The microbiota modulates the positive impact of the exercise

A job of Cajal Neuroscience Center (CNC)of the Higher Council for Scientific Research (CSIC)It shows that the microbiota is able to modulate the positive impact that moderate physical exercise has on memory.

First, the researchers observed in animal models that physical practice, about 40 minutes at medium speed, improves the diversity of bacteria that inhabit the intestine. In addition, they verified that these changes in the intestinal microbiota largely modulate the effects of physical exercise on the brain, such as the improvement of memory or neurogenesis.

The results published in ‘Ebiomedicine‘, Group Magazine’The Lancet‘, open a new way to develop future therapies, based on microbiota, that allow combating neurodegenerative diseases and cognitive disorders.

Researchers remember that the effects of sport on the brain have long known, such as their ability to deal with aging or to improve the evolution of diseases such as Alzheimer’s.

However, they warn that achieving these positive effects depends on the hormeis, that is, the curve that sets its evolution until it reaches a roof, known as inflection point, from which the increase in the intensity or duration of the exercise makes not only its effects disappear, but also begin to be counterproductive. The hormhetic curve varies depending on each individual, so the concrete intensity that determines the turning point is still studied.

Now, the work coordinated by José Luis Trejo, Researcher at the Cajal Neurosciences Center (CNC-CSIC), has demonstrated in an animal model that moderate exercise, with a duration of about 40 minutes and with an average speed, improves cognitive performance, spatial discrimination and the development of new neurons in the hippocampus, a key region in memory and learning.

Therefore, all these cognitive benefits depend on physical exercise, but above all, that this It is practiced moderately, Since an excessive increase in intensity or duration causes it to lose its effectiveness, as shown by the neutral results observed in mice. “There is an optimal point of exercise from which benefits are achieved, and moving from that dose may not only not help, but to prevent those improvements,” says Elisa Cintado, a researcher at the CNC-CSIC and first author of the study.

In addition to determining the ideal physical practice to achieve the effects on cognitive function and neurogenesis, that is, the generation of new neurons in the adult brain, the main conclusion of the study reveals that these benefits are mediated by changes in the composition of the intestinal microbiota. To do this, the researchers designed different exercise protocols, which included moderate training, one prolonged in the time and another of high intensity, and analyzed their Effects on memory, brain and microbiota of mice.

“Our experimental model allowed us to verify that, although we had known for a long time to exercise regularly improve the health of the brain, we did not know the specific role of the intestinal microbiota in this process,” explains Trejo.

The importance of microbiota

The intestinal microbiota, the set of microorganisms that inhabits the intestines, varies depending on lifestyle. Specifically, it highlights the role of moderate physical exercise in increasing bacterial diversity (indicator of a healthy microbiota) and specific bacterial genres, as the researchers observed.

The presence of some of these genres, such as’Acetatifactor‘Or certain species of the family of bacteria’Lachnopiracee‘, contributed positively to a better cognitive performance of animals.

To determine if these microbial changes were a mere correlation or had a causal role in the effects of the exercise, the scientists took another step: they performed fecal microbiota transplants. They took fecal samples of mice that had done moderate or long -lasting and transferred them to sedentary mice.

The result was that the sedentary animals that received the microbiota of runners (moderate) mice improved their memory and increased neurogenesis, just like the animals exercised. However, those who received the microbiota of long -term runners mice did not show this improvement. “This demonstrates in a causal way that the cognitive effects of the exercise can be mediated, in large part, by the intestinal microbiota,” says Catado.

The complex symbiosis between intestine and brain

The team also investigated the brain mechanisms involved in the cognitive improvement of exercised animals or those who received the microbiota of those who had performed moderate exercise. The results show that the beneficial effects on the brain were due to a Increase in neuronal stem cells (Neuron progenitor) and in the immature neurons of the hippocampus.

“The statistical correlations between the levels of certain intestinal bacteria and the cell markers of neurogenesis were consistent, which reinforces the hypothesis that the intestinal microbiota acts as a modulating of brain plasticity,” explains Trejo.

In addition, the researchers verified that this effect was not limited to the brain, but that the animals exercised moderately showed a better preservation of the blood cell barrier (network of blood vessels that protects the brain from harmful substances) and the intestinal epithelium (cells that prevent the passage of toxins and pathogens to the intestine). On the contrary, animal models under more intense physical practices showed alterations in both biological barriers.

Although the experiments were carried out in animal models, the results They raise implications for human health. According to the authors, the study supports the idea that the impact of the exercise on the brain depends deeply on the type, duration and intensity of it, and that customizing the physical exercise according to the physiological and microbial characteristics of the individual could maximize its benefits. “We should rethink the idea that is not always better. A moderate, constant and adapted practice to each person can be more effective for both the body and the brain,” says the CNC-CSIC researcher.

This research also opens a new way to develop future microbiota therapies. The possibility of using microbiota as a mediator to modulate brain functions constitutes a promising field in neurobiology, with applications in neurodegenerative diseases and cognitive disorders.