Effect Of Total Glucosides Of Paeony On Activation Of P38 Mitogen-activated Protein Kinase In The Kidney From Experimental 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 were not yet fully known. Accumulating evidence now indicates that chronic low-grade inflammation and activation of the innate immune system are closely involved in the pathogenesis of diabetes nephropathy. Mitogen-activated protein kinase (MAPK) play a significant role in its development and progression.The study in vivo and in vitro evidence demonstrated that p38 MAPK (p38) which Among mitogen-activated protein kinase (MAPK) family members, have significant protective effects on DN. Total glucosides of paeony(TGP) are active compounds extracted from the roots of the tradition herb Paeonia lactiflora Pall. It possesses a variety of pharmacological functions, include anti-inflammation, anti-oxidative stress and immunoregulatory activity. The purpose of the present study was to investigate the effect of TGP on the activation of p38 and nuclear factor-κB (NF-κB) protein and its the possible renoprotective effects mechanism in the kidney in experimental diabetic rat. Methods Fifty adult male Munich-Wistar 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, by gavage,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 the experimental model of diabetes, rats received a single intraperitoneal injection of STZ (60mg.kg -1.d-1). TGP was orally administered. Control group and model group treated with the same vehicle alone. Eight weeks after STZ injection, the following determinations were done in samples: (1) plasma glucose ( BG ), liver function, kidney function and plasma lipid were determined according to standard methods; (2) 24 hours urinary albumin excretion rate (UAER) were measured by enzyme immunoassay (EIA); (3) Renal lesions were evaluated using PAS staining, the mean glomerular volume (VG) and indices for tubulointerstitial injury (TII) were measured by using pathology image analysis system software; (4) Western-blotting for renal p-p38 and NF-κB-p65 protein were quantified densitometrically. Results 1. BG, Body weight (BW) ratio of KW to BW (KW/BW), UAER: 8 weeks after STZ injection, there was a significant increase in BG (P<0.01) and BW was significantly decreased (p<0.01) in diabetic rats compared with control group. The BG level of TGP group (50 mg,100 mg and 200mg.kg-1) had no statistically significant difference compared with model group. KW/BW in TGP group (50 mg,100 mg and 200mg.kg-1) was decreased compared with model group, but there had no statistically significant. UAER in model group were significantly higher than control group, and UAER in TGP group (50 mg,100 mg and 200mg.kg-1) were significantly lower than model group (P<0.05,P <0.01). Creatinine clearance rate (Ccr) in model group was increased compared with control group, but in TGP group (50, 100, 200 mg.kg?1) had no statistically significant difference compared with model group. 2. plasma lipid and liver function: TC and TG in model group was increased compared with control group, but TC and TG in TGP group (50, 100, 200 mg.kg?1) had no statistically significant difference compared with model group. In addition, ALT and AST had no difference between control group, model group, and TGP group(50, 100, 200 mg.kg?1). It shows that TGP have no effect on liver function. 3. Renal pathologic morphology: Compared with control group, VG and TII in model group was significantly increased. VG in TGP group (50 mg.kg?1) was significantly lower than model group(P<0.05),TII in TGP group (50 mg.kg?1) was lower than model group, but there had no statistically significant. VG and TII in TGP group (100, 200 mg.kg?1) was significantly lower than model group(P<0.05, P<0.01). 4.p-p38 protein expression in renal tissue: Western blot analysis noted that the expression of p-p38 protein in the kidney were significantly increased in diabetic rats, TGP treatment with 50, 100 and 200 mg.kg?1 could reduced p-p38 expression by 30.8%,24.0%,,60.1%, respectively. 5. NF-κB-p65 protein expression in renal tissue: Densitometric analysis of the Western blot showed increase in the amount of NF-κB-p65 in the kidney from diabetic rats with respect to normal rats, TGP treatment with 50, 100 and 200 mg.kg?1 could reduced NF-κB-p65 expression by 27.8%,45.9%,59.0%, respectively. Conclusion Our study suggest that TGP treatment ameliorates early renal injury via the inhibition of the activation of p38 and NF-κB in the kidney in diabetic rats.