Featured Research

from universities, journals, and other organizations

New clues to how the brain and body communicate to regulate weight

Date:
October 26, 2012
Source:
Beth Israel Deaconess Medical Center
Summary:
Researchers describe new findings that help explain the neurocircuitry underlying the fat-burning properties of brown fat.

Maintaining a healthy body weight may be difficult for many people, but it's reassuring to know that our brains and bodies are wired to work together to do just that -- in essence, to achieve a phenomenon known as energy balance, a tight matching between the number of calories consumed versus those expended. This careful balance results from a complex interchange of neurobiological crosstalk within regions of the brain's hypothalamus, and when this "conversation" goes awry, obesity or anorexia can result.

Given the seriousness of these conditions, it's unfortunate that little is known about the details of this complex interchange. Now research led by investigators at Beth Israel Deaconess Medical Center (BIDMC) provides new insights that help bring order to this complexity. Described in the October 26 issue of the journal Cell, the findings demonstrate how the GABA neurotransmitter selectively drives energy expenditure, and importantly, also help explain the neurocircuitry underlying the fat-burning properties of brown fat.

"Our group has built up a research program with the overall goal of unraveling the 'wiring diagram' by which the brain controls appetite and the burning of calories," says senior author Bradford Lowell, MD, PhD, a Professor of Medicine in BIDMC's Division of Endocrinology and Harvard Medical School. "To advance our understanding to this level, we need to know the function of specific subsets of neurons, and in addition, the upstream neurons providing input to, and the downstream neurons receiving output from, these functionally defined neurons. Until recently, such knowledge in the hypothalamus has been largely unobtainable."

A pearl-sized region that directs a multitude of important functions in the body, the hypothalamus is the brain's control center for energy balance. This balance results when the brain receives feedback signals from the body that communicate the status of fuel stores and then integrates this with input from the external world as well as a person's emotional state to modify feeding behavior and energy expenditure.

In this new study, the researchers investigated a unique population of neurons that are located at the base of the brain in the arcuate nucleus of the hypothalamus. "We genetically engineered mice such that they have a specific defect that prevents these neurons from releasing the inhibitory neurotransmitter, GABA," says Lowell. "Mice with this defect developed marked obesity and, remarkably, their obesity was entirely due to a defect in burning off calories," he explains, adding that food intake was entirely unaffected.

By next engineering another group of mice in which these neurons could be selectively turned on at different times, the team went on to show that the arcuate neurons act through a series of downstream neurons to drive energy expenditure in brown fat. Brown fat has been making headlines lately because many recent studies have revealed that, unlike energy-storing white fat, brown fat burns energy to generate heat. This process is called thermogenesis.

"Energy expenditure mediated by brown adipose tissue is critical in maintaining body weight and prevents diet-induced obesity. Its brain-based regulatory mechanism, however, is still poorly understood," says first author Dong Kong, PhD, an Instructor in Medicine in Lowell's laboratory. "Our discovery of a hypothalamus-based neurocircuit that ultimately controls thermogenesis is an important advance," adds Lowell. The investigators additionally found that when they turned on these neurons, energy expenditure was entirely dependent upon release of GABA. These results reveal that release of GABA from arcuate neurons selectively drives energy expenditure.

"Our findings have greatly advanced our understanding in the control of energy expenditure and have provided novel insights into the pathogenesis of obesity," says Kong.

The unique features of arcuate neurons are important because they could provide an opportunity to experimentally modify the brain's control of energy expenditure. Specifically, neurons receiving GABA-mediated signals from arcuate neurons are likely to play important roles in regulating energy expenditure, but not food intake.

"It is now important to fully delineate the upstream neurons that control these thermogenesis-regulating arcuate neurons, and also the downstream neurons that complete the 'circuit' to brown adipose tissue," Lowell adds. He and his colleagues have identified several specific types of neurons that act downstream of arcuate neurons, but more research is needed to provide a clear and definitive diagram. Such work could uncover new opportunities for pharmacologic interventions that might lead to effective treatments for obesity and its related complications such as diabetes.


Story Source:

The above story is based on materials provided by Beth Israel Deaconess Medical Center. Note: Materials may be edited for content and length.


Journal Reference:

  1. Dong Kong, Qingchun Tong, Chianping Ye, Shuichi Koda, PatrickM. Fuller, MichaelJ. Krashes, Linh Vong, RussellS. Ray, DavidP. Olson, BradfordB. Lowell. GABAergic RIP-Cre Neurons in the Arcuate Nucleus Selectively Regulate Energy Expenditure. Cell, 2012; 151 (3): 645 DOI: 10.1016/j.cell.2012.09.020

Cite This Page:

Beth Israel Deaconess Medical Center. "New clues to how the brain and body communicate to regulate weight." ScienceDaily. ScienceDaily, 26 October 2012. <www.sciencedaily.com/releases/2012/10/121026153740.htm>.
Beth Israel Deaconess Medical Center. (2012, October 26). New clues to how the brain and body communicate to regulate weight. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2012/10/121026153740.htm
Beth Israel Deaconess Medical Center. "New clues to how the brain and body communicate to regulate weight." ScienceDaily. www.sciencedaily.com/releases/2012/10/121026153740.htm (accessed April 17, 2014).

Share This



More Health & Medicine News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com
Thousands Of Vials Of SARS Virus Go Missing

Thousands Of Vials Of SARS Virus Go Missing

Newsy (Apr. 16, 2014) A research institute in Paris somehow misplaced more than 2,000 vials of the deadly SARS virus. Video provided by Newsy
Powered by NewsLook.com
Formerly Conjoined Twins Released From Dallas Hospital

Formerly Conjoined Twins Released From Dallas Hospital

Newsy (Apr. 16, 2014) Conjoined twins Emmett and Owen Ezell were separated by doctors in August. Now, nearly nine months later, they're being released from the hospital. Video provided by Newsy
Powered by NewsLook.com
Ebola Outbreak Now Linked To 121 Deaths

Ebola Outbreak Now Linked To 121 Deaths

Newsy (Apr. 15, 2014) The ebola virus outbreak in West Africa is now linked to 121 deaths. Health officials fear the virus will continue to spread in urban areas. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins