PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Why your brain tires when exercising

2013-03-05
(Press-News.org) A marathon runner approaches the finishing line, but suddenly the sweaty athlete collapses to the ground. Everyone probably assumes that this is because he has expended all energy in his muscles. What few people know is that it might also be a braking mechanism in the brain which swings into effect and makes us too tired to continue. What may be occurring is what is referred to as 'central fatigue'.

"Our discovery is helping to shed light on the paradox which has long been the subject of discussion by researchers. We have always known that the neurotransmitter serotonin is released when you exercise, and indeed, it helps us to keep going. However, the answer to what role the substance plays in relation to the fact that we also feel so exhausted we have to stop has been eluding us for years. We can now see it is actually a surplus of serotonin that triggers a braking mechanism in the brain. In other words, serotonin functions as an accelerator but also as a brake when the strain becomes excessive," says Associate Professor Jean-François Perrier from the Department of Neuroscience and Pharmacology, who has spearheaded the new research.

Help in the battle against doping

Jean-François Perrier hopes that mapping the mechanism that prompts central fatigue will be useful in several ways. Central fatigue is a phenomenon which has been known for about 80 years; it is a sort of tiredness which, instead of affecting the muscles, hits the brain and nervous system. By conducting scientific experiments, it is possible to observe and measure that the brain sends insufficient signals to the muscles to keep going, which in turn means that we are unable to keep performing. This makes the mechanism behind central fatigue an interesting area in the battle against doping, and it is for this reason that Anti Doping Danmark has also helped fund the group's research.

"In combating the use of doping, it is crucial to identify which methods athletes can use to prevent central fatigue and thereby continue to perform beyond what is naturally possible. And the best way of doing so is to understand the underlying mechanism," says Jean-François Perrier.

Developing better drugs

The brain communicates with our muscles using so-called motoneurons (see fact box). In several diseases, motoneurons are hyperactive. This is true, for example, of people suffering from spasticity and cerebral palsy, who are unable to control their movements. Jean-François Perrier therefore hopes that, in the long term, this new knowledge can also be used to help develop drugs against these symptoms and to find out more about the effects of antidepressants.

"This new discovery brings us a step closer to finding ways of controlling serotonin. In other words, whether it will have an activating effect or trigger central fatigue. It is all about selectively activating the receptors which serotonin attaches to," explains Jean-François Perrier.

"For selective serotonin re-uptake inhibitor (SSRI) drugs which are used as antidepressants, we can possibly help explain why those who take the drugs often feel more tired and also become slightly clumsier than other people. What we now know can help us develop better drugs," concludes Jean-François Perrier.

### The new results have just been published in the renowned scientific journal PNAS. Read the article 'Serotonin spillover onto the axon initial segment of motoneurons induces central fatigue by inhibiting action potential initiation'. DOI: 10.1073 PNAS article #: 201216150.

CONTACT

Associate Professor Jean-François Perrier
Department of Neuroscience and Pharmacology
University of Copenhagen
Telephone: +45 23 81 27 46
E-mail: Perrier@sund.ku.dk
Skype: jfoboulot

Jean-François Perrier will be travelling until March 11. If you cannot reach him by phone, send him an email and he will call you back.

Communications Officer Louise Graa Christensen
Faculty of Health and Medical Sciences
University of Copenhagen
Mobile: +45 24 34 03 22
E-mail: louise.christensen@sund.ku.dk

FACTS

About the research

In addition to Jean-François Perrier, the research team responsible for mapping the braking mechanism includes Florence Cotel and two researchers from the University of Oxford (Stephanie Cragg and Richard Exley). In order to be able to study the motoneurons, the researchers have studied large American turtles. This is because the adult turtle's spinal marrow, where the motoneurons are found, is accessible to experimentation but also resemble conditions in humans. It is in precisely this respect that that results obtained from cross-sections of the spinal marrow in turtles, help researchers to understand central fatigue in the nervous system of humans.

Masterful motoneurons

In the human brain there are about 100 billion nerve cells, or neurons. Each neuron consists of a cell body with dendrites and a nerve fiber called the axon, and they communicate with one another via synapses. Nerve cells use nerve impulses to send signals with the axon from the cell body to the nerve ends, which form synapses with the dendrites of the receiving cell.

A special kind of neuron, the motoneurons, are extremely important as they are responsible for ensuring contact between the brain and the muscles. Every time a motoneuron sends impulses to the muscles, it leads to the contraction of the muscle fibres contacted and thus a movement. In order to control the body's movements, the brain has to be able to control the impulse activity in groups of motoneurons so they are activated in the right sequence and to the right degree. It is here that serotonin plays a role as one of the neurotransmitters which are released from the synapses during the brain's ingenious control of the motoneurons and thereby our patterns of movement.

Serotonin and central fatigue

Serotonin is well known for being involved in many different human functions: Appetite, sleep, sex and motor control. Serotonin is released as soon as you start moving, and the more you move, the more serotonin is released. In other words, serotonin functions as an accelerator for movement and makes the motoneurons more active. However, when large amounts of serotonin are released, it causes a glut at the synapses through which the neurons communicate. This means that the serotonin starts binding with the receptors lying outside the synapses. Some of these receptors sit at the initial part of the axon, i.e. where nerve impulses are formed. And when the serotonin activates these receptors, the nerve impulse is obstructed, the result being that the muscle contraction is weakened and fatigue occurs.


ELSE PRESS RELEASES FROM THIS DATE:

A vaccine that works in newborns?

2013-03-05
Boston, Mass. - The underdeveloped immune systems of newborns don't respond to most vaccines, leaving them at high risk for infections like rotavirus, pertussis (whooping cough) and pneumococcus. Researchers at Boston Children's Hospital have identified a potent compound that activates immune responses in newborns' white blood cells substantially better than anything previously tested, and that could potentially make vaccines effective right at birth. The ability to immunize babies at birth—rather than two months of age, when most current vaccination series begin—would ...

Is baby still breathing? Is mom's obsession normal?

2013-03-05
CHICAGO --- A new mother may constantly worry and check to see if her baby is still breathing. Or she may fret about germs, obsessing whether she's properly sterilized the bottles, then wash and rewash them. A new Northwestern Medicine® study found that women who have recently given birth have a much higher rate of obsessive-compulsive symptoms than the general population. The study found 11 percent of women at two weeks and six months postpartum experience significant obsessive-compulsive symptoms compared to 2 to 3 percent in the general population. This is the ...

HIV infection appears associated with increased heart attack risk

2013-03-05
A study that analyzed data from more than 82,000 veterans suggests that infection with the human immunodeficiency virus (HIV) was associated with an increased risk of acute myocardial infarction (AMI, heart attack) beyond what is explained by recognized risk factors, according to a report published Online First by JAMA Internal Medicine, a JAMA Network publication. Due to the successful antiretroviral therapy (ART), people infected with HIV are living longer and are at risk for heart disease, authors wrote in the study background. Matthew S. Freiberg, M.D., M.Sc., of ...

Parkinson's disease brain rhythms detected

Parkinsons disease brain rhythms detected
2013-03-05
A team of scientists and clinicians at UC San Francisco has discovered how to detect abnormal brain rhythms associated with Parkinson's by implanting electrodes within the brains of people with the disease. The work may lead to developing the next generation of brain stimulation devices to alleviate symptoms for people with the disease. Described this week in the journal Proceedings of the National Academy of Sciences (PNAS), the work sheds light on how Parkinson's disease affects the brain, and is the first time anyone has been able to measure a quantitative signal ...

Mom's placenta reflects her exposure to stress and impacts offsprings' brains, Penn Vet team finds

2013-03-05
PHILADELPHIA — The mammalian placenta is more than just a filter through which nutrition and oxygen are passed from a mother to her unborn child. According to a new study by a research group from the University of Pennsylvania School of Veterinary Medicine, if a mother is exposed to stress during pregnancy, her placenta translates that experience to her fetus by altering levels of a protein that affects the developing brains of male and female offspring differently. These findings suggest one way in which maternal-stress exposure may be linked to neurodevelopmental diseases ...

New data show countries around the world grappling with changing health challenges

2013-03-05
SEATTLE – Alzheimer's disease is the fastest growing threat to health in the US. HIV/AIDS and alcohol are severely eroding the health of Russians. Violence is claiming the lives of young men in large swaths of Latin America, constituting a homicide-driven health crisis. Despite health gains in sub-Saharan Africa, infectious diseases still cause hundreds of thousands of child deaths. These are just some of the new findings from the Global Burden of Diseases, Injuries, and Risk Factors 2010 Study (GBD 2010), a systemic, scientific effort to quantify the comparative magnitude ...

New Lancet paper reveals that UK lags behind much of Europe on key measures of health

2013-03-05
SEATTLE – Britons are living longer lives and enjoying better health, but they are still grappling with disabling conditions such as back and neck pain and depression, often more than people in most other European countries. Health in the United Kingdom is eroded by preventable causes of death such as smoking, unhealthy diets, and use of alcohol and drugs. As a result, the UK's pace of decline in premature mortality has fallen well behind the average of 14 other original members of the European Union, Australia, Canada, Norway, and the United States (EU15+) over the past ...

The right dose for oncology

2013-03-05
King Mithridates understood that poison is only as good as the dosage taken. Each day, he ingested small quantities of poison in order to become immunize and escape his court's plotters. Oncologists run up against the same principle when fighting cancer. Sometimes, a small dose of chemotherapy may induce dangerous resistance mechanisms in malignant cells, resulting in relapse. Now, EPFL research published in the journal PLOS ONE reports a tool that could simply and accurately determine the right dose for individual patients. Dosage, a vital issue This novel tool, developed ...

Pharmaceutical advertising down but not out

2013-03-05
The pharmaceutical industry has pulled back on marketing to physicians and consumers, yet some enduring patterns persist. According to a new study led by researchers at the Johns Hopkins Bloomberg School of Public Health, advertising peaked in 2004, with industry promotion to physicians declining nearly 25 percent by 2010, to $27.7 billion or 9 percent of sales. Similar declines were seen in direct-to-consumer advertising, which remains concentrated among a small number of products. The number of products promoted to providers peaked at over 3,000 in 2004, and declined ...

Accurate water vapor measurements for improved weather and climate models

Accurate water vapor measurements for improved weather and climate models
2013-03-05
Humidity measurements in the atmosphere are of essential importance, since water vapour, as the most important natural greenhouse gas, has a strong influence on the Earth's atmospheric radiation balance and, thus, decisively influences our climate. In addition, water is responsible for meteorological phenomena such as the formation of clouds and precipitation. Hence, the atmospheric water content is an essential measurand in all climate models, but also when it comes to forecasting the weather; this measurand has to be determined with great accuracy if reliable predictions ...

LAST 30 PRESS RELEASES:

A hard look at geoengineering reveals global risks

When smoke signals danger: How Australian lizards evolved to escape fire

Beyond the surface: Atopic eczema linked to significantly higher risk of suicidal thoughts, major study finds

After weight loss regular exercise rather than GLP-1 weight-loss drug reduces leading cause of heart attack and strokes

EASD launches its first ever clinical practice guideline – the world’s first to focus on diabetes distress

Semaglutide provides powerful protection against diabetic retinopathy, the leading cause of blindness in working-age adults, Greek study suggests

Orforglipron taken orally once daily leads to significant body weight loss (ATTAIN-1 Study)

U of I researchers trace genetic code’s origins to early protein structures

Disease experts team up with Florida Museum of Natural History to create a forecast for West Nile virus

Researchers: Targeted efforts needed to stem fentanyl crisis

New UMaine research could help lower prescription drug costs

Molecular movie shows how mitochondria read their DNA

Loss of key male fertility gene leads to changes in expression of hundreds of other genes

Water’s density is key to sustainable lithium mining

Pioneering research reveals problem gambling quadruples the risk of suicide among young people four years later

New method improves the accuracy of machine-learned potentials for simulating catalysts

Astronomers discover rare Einstein cross with fifth image, revealing hidden dark matter

UCalgary researchers show brain shunts significantly benefit older adults with hydrocephalus

UCalgary researchers pursue new approach to manage deadly lung scarring

Psychotherapy can be readily integrated into brief “med-check” psychiatry visits

‘Wiggling’ atoms may lead to smaller, more efficient electronics

Alliance webinar highlights latest advances in cancer treatment

Climate change could drastically reduce aquifer recharge in Brazil

$1.7M DOD grant funds virtual cancer center to support research into military health

Brain organoids could unlock energy-efficient AI

AI-powered CRISPR could lead to faster gene therapies, Stanford Medicine study finds

Shared genetic mechanisms underpin social life in bees and humans

Prescribed opioid pain medications during pregnancy likely aren’t associated with increased risk of autism, ADHD

Sustainable, plant-based diet benefits both human and planetary health

IU researchers find that opioid pain meds prescribed during pregnancy do not cause increased risk of autism or ADHD

[Press-News.org] Why your brain tires when exercising