RESUMO
ObjectiveTo investigate the therapeutic effect of rhubarb decoction （RD） retention enema on a rat model of minimal hepatic encephalopathy （MHE） and its mechanism of action based on bile acid （BA） metabolomics. MethodsA total of 55 male Sprague－Dawley rats were randomly divided into blank group （NC group with 10 rats）， hepatic encephalopathy group （HE group with 15 rats）， MHE group with 15 rats， and MHE+rhubarb decoction treatment group （MHEY group with 15 rats）. Intraperitoneal injection of carbon tetrachloride （CCl4） and thioacetamide （TAA） was performed to establish a rat model of MHE or HE， and the rats were sacrificed after 2 weeks of administration. The serum levels of aspartate aminotransferase （AST）， alanine aminotransferase （ALT）， alkaline phosphatase （ALP）， total bilirubin （TBil）， and total bile acid （TBA） and the concentration of blood ammonia were measured； the colonic contents were collected to measure pH value； liver and brain tissue samples were collected， and HE staining was used to observe the histopathological changes of the liver； the bile was collected， and liquid chromatography－mass spectrometry was used to perform BA－targeted metabolomics analysis. Continuous data were expressed as mean±standard deviation； a one－way analysis of variance was used for comparison between multiple groups， and the least significant difference t－test was used for further comparison between two groups. ResultsCompared with the NC group， the HE group and the MHE group had a significant increase in searching platform latency （after modelling and after administration） and a significant reduction in the number of platform crossings （all P<0.05）； compared with the MHE group， the MHEY group had a significant reduction in searching platform latency （after administration） and a significant increase in the number of platform crossings， and the HE group had a significant increase in searching platform latency and a significant reduction in the number of platform crossings （all P<0.05）. Compared with the NC group， the HE group and the MHE group had significant increases in AST， ALT， ALP， TBil， TBA， blood ammonia， and colon pH value （all P<0.05）； compared with the MHE group， the MHEY group had significant reductions in AST， ALT， ALP， TBil， TBA， blood ammonia， and colon pH value （all P<0.05）， and the HE group had significant increases in AST， ALT， ALP， TBil， TBA， blood ammonia， and colon pH value （all P<0.05）. The MHE group had significantly lower TBA， primary BA， and secondary BA than the NC group （all P<0.05）； compared with the MHE group， the HE group had significantly lower TBA and primary BA （all P<0.05）， and the MHEY group had significantly higher TBA and primary BA （all P<0.05）. Compared with the NC group， the MHE group had significant reductions in GCDCA， GUDCA， GHDCA， TCDCA， TUDCA， GLCA， and TLCA （all P<0.05） and significant increases in γ－MCA， THCA， 7－KDCA， AlloLCA， and α－MCA （all P<0.05）， and compared with the MHE group， the MHEY group had significant increases in THDCA， TMCA， TCDCA， TUDCA， and TLCA （all P<0.05）. ConclusionRD retention enema can improve liver injury and cognitive function in a rat model of MHE induced by CCl4 and TAA by regulating the enterohepatic circulation of BA， possibly by increasing the synthesis of taurine－binding BA.