BUSM researchers show dieters can experience neurobiological similarities of drug addicts

November 09, 2009

(Boston) - Researchers from Boston University School of Medicine (BUSM) have shown that intermittent access to foods rich in fat and sugar induces changes in the brain which are comparable to those observed in drug dependence. The findings, reported in the journal Proceedings of the National Academy of Sciences, may explain how abstinence from these foods contributes to relapse eating among dieters as well as related eating disorders.

Forms of obesity and eating disorders can be defined as chronic relapsing conditions with alternating periods of abstinence (dieting to avoid "forbidden" foods-rich in sugar and fat also known as palatable foods) and relapse (compulsive, often uncontrollable, eating of highly-palatable foods) that continue despite negative consequences. Although the positive reinforcing properties of palatable foods are well known, less attention has been given to the increased probability of a behavioral response produced by removal of an aversive stimulus (intake of palatable food to relieve negative emotional states).

The researchers used 155 rats to measure the neurobiological responses. The first group, the diet cycled subjects, repeatedly ate standard rat chow for five days, followed by a highly palatable, high-sugar, chocolate-flavored chow for two days. The second group ate only standard food. The amount of food consumed was not restricted for either group. When the diet-cycled rats were fed standard chow, they showed less motivation to obtain it, refused it, although it was previously acceptable, and they exhibited anxiety. However when the rats resumed eating the palatable food, they overate and their anxiety-related behaviors returned to normal.

The researchers then looked at the role of the brain's stress system, which contributes to cycles of drug and alcohol binging and withdrawal, in driving these behaviors. They found that during abstinence from palatable foods, the rats showed increased corticotropin-releasing factor (CRF) gene expression and peptide in the amygdala, an area of the brain involved in fear, anxiety and stress responses. Similar to the anxiety, only when the diet-cycled group was fed palatable food did CRF levels return to normal. Importantly, the blockade of the CRF receptor 1 with a selective antagonist was able to prevent all the behavioral outcomes of palatable food withdrawal.

According to the researchers, CRF is a key stress neurotransmitter. "In observing the activation of the amygdaloid CRF system during abstinence from palatable foods, we understood the causes of recurrent dieting failures," said study co-author Pietro Cottone, PhD, an assistant professor and co-director of the Laboratory of Addictive Disorders in the Department of Pharmacology and Experimental Therapeutics at BUSM.

"CRF activation during abstinence from palatable foods induces a negative emotional state which is responsible for signs of anxiety and contributes to relapse to 'forbidden foods,'" added study co-author Valentina Sabino, PhD, an assistant professor and co-Director of the Laboratory of Addictive Disorders in the Department of Pharmacology and Experimental Therapeutics at BUSM. "The stress experienced by frequent dieters in abstinence from palatable food has neurobiological similarities to the negative emotional state of drug and alcohol addicts."
In addition to Cottone and Sabino, the paper, "CRF system recruitment mediates dark side of compulsive eating," was authored by Marisa Roberto, Michal Bajo, Lara Pockros, Jennifer B. Frihauf, Eva M. Fekete, Bruno Conti, George Koob and Eric Zorrilla from the Scripps Research Insitutute; Luca Steardo of the University of Roma La Sapienza (Rome, Italy); Kenner C. Rice of the National Institute on Drug Abuse of the National Institutes of Health (NIH), and Dimitri E. Grigoriadis of Neurocrine Biosciences.

This study was supported by the National Institute on Drug Abuse; the National Institute on Alcohol Abuse and Alcoholism; the National Institute of Diabetes and Digestive and Kidney Diseases; the Pearson Center for Alcoholism and Addiction Research; the Intramural Research Programs of the National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism.

Boston University Medical Center

Related Stress Articles from Brightsurf:

Stress-free gel
Researchers at The University of Tokyo studied a new mechanism of gelation using colloidal particles.

Early life stress is associated with youth-onset depression for some types of stress but not others
Examining the association between eight different types of early life stress (ELS) and youth-onset depression, a study in JAACAP, published by Elsevier, reports that individuals exposed to ELS were more likely to develop a major depressive disorder (MDD) in childhood or adolescence than individuals who had not been exposed to ELS.

Red light for stress
Researchers from the Institute of Industrial Science at The University of Tokyo have created a biphasic luminescent material that changes color when exposed to mechanical stress.

How do our cells respond to stress?
Molecular biologists reverse-engineer a complex cellular structure that is associated with neurodegenerative diseases such as ALS

How stress remodels the brain
Stress restructures the brain by halting the production of crucial ion channel proteins, according to research in mice recently published in JNeurosci.

Why stress doesn't always cause depression
Rats susceptible to anhedonia, a core symptom of depression, possess more serotonin neurons after being exposed to chronic stress, but the effect can be reversed through amygdala activation, according to new research in JNeurosci.

How plants handle stress
Plants get stressed too. Drought or too much salt disrupt their physiology.

Stress in the powerhouse of the cell
University of Freiburg researchers discover a new principle -- how cells protect themselves from mitochondrial defects.

Measuring stress around cells
Tissues and organs in the human body are shaped through forces generated by cells, that push and pull, to ''sculpt'' biological structures.

Cellular stress at the movies
For the first time, biological imaging experts have used a custom fluorescence microscope and a novel antibody tagging tool to watch living cells undergoing stress.

Read More: Stress News and Stress Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.