Bile acids reach the brain as soon as we finish eating to stop food intake: they travel from the digestive tract, temporarily lodge in the bloodstream, and suddenly reach the hypothalamus after eating. This discovery, observed in mice by researchers from the Federal Polytechnic School of Lausanne (EPFL), provides new details on the signals and mechanisms of control of satiety and may have implications for the treatment of obesity in humans.
The gut-brain axis It is one of the most important systems for regulating eating behavior and other bodily functions. It also presents circuits or subsystems that fulfill a transcendental role.
One of them is the one that is established in the hypothalamus, where the activity of multiple hormones, proteins and other signals “informs” the brain about our availability of energy.
According to a Press release, bile acids should also be added to the list of signals aimed at regulating the feeling of hunger and stopping food intake in time.
It was known that insulin or leptin communicated to the brain everything related to our energy needs through the hypothalamus, but it was unknown that bile acids could act in that circuit.
In previous studies, it had been found that bile acids could be observed in the brain, but it was not clear what their functions were.
Now, the new study published in the journal Nature Metabolism has identified the purpose of its journey to the brain from the gut: regulate the urge to continue eating beyond what is advisable for our body.
From the gut to the brain
In the intestine, bile acids are one of the most abundant metabolites, functioning as signaling molecules to transmit data such as the availability of a specific class of nutrients, for example, to the brain.
In the brain, the hypothalamus welcomes them with open arms: this region of the brain base lacks the barriers against external agents and threats that all other regions of the brain possess.
The researchers were able to verify in rodents that these metabolites transmit signals from the gut to the brain to regulate food intake at the right time. It was even possible to verify that bile acids play an anorexic or severely decreased appetite function in obese mice.
Can they have the same impact on human beings? According to Alessia Perino, lead researcher in the new study, “bile acids block the release of peptides dedicated to stimulating appetite after food intake, but also enhance this action by reducing the expression of related neurotransmitters. All this constitutes an acute system of hunger suppression that favors the feeling of satiety ”, he indicated.
Already in Ancient Greece there was talk of the role of bile in regulating mood and mood, but scientific advances allow us to determine today that bile acids and their connection with the hypothalamus play a vital role in terms of satiety. and appetite control.
In this way, they can become perfect allies for the development of new anti-obesity therapies, directly involved in a large part of the chronic diseases that affect humanity to a greater extent.
According to the World Health Organization (WHO), obesity has reached epidemic proportions globally, affecting almost all ages equally. Every year, 2.8 million people die from it, as it is linked to different health disorders.
Central anorexigenic actions of bile acids are mediated by TGR5. Perino, A., Velázquez-Villegas, L.A., Bresciani, N. et al. Nature Metabolism (2021).DOI:https://doi.org/10.1038/s42255-021-00398-4
The action of bile acids in the hypothalamus. Credit: EPFL / Schoonjans’ lab.
Eddie is an Australian news reporter with over 9 years in the industry and has published on Forbes and tech crunch.