Building a treatment strategy for depression using antioxidant particles that improves the intestinal environment

Depressive disorder, or depression, is the most common mental disorder and a leading cause of disability worldwide. Yet, there remains much to be discovered about depression. There are existing treatment options but, in treatment-resistant depression, symptoms persist. There is a strong relationship between the gut and the brain and it is possible the gut holds answers for treatment-resistant depression. Dr Yutaka Ikeda, Department of Materials Science at the Faculty of Pure and Applied Sciences at the University of Tsukuba, is interested in the effect of the intestinal environment on various diseases. He is working closely with Professor Yukio Nagasaki from the Faculty of Pure and Applied Sciences, University of Tsukuba, and Professor Ryo Inoe at Setsunan University, to investigate drug delivery systems and drug development, with a particular focus on polymer-based drugs. In one project, the researchers explored the involvement of intestinal reactive oxygen species (ROS) in the progress of depression via the gut-brain axis. This is an interesting aspect to investigate as in chronic stress ROS is overproduced and excessive levels disturb the intestinal environment. The researchers designed a novel polymer-based antioxidant called siSMAPoTN with a poly(ethylene glycol) (PEG) shell. The team found that continuous administration of siSMAPoTN reduced oxidative stress in the colon and protected the mucosal layer and intestinal barrier function. This means that by removing excess ROS, it is possible to alleviate the damage caused by chronic restraint stress (CRS) in the intestine.