Study describes mechanism that makes people more vulnerable to stimuli that cause hunger


The holiday season is difficult for anyone who is watching their weight. The sights and smells of food are hard to resist. One factor in this response to hunger is a hormone found in the stomach that makes us more vulnerable to tasty smells, encouraging overeating and obesity.

New research on the hormone ghrelin was published today Cell Reports on December 4, 2018, led by Dr. Alain Dagher's laboratory at the Montreal Neurological Institute and McGill University Hospital.

Previous research by Dr. Dagher's group and others has shown that ghrelin stimulates the feeding and production of dopamine, a neurotransmitter important for the reward response. In the current study, the researchers injected 38 grains of ghrelin and exposed them to a variety of odors, both food and non-food, while displaying neutral images of random objects, so that over time, subjects associated images with odors .

Using functional magnetic resonance imaging (fMRI), the researchers recorded activity in regions of the brain known to be involved in the reward response of dopamine. They found that activity in these regions was greater in patients with ghrelin injections, but only when responding to images associated with food smells. This means that ghrelin is controlling the extent to which the brain associates reward with food odors.

The subjects also evaluated the pleasantness of the images associated with food odor, and the results showed that ghrelin reduced response time and increased the sensation of pleasure of food-associated images, but had no effect on their reactions to images associated with odors not food.

People who struggle with obesity often have abnormal reactivity to food-related tips that are plentiful in our environment, for example, fast food advertising. This study shows that ghrelin may be an important factor in its increased response to food suggestions. The identified brain regions have been associated with a neural endophenotype that confers vulnerability to obesity, suggesting a genetically based hypersensitivity to food-related images and odors.

"Obesity is becoming more common all over the world and is well known to cause health problems such as heart disease and diabetes," says Dr. Dagher. "This study describes the mechanism by which ghrelin makes people more vulnerable to hunger-inducing stimuli, and the more we know about it, the easier it will be to develop therapies that counteract that effect."


Posted in: Medical News | News from Medical Research | News about medical conditions

Tags: Brain, Cellular, Diabetes, Dopamine, Ghrelin, Heart, Heart Disease, Hormone, Hospital, Hypersensitivity, Image, MRI, Nervous System, Neuroscience, Obesity, Research, Stomach


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