Let’s start by comparing the nervous system that has the entire digestive system, about a hundred million neurons, with the brain . A hundred million neurons may seem like a lot, but in the brain we have about 86,000 million neurons. So for every neuron in the intestine , we have 860 in the head. The figures are on another scale, it is as if we were comparing a salary in which they pay you one euro a month with one in which they pay you 860 euros. But it is also that neurons in the intestine form very simple structures with simple functions that cannot be compared at all with the macrostructures that exist in the brain . So neither quantitatively nor qualitatively these structures are comparable.
The second gaffe is about intestinal serotonin. On this subject, it must be understood that many of the substances that we produce in the body, depending on where they are produced, have different functions and serotonin, which in the brain is a neuroactive molecule involved in our moods , is no exception.
In the intestine there are epithelial cells, not neuronal, that produce serotonin to control the peristaltic movements of the intestine, the movements that move all food throughout the entire intestine. As the intestine is very large, if we count all the seronine that we have in the body, it turns out that around 90% is in the intestine. But, and this is a big but, it has not been shown that the serotonin that we have in the intestine reaches the brain and can influence its functioning.
Apart from all this, it is true that there are studies that indicate that the bacterial flora could influence certain processes controlled by the brain such as appetite or some mood. But these studies are still very preliminary, so you have to be very cautious with the results.
In addition, the fact that changes in a tissue, such as changes in the bacterial flora, influence the brain is not something special about the intestine, but rather the consequence that all the parts of the body form a whole that communicates, that is it influences each other, and this influences the brain .
About Neurocosas:
Directed and presented by Pablo Barrecheguren, Neurocosas is a scientific dissemination project carried out by Big Van, Scientists on Wheels and Muy Interesante funded with the help of the Spanish Foundation for Science and Technology.
