When under stress, many of us reach for sugary foods to make us feel better. Now, researchers from the Monell Chemical Senses Center in Philadelphia, PA, may have discovered why this is. In a new study, the investigators identified receptors for stress-activated hormones located in oral taste buds responsible for detecting sweet, savory and bitter tastes.
The research team, led by M. Rockwell Parker, PhD, recently published their findings in the journal Neuroscience Letters.
According to the researchers, stress can increase secretion of hormones called glucocorticoids (GCs). These hormones activate GC receptors located in the body's cells.
The team explains that GC hormones work by binding to receptors inside their target cells. This activates the receptors, causing them to move to the cell nucleus where it influences protein assembly and gene expression. Activation of the GC receptors is known to influence taste preferences in humans and rodent models.
It is common knowledge that stress greatly influences our food choices. It can lead to emotional eating - an overindulgence of high-calorie, sweet and fatty foods - in an attempt to abolish negative feelings.
With this in mind, the Monell team wanted to see whether taste buds on the tongue contain GC receptors, and if so, whether stress activates these receptors, making us reach for the chocolate.
Stress may trigger GC secretion and receptor activation in sweet-associated taste buds
In mouse models, the researchers found that GC receptors are located on the tongue in cells that are made up of taste receptors responsible for identifying sweet, savory (umami) and bitter tastes.
The highest levels of GC receptors were found in taste cells called Tas1r3, which are specifically sensitive to sweet and umami tastes.
In order to determine whether these GC receptors are triggered by stress, the researchers looked at the number of taste cells that had GC receptors in the nuclei among both stressed and non-stressed mice.
The findings revealed that stressed mice had a 77% higher level of GC receptors in their taste cell nuclei than non-stressed mice.
The researchers say the study results indicate that sweet taste perception and intake of sugary foods may be directly influenced by GC secretion and GC receptor activation, which is triggered by stress.
"Taste provides one of our initial evaluations of potential foods. If this sense can be directly affected by stress-related hormonal changes, our food interaction will likewise be altered," explains Parker, adding:
"Sweet taste may be particularly affected by stress. Our results may provide a molecular mechanism to help explain why some people eat more sugary foods when they are experiencing intense stress."
The researchers add that stress is also known to increase intake of salty foods. But in this study, the team did not find any GC receptors in taste buds associated with salty and sour tastes. Parker says this may be because stress could have an influence on salt taste processing in the brain.
Taste buds are not only found on the tongue; they are also present in the gut and pancreas. The team hypothesizes that stress may also affect taste receptors in these areas.
"Taste receptors in the gut and pancreas might also be influenced by stress, potentially impacting metabolism of sugars and other nutrients and affecting appetite," explains senior author Dr. Robert Margolskee.
But the researchers note that further studies are warranted to better determine the mechanisms behind this.
Earlier this year, Medical News Today reported on a study published in the journal Chemosensory Perception, which found that smoking may hinder taste bud regeneration, affecting smokers' ability to taste the bitterness of coffee.