The link between intestines and brain is no longer to be proven. Scientists still discover the magnitude of the connections between these two systems, dependent on each other, which could explain certain diseases such as diabetes or obesity. Their results are published in the journal Science.
The NOD2 receiver was studied in particular
In this work, the researchers were interested in the NOD2 receptor, present among others, in immune cells. Ivo G. Boneca, responsible for the biology and genetic unit of the bacterial wall at the Institut Pasteur, admits to having left an observation: “We had noticed that mice not expressing the NOD2 receiver presented an overweight, especially the elderly females “.
Scientists then ask themselves the question of a link and work on these receivers. “”We therefore tried to find out where this receiver was expressed and we were surprised to find it in the brain, within the hypothalamus, this cerebral gland which governs elements such as body temperature or satiety “ adds the scientist.
A receiver that detects intestinal bacteria
Thanks to brain imaging techniques, the team of researchers therefore noted that compounds of bacterial walls, which can be considered as elements derived from the intestinal microbiota – and called Muropeptides by study authors – were detected by the NOD2 receiver.
“”The walls present in the intestine, blood and brain are considered the markers of bacterial proliferation “ Addeivo G. Boneca. In the event that the NOD2 receptor is faulty, as in elderly female mice, these neurons are no longer repressed by the Muropeptides; The brain then loses control of food intake and body temperature.
Normally, food consumption induces an expansion of the intestinal microbiota. This expansion is followed by an increase in the release of Muropeptides by intestinal bacteria. When these walls reach the brain, they target a subset of inhibitory hypothalamic neurons. In older women, the activation of nod2 neural receptors by these walls decreases neuronal activity, which in turn helps to regulate satiety and body temperature.
A link not yet established in humans
This discovery, although it is valid on the mouse only for the moment, remains promising for scientists. “”Indeed, we already know that the NOD2 receiver is associated with other pathologies of the two systems, both digestive, as in Crohn’s disease, but also in the brain system, with a function in bipolar disease “ still specifies Ivo G. Boneca.
Avoid diabetes and obesity in elderly women
The objective for the authors is now to transpose their conclusions into humans. “”We must continue our research to study the effects of this intestinal mocrobiota receiver in humans. The next step is to select a cohort to study the same phenotype as in mice, namely the elderly and overweight. The objective would be to lead to the understanding of this deregulation mechanism which intervenes with age in order to fight against, upstream of its trigger or why not by acting on the microbiota “ concludes the manager of the biology and genetic unit of the bacterial wall at the Institut Pasteur. This could avoid the installation of pathologies such as diabetes or obesity in these women.