Protective mechanisms of Tuina therapy against lipopolysaccharide-induced fever in young rabbits based on untargeted metabolomics analysis.

OBJECTIVE: To investigate the effect of Tuina on the plasma metabolites of lipopolysaccharide-induced febrile in infant rabbits. METHODS: Twenty-four infant New Zealand rabbits were selected and randomly divided into three groups: saline, model, and Tuina. The fever model was established by injecting LPS intravenously through the ear margin vein in the model group and Tuina group, respectively. The modeling was considered successful when the anal temperature increased by 0.5℃ or above within 1 h. In the Tuina group, six Tuina techniques (i.e., opening Tianmen / the heaven gate, pushing Kangong / the superciliary arch, kneading Taiyang and the prominent bone behind the ears, clearing Tianheshui, spine pinching) that alleviate fever were performed on the young rabbits 1 h after the modeling, whereas the model and saline groups were not given Tuina treatment, with the real-time anal temperature monitored during the experiment. The plasma was taken 3 h after the modeling for liquid chromatography-mass spectrometry (LC-MS) untargeted metabolomics study. RESULTS: Our results showed a fever-reducing effects of Tuina therapy on lipopolysaccharide-induced fever in young rabbits, as indicated by a significantly lower anal temperature, maximum rise in body temperature, and body response index at 2 and 3 h after modeling in the Tuina group compared to the model group, with reductions in the PGE2 expression observed in the blood and hypothalamus. The differential metabolites including riboflavin, nicotinamide N-oxide, porphobilinogen, 5-hydroxyindoleacetic acid, gamma-aminobutyric acid, and lysoPC (16:1 (9Z)/0:0) were found following the Tuina intervention. Tuina primarily involves glycine-serine-threonine, arginine-proline, porphyrin-chlorophyll, pyrimidine, primary bile acid biosynthesis, and cyanoamino acid metabolic pathways. CONCLUSION: Tuina therapy has proven to be effective in reducing body temperature and down-regulating PGE2 expression in LPS-induced febrile young rabbits, with its mechanism of fever-reducing action possibly associated with the changes in plasma metabolites and metabolic pathways.