基于AMPK/Akt/GSK-3β信号通路探讨六黄止渴方对db/db小鼠血糖的调控作用及机制OA

Objective:To investigate the regulatory effects and underlying mechanisms of Liuhuang Zhike prescription(LHZK)on blood glucose in type 2 diabetic db/db mice based on the AMP-activated protein kinase/protein kinase B/glycogen synthase kinase-3β(AMPK/Akt/GSK-3β)signaling pathway.Methods:Db/db mice were used as the model animals,and db/m mice served as the blank control.Forty db/db mice were randomly divided into the model group,metformin group(0.14 g·kg-1),and low-,medium-,and high-dose(4.11,8.21,16.43 g·kg-1)LHZK groups,with 8 mice in each group.The db/db mice in the metformin and LHZK groups were administered the corresponding drugs by gavage,while the blank control and model groups were given distilled water by gavage once daily for 8 consecutive weeks.Food intake,water consumption,body weight,and fasting blood glucose(FBG)were measured weekly.An automatic biochemical analyzer was used to determine glycated serum protein(GSP),serum triglycerides(TG),total cholesterol(TC),high-density lipoprotein cholesterol(HDL-C),and low-density lipoprotein cholesterol(LDL-C)levels.Hematoxylin-eosin(HE)staining was used to observe pathological morphological changes in the liver and pancreatic tissues.Oil red O staining was used to assess lipid accumulation in liver tissue.The anthrone colorimetric method was used to determine hepatic glycogen content.Real-time quantitative PCR(Real-time PCR)was used to detect the mRNA expression levels of insulin receptor substrate-1(IRS-1),Akt2,phosphoenolpyruvate carboxykinase(PEPCK),and glucose-6-phosphatase(G6Pase)in liver tissue.Western blot was used to detect the protein expression of AMPKα,phosphorylated AMPKα(p-AMPKα),GSK-3β,p-GSK-3β,glycogen synthase(GS),and phosphorylated GS(p-GS)in liver tissue.Results:Compared with the blank control group,the model group showed significantly increased food intake,water consumption,body weight,FBG,and GSP levels(P<0.01).Pancreatic islets exhibited marked parenchymal cell hyperplasia and interstitial inflammatory cell infiltration.Liver tissue showed obvious steatosis,accompanied by a compensatory increase in hepatic glycogen content(P<0.01).Hepatic G6Pase mRNA expression was increased,while IRS-1 and Akt2 mRNA expression levels were significantly decreased(P<0.01).The p-AMPKα/AMPKα protein expression ratio showed a decreasing trend,whereas the p-GSK-3β/GSK-3β and p-GS/GS protein expression ratios were significantly increased(P<0.01).Compared with the model group,food intake and water consumption showed decreasing trends in all treatment groups.Food intake was significantly reduced in the low-and high-dose LHZK groups and in the metformin group(P<0.05,P<0.01),and water consumption was significantly reduced in the low-dose LHZK group and in the metformin group(P<0.05,P<0.01).No statistically significant differences in body weight were observed among the LHZK groups,whereas body weight in the metformin group was significantly increased(P<0.05,P<0.01).FBG showed a decreasing trend in all treatment groups,with significant decreases in the low-dose LHZK group and the metformin group(P<0.05,P<0.01).GSP levels were significantly reduced in the low-dose LHZK group and in the metformin group(P<0.05,P<0.01).Hepatic steatosis and pancreatic pathological injury were alleviated to varying degrees in all treatment groups.Hepatic glycogen content further increased in all treatment groups,with significant increases in the medium-and high-dose LHZK groups(P<0.05).Real-time PCR results showed that all treatment groups downregulated the mRNA expression of G6Pase and PEPCK in the liver tissues of db/db mice,with significant downregulation of PEPCK mRNA in the low-dose LHZK and metformin groups(P<0.01).Meanwhile,all treatment groups upregulated IRS-1 and Akt2 mRNA expression,with the most pronounced upregulation observed in the medium-dose LHZK group(P<0.01).The p-AMPKα/AMPKα protein expression ratio was significantly increased in the low-and medium-dose LHZK groups(P<0.01).The p-GSK-3β/GSK-3β protein expression ratio was significantly increased in all treatment groups(P<0.05,P<0.01),whereas the p-GS/GS protein expression ratio was significantly decreased in all treatment groups(P<0.01).Conclusion:LHZK effectively reduces FBG and GSP levels in type 2 diabetic mice and improves hepatic steatosis and pancreatic islet pathological injury.Its hypoglycemic mechanism may be associated with regulation of the AMPK/Akt/GSK-3β signaling pathway and promotion of hepatic glycogen synthesis.