ABSTRACT
ObjectiveTo validate the alleviating effect of Gegen Qinliantang （GGQLT） on insulin resistance in db/db diabetic mice by regulating the silent information regulator 1 （SIRT1）/forkhead transcription factor O1 （FoxO1） autophagy pathway. MethodSeventy-five SPF-grade spontaneous type 2 diabetic db/db mice and 15 control db/m mice were selected and maintained on regular feed for one week before measuring blood glucose. They were randomly divided into six groups， with 15 mice in each group. The groups included a normal group （physiological saline， 0.2 g·kg-1）， a metformin group （0.2 g·kg-1）， high-， medium-， and low-dose GGQLT groups （31.9， 19.1， 6.9 g·kg-1）， and a model group （physiological saline， 0.2 g·kg-1）. They were orally treated with corresponding drugs for eight weeks， once daily. Fasting blood glucose （FBG） was measured using a Roche glucometer. Serum levels of high-density lipoprotein cholesterol （HDL-C）， low-density lipoprotein cholesterol （LDL-C）， triglyceride （TG）， and total cholesterol （TC） were measured using an automated biochemical analyzer. Fasting serum insulin （INS） levels were determined using enzyme-linked immunosorbent assay （ELISA）， and the homeostasis model assessment of insulin resistance （HOMA-IR） was calculated. Western blot was used to detect the expression of Beclin-1， microtubule-associated protein 1 light chain 3 （LC3）， and SIRT1/FoxO1 autophagy pathway-related proteins in liver tissues. Immunohistochemistry was performed to assess the expression of SIRT1， FoxO1， Beclin-1， and LC3B proteins in liver tissues. Transmission electron microscopy was used to observe the formation of autophagosomes in the liver. ResultCompared with the normal group， the model group showed significant increases in FBG， FINS， HOMA-IR， TC， TG， LDL-C， and HDL-C levels （P<0.01）， and significant increases in the expression of SIRT1， Beclin-1， LC3， and FoxO1 proteins in liver tissues （P<0.01）. Transmission electron microscopy revealed the highest number of autophagosomes in the model group. Compared with the model group， the metformin group and the low-， medium-， and high-dose GGQLT groups showed significant decreases in serum FBG， FINS， HOMA-IR， TC， TG， LDL-C， and HDL-C levels （P<0.05， P<0.01）， significant decreases in the expression of SIRT1， Beclin-1， LC3 （P<0.05， P<0.01）， and up-regulated FoxO1 protein （P<0.01）. Transmission electron microscopy showed a reduction in the degree of autophagy in the treatment groups. Compared with the metformin group， the medium- and high-dose GGQLT groups showed significant decreases in FBG， FINS， and TG levels （P<0.01）， significant decreases in the expression of SIRT1， Beclin-1， and LC3 in liver tissues （P<0.05， P<0.01）， and reduced FoxO1 protein （P<0.01）. The high-dose GGQLT group showed reduced HOMA-IR， TC， LDL-C， and HDL-C levels （P<0.05， P<0.01）. Transmission electron microscopy revealed a significant reduction in autophagosomes in the medium- and high-dose GGQLT groups. ConclusionGGQLT can significantly improve glucose and lipid metabolism disorders， alleviate insulin resistance in db/db mice， and prevent and treat type 2 diabetes by activating the SIRT1/FoxO1 autophagy pathway.