降糖消渴颗粒对糖尿病小鼠肝脏内质网应激及脂质代谢的影响

Effects of Jiangtang Xiaoke Granule on hepatic lipid metabolism and endoplasmic reticulum stress in diabetic mice

[目的]观察降糖消渴颗粒对2型糖尿病小鼠肝脏中内质网应激和脂质代谢相关指标表达的影响,研究其改善糖尿病肝脏脂质代谢紊乱的可能机制。[方法]雄性8周龄KK-Ay小鼠,高脂饲料喂养,诱导2型糖尿病模型,以空腹血糖≥13.9 mmol/L作为成模标准。成模后小鼠随机分为模型组、吡格列酮组、降糖消渴颗粒高、中、低(7,3.5,1.75 g/kg)剂量组,并设正常对照组,C57BL/6J小鼠,普通饲料喂养。治疗10周后,摘取各组小鼠肝脏,剪取肝脏相同部位组织,生理盐水冲洗,10%福尔马林固定液固定待检,余下肝组织液氮保存备用。逆转录-聚合酶链反应(RT-PCR)法检测小鼠肝脏IRE1α、XBP1、SREBP-1c、SREBP2、Insig-1、FAS的mRNA表达情况;免疫组化法检测小鼠肝脏中p-eIF2α、GRP78的蛋白表达情况。[结果]模型组小鼠肝脏中SREBP-1c、SREBP2、IRE1α、XBP1的mRNA表达明显上调(P<0.01),Insig-1的mRNA表达明显下调(P<0.01),FAS的mRNA表达也有所增高(P<0.05)。高剂量(7 g/kg)降糖消渴颗粒可显著下调SREBP-1c的mRNA表达量(P<0.01);低、中剂量(1.75,3.5 g/kg)作用比较广泛且突出,均可减少SREBP-1c和SREBP2的mRNA表达(P<0.01)以及FAS的基因表达量(P<0.05)。除此之外,中剂量还具有下调IRE1α的mRNA表达(P<0.05),增加Insig-1的mRNA表达量(P<0.05)的作用。低、中、高剂量降糖消渴颗粒均可显著降低p-eIF2α、GRP78的蛋白表达量(P<0.01)。[结论]2型糖尿病小鼠肝脏的脂质合成作用与内质网应激反应具有相关性。低、中(1.75,3.5 g/kg)剂量降糖消渴颗粒可在一定程度上下调实验小鼠肝脏中脂质代谢相关因子的表达,以减少肝脏脂质的过度合成,同时减轻肝脏内质网应激反应,共同起到改善糖尿病肝脏脂质代谢紊乱的作用。

[Objective]To investigate the effect of Jiangtang Xiaoke Granule(JTXKG)on correlative indexes of endoplasmic reticulum stress and lipid metabolism in type 2 diabetic KK-Ay mice which were induced by high fat diet.The effect of JTXKG on T2DM was discussed from releasing the hepatic lipid metabolism disorders.[Methods]Male 8-week-old KK-Ay mice,were fed by high-fat-diet,T2DM model were established by FBG≥13.9 mmol/L.The T2DM mice were then randomly divided into model group,pioglitazone group and JTXKG groups in low(1.75 g/kg),medium(3.5 g/kg),and high(7 g/kg)doses.The normal group had C57BL/6J in it and feed by normal diet.After 10-week treatment,tissue from the same part of the liver were taken and fixed with 10%formalin,the rest of the liver tissue was stored in liquid nitrogen.the liver gene expression of IRE1α,XBP1,SREBP-1c,SREBP2,Insig-1,FAS were examined by real-time fluorescence quantitative PCR(FQ-PCR),the protein expression of p-eIF2αand GRP78 were examined by immunohistochemistry method and the effects of JTXKG on the above indexes were observed.[Results]In this experiment,the gene expression of SREBP-1c,SREBP2,IRE1α,XBP1 increased significantly(P<0.01),respectively,the gene expression of Insig-1in model group decreased significantly(P<0.01)and the gene expression of FAS increased(P<0.05).T2DM mice supplemented with 7 g/kg dose of JTXKG have lower gene expression of SREBP-1c(P<0.01).Both 3.5 g/kg and 1.75 g/kg dose of JTXKG have a significant effect on reducing the gene expression of SREBP-1c,SREBP2(P<0.01)and FAS(P<0.05).Otherwise,3.5 g/kg dose of JTXKG has increased the gene expression of IRE1αand decreased the gene expression of Insig-1(P<0.05).All dose of JTXKG could reduce the protein expression of p-eIF2αand GRP78 significantly(P<0.01).[Conclusion]Hepatic lipid synthesis of T2DM mice is correlated with endoplasmic reticulum stress.Both 3.5 g/kg and 1.75 g/kg dose of JTXKG can decrease hepatic lipogenesis,reduce lipid deposition and inhibit the endoplasmic reticulum stress in the liver of T2DM mice.In this way,the lipid metabolism disorder of T2DM mice can be relieved.