Archive for the ‘Endorphins’ Category

Researchers at The University of Auckland have shown for the first time that the mere presence of carbohydrate solution in the mouth immediately boosts muscle strength, even before it is swallowed.

The results suggest that a previously unknown neural pathway is activated when receptors in the mouth detect carbohydrate, stimulating parts of the brain that control muscle activity and producing an increase in muscle strength.

Previous research had shown that the presence of carbohydrate in the mouth can improve physical performance during prolonged activity, but the mechanism involved was not known and it was unclear whether a person must be fatigued for the effect to be seen.

“There appears to be a pathway in the brain that tells our muscles when energy is on the way,” says lead researcher Dr Nicholas Gant from the Department of Sport and Exercise Science.

“We have shown that carbohydrate in the mouth produces an immediate increase in neural drive to both fresh and fatigued muscle and that the size of the effect is unrelated to the amount of glucose in the blood or the extent of fatigue.”

The current research has been published in the journal Brain Research and has also captured the attention of New Scientist magazine.

In the first of two experiments, 16 healthy young men who had been doing biceps exercises for 11 minutes were given a carbohydrate solution to drink or an identically flavored energy-free placebo. Their biceps strength was measured before and immediately afterward, as was the activity of the brain pathway known to supply the biceps.

Around one second after swallowing the drink, neural activity increased by 30 percent and muscle strength two percent, with the effect lasting for around three minutes. The response was not related to the amount of glucose in the bloodstream or how fatigued the participants were.

“It might not sound like much, but a two percent increase in muscle strength is enormous, especially at the elite level. It’s the difference between winning an Olympic medal or not,” says co-author Dr Cathy Stinear.

As might be expected, a second boost in muscle strength was observed after 10 minutes when carbohydrate reached the bloodstream and muscles through digestion, but no additional boost in neural activity was seen at that time.

“Two quite distinct mechanisms are involved,” says Dr Stinear. “The first is the signal from the mouth via the brain that energy is about to be available and the second is when the carbohydrate actually reaches the muscles and provides that energy,” says Dr Stinear.

“The carbohydrate and placebo solutions used in the experiment were of identical flavor and sweetness, confirming that receptors in the mouth can process other sensory information aside from the basic taste qualities of food. The results suggest that detecting energy may be a sixth taste sense in humans,” says Dr Gant.

In the second experiment, 17 participants who had not been doing exercise and were not fatigued simply held one of the solutions in their mouths without swallowing. Measurements of the muscle between the thumb and index finger were taken while the muscle was either relaxed or active.

A similar, though smaller effect was observed as in the first experiment, with a nine percent increase in neural activity produced by the carbohydrate solution compared with placebo. This showed that the response is seen in both large powerful muscles and in smaller muscles responsible for fine hand movements.

“Together the results show that carbohydrate in the mouth activates the neural pathway whether or not muscles are fatigued. We were surprised by this, because we had expected that the response would be part of the brain’s sophisticated system for monitoring energy levels during exercise,” says Dr Stinear.

“Seeing the same effect in fresh muscle suggests that it’s more of a simple reflex – part of our basic wiring – and it appears that very ancient parts of the brain such as the brainstem are involved. Reflexive movements in response to touch, vision and hearing are well known but this is the first time that a reflex linking taste and muscle activity has been described,” she says.

Further research is required to determine the precise mechanisms involved and to learn more about the size of the effect on fresh versus fatigued muscle.

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Article adapted by MD Sports from original press release.
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Contact: Pauline Curtis
The University of Auckland

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Boosting an exercise-related gene in the brain works as a powerful anti-depressant in mice—a finding that could lead to a new anti-depressant drug target, according to a Yale School of Medicine report in Nature Medicine.

“The VGF exercise-related gene and target for drug development could be even better than chemical antidepressants because it is already present in the brain,” said Ronald Duman, professor of psychiatry and senior author of the study.

Depression affects 16 percent of the population in the United States, at a related cost of $83 billion each year. Currently available anti-depressants help 65 percent of patients and require weeks to months before the patients experience relief.

Duman said it is known that exercise improves brain function and mental health, and provides protective benefits in the event of a brain injury or disease, but how this all happens in the brain is not well understood. He said the fact that existing medications take so long to work indicates that some neuronal adaptation or plasticity is needed.

He and his colleagues designed a custom microarray that was optimized to show small changes in gene expression, particularly in the brain’s hippocampus, a limbic structure highly sensitive to stress hormones, depression, and anti-depressants.

They then compared the brain activity of sedentary mice to those who were given running wheels. The researchers observed that the mice with wheels within one week were running more than six miles each night. Four independent array analyses of the mice turned up 33 hippocampal exercise-regulated genes—27 of which had never been identified before.

The action of one gene in particular—VGF—was greatly enhanced by exercise. Moreover, administering VGF functioned like a powerful anti-depressant, while blocking VGF inhibited the effects of exercise and induced depressive-like behavior in the mice.

“Identification of VGF provides a mechanism by which exercise produces antidepressant effects,” Duman said. “This information further supports the benefits of exercise and provides a novel target for the development of new antidepressants with a completely different mechanism of action than existing medications.”

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Article adapted by MD Sports Weblog from original press release.
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Contact: Jacqueline Weaver
Yale University
Nature Medicine

Endorphins and other morphine-like substances known as opioids, which are released during exercise, don’t just make you feel good — they may also protect you from heart attacks, according to University of Iowa researchers.

It has long been known that the so-called “runner’s high” is caused by natural opioids that are released during exercise. However, a UI study, which is published in the online edition of the American Journal of Physiology’s Heart and Circulatory Physiology, suggests that these opioids may also be responsible for some of exercise’s cardiovascular benefits.

Working with rats, UI researchers showed that blocking the receptors that bind morphine, endorphins and other opioids eliminates the cardiovascular benefits of exercise. Moreover, the UI team showed that exercise was associated with increased expression of several genes involved in opioid pathways that appear to be critical in protecting the heart.

“This is the first evidence linking the natural opioids produced during exercise to the cardio-protective effects of exercise,” said Eric Dickson, M.D., UI associate professor and head of emergency medicine in the Roy J. and Lucille A. Carver College of Medicine and the study’s lead investigator. “We have known for a long time that exercise is great for the heart. This study helps us better understand why.”

Studies have shown that regular vigorous exercise reduces the risk of having a heart attack and improves survival rates following heart attack, even in people with cardiovascular disease. In addition, exercise also decreases the risk of atherosclerosis, stroke, osteoporosis and even depression. However, despite these proven health benefits, much less is understood about how exercise produces these benefits.

The UI study investigated the idea that the opioids produced by exercise might have a direct role in cardio-protection. The researchers compared rats that exercised with rats that did not. As expected, exercised rats sustained significantly less heart damage from a heart attack than non-exercised rats. The researchers then showed that blocking opioid receptors completely eliminated these cardio-protective effects in exercising rats, suggesting that opioids are responsible for some of the cardiac benefits of exercise.

The UI team also showed that exercise was associated with transient increases in expression of several opioid system genes in heart muscle, and changes in expression of other genes that are involved in inflammation and cell death. The researchers plan to investigate whether these altered gene expression patterns reveal specific cardio-protective pathways.

A better understanding of how exercise protects the heart may eventually allow scientists to harness these protective effects for patients with decreased mobility.

“Hopefully this study will move us closer to developing therapies that mimic the benefits of exercise,” Dickson said. “It also serves as a reminder of how important it is to get out and exercise every day.”

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Article adapted by MD Only Weblog from original press release.
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Contact: Jennifer Brown
University of Iowa

In addition to Dickson, the UI research team included Christopher Hogrefe, Paula Ludwig, Laynez Ackermann, Lynn Stoll, Ph.D., and Gerene Denning, Ph.D.

STORY SOURCE: University of Iowa Health Science Relations, 5135, Westlawn, Iowa City, Iowa 52242-1178

ORIGINAL ARTICLE: Abstract is available Click here