UPLC-HRMS based metabolomics reveals the sphingolipids with long fatty chains and olefinic bonds up-regulated in metabolic pathway for hypoxia preconditioning

Hypoxia preconditioning (HPC) could protect cells, tissues, organs and systems from hypoxia injury, but the molecular mechanism still remained unclear. The ultra-high performance liquid chromatography coupled high resolution mass spectrometry (UPLC-HRMS) based metabolomics method was utilized to explore the key endogenous metabolites and metabolic pathways related to HPC. Our results clearly showed that the HPC mice model was established and refined, suggesting that there were significant differences between the control group and 6 × HPC group at the molecular levels. A serious of statistical analyses, including univariate analysis and multivariate analysis, were performed by the Progenesis QI software package and MetaboAnalyst web-server. The sphingolipid metabolic pathways were noticed due to the low p-value and high pathway impact calculated by the MetaboAnalyst and the pathways were altered under HPC condition. Especially, the sphingolipid compound sphingomyelin, ceramide, glucosylceramide, galactosylceramide and lactosylceramide were mapping in this metabolic pathway. Interestingly, these sphingolipid metabolites with olefinic bond in the long fatty chain were up-regulated, while those sphingolipids without olefinic bond were down-regulated. The results indicated that C24:1-Cers played a critical role in HPC and had potential in endogenous protective mechanism. Our data provided an insight to further reveal the protection mechanism of HPC.