Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Identify Another Piece of the Weight-Control Puzzle

12.08.2008
As scientists continue to investigate the brain's intricate neurocircuitry and its role in maintaining energy balance, they are forming a clearer picture of the myriad events that lead to weight gain and weight loss.

Controlling body weight is a complicated process, as any frustrated dieter might attest. But as scientists continue to investigate the brain’s intricate neurocircuitry and its role in maintaining energy balance, they are forming a clearer picture of the myriad events that lead to weight gain and weight loss.

In the August 10 on-line issue of Nature Neuroscience, a study led by scientists at Beth Israel Deaconess Medical Center (BIDMC) identifies another piece of this complex puzzle, demonstrating that the neurotransmitter GABA --one of the master communicators among neurons – plays a role in controlling energy balance.

“Body weight maintenance is made up of three basic stages,” explains the paper’s senior author Bradford Lowell, MD, PhD, an investigator in the Division of Endocrinology, Diabetes and Metabolism at BIDMC whose laboratory is working to identify the specific neurocircuits responsible for controlling food intake and/or energy through functional neuroanatomical mapping studies.

“In the first stage, the brain receives sensory input from the body [including information provided by circulating hormones such as leptin and ghrelin and from fuels such as glucose and fatty acids],” says Lowell, who is also a Professor of Medicine at Harvard Medical School.

In the second stage, he adds, the brain integrates this sensory information with cues it has received from the environment (such as aromas and other enticements) along with information gathered from the organism’s emotional state. Then, in the final stage, the brain’s neurocircuitry takes over, enabling the brain to make appropriate alterations in food intake and energy expenditure in order to maintain energy balance – and prevent weight gain and obesity.

Previous work had primarily focused on identifying the neuropeptides involved in this process. And indeed, this group of neurotransmitters often proves essential to maintaining energy balance – but not always.

“It is well known that AgRP [Agouti-related protein] neurons play a critical role in feeding and energy balance regulation,” explains Qingchun Tong, PhD, a postdoctoral fellow in the Lowell laboratory and the study’s first author. “However, the deletion of AgRP and NPY [two neuropeptides released from the AgRP neurons] produces little metabolic effect.”

An alternate theory proposed that release of the GABA neurotransmitter was mediating the function of AgRP neurons, an idea that had long been postulated but never examined.

To test this hypothesis, Tong and his colleagues generated a group of mice with disrupted release of GABA specifically from the AgRP neurons. As predicted, the genetically altered mice exhibited profound metabolic changes.

“The mice with AgRP neuron-specific disruption of GABA release were lean, had higher energy expenditure and showed resistance to diet-induced obesity,” says Tong. “We also found that these animals showed reduced food intake response to the hormone ghrelin. This suggests to us that the neurocircuit engaging GABA release from the AgRP neurons mediates at least part of ghrelin’s appetite-stimulating action.”

A series of studies to examine the function of glutamate and GABA release from other groups of neurons are currently underway as investigators continue to dissect the brain’s neurocircuitry.

“As these new findings demonstrate, GABA release is an important component that mediates the function of AgRP neurons,” says Tong. “Discoveries such as this will ultimately help us to design an efficient strategy to tackle the current epidemic of obesity and metabolic disease.”

This work was funded, in part, by grants from the National Institutes of Health and support from the North American Association for the Study of Obesity.

In addition to Lowell and Tong, coauthors include BIDMC investigators Chian-Ping Ye and Juli Jones and University of Texas Southwestern Medical Center investigator Joel Elmquist.

Beth Israel Deaconess Medical Center is a patient care, teaching and research facility of Harvard Medical School and consistently ranks among the top four in National Institutes of Health funding among independent hospitals nationwide. BIDMC is clinically affiliated with the Joslin Diabetes Center and is a research partner of Dana-Farber/Harvard Cancer Center. BIDMC is the official hospital of the Boston Red Sox.

Bonnie Prescott | Newswise Science News
Further information:
http://www.bidmc.harvard.edu

More articles from Health and Medicine:

nachricht 'Icebreaker' protein opens genome for t cell development, Penn researchers find
21.02.2018 | University of Pennsylvania School of Medicine

nachricht Similarities found in cancer initiation in kidney, liver, stomach, pancreas
21.02.2018 | Washington University School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

21.02.2018 | Life Sciences

The “Holy Grail” of peptide chemistry: Making peptide active agents available orally

21.02.2018 | Life Sciences

Atomic structure of ultrasound material not what anyone expected

21.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>