Toxicokinetic And Metabolomic Investigation Of Perchlorate Exposure On Rats

Perchlorate was a water-soluble persistent inorganic pollutant with potentially adverse effect on thyroid and nervous system.In this research,the level of perchlorate in commercial foods was monitored and exposure assessment was conducted.Next,the distribution,metabolism and excretion of perchlorate were investigated to explicate the toxicokinetics of perchlorate.Comprehensive metabolomics and lipidomics analysis on sreum from rats were carried out based on LC-HR-MS method and multivariate statistical analysis.In this study,an LC-MS method was established to determine the levels of perchlorate in 5 categories of food samples,including vegetables,fruits,eggs,meats,and drinking water,which collected from 3 main urban areas in Wuhan,China.Almost all the samples(94.54%)were detected with perchlorate with a range of LOQ to 331.41?g/kg wet weight,with a total average of 15.04?g/kg.Although the average perchlorate levels in 5 categories of food samples varied a lot(from 3.65?g/kg in meats to 27.39?g/kg in vegetables),the concentrations of perchlorate were not statistically significant among those 5 food categories.Estimated daily intake(EDI)of perchlorate was evaluated according to the food consumption and measured perchlorate levels in this study.The mean and the 95^th percentile values for EDI were0.34?g/kg bw/day and 1.27?g/kg bw/day for adult men while 0.38?g/kg bw/day and 1.44 ?g/kg bw/day for women.The levels and EDIs of perchlorate in this study were lower than NAS and the U.S.EPA,but higher than EFSA approach,which indicated the estimated dietary exposure to perchlorate was likely to cause health concerns.In order to investigate the relationship between the toxicokinetics of perchlorate and toxicology effect in rats.The toxicokinetics after oral gavage and intravenous injection of 0.5 mg/kg,5 mg/kg,and 50 mg/kg perchlorate were evaluated.The concentration-time curve of perchlorate in rat serum showed double peaks after oral gavage,which was in accordance with the non-compartment model.While double peaks were not appearing after intravenous injection,which was corresponded to the typical one-compartment model.Toxicokinetic results showed that the elimination half-lives of rats after intravenous injection of three doses of perchlorate were 5.58 h,5.78 h,and 5.70 h,respectively,which were 7.05±0.19 h,7.17±0.16 h,and7.18±0.41 h in the garbage.The bioavailability of perchlorate at different doses by oral gavage were 91.72%,93.53%,and 97.56%,respectively.To evaluate the tissue distribution and excretion characteristics of perchlorate in rats,a dosage of 0.5 mg/kg,5 mg/kg and 50 mg/kg was performed by oral administration.The apparent volume of distribution after oral gavage was 1.6 m L/kg,which indicated that perchlorate diffused evenly into the tissue.The total excretion of perchlorate in urine was 81.72%,72.53%,and 85.80%after 24h by oral gavage,which indicated that perchlorate was mainly excreted in urine.To comprehensively assess metabolite change in perchlorate exposure to the rats,an ultra high performance liquid chromatography coupled with Q-Exactive quadrupole orbitrap mass spectrometry(UHPLC-QE-MS)was used to analyze metabolites and identify potential biomarkers in serum.Serum samples were collected from continuously 14 days exposure group rats and control group rats.Multivariate analysis was conducted to analyze the metabolite profiles and to identify potential biomarkers of perchlorate exposure.According to the variable of importance in the project(VIP)and S-plots,10 metabolites were identified as the potential biomarkers,namely L-phenylalaline,phosphatidylcholines(PC),pentose phosphate,and tryptophan,which were significantly altered in the control and perchlorate exposure group.Overall,the results indicated that obvious metabolic disturbances were occurred by perchlorate,which provided novel insights into the molecular mechanism of the toxicology of perchlorate.Lipidome of serum in perchlorate exposure and control group rats was analyzed by UPLC-QE-MS.The untargeted analysis made a clear separation of the lipidome of serum in perchlorate exposed and control group rats,which illustrated that PC,phosphatidylethanolamine(PE),Lyso-PC(LPC),ceramides(Cer),sphingomyelin(SM),and phosphatidylserines(PS)possessed significant features among those lipid metabolites.The lipid profiles indicated that the glycerophospholipid and sphingolipid metabolism were significantly disordered in perchlorate exposure group rats.The lipidomic profiles of perchlorate exposure could be integrated with further omics approaches used in toxicology research,in order to advance the understanding of the molecular metabolic dynamics involved in the relative metabolism disorders induced by perchlorate.