Objective To investigate the molecular mechanism of lipid metabolism disorder in mouse spleen tissues due to high-altitude hypoxia.Methods Ten C57BL/6 male mice were randomly divided into normoxia group(maintained at an altitude of 400 m)and high-altitude hypoxia group(maintained at 4200 m)for 30 days(n=5).Lipidomics and metabolomics analyses of the spleen tissue of the mice were conducted using liquid chromatography-mass spectrometry(LC-MS)to identify the differential metabolites,which were further analyzed by KEGG enrichment and pathway analyses,and the differential genes were screened through transcriptome sequencing.Bioinformatics analysis was conducted to identify the upstream target genes of the differential metabolites in specific metabolic pathways.RT-qPCR and Western blotting were used to detect mRNA expressions of 11β-hydroxysteroid dehydrogenase 1(HSD11B1),steroid 5α reductase 1(SRD5A1),prostaglandin-endoperoxide synthase 1(PTGS1),hematopoietic prostaglandin D synthetase(HPGDS),xanthine dehydrogenase(XDH),purine nucleoside phosphorylase(PNP),hypoxanthine guanine-phosphoribosyltransferase(HPRT)and extracellular 5'-nucleotidase(NT5E)and protein expressions of HSD11B1,SRD5A1,XDH,PNP and HPRT in the mouse spleens.Results We identified a total of 41 differential lipid metabolites in the mouse spleens,and these metabolites and the differential genes were enriched in steroid hormone biosynthesis,arachidonic acid metabolism,and purine metabolism pathways.Compared to the mice kept in normoxic conditions,the mice exposed to high-altitude hypoxia showed significantly upregulated expressions of adrenosterone,androsterone,prostaglandin D2,prostaglandin J2,xanthine,xanthosine,and uric acid in the spleen with also changes in the expression levels of HSD11B1,SRD5A1,PTGS1,HPGDS,XDH,PNP,HPRT,and NT5E.Conclusion High-altitude hypoxia can result in lipid metabolism disorder in mouse spleen tissue by affecting steroid hormone biosynthesis,arachidonic acid metabolism,and purine metabolism pathways.