红芪多糖对早期糖尿病肾病db/db小鼠肾间质纤维化的影响

Protective effects of hedysarum polybotrys polysacchcaide on renal interstitid fibrosis in db/db mice with early diabetic nephropathy

目的通过研究红芪多糖(HPS)对早期糖尿病肾病(DN)db/db小鼠肾组织中转化生长因子-β1(TGF-β1)与结缔组织生长因子(CTGF)表达的影响,探讨HPS对早期DN小鼠肾脏的保护作用机制。方法 SPF级6周龄雄性小鼠60只,其中db/db小鼠50只,用随机数字表法分为5组:HPS高、中、低剂量组(200、100、50 mg/kg HPS溶液灌胃)、替米沙坦组(5 mg/kg替米沙坦溶液灌胃)、模型组(等体积蒸馏水灌胃),每组10只;db/m小鼠10只,作为正常对照组,给予等体积蒸馏水灌胃。连续灌胃8周,于治疗前及治疗后每2周检测血糖浓度,第4周末及第8周末收集小鼠24 h尿液,ELISA法检24 h尿微量白蛋白水平。框后静脉取血,血清用于检测血清肌酐(Scr)、尿素氮(BUN)。处死小鼠,剥离肾脏,左肾皮质用于HE染色,观察肾脏病理学变化;右肾皮质用于RT-PCR、Western blotting检测肾组织TGF-β1及CTGF mRNA和蛋白的表达量。结果与正常组比较,模型组小鼠血糖、Scr、BUN 24 h尿微量白蛋白水平显著升高(P<0.01);肾小球肥大,系膜区明显增宽,毛细血管基底膜增厚;TGF-β1及CTGF mRNA和蛋白的表达水平显著升高(P<0.01)。与模型组比较,除HPS低剂量组外(P>0.05),其余各治疗组小鼠血糖、Scr、BUN和24 h尿微量白蛋白水平均明显下降(P<0.05);肾小球肥大,系膜区明显增宽,毛细血管基底膜增厚情况均有不同程度改善;TGF-β1及CTGF mRNA和蛋白的表达水平明显降低(P<0.01);HPS中剂量组疗效明显优于替米沙坦组。结论 HPS能够防治db/db小鼠早期DN,其机制可能与HPS抑制TGF-β1及CTGF mRNA在肾脏的表达有关。

Objective To investigate the influence of hedysarum polybotrys polysacchcaide （HPS） on the expression of transforming growth factorβ1（TGF-β1） and connective tissue growth factor （CTGF） as well as its kidney-protective mechanism in early diabetic nephropathy （DN） db/db mice. Methods 60 male mice at SPF 6 were used for this study. The above 50 db/db mice were divided into 5 groups （n = 10 in each group） by using the random number table method： high-dose, mid-dose and low-dose HPSgroup （200, 100, 50 mg/kg, ig）, telmisartan group （5 mg/kg, ig）, and model group （distilled water of the same volume, ig）. The remaining 10 db/m mice in the normal control group received equal vol- ume of distilled water via intragastric administration for 8 weeks. For mice in all groups, blood glucose levels were measured before the experiment and once every two weeks after intervention. 24h urine was collected at the end of week 4 and 8 to measure urinary albumin levels by using ELISA method. Blood samples were drawn from the eyeball veins to measure the levels of serum creatinine （Scr） and blood urea nitrogen （BUN）. Rat kidney tissue was dissected after sacrifice of these mice. Left kidney underwent HE staining to observe pathological changes in the renal cortex while the right kidney was used to detect the expression of TGF-β1 and CTGF mRNA and protein by using RT-PCR and Western blotting. Results Compared with the normal control group, blood glucose, Scr, BUN and 24 h urinary albumin levels in- creased significantly （P 〈0.01 ） in the model group; glomerular hypertrophy, mesangial widening, and capillary basement membrane thickening were observed. Expressions of TGF-β1 and CTGF mRNA and protein were significantly increased （P 〈 0.01 ）. Compared with the model group, blood glucose, Scr, BUN and 24 h urinary albumin levels decreased significantly （ P 〈 0.05 ） in all treatment groups except the low-dose HPS group （ P 〉 0.05 ） ; glomerular hypertrophy, mesangial widening and capillary base- ment membrane thickening presented with different degrees of improvement; expressions of TGF-β1 and CTGF mRNA and protein significantly decreased （ P 〈 0.01 ） ; curative effect of the mid-dose HPS group was superior to that of the telmisartan group. Conclusion HPS could prevent early diabetic nephropathy （DN） in db/db mice; its mechanism may be related to the inhibition of TGF-β1 and CTGF mRNA ex- pression level in the kidney.