BDNF and irritable bowel syndrome: Acupuncture at ST25 downregulates the expressions of GFAP and P2 × 3 receptors in the DRG and spinal cord, BDNF and TrkB proteins and mRNA in the colon and DRG, and TRP phosphatidylinositol (Prit) in DRG and capsaicin receptor (TRPV1) in the colonic mucosa (Weng et al., 2015; Ji and Huang, 2020), thus improving colonic pain sensitivity in IBS model rats (Chen et al., 2021; Jin et al., 2021).