The ultimate goal of our research is to propose new strategies for prevention and treatment of various gastrointestinal diseases. The lower gastrointestinal diseases such as ulcerative colitis and Crohn’s disease have received a lot of attention in addition to the upper GI diseases such as gastric ulcers and gastritis. In addition, it is well known that various drugs including non-steroidal anti-inflammatory drugs and anti-cancer agents, used clinically for patients frequently cause gastrointestinal injury as side effects. Now, we focus on investigating the pathogenic mechanisms of these inflammatory bowel diseases and drug-induced gastrointestinal toxicities, mainly using experimental animal models by pharmacological approaches. We are further investigating the pathogenesis of functional bowel disorders, fibrosis, tumor, and taste abnormality.