"It has also been well established that ghrelin activates feeding through its effects on the hypothalamus, where ghrelin receptors are densely concentrated. However, ghrelin also has specific effects on many brain regions implicated in reward and motivation.
[After ghrelin infusion], food pictures become even more salient—people actually see them better. It influences not only visual processing, but also memory. People remembered the food pictures better when ghrelin was high.”"
A gut hormone that causes people to eat more does so by making food appear more desirable, suggests a new report in the May issue of Cell Metabolism, a publication of Cell Press. In a brain imaging study of individuals, the researchers found that reward centers respond more strongly to pictures of food in subjects who had received an infusion of the hormone known as ghrelin.
The findings suggest that the two drives for feeding—metabolic signals and pleasure signals—are actually intertwined.
“When you go to the supermarket hungry, every food looks better,” said Alain Dagher of the Montreal Neurological Institute at McGill University. “Your brain assigns a cost versus benefit to every food item. Now, we’ve found that it is ghrelin that acts on the brain to make food more appealing.”
Ghrelin levels are known to rise before a meal and fall afterwards, suggesting that it causes hunger and encourages eating. |
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