Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Obesity Predisposition Traced to the Brain’s Reward System

30.07.2008
New research links overeating and obesity with the brain system implicated in pleasure and addictive behaviors strengthening the argument that obesity could be approached as an addictive disorder. This is the first study to demonstrate that obesity predisposition is associated with impairments in all midbrain dopamine systems that are in place early in postnatal life.

The tendency toward obesity is directly related to the brain system that is involved in food reward and addictive behaviors, according to a new study.

Researchers at Tufts University School of Medicine (TUSM) and colleagues have demonstrated a link between a predisposition to obesity and defective dopamine signaling in the mesolimbic system in rats. Their report appears in the August 2008 issue of The FASEB Journal.

The mesolimbic system is a system of neurons in the brain that secretes dopamine, a neurotransmitter or chemical messenger, which mediates emotion and pleasure. The release of the neurotransmitter dopamine in the mesolimbic system is traditionally associated with euphoria and considered to be the major neurochemical signature of drug addiction.

“Baseline dopamine levels were 50 percent lower and stimulated dopamine release was significantly attenuated in the brain reward systems of obesity-prone rats, compared with obesity-resistant rats. Defects in brain dopamine synthesis and release were evident in rats immediately after birth,” said Emmanuel Pothos, PhD, assistant professor in the department of pharmacology and experimental therapeutics at TUSM and member of the neuroscience program faculty of the Sackler School of Graduate Biomedical Sciences.

“Previous research has demonstrated that food intake leads to an increase in the release of dopamine, in the circuits that mediate the pleasurable aspects of eating,” Pothos explains. “Also, chronic food deprivation resulting in decreased body weight leads to decreased dopamine levels. Therefore, increased food intake may represent a compensatory attempt to restore baseline dopamine levels.”

Pothos says, “These findings have important implications in our understanding of the obesity epidemic. The notion that decreased dopamine signaling leads to increased feeding is compatible with the finding from human studies that obese individuals have reduced central dopamine receptors.” He speculates that an attenuated dopamine signal may interfere with satiation, leading to overeating.

Pothos and colleagues conducted their research using obesity-prone and obesity-resistant rats. Adult obesity-prone rats consumed more food and were 20% heavier than obesity-resistant rats.

The researchers measured electrically-evoked dopamine release from nerve terminals. “We also measured regulators of dopamine synthesis and release in midbrain dopamine pathways,” explains Brenda Geiger, first author and graduate student in the pharmacology and experimental therapeutics department at TUSM. “Our molecular analysis suggests that the central dopamine deficits are most likely caused by reduced expression of the genes encoding two proteins, one that is involved in dopamine synthesis, and another that is a transporter responsible for packaging dopamine into vesicles from which it is later released upon stimulation.”

“Obesity has so far been approached mostly as a metabolic rather than as an addictive disorder; and obesity research has primarily focused on brain systems that regulate body weight through the maintenance of energy balance. The current study challenges this approach by focusing on brain pathways implicated in pleasure and reward. These pathways could override energy balance and induce hyperphagia and obesity by altering the reward value of food, particularly palatable high-energy food, very early in life,” says Pothos, who is the study’s corresponding and senior author.

According to Gerald Weissmann, MD, editor-in-chief of The FASEB Journal, "Now we know why so many people stay addicted to food: it fuels the mid-brain pleasure machinery. We eat not only for nourishment, but also for pleasure. This study provides the molecular link between eating and mental health." The FASEB Journal (http://www.fasebj.org) is published by the Federation of American Societies for Experimental Biology (FASEB).

This research was funded by grants from the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute on Drug Abuse, both institutes of the National Institutes of Health, and the Smith Family Awards for Excellence in Biomedical Research. The work was conducted in the Department of Pharmacology and Experimental Therapeutics at Tufts University School of Medicine and the Tufts Center for Neuroscience Research (CNR).

Geiger BM, Behr GG, Frank LE, Caldera-Siu AD, Beinfeld MC, Kokkotou EG, Pothos EN. The FASEB Journal. 2008 (August); 22 (8): 2740-2746. “Evidence for defective mesolimbic dopamine exocytosis in obesity-prone rats.”

About Tufts University School of Medicine
Tufts University School of Medicine and the Sackler School of Graduate Biomedical Sciences at Tufts University are international leaders in innovative medical education and advanced research. The School of Medicine and the Sackler School are renowned for excellence in education in general medicine, special combined degree programs in business, health management, public health, bioengineering and international relations, as well as basic and clinical research at the cellular and molecular level. Ranked among the top in the nation, the School of Medicine is affiliated with six major teaching hospitals and more than 30 health care facilities. The Sackler School undertakes research that is consistently rated among the highest in the nation for its impact on the advancement of medical science.

Siobhan Gallagher | Newswise Science News
Further information:
http://www.tufts.edu

More articles from Studies and Analyses:

nachricht Real-time feedback helps save energy and water
08.02.2017 | Otto-Friedrich-Universität Bamberg

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>