Intrauterine growth retardation affects liver bile acid metabolism in growing pigs:effects associated with the changes of colonic bile acid derivatives

Background:Intrauterine growth retardation(IUGR)is associated with severely impaired nutrient metabolism and intestinal development of pigs.Our previous study found that IUGR altered intestinal microbiota and metabolites in the colon.However,the consequences of IUGR on bile acid metabolism in pigs remained unclear.The present study aimed to investigate the bile acid metabolism in the liver and the profile of bile acid derivatives in the colon of grow-ing pigs with IUGR using bile acid targeted metabolomics.Furthermore,we determined correlations between colonic microbiota composition and metabolites of IUGR and normal birth weight(NBW)pigs at different growth stages that were 7,21,and 28-day-old,and the average body weight(BW)of 25,50,and 100 kg of the NBW pigs.Results:The results showed that the plasma total bile acid concentration was higher(P＜0.05)at the 25 kg BW stage and tended to increase(P=0.08)at 28-day-old in IUGR pigs.The hepatic gene expressions related to bile acid synthe-sis(CYP7A1,CYP27A1,and NTCP)were up-regulated(P＜0.05),and the genes related to glucose and lipid metabolism(ATGL,HSL,and PC)were down-regulated(P＜0.05)at the 25 kg BW stage in IUGR pigs when compared with the NBW group.Targeted metabolomics analysis showed that 29 bile acids and related compounds were detected in the colon of pigs.The colonic concentrations of dehydrolithocholic acid and apocholic acid were increased(P＜0.05),while isodeoxycholic acid and 6,7-diketolithocholic acid were decreased(P＜0.05)in IUGR pigs,when compared with the NBW pigs at the 25 kg BW stage.Moreover,Spearman's correlation analysis revealed that colonic Unclassified_[Mogi-bacteriaceae],Lachnospira,and Slackia abundances were negatively correlated(P＜0.05)with dehydrolithocholic acid,as well as the Unclassified_Clostridiaceae abundance with 6,7-diketolithocholic acid at the 25 kg BW stage.Conclusions:These findings suggest that IUGR could affect bile acid and glucolipid metabolism in growing pigs,especially at the 25 kg BW stage,these effects being paralleled by a modification of bile acid derivatives concentra-tions in the colonic content.The plausible links between these modified parameters are discussed.