Hunger hormone: Makes food more attractive

May 06, 2008

A new brain-imaging study by researchers at the Montreal Neurological Institute, McGill University reveals that ghrelin - a stomach hormone, acts on specific regions of the brain to enhance our response to food related cues and eating for pleasure. This study, published in the May 7 issue of Cell Metabolism, is critical to advance understanding and treating obesity, a condition affecting millions world-wide.

Appetite was previously thought of as being controlled by two separate mechanisms: homeostatic and non-homeostatic or hedonic food consumption. Homeostatic feeding is controlled by hormones such as ghrelin, that act on the brain to tell the body when to eat in an attempt to keep a constant body weight. Hedonic consumption is triggered by visual or smell cues. For example, wanting to eat a piece of cake just because it looks good and will bring pleasure when eaten. This study demonstrates that both food consumption behaviours are inter-connected and a key player in their regulation is the stomach hormone ghrelin.

“Our study demonstrates that ghrelin actually activates certain regions of the brain to be more responsive to visual food cues, thereby enhancing the hedonic and incentive responses to food-related cues,’ says Dr. Alain Dagher, neurologist at the Montreal Neurological Institute, McGill University and principal investigator in the study. “Ghrelin is a hormone that triggers hunger, and is secreted by the stomach [when it is empty]. An easy analogy would be to think about when you go shopping on an empty stomach, you tend to buy more food and products higher in calories. The reason is that your brain views the food as more appealing, largely due to the action of ghrelin on the brain.”

The study supports the view that obesity must be understood as a brain disease and that hunger should also be looked at as a kind of food addiction. Obese individuals may eat too much largely due to excess hunger. Dr. Dagher and colleagues found that ghrelin worked on regions of the brain known to be involved with reward and motivation, the same regions implicated in drug addiction – the amygdala, insula, the orbitofrontal cortex (OFC) and striatum. “These areas work together to assign incentive value to objects in the world and to actions, and exert very powerful control over our behavior. They are all targets of addictive drugs (like cocaine and nicotine), and are also targets of feeding signals like ghrelin,” explains Dr. Dagher.

Participants in the study were shown images of food and scenery [as a control] before and after receiving ghrelin intravenously during functional magnetic resonance imaging (fMRI). In addition to analyzing the activation of different brain regions, subjects also answered questions about their mood and appetite before and after seeing sets of images. The effects of ghrelin on the amygdala and OFC correlated with the self-rated hunger ratings.

This study has shown that ghrelin action is more complex than previously thought and furthers our understanding of how drug treatment might be used to combat obesity. This research may also inform public policy. If food is thought of as potentially ‘addictive,’ this would support action to limit or ban fast food from schools and junk food advertisements geared towards children, in the same way that results proving nicotine to be addictive spurred the current public policy towards nicotine

Source: Montreal Neurological Institute and Hospital

Explore further: New compounds protect nervous system from the structural damage of MS

add to favorites email to friend print save as pdf

Related Stories

Genetic changes behind sweet tooth

Apr 04, 2011

The substance ghrelin plays an important role in various addictions, such as alcoholism and binge-eating. It also impacts on sugar consumption, which is due, in part, to genetic factors, reveals new research from the University ...

Recommended for you

3-D printing offers innovative method to deliver medication

28 minutes ago

3-D printing could become a powerful tool in customizing interventional radiology treatments to individual patient needs, with clinicians having the ability to construct devices to a specific size and shape. That's according ...

Mystery of the reverse-wired eyeball solved

Feb 27, 2015

From a practical standpoint, the wiring of the human eye - a product of our evolutionary baggage - doesn't make a lot of sense. In vertebrates, photoreceptors are located behind the neurons in the back of the eye - resulting ...

Neurons controlling appetite made from skin cells

Feb 27, 2015

Researchers have for the first time successfully converted adult human skin cells into neurons of the type that regulate appetite, providing a patient-specific model for studying the neurophysiology of weight ...

Quality control for adult stem cell treatment

Feb 27, 2015

A team of European researchers has devised a strategy to ensure that adult epidermal stem cells are safe before they are used as treatments for patients. The approach involves a clonal strategy where stem cells are collected ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.