ABSTRACT
ObjectiveTo discuss the effect of modified Gegen Qinliantang （MGQT） on blood glucose and lipids and Takeda G protein-coupled receptor 5 （TGR5）-related pathways in pancreatic tissue of obese type 2 diabetes mellitus （T2DM） mice. MethodA total of 10 male specific pathogen free （SPF） m/m mice （7 weeks old） and 50 male SPF （7 weeks old） were adaptively fed for one week in SPF laboratory. The m/m mice were included in the blank group. T2DM was induce d in the 50 db/db mice. The model mice were randomized into the model group， metformin group （0.2 g·kg-1）， high-dose， medium-dose， and low-dose （31.9， 19.1， 6.4 g·kg-1） MGQT groups， with 10 in each group， and the drug dose was10 mL·kg-1. The model group and the blank group received distilled water of the same volume. The administration lasted 12 weeks （once/day）. Fasting blood glucose （FBG） was detected regularly. After 12 weeks of administration， serum levels of glycated serum protein （GSP）， serum glucose （GLU）， total cholesterol （TC）， triglycerides （TG）， high-density lipoprotein cholesterol （HDL-C）， and low-density lipoprotein cholesterol （LDL-C） were detected. Pathological changes in the pancreatic tissue were based on hematoxylin-eosin （HE） staining. Western blot was used to determine the protein expression of TGR5， protein kinase A （PKA）， phosphorylated （p）-PKA， cyclic-AMP response element binding protein （CREB）， p-CREB， proprotein convertase 1/3 （PC1/3）， and glucagon-like peptide-1 （GLP-1） in pancreatic tissues. The level of cyclic adenosine monophosphate （cAMP） in pancreatic tissue was determined by enzyme-linked immunosorbent assay （ELISA）. ResultCompared with the blank group， the model group had pathological changes in pancreatic tissue， high levels of FBG， GSP， GLU， TC， TG， and LDL-C （P<0.01）， low level of HDL-C （P<0.05）， low protein expression of TGR5， p-PKA （Thr197）/PKA， p-CREB （Ser133）/CREB， PC1/3， and GLP-1 in pancreatic tissue （P<0.01）， and low content of cAMP in the pancreas （P<0.01）. Pancreatic tissue lesion in the treatment groups were milder than that in the model group. Both the high-dose MGQT and metformin can reduce the levels of FBG， GSP， GLU， TC， TG， and LDL-C in db/db mice （P<0.05， P<0.01） and increase the level of HDL-C （P<0.01）. Except the GLP-1 protein in the medium-dose MGQT group， the protein expression of TGR5， p-PKA （Thr197）/PKA， p-CREB （Ser133）/CREB， PC1/3， and GLP-1 in the high-dose and medium-dose MGQT groups and the metformin group increased compared with that in the model group （P<0.05， P<0.01）. The content of cAMP in the pancreatic tissue of the high-dose and medium-dose MGQT groups and the metformin group was raised compared with that in model group （P<0.05， P<0.01）. ConclusionMGQT can improve the glucose homeostasis in db/db mice with T2DM by regulating TGR5/cAMP/GLP-1 signaling pathway-related protein expression.
ABSTRACT
ObjectiveTo observe the effect of modified Gegen Qinliantang on the expression levels of proteins related to the farnesoid X receptor/small heterodimer partner/peroxisome proliferator-activated receptor α （FXR/SHP/PPARα） signaling pathway in the liver tissue of db/db model mice with type 2 diabetes mellitus （T2DM） and explore the underlying mechanism of action of modified Gegen Qinliantang. MethodThirty db/db mice were randomly divided into model group， metformin group （0.2 g·kg-1）， and high-， medium-， and low-dose modified Gegen Qinliantang groups （31.9， 19.1， 6.4 g·kg-1）， with 6 mice in each group. An additional six m/m mice were assigned to the blank group. Respective drugs were administered via oral gavage for 12 weeks. Mouse body weight， fasting blood glucose （FBG）， total cholesterol （TC）， triglyceride （TG）， high-density lipoprotein cholesterol （HDL-C）， and low-density lipoprotein cholesterol （LDL-C） levels were measured. Oil red O staining was used to observe hepatic lipid accumulation and periodic acid-schiff （PAS） staining was used to assess hepatic glycogen deposition. Ammonium ferric sulfate staining was used to observe cholesterol deposition in intestinal tissues. Western blot was employed to detect the expression of FXR， cholesterol 7α-hydroxylase （CYP7A1）， SHP， and PPARα proteins in liver tissues， and enzyme-linked immunosorbent assay （ELISA） was used to measure serum free fatty acid （FFA） levels. ResultAt the end of the treatment， compared with the blank group， the model group exhibited significant increases in mouse body weight， FBG， FFA， TC， TG， and LDL-C levels （P<0.01）， along with significant hepatic lipid droplets， reduced hepatic glycogen， noticeable cholesterol accumulation in intestinal tissues， significantly decreased expression of FXR， SHP， PPARα proteins， and significantly increased expression of CYP7A1 protein in liver tissues （P<0.01）. Compared with the model group， the metformin group and the high- and medium-dose modified Gegen Qinliantang groups demonstrated significant reductions in mouse body weight， FBG， FFA， TC， TG， LDL-C levels （P<0.05， P<0.01）， significant increases in HDL-C levels （P<0.05， P<0.01）， decreased hepatic lipid accumulation， increased hepatic glycogen， reduced intestinal cholesterol accumulation， significantly increased expression of FXR， SHP， PPARα proteins， and significantly decreased expression of CYP7A1 protein in liver tissues （P<0.01）. ConclusionModified Gegen Qinliantang may regulate the FXR/SHP/PPARα signaling pathway to suppress FFA levels and improve lipid metabolism in T2DM mice.