A Brain Pathway That Regulates Eating
Post by Rebecca Hill
The takeaway
Overeating leading to obesity can be caused by mutations in brain signaling molecules. One neural circuit in the hypothalamus regulates this overeating behavior.
What's the science?
The brain regulates eating by taking signals from our body about our internal state and processing them into behavioral responses such as eating. Brain-derived neurotrophic factor (BDNF) is a signaling molecule in the brain expressed in the hypothalamus, the brain area responsible for regulating hunger, and other bodily functions. This week in Nature, Kosse and colleagues studied which specific pathway in the brain controls our eating and jaw movements.
How did they do it?
Using optogenetics, a technique that uses light to control the activity of certain cells in the brain, the authors activated or inhibited the activity of BDNF cells in the hypothalamus of mice. The authors fasted mice before the experiment to make sure the mice would be hungry enough to eat. They then measured how much food mice ate to determine how this affected the feeding behavior controlled by these cells. The authors also specifically examined this effect in obese mice to determine if feeding behavior changed after BDNF cell activity was inhibited.
What did they find?
When the authors activated BDNF cells in the hypothalamus, fasted mice did not increase feeding behavior. This means that even though mice had a drive to eat, BDNF cell activity prevented them from feeding. When the authors inhibited BDNF cells in the hypothalamus, mice ate more due to more jaw movements triggered by this neural pathway. When BDNF cell activity was inhibited in obese mice, mice continued feeding behavior despite not needing to eat. This means that the BDNF cell pathway in the hypothalamus processes input about the energy state of an animal and outputs feeding behavior from it.
What's the impact?
This study is the first to find a neural pathway linked to feeding behavior in which its breakdown leads to obesity. Obesity is a widespread issue, with many struggling to overcome eating behaviors. With the information found in this study, we may be able to develop more effective treatments for overeating behaviors.