Featured Research

from universities, journals, and other organizations

Signaling path in brain may prevent that 'I'm full' message

Date:
March 1, 2011
Source:
UT Southwestern Medical Center
Summary:
Researchers have identified a signaling pathway in the brain that's sufficient to induce cellular leptin resistance, a problem that decreases the body's ability to "hear" that it is full and should stop eating.

Researchers at UT Southwestern Medical Center have identified a signaling pathway in the brain that's sufficient to induce cellular leptin resistance, a problem that decreases the body's ability to "hear" that it is full and should stop eating.

"Leptin resistance is a significant factor, yet the mechanisms that underlie the problem remain unclear," said Dr. Joel Elmquist, professor of internal medicine and pharmacology at UT Southwestern and senior author of the study appearing in the March issue of Cell Metabolism. "The fact that this cellular pathway may be involved is a novel observation."

Leptin is a hormone released by fat cells that is known to indicate fullness, or satiety, in the brain. If the body is exposed to too much leptin, however, it will become resistant to the hormone. Once that occurs, the body can't "hear" the hormonal messages telling the body to stop eating and burn fat. Instead, a person remains hungry, craves sweets and stores more fat instead of burning it.

Leptin resistance also causes an increase in visceral, or belly, fat, which has been shown to predispose people to an increased risk of heart disease, diabetes and metabolic syndrome.

For the current study, the researchers induced leptin resistance in organotypic brain slices from mice. This research technique, used commonly in neuroscience, enabled the researchers to maintain the cellular and anatomical relationships and some of the network connections that normally exist within the brain.

"We're not dispersing cells. We're leaving them in a microenvironment that simulates what's going on in the brain," Dr. Elmquist said.

When the researchers began manipulating the network -- known as cAMP-EPAC pathway -- they found that activating this previously unexplored signaling avenue is enough to induce leptin resistance within hypothalamic neurons, a critical site of leptin action. They also found that when the pathway was blocked, the cells were no longer resistant to leptin.

"In the follow-up experiments, which we conducted in mice, we were able to induce leptin resistance simply by infusing activators of this pathway, further supporting our theory that this signaling pathway may contribute to leptin resistance in obesity," said Dr. Makoto Fukuda, instructor of internal medicine at UT Southwestern and the study's lead author.

Dr. Elmquist said that while the EPAC signaling pathway itself is not novel, this is the first time it has been studied in the hypothalamus and in the context of energy balance and leptin signaling.

The next step, Dr. Elmquist said, is to investigate how critical the EPAC pathway actually is in leptin responsive neurons and to determine its role in maintaining energy balance and leptin sensitivity.

"These results are potentially interesting and provocative, but the physiological importance remains to be seen," Dr. Elmquist said. "If, however, this pathway is indeed important, it will offer new insights into the mechanisms that high levels of leptin cause in leptin resistance."

Other UT Southwestern researchers involved in the study were Drs. Kevin Williams and Laurent Gautron, both instructors of internal medicine.

The study was supported by the National Institutes of Health, American Diabetes Association, American Heart Association and the Smith Family Foundation.


Story Source:

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


Journal Reference:

  1. Makoto Fukuda, Kevin W. Williams, Laurent Gautron, Joel K. Elmquist. Induction of Leptin Resistance by Activation of cAMP-Epac Signaling. Cell Metabolism, Volume 13, Issue 3, 2 March 2011, Pages 331-339 DOI: 10.1016/j.cmet.2011.01.016

Cite This Page:

UT Southwestern Medical Center. "Signaling path in brain may prevent that 'I'm full' message." ScienceDaily. ScienceDaily, 1 March 2011. <www.sciencedaily.com/releases/2011/03/110301122146.htm>.
UT Southwestern Medical Center. (2011, March 1). Signaling path in brain may prevent that 'I'm full' message. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2011/03/110301122146.htm
UT Southwestern Medical Center. "Signaling path in brain may prevent that 'I'm full' message." ScienceDaily. www.sciencedaily.com/releases/2011/03/110301122146.htm (accessed August 2, 2014).

Share This




More Health & Medicine News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Texas Quintuplets Head Home

Texas Quintuplets Head Home

Reuters - US Online Video (Aug. 1, 2014) After four months in the hospital, the first quintuplets to be born at Baylor University Medical Center head home. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Patient Coming to U.S. for Treatment

Ebola Patient Coming to U.S. for Treatment

Reuters - US Online Video (Aug. 1, 2014) A U.S. aid worker infected with Ebola while working in West Africa will be treated in a high security ward at Emory University in Atlanta. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. 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