Effects Of Maternal Decabromodiphenyl Ethane Exposure On Gut Microbiome And Metabolome In Sprague-Dawley Rat

BackgroundDecabromodiphenyl ethane(DBDPE)is a new brominated flame retardant used widely,the health threats related to its multiple organ toxicity with the help of intergenerational transmission are increasing.Environmental pollutants have risk of triggering imbalance in the homeostasis of gut microbial community,the structural and functional transformation of gut microbiota is a sensitive signal reflecting the health status of the organism.However,there are limited studies about the effects of DBDPE on gut microbiome and fecal metabolome in maternal generation and its offspring.ObjectiveThis study was mainly aimed at the gut microbiome and fecal metabolome of female rats and their offspring exposed to DBDPE in early life.The purpose of this research was to explore the abundance and diversity of gut microbiota in female rats and its offspring by 16S rRNA gene sequencing,and to clarify the perturbation of metabolic function in adult offspring gut microbial community based on the combination of untargeted metabolomics and targeted metabolomics techniques.Methods1.The female rats were cohoused with male rats to establish pregnant rat model.Pregnant rats were divided into three groups randomly,there are control group,lowdose exposure group(75 mg/kg/d DBDPE)and high-dose exposure group(600 mg/kg/d DBDPE)respectively.The pregnant rats were administrated with DBDPE dissolved in corn oil by oral gavage during pregnancy(group a and group b)or lactation period(group c),then feed their offspring until 4-week-old and 8-week-old.The animals were monitored for body weight,liver/body weight and behaviors.Fecal samples were collected from female rats at the end of pregnancy and lactation,and from the offspring at the 4-week-old and 8-week-old.The gut microbiota in the feces was analyzed through 16S rRNA gene sequencing based on the Illumina Miseq PE300 platform.2.The concentration of SCFAs in fecal samples was quantified by Gas Chromatograph-Mass Spectrometer(GC-MS).3.The untargeted metabolic profiles of gut microorganisms in adult offspring among each group were analyzed using Ultra-performance Liquid Chromatography with Quadrupole Time-of-Flight Mass Spectrometry(UPLC-Q-TOF/MS).A Liquid Chromatography-Triple Quadrupole Mass Spectrometer(LC-TQ-MS)was used for precise quantification of known biomarkers.Results1.16S rRNA gene sequencing demonstrated that maternal DBDPE exposure could increase the α-diversity of gut microbiota in immatured offspring.The βdiversity analysis showed a separation in pregnant rats and their adult offspring between control and exposure group through nonmetric multidimensional scaling(NMDS)and Principal Component Analysis(PCA)analysis.At the genus level,the abundance of Clostridium and Romboutsia were elevated in immatured offspring,while the abundance of Jeotgalicoccus,Staphylococcus,Clostridium and Lactobacillus were reduced in adult offspring.2.The SCFAs produced by gut microbiota dramatically increased in pregnant rats,and the content of acetic acid,propionic acid,butyric acid and valeric acid in the adult offspring in each group showed statistically significant differences.3.Untargeted metabolomics identified 41 differential metabolites and 7 metabolic pathways between adult offspring from various groups.Targeted metabolomic showed that maternal high dose DBDPE exposure obviously decreased the level of glutathione,taurine,and L-carnitine in their adult offspring.An interesting link between some gut bacteria(especially from the Firmicutes)and fecal metabolites(such as allylamine and L-methionine)demonstrated the shifts in gut microbiota may drive the metabolic process of fecal metabolites.ConclusionGut microbiota is a warning sign of metabolic dysfunction in the body after DBDPE exposure.In this study,DBDPE disturbed the normal structure and metabolic function of the gut microbial community in pregnant rats and their offspring,and inhibited the weight gain in adult offspring through interfering with energy metabolism.The gut microbiota and its metabolites are critical target for the response of the offspring organism after maternal DBDPE exposure.