How Your Brain Controls Whether You Find a Salty Snack Tasty or TerribleNews
The Context: Why is it that sometimes you feel a desperate need for a salty snack, and other times you can’t think of anything worse? Your brain is responsible for regulating your affinity (or aversion) to salt to maintain healthy levels within the body, but scientists have not been sure exactly how it does this.
The Study: New research from NYSCF – Robertson Neuroscience Investigator Yuki Oka, PhD, of the California Institute of Technology reveals a distinct neural circuit in the mouse brain responsible for regulating whether you react to salt with a ‘yuck’ or yum’. The study appears in Cell.
The Importance: This study helps illuminate the intricate brain circuitry behind salt regulation, providing important insights into how the body maintains homeostasis.
Salt plays a bigger role in your body than you might think: we need to maintain a delicate balance of sodium in our blood to continue functioning properly.
“Low sodium concentration is palatable, while higher concentrations—for example, ocean water—taste disgusting,” Dr. Oka told CalTech News. “But when you’re really in need of salt, you don’t mind the bad taste. The palatability or ‘tastiness’ of salt changes based on its concentration and the body’s internal sodium need.”
The Oka lab has previously discovered how the brain controls our affinity for salt through neurons in a region called the hindbrain, but how it regulates our aversion to salt has been unclear.
In their new study, the team found that neurons located in the forebrain are responsible for managing our tolerance to salt. When these neurons are active, mice can tolerate a super-salty snack that they might otherwise find aversive, a necessary measure for ensuring they get enough salt. If these neurons are blocked, a sodium-lacking mouse will turn its back to an extra-salty snack, even if they desperately need the boost.
However, it appears that these newly-discovered salt tolerance neurons aren’t directly connected to the previously-identified salt affinity neurons. So what’s controlling them?
The answer lies with a hormone called prostaglandin E2 (PGE2). PGE2 is typically associated with inflammation, making it a surprising intermediary for salt aversion. However, it appears PGE2 is binding to the salt tolerance neurons to control their activity.
“This unexpected association between prostaglandin and sodium consumption raises important questions regarding how an inflammatory state might influence sodium intake, offering new insights into the interplay between sodium levels and the body’s pro-inflammatory condition,” remarked Yameng Zhang, a graduate student in the Oka lab.
Parallel neural pathways control sodium consumption and taste valence
Yameng Zhang, Allan-Hermann Pool, Tongtong Wang, Lu Liu, Elin Kang, Bei Zhang, Liang Ding, Kirsten Frieda, Richard Palmiter, Yuki Oka. 2023. Cell. DOI: https://doi.org/10.1016/j.cell.2023.10.020
Cover image credit: CalTech