TPH2 and gastritis: Zuojin Pill alleviates colitis by regulating the gut microbiota and reduces stomach inflammation via mitogen-activated protein kinase (MAPK) signaling 10,11, helps to mitigate GI dysfunction caused by stress via the TPH2/5-HT pathway 6, and alleviates chronic atrophic gastritis from various causes by normalizing gastric epithelial cell function through TGF-beta1/PI3K/Akt pathway activation 12-14.