Nature: Shocked! Certain gut bacteria can actually increase motivation and performance

In a new study, researchers from the University of Pennsylvania in the United States studied mice and found that certain types of gut bacteria activate nerves in the gut, which promotes the desire
to exercise.
They revealed this gut-to-brain pathway, which could help explain why some gut bacteria promote athletic performance
.
The results of the study were published online in Nature on December 14, 2022, in the paper "A microbiome-dependent gut–brain pathway regulates motivation for exercise.
"

In this study, the authors found that in a large group of lab mice, the difference in running performance was largely attributed to the presence of certain gut bacterial species
in the better-performing mice.
They traced this effect back to the small molecules called metabolites produced by these gut bacteria--- which stimulate sensory nerves in the gut, thereby enhancing the activity
of brain regions that control motivation during exercise.

Dr.
Christoph Thaiss, corresponding author and assistant professor of microbiology at the University of Pennsylvania's Perelman School of Medicine, said, "If we can confirm that similar pathways exist in humans, it may provide an effective way to increase people's exercise levels to improve public health
in general.
" ”

Thaiss and colleagues conducted the study to look broadly for factors
that determine athletic performance.
They recorded the genome sequences of genetically diverse mice, gut bacterial species, metabolites in the blood, and other data
.
They then measured how many of their daily autonomous runs on the wheel, as well as their endurance
.
They analyzed the data using machine learning to look for mouse attributes
that best explained the large inter-individual differences in running performance in these mice.
They were surprised to find that genetics seemed to account for only a small fraction of these performance differences, while differences in gut bacterial populations seemed to be more important
.
In fact, they observed that giving mice broad-spectrum antibiotics to clear their gut bacteria reduced their running performance by about
half.

Finally, in a years-long scientific scouting involving more than a dozen independent labs in Pennsylvania and elsewhere, the authors found that two bacterial species strongly associated with better running performance--- Eubacterium rectale and Coprococcus eutactus, produced metabolites
called fatty acid amides (FAA).
。 Fatty acid amides stimulate receptors called CB1 endocannabinoid receptors buried on the surface of sensory nerves buried in the gut, which are connected to the brain via the
spine.
During exercise, stimulating these sensory nerves that are full of CB1 receptors leads to increased
levels of the neurotransmitter dopamine in a brain region called ventral striatum.
The ventral striatum is a key node
in the brain's reward and motivation network.
They concluded that extra dopamine in this brain region during exercise boosted performance
by enhancing the desire to exercise.

Prediction
of locomotion performance in mice of diverse distant lines.
Image from Nature, 2022, doi:10.
1038/s41586-022-05525-z
.

Co-author J.
Smith, associate professor of biology in the College of Arts and Sciences at the University of Pennsylvania Dr.
Nicholas Betley said, "This gut-to-brain motivational pathway may have evolved to link nutrient availability and the state of the gut bacterial population to readiness to engage in prolonged physical activity
.
" This research direction can be developed into a completely new branch of
exercise physiology.
”

These discoveries have opened up many new avenues
of scientific investigation.
For example, there is evidence that better-performing mice experienced a stronger sense of "running pleasure," in this case, as measured by reduced pain sensitivity--- suggesting that this well-known phenomenon is also at least partially controlled
by gut bacteria.
The authors now plan further research to confirm the presence
of this gut-to-brain pathway in humans.

In addition to potentially providing inexpensive, safe, diet-based ways for the average person to run and optimize the performance of elite athletes, he added, exploration of this pathway could also yield easier ways to alter motivation and mood
in situations such as addiction and depression.
(Biovalley Bioon.
com)

Resources:

Lenka Dohnalová et al.
 A microbiome-dependent gut–brain pathway regulates motivation for exercise, Nature, 2022, doi:10.
1038/s41586-022-05525-z.