We have known for a long time that there is a strong connection between the intestine and the brain, so that over the last twenty years several studies have discovered, for example, links between autoimmune disorders and different psychiatric conditions. The strong suspicion is that the intestinal microbiome, ie the set of all bacteria that live in the various parts of our intestine, strongly influences the health of the brain but this relationship is fundamentally unknown.
A new study, conducted by scientists at Weill Cornell Medical College provides new insights into the molecular cellular processes that underlie communication between the same microbes in the gut and brain cells. As David Artis, director of the Jill Roberts Institute for Research in Inflammatory Bowel Disease and professor of immunology, explains, this research represents a sort of initial path to understanding “the whole picture” about the chronic gastrointestinal conditions that affect mental health and even the behavior.
The researchers used experiments carried out on mice to understand the changes that occur in brain cells when the intestinal microbiome begins to run out. The researchers, in fact, reduced the microbial populations in the intestines of the mice through antibiotics. These mice showed very low learning abilities, for example in learning that a danger or threat was no longer present. By analyzing the microglia of the brain of mice, the researchers discovered an altered gene expression in these cells that influenced the connection between brain cells during the learning processes.
Furthermore, in mice with a lower quantity of bacteria in the intestine, changes could be noted in the concentrations of different metabolites linked to various neuropsychiatric disorders that also occur in humans, such as schizophrenia or autism. “Brain chemistry essentially determines how we feel and respond to our environment, and the evidence is showing that chemicals derived from intestinal microbes play an important role,” says Frank Schroeder, a professor at the Boyce Thompson Institute and one of the authors of the study.
This study conforms to the existence of a strong connection between the intestine and the brain and how this same connection influences our life day by day and only now we are beginning to understand how the intestine itself, or rather the bacteria inside it, can influence even diseases like autism, Parkinson’s and depression. Perhaps in the future we will be able to identify new targets for the treatment of these diseases, as Conor Liston suggests, an associate professor of neuroscience in the Feil Family Brain & Mind Research Institute and another author of the study.