Estrogen Works in the Brain to Keep Weight in Check, Study Shows

A recent UT Southwestern Medical Center study found that estrogen regulates energy expenditure, appetite and body weight, while insufficient estrogen receptors in specific parts of the brain may lead to obesity.

"Estrogen has a profound effect on metabolism," said Dr. Deborah Clegg, associate professor of internal medicine and senior author of the study published Oct. 5 in Cell Metabolism. "We hadn't previously thought of sex hormones as being critical regulators of food intake and body weight."

The mouse study is the first to show that estrogen, acting through two hypothalamic neural centers in the brain, keeps female body weight in check by regulating hunger and energy expenditure. Female mice lacking estrogen receptor alpha -- a molecule that sends estrogen signals to neurons -- in those parts of the brain became obese and developed related diseases, such as diabetes and heart disease.

Similar results were not seen in male mice, although researchers suspect other unknown estrogen receptor sites in the brain play a similar role in regulating metabolism for males as well.

Estrogen receptors are located throughout the body, but researchers found two specific populations of estrogen receptors that appear to regulate energy balance for female mice.

The findings are potentially important for millions of postmenopausal women, many of whom have decided against hormonal replacement therapy. The study could lead to new hormonal replacement therapies in which estrogen is delivered to specific parts of the brain that regulate body weight, thereby avoiding the risks associated with full-body estrogen delivery, such as breast cancer and stroke.

Doctors stopped routinely recommending long-term estrogen therapy for menopausal women in 2002 when a Women's Health Initiative study showed the hormone also led to increased risk of cardiovascular disease.
"The role of estrogen in postmenopausal women continues to remain uncertain," Dr. Clegg said. "Current research is focused on the timing and the type of estrogen supplementation that would be most beneficial to women. Our findings further support a role for estrogens in regulating body weight and energy expenditure, suggesting a benefit of estrogen supplementation in postmenopausal women."

Other UT Southwestern researchers involved in the study included lead author Dr. Yong Xu, a former postdoctoral researcher in Dr. Clegg's lab; Dr. Carol Elias, assistant professor of internal medicine; and Dr. Joel Elmquist, professor of internal medicine.

The research was supported by grants from the National Institutes of Health, the American Heart Association and the American Diabetes Association.


Via: Sciencedaily

Pushing the Limits of Performance

Deceiving the brain can lead to an improvement of up to five per cent in sporting performance, according to research from Northumbria University -- news which could have a significant impact on athletes' chances in the 2012 Olympics.



In a research project, trained cyclists were asked to race against an avatar on a computer screen which they believed was moving at the rate of the cyclist's personal best.
However, the avatar was actually going at a speed one per cent faster than the cyclist's fastest time. Despite this, the cyclists, who could also see themselves as an avatar cycling the virtual course, were able to match their opponent, going faster than they ever had before.

Researchers believe this is because there is a reserve of energy production that can be tapped into, even in well-trained athletes.

In training, the mind anticipates the end of a bout of exercise in order to set an initial pace. Sensory receptors, which monitor the body's responses, feed this information back to the brain, allowing it to control the body's resources to last until the end of the exercise to avoid damage.

Professor Kevin Thompson, Head of Sport and Exercise Sciences at Northumbria University, who carried out the research along with PhD student Mark Stone, said: "We feel that this system is conservative and even in well-trained individuals, who have a well developed pacing template, there is a reserve of energy production which can be utilised to further enhance performance."

He added: "These findings demonstrate a metabolic reserve exists which, if it can be accessed, can release a performance improvement of between two and five per cent in terms of their average power output.
"At elite level sport, even an increase of one per cent in average speed can make the difference between somebody being placed in a race or not.''

The study found that adding a competitive opponent to motivate participants to access this reserve was not effective when the participant was aware that their opponent was exercising at a power output 2% or 5% greater, but was effective when participants did not know.

Prof Thompson added: "We believe a small deception of the brain can enhance performance. Despite the internal feedback to the brain being heightened by the extra power output being produced, the participants still believed it was possible to beat their opponent."

Vía: ScienceDaily