Researchers have identified the role of two populations of neurons in the feeling of hunger. Their activity can influence food intake and weight gain.
The human brain still harbors many mysteries. As proof: an American team has just discovered two new populations of neurons involved in the feeling of hunger. Their study, published in Cell, points out that the activation of these cells reduces food intake in mice. Which could constitute a new therapeutic target against obesity.
The neurons in question are located in part of the brainstem, the raphe nuclei. This region has already been associated with food, without specific cells having been identified. It is now done.
Two distinct roles
The work, carried out by researchers at Rockefeller University (United States), made it possible to isolate two specific groups of neurons. To do this, they examined the brain activity of mice in normal times and when they were overfed. And neuronal activity varies depending on these two situations.
In fact, the populations identified fulfill very different roles. In one case, the feeling of fullness causes a spike in the activity of neurons responsible for releasing glutamate. This chemical allows nerve cells to communicate with each other.
In obese mice, the production of glutamate – artificially stimulated – results in a cessation of food intake, and weight loss. Conversely, hunger activates another group of neurons. These release γ-aminobutyric acid (GABA), which has the effect of increasing food consumption.
A complex pathology
The main author of this study, Alexander Nectow, summarizes his observations in a simple manner. Two explanations are possible. In one case, cells are only a reflection of an activity – not its cause. In the other case, “they take part in the feeling of hunger and the reaction that follows,” he explains. We are leaning towards the latter possibility. “
The tests carried out on mice have also proved convincing. Activation of glutamate-producing neurons made it possible to lose weight in excessively fed animals. “We are excited by the fact that prolonged inhibition of these neurons can significantly reduce weight,” says Marc Schneeberger Pane, also author of the work.
It remains to be seen whether these results can be reproduced in humans. Because obesity is a disease dependent on several factors. Acting on just one of them may prove to be insufficient.
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