group rats.Immunostaining for OPN was markedly increased in model group in tubulointerstitium(P＜0.01),elevated expression of OPN protein in renal tubulointerstitium in diabetic rats were only significantly inhibited by TGP treatment with 100 and 200mg.kg^-1(p＜0.01).There was minimal immunohistohemistrical staining forα-SMA in renal tubulointerstitium of control group rats.Immunostaining forα-SMA was markedly increased in model group in tubulointerstitium(P＜0.01),and increased expression ofα-SMA protein were significantly inhibited by TGP treatment with 50,100 and 200mg.kg^-1(p＜0.01).Conclusion The oxidative stress is increased in the diabetic rat kidney,and TGP can prevent renal damage associated with diabetes by attenuating the oxidative stress.