If someone invited you to have a piece of cake and you started a diet this morning to lose a little weight, would you grab a fork and take the first bite of the cake, or would you say no and walk away?
Our drive to eat is controlled by a complex network of cells in the brain, and these cells use signals from within the body—as well as sensory information about the food in front of us—to determine our behavior.
Cells decide when to bite first
Scientists from the Scripps Research Institute have identified a group of neurons in a small, little-studied area of the brain—the lateral hypothalamic nucleus—that controls when an animal takes its first bite of food.
The team of scientists set out to selectively manipulate a group of lateral hypothalamic nucleus cells that become more active during binge eating episodes in the study, published in the journal Molecular Psychiatry on July 4. Other scientists had observed that many lateral hypothalamic nucleus cells become active after a large meal, but the team wondered how these cells might influence appetite.
Do you start with water or food?
The research team found that the group of cells sensitive to binge eating was able to dramatically change the behavior of the mice. Hungry mice usually start eating quickly as soon as it becomes available, but when the researchers turned on this group of cells in the lateral hypothalamic nucleus, the mice were much slower to start eating, but were much faster to drink water.
“Our results tell us that this specific group of lateral hypothalamic nucleus cells directs the early stages of hunger-induced decision-making before eating actually begins,” Dr. Jeff Dunning, a scientist at Scripps Research and the study’s first author, told EurekAlert. “The effect on water intake is somewhat counterintuitive, but it may be related to food-induced thirst, the phenomenon in which thirst is stimulated as soon as we start eating.”
Sweet foods
By manipulating smaller groups of cells within the lateral hypothalamic nucleus, the team learned which groups of cells were responsible for delaying eating and accelerating drinking. They also discovered that another group of lateral hypothalamic nucleus cells stimulates another effect, prompting mice to eat more sweet foods.
“Together, these findings reveal that lateral hypothalamic nucleus neurons exert a complex array of functions,” said lead researcher Dr. Candice Conti, an associate professor in the Department of Molecular Medicine at The Scripps Research Institute. “Several previous studies have shown that lateral hypothalamic nucleus activity can limit the amount of food we eat, but the fact that some lateral hypothalamic nucleus neurons control the initiation of eating or drinking, or even encourage the consumption of sweet foods, is completely new.”
Eating disorders
Conti, Dunning and colleagues believe their findings may be relevant to eating disorders, where people have either too much or too little control over whether to start eating and decide whether to take the first bite or wait longer.
In addition to food and water, similar mechanisms may play a role in the loss of control over substance use, such as drug addiction, which the team is currently investigating.