New research has identified receptor sites for stress-activated hormones on oral taste cells that are responsible for our ability to taste sweet, bitter and umami.
The findings suggest that these hormones, known as glucocorticoids, may act directly on taste receptor cells under conditions of stress to affect how these cells respond to sugars and certain other taste stimuli.
"Sweet taste may be particularly affected by stress," suggested lead author M. Rockwell Parker, PhD, from the Monell Chemical Sciences Center in the US. "Our results may provide a molecular mechanism to help explain why some people eat more sugary foods when they are experiencing intense stress."
But, the implications of the study don't finish at a potential influence on how we perceive the foods we put in our mouth. According to senior author Robert Margolskee, MD, PhD, the fact that taste cells are found throughout our body may mean that stress-induced hormones can have much wider effects.
"Taste receptors in the gut and pancreas might also be influenced by stress, potentially impacting metabolism of sugars and other nutrients and affecting appetite," he said - noting that future studies will continue to explore how stress hormones act to affect the taste system.
Writing in Neuroscience Letters, the Monell team reveal that glucocorticoid (GC) type stress hormones affect the body by activating specialized receptors known as GC receptors - which are usually located inside of cells.
Knowing that stress can have major effects on metabolism and food choice, Parker and colleagues used a mouse model to test whether taste receptor cells contain these GC receptors.
They found that GC receptors are present on the tongue, noting that they are specifically localised to the cells that contain receptors for sweet, umami and bitter taste.
Indeed, the highest concentrations of GC receptors were found in Tas1r3 taste cells, which are sensitive to sweet and umami taste, the tram reported.
The Monell researchers then assessed whether the GC receptors they had identified in taste cells are activated by stress by comparing the proportion of taste cells with translocated receptors (that have been modified by activation) in stressed and non-stressed mice.
Compared to their non-stressed counterparts, they found that stressed mice had a 77% increase of GC receptors within taste cell nuclei.
When taken together, the results suggest that sweet taste perception and intake - which are known to be altered by stress - could be specifically affected by the secretion of stress hormones and the subsequent activation of GC receptors in taste cells, said the team.
"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," explained Parker - noting that although stress is known to affect intake of salty foods, GC receptors were not found in cells thought to be responsible for detecting sally and sour taste.
One explanation for this, he said, is that stress may influence salt taste processing in the brain.
Source: Neuroscience Letters
Volume 571, 13 June 2014, Pages 72–77, doi: 10.1016/j.neulet.2014.04.047
"Expression and nuclear translocation of glucocorticoid receptors in type 2 taste receptor cells"
Authors: M. Rockwell Parker, Dianna Feng, Brianna Chamuris, Robert F. Margolskee