Mechanism of Gegen Qinliantang in Improving Ectopic Lipid Accumulation in Liver of db/db Mice with Type 2 Diabetes Mellitus by Regulating AMPK-FoxO3a Autophagy Axis / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the mechanism of Gegen Qinliantang （GQT） in improving ectopic lipid accumulation in the liver of db/db mice with type 2 diabetes mellitus （T2DM） by regulating the adenosine monophosphate-activated protein kinase （AMPK）-forkhead box O3a （FoxO3a） autophagy axis， to provide a scientific basis for clarifying the hypoglycemic mechanism of GQT and its clinical application. MethodSeventy-five spontaneous T2DM db/db mice and 15 normal db/m mice were selected and maintained on a regular diet for one week， followed by the measurement of blood glucose. They were then randomly divided into six groups， with 15 mice in each group， including normal group （0.2 g·kg-1 saline）， metformin group （0.2 g·kg-1）， high-， medium， and low-dose GQT group （31.9， 19.1， 6.9 g·kg-1）， and model group （0.2 g·kg-1 saline）. The mice were orally administered the corresponding drugs once daily for 12 weeks. Fasting blood glucose （FBG） and glycated hemoglobin （HbA1c） were detected. Fasting insulin （FINS） and free fatty acid （FFA） levels were measured by enzyme-linked immunosorbent assay （ELISA）. Pathological changes in liver tissues were observed by hematoxylin-eosin （HE） staining. The protein expression levels of phosphorylated （p）-AMPK， p-FoxO3a， and autophagy-related proteins microtubule-associated protein 1 light chain 3 Ⅱ （LC3Ⅱ） and p62 were detected using Western blot. Immunofluorescence was used to detect the expression of hypoxia-inducible factor-1α （HIF-1α） in liver tissues. Real-time polymerase chain reaction （Real-time PCR） was performed to detect the mRNA expression of AMPK， FoxO3a， and LC3 in liver tissues. ResultCompared with the normal group， the model group showed pathological changes in liver tissues， increased FBG， HbA1c， FINS， and FFA levels （P<0.01）， increased protein expression levels of p-AMPK， p62， and HIF-1α， decreased protein expression levels of p-FoxO3a and LC3Ⅱ in liver tissues （P<0.01）， decreased mRNA expression of AMPK， and increased expression of FoxO3a （P<0.01）. Compared with the model group， the treatment groups showed relieved liver tissue lesions and decreased FBG， HbA1c， FINS， and FFA levels （P<0.01）. The expression of p-AMPK， p62， and HIF-1α increased， while the expression of p-FoxO3a showed a dose-dependent decrease in the high-dose GQT group. The expression of LC3Ⅱ increased in the metformin group and the high-dose GQT group （P<0.01）. The mRNA expression of AMPK showed a dose-dependent increase， and the expression of FoxO3a showed a dose-dependent decrease in the treatment groups （P<0.01）. ConclusionGQT can improve ectopic lipid accumulation in the liver of T2DM db/db mice， which may be related to the regulation of the AMPK-FoxO3a autophagy axis.