Do you know that your sense of smell has something to do with your success in getting fit? A recent study in mice proposes that there is a connection between exercise and the expression of genes related to scent perception.
Typically, mice are used in scientific studies for several reasons, which include their small size, easiness to keep, they reproduce fast, and they are believed to be somewhat similar to humans, specifically in terms of genetic and behavioral characteristics.
To achieve the result, Sachiko Haga-Yamanaka and co-investigators at the University of California, Riverside, placed mouse models on a running wheel.
Voluntary wheel running, or VWR, the study authors wrote in their research, "is an intrinsically motivated and naturally rewarding behavior for mice, and even wild mice run" are running on a wheel placed in nature.
'Vomeronasal Organ' for Getting Fitter
Studying a part of the olfactory system known as the vomeronasal organ found in the nose of a rodent, as well as its equivalent neurons in the brain, the scientists found that there about 132 genes changed in high-runners. The high-runner rodents were the ones the researchers bred together earlier on.
Referring to their finding, Haga-Yamanaka said, the olfactory system became inherently "different between the high-runner and control lines" while the models were on their "selective breeding process."
She added, their findings suggest that the chemosensory receptors, which the altered genes expressed, are essential trait locations for the regulation of voluntary exercise in rodents.
Essentially, they observed that the high-runner mice had a distinctive sense of smell. Specifically, the study authors found that the vomeronasal organ senses chemicals produced by animals, known as "pheromones," that end up in the air.
Such a new insight, the researchers claimed, could one day develop the foundation of sensory stimuli for getting fitter.
Link of this Study in Mice to Humans
It remains unclear if such odors function by increasing the motivation of the mouse for exercise or if it enhances what the study authors described in their study as the neurobiological "reward" it gets when running.
Haga-Yamanaka explained, while humans do not seem to have a vomeronasal organ, "the vomeronasal in rodents can be a model specifically of human smell, to some extent."
Furthermore, she added, some vomeronasal receptors appear to be conveyed in the olfactory organ in humans, and some of the "central brain circuitry" appear to be very similar.
According to study co-author Theodore Garland Jr., it is not inconceivable that in the future, they might be able to separate the chemicals "and use them as air fresheners in gyms" to motivate people to exercise even more.
Testable Hypotheses
There is still a need for researchers to identify how the high runners identify odors differently from regular rodents, whether it is the pheromone's concentration sensed or something else.
The notion that smells can impact reward gotten from exercise or motivation to start exercising are both "testable hypotheses" in the future, Haga-Yamanaka added.
In principle, she explained, such experiments would be that challenging to conduct. For instance, one can utilize surveys of humans prior to, during, and after they exercise to ask how driven or rewarded they feel awhile, at the same time, providing some with a scent and others with none.
On the other hand, the study author also said functional magnetic resonance imaging or FMRI to study the brain and gauge patterns of brain activity.
There, one would see if reward centers "light up" more when provided with certain odors during exercise, explained Haga-Yamanaka. He added that to this point, they are aware, "such studies" have not been conducted.
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