Psychiatric disorder including depression is one of five major diseases in Japan. Hence, development of epoch-making therapeutic approach is earnestly desired. Recently, dysregulation of gut-brain axis is a major cause for depression, but its underlying mechanisms remain unclear. Thus, using animal models for depression, we are investigating mechanisms for induction of brain and gut inflammation, functional alteration of gut microbiota and bioactive lipids, etc. Moreover, research projects on taste disorder induced by anti-cancer drugs and diabetes, and peptide drug development against intractable diseases, rare disorders and aging are now in progress. Our projects should provide novel nutritional and neuroscientific evidences for preventive and therapeutic approach for development of diseases and drug-related adverse events.