生长激素释放激素受体激动剂MR409对db/db小鼠糖尿病肾病作用的研究

Protective role of growth hormone releasing hormone receptor agonist MR409 in experimental diabetic nephropathy

目的:探讨人工合成的生长激素释放激素受体激动剂MR409对db/db小鼠糖尿病肾病和肾脏纤维化的影响。方法:将db/db小鼠随机分为模型组和MR409治疗组,野生型小鼠为对照组,每组10只。MR409治疗组小鼠隔天皮下给予MR409(每只15µg),对照组和模型组小鼠隔天皮下给予等量溶剂对照,干预8周。取第8周末小鼠血清和尿液进行生化指标检测,HE、PAS、Masson和天狼星红染色用于评价肾损伤和肾纤维化程度,二氢乙啶(DHE)荧光染色检测评价肾脏中活性氧的含量,Western blot检测肾脏纤维化以及氧化应激相关蛋白的表达。结果:与db/db小鼠相比,MR409治疗可显著降低db/db小鼠尿蛋白/肌酐比、血清中胆固醇和甘油三脂含量以及肾间质纤维化和肾小球硬化面积(P<0.05),MR409还可显著降低肾脏中活性氧水平及NADPH氧化酶亚基p22phox和gp91phox、纤连蛋白(FN)和转化生长因子β1(TGFβ1)蛋白的表达量(P<0.05)。结论:生长激素释放激素受体激动剂MR409能有效减轻db/db小鼠糖尿病肾损伤,其机制可能与降低氧化应激和肾纤维化有关。

AIM:To investigated whether MR409,a synthetic agonist of growth hormone-releasing hormone receptor(GHRHR),protects against renal injury and fibrosis in diabetic(db/db)mice.METHODS:Wild-type(WT)or db/db mice were randomly divided into 3 groups(WT,db/db and MR409-db/db group)and treatment for 8 weeks.The mice in MR409-db/db group received subcutaneous injection MR409(15µg per mouse)once on alternate days,while the mice in WT group and db/db group were given the same amount of organic solvent.At the end of the 8th week of treatment,the serum and the urine were harvested and used for measuring biochemical indexes.Hematoxylin-eosin(HE),PAS,Masson and Sirius red staining methods were used to evaluate renal injury and fibrosis.Dihydroethidium(DHE)fluores‐cence staining was used to detect renal oxidative stress in situ,and Western blot was used to determine the expressions of fibrosis and oxidative stress-related proteins.RESULTS:Compared with db/db mice,treatment with MR409 significantly reduced the ratio of urinary protein/creatinine,serum level of cholesterol and triglyceride,renal interstitial fibrosis and glo‐merulosclerosis area in the db/db mice(P<0.05).MR409 also remarkedly reduced renal oxidative fluorescence intensity and the protein expression levels of NADPH oxidase subunits,p22phox and gp91phox,and fibrosis factors,fibronectin and transforming growth factorβ1(P<0.05).CONCLUSION:The GHRHR agonist MR409 effectively protects against dia‐betic renal injury in db/db mice,and the underlying mechanisms may may be related to the reduction of oxidative stress and renal fibrosis.