The gut is often referred to as the second brain. There are tons of nerves and neurons found in the gut that are connected to the brain through either vagal and sympathetic nerves and thus these two areas of our bodies are intricately intertwined. Neurotransmitters, cytokines, and other small molecules create systemic connections between the gut and brain, making both of them important influencers of each other.
For example, some microorganisms can trigger immune cells to release cytokines and then the brain can respond to this release through signalling of other cell types. Some microorganisms have also been shown to produce corticosteroid and neurotransmitters directly which can then influence brain states through these systemic connections. With such a diverse gut microbiome, there are tons of byproducts produced by the gut microorganisms which can alter and affect brain states. Additionally, since the gut and brain and so connected, it is also then possible for the changes in brain state and release to cause changes in the gut microbiota.
We have seen how significantly the gut microbiota has been able to control human health, immune responses and diseases. However, with this new information on the gut’s ability to influence brain, it is clear that the gut microbiota may also be able to influence mental health states as well. Several studies have shown that different bacterial species have been able to affect things like depression and autism spectrum disorder (ASD). Therefore, understanding the way in which specific bacteria interact with the brain and different neurotransmitters could be a crucial turning point in promoting mental health and aiding different diseases.
