Table salt is the most common and universal ingredient in food. Salt is essential for the body and it regulates a number of our body functions, but it is also addictive and consumption of excessive salt may lead to a number of health problems. A new research study has now identified nerve cells that drive and quench cravings for salt. The research is said to be an entry point into helping human beings control and overcome salt cravings. A team of researchers conducted experiments that lead to the identification of a group of neurons in the hind brain of mice which regulate the drive to consume sodium. The study was lead by graduate student Sangjun Lee and the team used genetic tools to manipulate the activity of this particular group of neurons, so that they could be stimulated using light.
The researchers found that artificially stimulating these neurons lead to the mice going to lick a piece of rock salt repeatedly, even when their bodies' sodium reserves were intact. The researchers then monitored the activity of these neurons when the mice were eating the sodium. They observed that within seconds of the sodium hitting the tongue of the mice, the activity of the sodium-appetite neurons was inhibited. On the other hand, a direct infusion of sodium into the bellies of the mice, did not have the same effect on the mices' neurons. Additionally, the neural suppression was also not seen to be occurring when sodium receptors on the mice's tongues were pharmacologically blocked.
The results of the research indicated that oral sodium signals that are controlled by the taste system are important for regulating and inhibiting the sodium-appetite neurons. Yuki Oka, assistant professor of biology and Chen Scholar, in whose laboratory the experiments were conducted said, "The desire to eat salt is the body's way of telling you that your body is low on sodium. Once sodium is consumed, it takes some time for the body to fully absorb it. So, it's 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." The study results have appeared online, ahead of their publication in the journal Nature.