Effect of Modified Da Chaihutang on FXR/FGF15/FGFR4 Signaling Pathway in Mice with Cholesterol Gallstone Differentiated into Damp-Heat Syndrome / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the effect of modified Da Chaihutang on cholesterol gallstone （CS） in mice due to damp-heat based on the farnesoid X receptor （FXR）/fibroblast growth factor 15 （FGF15）/fibroblast growth factor receptor 4 （FGFR4） pathway and explore the molecular biological mechanisms of CS differentiated into damp-heat syndrome from the perspective of correspondence between prescription and syndrome. MethodForty-eight six-week-old mice were randomly divided into the blank group， model group， modified Da Chaihutang （23.4 g·kg-1） group， and ursodeoxycholic acid （0.12 g·kg-1） group， with 12 mice in each group. The ones in the latter three groups were exposed to "internal dampness + external dampness + high-cholesterol diet" for 12 weeks for inducing CS due to damp-heat. Mice in the modified Da Chaihutang group and ursodeoxycholic acid group were gavaged with the corresponding drugs， while those in the model and blank groups with the same amount of normal saline for a total of four weeks. Before and after modeling， mice in each group were subjected to open field tests for determining their activities and mental states. Such general conditions as body mass， food intake， fur， and urine and stool of mice in each group were observed and recorded weekly for judging the damp-heat syndrome. After the intervention， the sampled liver and gallbladder tissues of mice in each group were stained with hematoxylin-eosin （HE） staining， and the serum γ-glutamyltransferase （GGT）， alkaline phosphatase （ALP）， and total bilirubin （TBIL） were determined. The total cholesterol （TC） and total bile acid （TBA） contents in bile were measured by enzyme-linked immunosorbent assay （ELISA）. The mRNA and protein expression levels of FXR， FGF15， FGFR4， and cholesterol 7α-hydroxylase gene （CYP7A1） were assayed by real-time fluorescence quantitative polynucleotide chain reaction （Real-time PCR） and Western blot. ResultCompared with the blank group， the model group exhibited enlarged gallbladder， brown turbid bile with flocculent precipitation visible to the naked eye， obvious damp-heat syndrome， lipoid degeneration in the liver tissue， rough and thickened gallbladder wall， elevated ALP， GGT， and TBIL in serum （P<0.01） and TC in bile （P<0.01）， reduced TBA （P<0.01）， up-regulated FXR， FGF15， and FGFR4 mRNA and protein expression in ileum （P<0.05， P<0.01）， and down-regulated CYP7A1 mRNA and protein expression （P<0.01）. Compared with the model group， the two medication groups displayed improved bile turbidity， and the bile in the modified Da Chaihutang group became clearer. After intervention， the damp-heat syndrome of mice in the modified Da Chaihutang group was significantly alleviated. The liver and gallbladder lesions of mice in the two medication groups were significantly relieved， manifested as reduced serum ALP， GGT， and TBIL （P<0.01）. The reduction in ALP and TBIL of the modified Da Chaihutang group was more significant （P<0.01）. The TC contents in the bile of mice from the two medication groups were significantly lowered， whereas the TBA contents were elevated （P<0.01）， with more significant changes present in the modified Da Chaihutang group （P<0.01）. The mRNA and protein expression levels of FXR， FGF15， and FGFR4 in the modified Da Chaihutang group were down-regulated （P<0.05， P<0.01）， while the mRNA and protein expression levels of CYP7A1 rose （P<0.05）， except that the elevation in FGF15 and FGFR4 protein expression and reduction in CYP7A1 protein expression were not significant. The mRNA and protein expression levels of FXR， FGF15， and FGFR4 in the ursodeoxycholic acid group all decreased， among which the reduction in FXR was remarkable （P<0.05）， and the mRNA and protein expression levels of CYP7A1 were significantly up-regulated （P<0.05）. ConclusionModified Da Chaihutang significantly improves the stone， liver function， bile composition， abnormal cholesterol-bile acid metabolism， and damp-heat syndrome in the model mice of CS differentiated into damp-heat syndrome， which may be related to its regulation of key factors FXR， FGF15， FGFR4， and CYP7A1 mRNA and protein expression in the cholesterol-bile acid metabolism pathway.