Effects of manual acupuncture on fatty acid metabolism in a rat model of diarrhea-predominant irritable bowel syndrome: a multi-tissue metabolomic and plasma lipidomic investigation

Diarrhea-predominant irritable bowel syndrome (IBS-D) is a subtype of IBS. Many patients are dissatisfied with the efficacy of drug treatment and seek complementary and alternative medical therapies, especially acupuncture treatment. In this study, we evaluated the effect of manual acupuncture (MA) on IBS-D using a rat model and investigated the underlying mechanism of action by analyzing the changes in untargeted metabolomics of plasma/liver/colon and targeted plasma lipidomics. Thirty male Sprague-Dawley rats were divided into Control, IBS-D and MA groups (n = 10 each). IBS-D/MA groups received acetic acid enemas combined with restraint stress. The Control group received saline enemas. The MA group received daily MA at ST36 for 2 weeks after modeling. Pain and stool quality were measured by the abdominal withdrawal reflex (AWR) and Bristol stool form scale (BSFS). Plasma/liver/colon samples were collected for ultra-high performance liquid chromatography (UHPLC)/Q-Orbitrap mass spectromy (MS) untargeted metabolomics. Plasma was also subjected to UHPLC-MS/MS targeted lipidomics. MA treatment improved BSFS and AWR scores in IBS-D model rats, suggesting reduced intestinal hypersensitivity. Metabolomic results showed that MA impacted 18 metabolites in the plasma, liver and colon, which were mainly involved in arachidonic acid metabolism, biosynthesis of unsaturated fatty acids, and amino sugar and nucleotide sugar metabolism. Targeted lipidomic results showed MA restored the low levels of four medium-chain and one long-chain fatty acids to normal levels in IBS-D, suggesting that acupuncture treatment of IBS-D involves fatty acid metabolic pathways. MA reduced markers of intestinal hypersensitivity and impacted a number of metabolic pathways in a rat model of IBS-D.