Targeted lipidomics and amino acid profiling of acute arsenic exposure in mice using liquid chromatography-mass spectrometry Hui Ling Leea; Cheng Yen Tsaia; Wei Ting Junga; Pinpin Linb aDepartment of Chemistry, Fu Jen Catholic University, Xinzhuang Dist, New Taipei City 24205 Taiwan. bNational Institute of Environmental Health Sciences, National Health Research Institutes, Zhunan, Miaoli County 350, Taiwan MP579 More information on this study Overview In this study, mice were gavaged with three different doses of sodium arsenite. The concentrations of endogenous eicosanoids in mouse serum increased following arsenic treatment, which could be related to the degradation of membrane phospholipids. Consequently, more free arachidonic acid was released and further metabolized through the COX, LOX, and CYP450 enzymatic pathways. The levels of PGF 2α and PGE 2 in the serum of mice treated with 5, 10, and 20 mg/kg arsenic differed dose- dependently and were substantially higher than those of vehicle controls. This suggests that PGF 2α and PGE 2 play a role as biomarkers, indicating increased availability of arachidonic acid and induction of COX-2. Arsenic treatment changed the eicosanoid profiles in mouse serum, which suggests that arsenic caused the breakdown of membrane lipids and engendered a higher risk for incidence of cancers in the arsenic exposure. In our study, serum levels of valine (Val), leucine (Leu), proline (Pro), phenylalanine (Phe), tryptophan (Trp), tyrosine (Tyr), asparagine (Asn), glutamic acid (Glu), and arginine (Arg) were increased after exposure to arsenic. This observation suggests that changes in serum concentrations of eicosanoids and amino acids facilitate evaluating the potential risk of arsenic exposure. Introduction Lipidomics is the area of study dedicated to the comprehensive analysis and characterization of the functions and metabolism of lipids in biological samples. One of the most comprehensively studied classes of lipids is polyunsaturated fatty acids (PUFAs). Eicosanoids are a series of bioactive lipid mediators that are metabolized from PUFAs and generated majorly from the precursor arachidonic acid. This study identified the profiles of target eicosanoids after acute exposure to arsenic. The principle objective was to determine and validate 10 eicosanoids in mouse serum using on-line solid-phase extraction integrated with liquid chromatography–electrospray tandem mass spectrometry. To our knowledge, this is the first study to quantify eicosanoids in mouse serum. This approach provides simple sample preparation, small sample volumes, and a precise and accurate method for determining changes in the profile of these eicosanoids in mouse serum after acute exposure to arsenic. Method Results and discussion Fig. 3 On-line SPE LC-MS/MS MRM chromatogram analysis of 10 ng/mL standards. Fig. 4 Effect of NaAsO2 on (A) target lipidomics profile, (B) amino acids in mouse serum and (C) 8-OHdG level in mouse urine. ICR mice were gavaged with the 5, 10, and 20 mg/kg NaAsO2 for 48 h (n = 4). This study proposes a new on-line SPE LC-MS/MS approach for quantifying the profile of target eicosanoids in mouse serum after acute exposure to arsenic. This is the first study to demonstrate that the eicosanoids were determined in the mouse serum. Our sample preparation protocol achieves a low sample consumption of 10 μL of mouse serum. This valid and effective analytical method demonstrated an accuracy of 82.4% to 124.4% and precision of 0.4% to 17.4% for the 10 eicosanoids tested in mouse serum. In conclusion, screening the profile of target eicosanoids facilitates identification of inflammatory and carcinogenic signaling in clinical and epidemiological research. Conclusions Acknowledgements This study was supported by the Ministry of Science and Technology, Taiwan (MOST106-2113-M-030-003)