In 2010, 4.4% of the world’s population suffered from major depressive disorder (MDD). As a significant contributor to global disease burden, MDD accounts for 8.2% of global years lost due to disability and 2.5% of global disability-adjusted life years. Despite years of research, the mechanisms of MDD are still poorly defined and conventional treatments fail in roughly one-third of depression patients.
The gut-brain axis is the bidirectional communication between the gut and brain in which the microbial community residing in the gut, formally known as the intestinal microbiota, may play a regulatory role. Changes in the composition of this community have been associated with psychiatric disorders, such as MDD. Although some research has been done using humanized animal models to investigate the role of the intestinal microbiota in MDD, none have used fecal microbiota transplant to colonize germ-free (GF) mice with microbiota from a single, well characterized MDD patient. Here, GF mice were colonized with fecal microbiota from either a well characterized MDD patient or healthy control. Two weeks post-colonization, behavioural testing was completed to assess for depressive-like behaviour in the mice. Additionally, mouse brain tissue was analyzed for changes in brain-derived neurotrophic factor expression.
Research investigating the role of the intestinal microbiota in MDD contributes to the ongoing advancement of knowledge pertaining to the intestinal microbiota, MDD, and the gut-brain axis. A greater understanding may lead to the development of improved treatments, alleviating the suffering of many.