Researchers at the California Institute of Technology (Caltech) have identified neurons that drive and quench salt cravings in the mouse brain, which would serve as an entry point into regulating sodium cravings in humans.
The research, done in the laboratory of Yuki Oka, assistant professor of biology at Caltech, was published online Wednesday ahead of its publication in the journal Nature.
Sodium, an ion found in table salt, plays a critical role in various body functions, such as cardiovascular activity, fluid balance, and nerve signaling.
However, eating too much salt has potential health risks and can lead to cardiovascular and cognitive disorders.
In every animal species, the body strictly regulates and maintains sodium levels. Because animals cannot metabolically create sodium themselves, the ions have to be ingested from external food sources.
When the body is low on sodium, the brain triggers specific appetite signals that drive the consumption of sodium. Though the mechanisms of these appetite signals are not fully understood, the Caltech researchers discovered a small population of neurons in the mouse hindbrain that controls the drive to consume sodium.
The research team used genetic tools to manipulate the activity of these neurons so that they could be stimulated with light. They observed that artificially stimulating these neurons caused mice to lick a piece of rock salt repeatedly, even when their bodies were completely sated with sodium.
"The desire to eat salt is the body's way of telling you that your body is low on sodium," Oka said. "It is interesting that just the taste of sodium is sufficient to quiet down the activity of the salt-appetite neurons, which means that sensory systems like taste are much more important in regulating the body's functions than simply conveying external information to the brain."
In the future, the team would like to understand how sodium-appetite neurons are modulated over time, which may open up avenues to help people with health issues to eat less sodium in their diets, according to the study.