绿原酸通过抑制内质网应激改善大鼠糖尿病氧化性肾损伤

Improvement of Chlorogenic Acid for Oxidative Renal Injury in Diabetic Rats through Inhibiting Endoplasmic Reticulum Stress

目的:探讨绿原酸(CGA)对链脲佐菌素(STZ)诱导的糖尿病肾病(DN)大鼠氧化应激的肾脏保护作用及其可能机制。方法:将40只大鼠随机分为5组:正常对照组、模型组、CGA低(5 mg·kg-1)、中(10 mg·kg-1)、高(20 mg·kg-1)剂量组,每组8只。除正常对照组外,其余各组腹腔单次注射STZ(60 mg·kg-1)建立大鼠糖尿病模型。腹腔注射给药,1次/d,连续给药6周。测定大鼠血糖、尿蛋白、尿素氮(BUN)、血清肌酐(SCr)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)水平;免疫印迹法检测内质网应激(ERS)信号通路关键分子[C/EBP同源蛋白(CHOP)、活化转录因子6(ATF6)、磷酸化蛋白激酶R(p-PERK)和磷酸化鸡真核生物翻译起始因子2α(p-eIF2α)]的蛋白表达水平;RTPCR检测CHOP、ATF6和PERK的mRNA表达水平。结果:与模型组相比,CGA组血糖、尿蛋白、BUN、SCr、MDA水平、CHOP、ATF6、p-PERK、p-eIF2α的蛋白表达水平及CHOP、ATF6和PERK的mRNA表达水平显著降低(P <0. 05或P <0. 01),SOD、GSH-Px和CAT活性显著提高(P <0. 05或P <0. 01),以上作用均呈剂量依赖性。结论:CGA对STZ诱导的DN大鼠有抗氧化作用,其机制可能与抑制DN内质网应激反应有关。

Objective: To investigate the protective effect of chlorogenic acid( CGA) on oxidative stress induced by streptozotocin( STZ)in diabetic nephropathy( DN) rats and its possible mechanism. Methods: Totally 40 rats were randomly divided into 5 groups: the normal control group,the model group,CGA low( 5 mg·kg-1),medium( 10 mg·kg-1) and high( 20 mg·kg-1) dose groups with 8 ones in each group. Except the normal control group,the diabetic rats were induced by single intraperitoneal injection of STZ( 60 mg·kg-1).Intraperitoneal injection was given once a day for 6 weeks. The levels of blood sugar,urinary protein,urea nitrogen( BUN),serum creatinine( SCr),malondialdehyde( MDA),glutathione peroxidase( GSH-Px),catalase( CAT) and superoxide dismutase( SOD)were measured in rats. Immunoblotting assay was used to detect the expressions of key molecules of endoplasmic reticulum stress( ERS) signaling pathway [C/EBP-homologous protein( CHOP),activated transcription factor 6( ATF6),phosphorylated protein kinase R( p-PERK) and phosphorylated chicken eukaryotic translation initiation factor 2( p-eIF2α)]. RT-PCR was used to detect the mRNA expressions of CHOP,ATF6 and PERK. Results: Compared with those in the model group,the levels of blood sugar,the levels of urinary protein,BUN,SCr and MDA,the expressions of CHOP,ATF6,p-PERK and p-eIF2α,and the mRNA expressions of CHOP,ATF6 and PERK in CGA groups decreased significantly( P < 0. 05 or P < 0. 01),while the activities of SOD,GSH-Px and CAT increased significantly( P < 0. 05 or P < 0. 01),and the above effects were dose-dependent. Conclusion: CGA has antioxidant effect in STZ-induced DN rats,and its mechanism may be related to the inhibition of DN endoplasmic reticulum stress response.