桑叶总黄酮对1型糖尿病小鼠肾间质纤维化的防治作用及机制

摘要

目的 观察桑叶总黄酮对1型糖尿病小鼠肾间质纤维化的防治作用及其可能机制.方法 采用腹腔注射链脲佐菌素(STZ)150 mg·kg-1制备糖尿病小鼠模型,造模成功后分为模型组、桑叶总黄酮低(0.25 g·kg-1)、中(0.5 g·kg-1)、高(1 g·kg-1)剂量组各10只,另设正常对照组8只.每日灌胃1次,连续给药12周后,测定各组小鼠空腹血糖(FBG)、血清肌酐(Cr)、尿素氮(BUN)、尿微量白蛋白(mAlb);Masson染色、天狼星红(Sirus red)染色以及IV型胶原蛋白(collagen Ⅳ)免疫组织化学染色检测小鼠肾皮质中胶原蛋白表达;层黏连蛋白(laminin)染色评估小鼠肾小球及肾小管基底膜的增厚程度.Western blot 检测小鼠肾皮质中上皮间质转化(epithelial-mesenchymal transition,EMT)及信号通路PI3K/Akt/mTOR的相关蛋白表达.结果 中、高剂量的桑叶总黄酮能够明显降低糖尿病小鼠血糖、血清肌酐、尿素氮及尿微量白蛋白水平,并通过抑制PI3K/Akt/mTOR信号通路的激活,增加上皮型标志物E-cadherin,降低间质型标志物α-SMA的蛋白表达,改善肾脏组织的病理形态变化.结论 中、高剂量桑叶总黄酮能减轻1型糖尿病小鼠肾间质纤维化水平,其机制可能与抑制PI3K/Akt/mTOR信号通路的激活有关.%Aim To observe the effect of total flavonoid from Mori folium(TFMF) on renal interstitial fibrosis in type 1 diabetic mice and its possible mechanism.Methods Diabetic mice were induced by intraperitoneal injection of streptozotocin(STZ) dissolved in 0.01 mol·L-1 citrate buffer(pH 4.5) at 150 mg·kg-1 body weight after 12 h of food deprivation.Forty model mice were divided randomly into four groups: model group, and low-(0.25 g·kg-1), moderate-(0.5 g·kg-1), high-dose groups(1 g·kg-1) fed with TFMF once daily.In addition, eight normal mice were used as normal group.After 12 weeks, the fasting blood glucose(FBG), serum creatinine(Cr), blood urea nitrogen(BUN) and microalbuminuria(mAlb) were measured.Masson staining, Sirius red staining and collagen type Ⅳ immunohistochemical staining were used to detect the expression of collagen protein in the cortex, while laminin staining to assess the degree of glomerular and renal tubular basement membrane thickening.The protein expressions related to epithelial-mesenchymal transition and PI3K/Akt/mTOR in the renal cortex of mice were detected by Western blot.Results The moderate and high dose of TFMF could significantly decrease the levels of FBG, Cr, BUN and mAlb in diabetic mice, meanwhile decreasing the expression of α-SMA protein by inhibiting the activation of PI3K/Akt/mTOR signaling pathway, which led to the amelioration of the pathological alterations of renal tissue.Conclusions The moderate and high dose of TFMF can reduce the level of renal interstitial fibrosis in type 1 diabetic mice, and its mechanism may be related to the inhibition of activation of PI3K/Akt/mTOR signaling pathway.