二甲双胍对2型糖尿病模型大鼠TNF-α表达的影响

Effects of metformin on expression of renal tissue and serum level of TNF-α in type 2 diabetic rats

目的观察不同剂量二甲双胍对2型糖尿病(T2DM)模型大鼠肾组织及血清肿瘤坏死因子-α(TNF-α)表达的影响,探讨二甲双胍对糖尿病肾病的保护机制。方法从53只SD大鼠中随机选取8只作为正常对照组(NC组),其余大鼠给予高脂饲料喂养结合链脲佐菌素(STZ)腹腔小剂量注射,建立T2DM大鼠模型。模型大鼠随机分组,分别为糖尿病模型组(T2DM组);二甲双胍干预治疗组:M1组[150 mg/(kg·d)]、M2组[300 mg/(kg·d)]、M3组[500mg/(kg·d)];格列本脲组[GLY,5 mg/(kg·d)]。干预组给药8周后,观察各组大鼠血糖(BG)、糖化血红蛋白(Hb A1c)、尿素氮(BUN)、尿白蛋白肌酐比(UACR);采用免疫组化法检测肾小球TNF-α蛋白表达,ELISA法检测血清中TNF-α的水平。结果各剂量二甲双胍及GLY干预组BG、Hb A1c、UACR和BUN明显低于T2DM组,但高于NC组(P<0.05),且M2、M3组低于M1组(P<0.05);GLY组与各剂量二甲双胍组BG、Hb A1c水平比较差异无统计学意义(P>0.05);GLY与M2、M3组UACR、BUN水平比较差异有统计学意义(P<0.05)。各剂量二甲双胍及GLY干预组血清TNF-α表达水平较T2DM组明显降低(P<0.05),但高于NC组(P<0.05),M3组低于M1组(P<0.05);GLY与M2、M3组差异有统计学意义(P<0.05)。二甲双胍干预组肾脏TNF-α蛋白的含量明显下降,但高于NC组,且各干预组之间差异有统计学意义(P<0.05);GLY与M2、M3组差异有统计学意义(P<0.05)。结论二甲双胍可减轻T2DM大鼠肾组织TNF-α的表达及血清中TNF-α的含量,并呈一定的剂量依赖性,可能与二甲双胍的肾脏保护作用有关。

Objective To observe the effects of different doses of metformin on the expression of renal tissue tumor necrosis factor-α（ TNF-α） and serum levels of TNF-α in Type 2 diabetes（ T2DM） model rats and discuss the mechanism of the metformin in the protection against diabetic renal injury. Methods 8 rats were randomly selected in 53 SD rats as the normal control group（ NC）. The remaining rats were fed with high fat-diet and intraperitoneal injection of low dose of streptozotocin（ STZ） to establish the model rats of T2DM. All model rats were randomly divided into T2 DM model group（ group T2DM）,metformin groups[M1,150 mg /（ kg·d）; M2,300 mg /（ kg·d）; M3,500 mg /（ kg·d） ] and glyburide group[GLY,5mg /（ kg·d） ]. The rats of metformin and GLY groups continuously received treatment fro eight weeks. After 8 weeks,blood glucose（ BG）,glycated hemoglobin（ Hb A1c）,BUN and urinary albumin / urine creatinine（ UACR） were detected. The expression of renal tissue TNF-α was detected by using immunohistochemistry assay. The levels of serum TNF-α was tested by ELISA. Results The levels of BG,Hb A1 c,UACR and BUN in Metformin and GLY groups were significantly decreased than those of T2 DM group,while higher than those of NC group（ P〈 0. 05）. The levels of BG and Hb A1 c were not statistically significant between GLY and MET groups; the levels of UACR and BUN in Metformin groups were significantly lower than GLY group. The levels of serum TNF-α in Metformin and GLY groups were significantly decreased compared with that of T2DM group（ P〈 0. 05）,but higher than that of NC group（ P〈 0. 05）,which in M3 were lower than that in M1group（ P〈 0. 05）,the levels of serum TNF-α in MET groups were significantly lower than GLY group（ P〈 0. 05）.The expression of renal tissue TNF-α protein was significantly decreased compared with that of T2 DM group,which also had significant differences among different doses of metformin groups（ P〈 0. 05）,and the expression of renal tissue TNF-α protein in MET groups was significantly lower than GLY group（ P〈 0. 05）. Conclusion Metformin can suppress the expression of renal tissue TNF-α and reduce the serum TNF-α level of type 2 diabetic rats with a dose-dependent manner,which may partly contribute to its reno-protection.