Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Brain study shows some animals crave exercise

01.12.2003


Like junkies without drugs, mice without running wheels crave what they lack, suggesting that some animals can develop an addiction for exercise, report scientists in the Dec. 1 issue of the journal Behavioral Neuroscience.



We all know someone who can’t get enough exercise: the marathon runner who jogged 26 miles in all 50 states, the neighbor who speed walks at the crack of dawn or the cyclist who zooms by every Sunday. We might say these people are addicted to physical activity. But the debate on exercise addiction has remained largely unresolved - until now, that is.

The new study, conducted at the University of Wisconsin-Madison, adds evidence that the same brain circuitry involved in other types of craving - such as for food, drugs or sex - is activated in mice that are denied access to the running wheel. The findings, say the researchers, lend support to the addictive nature of exercise in some animals.


The researchers studied changes in brain activity in two groups of rodents: typical laboratory mice and a special breed of mice selected over 29 generations for their affinity for voluntary wheel running.

"All mice run on wheels, and, therefore, have a motivation to run," says Justin Rhodes, a postdoctoral fellow at Oregon Health & Science University who completed the study while a graduate student at UW-Madison. But he adds that the specially bred mice have a genetic predisposition to run longer distances.

"They represent those few extreme individuals in the population with an intense desire or compulsion to run," he says.

To understand what drives these mice to run faster and farther than the average mouse, Rhodes and his colleagues at UW-Madison designed a study to measure changes in brain activity when both groups of mice were granted or denied access to the running wheel. For six days, they let all mice run as long as they wanted, and they recorded their distances. By and large, the high wheel running mice, compared to the other group, covered more ground in the same amount of time on their spinning treadmills. On the sixth day, for example, these mice averaged about six miles, compared to about two miles among the controls.

On the seventh day, the researchers blocked half the mice in each group from the wheel while giving free access to the other half. Five hours later, when the mice usually reach their running peak, the researchers compared brain activity in each mouse by measuring levels of Fos, a gene that’s expressed in response to neuronal excitement.

"We thought we’d see more activity in the mice doing the running, but that’s not what we saw at all," says Stephen Gammie, assistant professor of zoology at UW-Madison and senior author of the recent paper.

Instead, Gammie, Rhodes and their Wisconsin colleague Theodore Garland, Jr., (now at the University of California, Riverside) found that all the mice denied access showed higher levels of neuronal stimulation in 16 out of 25 brain regions. Stimulation was even greater in mice that typically ran longer distances, showing a correlation between brain activity levels and average amount of wheel running.

"In the high-running mice, certain brain regions displayed extremely high levels of activity, more than normal," says Rhodes. "These were the same brain regions that become activated when you prevent rats from getting their daily fix of cocaine, morphine, alcohol or nicotine."

The researchers explain that blocking the running behavior in the mice bred to do more voluntary wheel spinning triggers a neuronal response - activation of brain regions involved in reward circuitry - that drives them to run. Explains Gammie, "These mice have run for six days. They want to run, and they’re ready to run, but they can’t. Change in brain activity is an indication of their motivation to run."

These findings then would suggest that all mice have the motivation to run, since each blocked mouse showed neuronal stimulation, but that some mice may actually crave it. After all, abstaining from their running regimen signals the same pathways involved in the craving for drugs of abuse, says Rhodes.

Whether these findings on exercise motivation hold true for humans remains to be studied. If it does, anecdotal evidence from Rhodes and Gammie would suggest that they’ve got more in common with the study’s control mice: While they bike or play ultimate Frisbee, neither one says he feels the compulsion to do it on a regular basis.

"I need to force myself to do it," admits Rhodes. But he keeps on pedaling, he says, because he knows it’s good for his body and mind.


- Emily Carlson 608-262-9772, emilycarlson@wisc.edu

The research was supported in part by funds from the National Science Foundation, the National Institutes of Health, the UW-Madison Graduate School and the Department of Zoology.

Additional Contact:
Justin Rhodes,
503-220-8262, Ext. 54392,
rhodesju@ohsu.edu

Stephen Gammie | EurekAlert!
Further information:
http://www.wisc.edu/

More articles from Life Sciences:

nachricht Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden

nachricht The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>