Key Brain Cells Discovered in Delaying First Bite of Food

Scientists at Scripps Research have pinpointed a group of neurons in the previously overlooked parasubthalamic nucleus (PSTN) that govern the initiation of feeding behavior. These cells integrate sensory cues and internal signals to determine when an animal will start eating.

The study published in Molecular Psychiatry was to specifically alter a subset of PSTN cells that become more active during episodes of binge eating. The team wondered how these cells might affect appetite since other scientists have noted that many PSTN cells become active after a big meal.

In our study, we used a technique that let us turn on cells in the mouse brain that were activated by a specific experience—in this case, binge-eating. Once we have captured this ensemble of PSTN cells, we can turn them on like a light switch and watch what happens to the animals’ eating and drinking.”

Jeff Dunning, Ph.D., Staff Scientist and First Author, Scripps Research

The group of cells that the researchers discovered were sensitive to binge eating and were able to significantly alter the behavior of mice. When food is presented to hungry mice, they typically begin gorging on it right away. It was surprising to see that mice were much slower to start eating and much faster to drink water when researchers turned on this group of PSTN cells.

Our results tell us that this specific group of PSTN cells guide the early stages of hunger-driven decision making, before eating actually occurs. The effect on water drinking is somewhat counterintuitive, but it might be related to prandial thirst- the phenomenon whereby thirst gets stimulated as soon as we start eating.”

Jeff Dunning, Ph.D., Staff Scientist and First Author, Scripps Research

Through the manipulation of even more subsets of cells within the PSTN, the researchers were able to identify precisely which cell groups were in charge of accelerated drinking and delayed eating. They also found that mice are encouraged to eat more sweet foods by a different subset of PSTN cells.

Altogether, these results reveal that PSTN neurons exert a complex combination of functions. Several studies had previously shown that PSTN activity can limit the amount of food eaten, but the fact that certain PSTN neurons control the onset of feeding or drinking, or even promote the consumption of food ‘treats,’ is entirely novel.”

Candice Contet, Ph.D., Study Senior Author and Associate Professor, Department of Molecular Medicine, Scripps Research

Contet, Dunning, and associates believe that their research may be relevant to eating disorders in which individuals have insufficient or excessive control over when to start eating - the choice to take a bite right away or to hold off. Similar mechanisms could also be involved in the loss of control over rewarding substances like drugs of abuse, which the team is currently looking into, but they do not just apply to food and water.