大蒜素通过TGF-β1/Smads通路抑制2型糖尿病大鼠肝纤维化的研究

Allicin Inhibiting Liver Fibrosis in Type 2 Diabetic Rats through TGF-β1/Smads Pathway

目的:探讨大蒜素对2型糖尿病大鼠肝脏纤维化和转化生长因子-β1(TGF-β1)/Smads信号通路的影响。方法:60只SD大鼠随机分为正常对照组、模型组、二甲双胍组(阳性对照,200 mg·kg^(-1))和大蒜素低、中、高剂量组(5,10,20 mg·kg^(-1))。正常对照组大鼠常规饲养,其余各组通过高糖高脂饲料喂养加腹腔注射链尿佐菌素(STZ)制备2型糖尿病大鼠模型。造模完成后,各组均1次/d灌胃给药(正常对照组和模型组灌胃给予生理盐水)。4周后,测定空腹血糖(FBG)水平;生化分析法检测血清丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、总胆红素(TBIL)、白蛋白(Alb)水平;化学发光法检测血清透明质酸(HA)、层黏连蛋白(LN)、Ⅲ型前胶原(PCⅢ)、Ⅳ型胶原(Ⅳ-C)水平;HE染色观察肝组织病理学改变,Masson染色观察肝组织纤维化状况并计算胶原容积分数(CVF);Western blotting法检测肝组织转化生长因子β1(TGF-β1)、磷酸化Smad2(p-Smad2)、p-Smad3、Ⅰ型和Ⅲ型胶原蛋白(CollagenⅠ、CollagenⅢ)表达。结果:与正常对照组比较,模型组大鼠FBG水平和血清ALT、AST、TBIL、HA、LN、PCⅢ、Ⅳ-C水平显著升高(P<0.01),Alb水平显著降低(P<0.01);肝组织呈现脂肪变性,肝索排列紊乱,肝细胞肿胀,炎性细胞浸润等病理学改变;肝组织中央静脉周围及汇管区可见胶原纤维增粗并形成纤维隔,CVF显著升高(P<0.01);肝组织TGF-β1、p-Smad2、p-Smad3、CollagenⅠ、CollagenⅢ表达显著升高(P<0.01)。与模型组比较,大蒜素中、高剂量组和二甲双胍组FBG水平和血清ALT、AST、TBIL、HA、LN、PCⅢ、Ⅳ-C水平显著降低(P<0.01),Alb水平显著升高(P<0.01);肝组织病理学改变和纤维化状况均明显改善,CVF显著降低(P<0.01);肝组织TGF-β1、p-Smad2、p-Smad3、CollagenⅠ、CollagenⅢ表达显著降低(P<0.01)。结论:大蒜素对2型糖尿病大鼠肝纤维化具有抑制作用,其机制可能与抑制TGF-β1/Smads通路进而抑制细胞外基质生成有关。

Objective:To investigate the effects of allicin on liver fibrosis and transforming growth factor-β1(TGF-β1)/Smads signaling pathway in type 2 diabetic rats.Methods:Totally 60 experimental SD rats were randomly divided into normal control group,model group,metformin group(positive control,200 mg·kg^(-1))and allicin low,medium and high dose groups(5,10 and 20 mg·kg^(-1)).The rats in normal control group were fed routinely,while the rats in other groups were fed high-fat diet and intraperitoneal injection of streptozotocin to make diabetes mellitus rat model.After modeling,the corresponding drugs were given by intragastric administration once a day(the rats in normal control group and model group were given normal saline by intragastric administration).Four weeks later,the levels of fasting blood glucose(FBG)and alanine aminotransferase(ALT),aspartate aminotransferase(AST),total bilirubin(TBIL)and albumin(Alb)in serum were detected by biochemical analysis;the levels of hyaluronic acid(HA),laminin(LN),typeⅢprocollagen(PCⅢ)and type IV collagen(CIV)in serum were detected by chemiluminescence detection;the liver tissue histopathological changes were observed after HE staining,the liver tissue fibrosis was observed after sirius staining,and the collagen volume fraction(CVF)was calculated;the expressions of TGF-β1,p-Smad2,p-Smad3,CollagenⅠand CollagenⅢin liver tissue were detected by Western blotting.Results:Compared with those in the normal control group,the levels of FBG and ALT,AST,TBIL,HA,LN,PCIII and CIV in serum of the rats in model group were significantly increased(P<0.01),while the level of ALB was significantly decreased(P<0.01);around the central vein of liver tissue and the portal area,thickening of collagen fibers and formation of fibrous septa could be seen,and the CVF significantly increased(P<0.01);the expressions of TGF-β1,p-Smad2,p-Smad3,CollagenⅠand CollagenⅢin liver tissue were significantly up-regulated(P<0.01).Compared with those in the model group,the levels of FBG and ALT,AST,TBIL,HA,LN,PCⅢand CIV in serum of the rats in allicin medium and high dose groups and metformin group were significantly decreased(P<0.01),while the content of Alb was significantly increased(P<0.01);the liver tissue histopathological changes and fibrosis were significantly improved,and the CVF was significantly decreased(P<0.01);the expressions of TGF-β1,p-Smad2,p-Smad3,CollagenⅠand CollagenⅢin myocardial tissue were significantly down-regulated(P<0.01).Conclusion:Allicin has an inhibitory effect on liver fibrosis in type 2 diabetic rats,and the mechanism may be related to the inhibition of TGF-β1/Smads pathway and the inhibition of extracellular matrix production.