In a new study published in Nature, scientists have gained advanced insights into how stress impacts the body. More specifically, senior author Ya-Chieh Hsu, the Alvin and Esta Star Associate Professor of Stem Cell and Regenerative Biology at Harvard, and his team have found evidence to back up anecdotal stories about hair turning grey (or even bright white) after acute stress. Hsu found that when the fight or flight response is triggered, permanent damage to our pigment-regenerating stem cells in hair follicles can result.
Stress affects the whole body, so the first step was to track down the system that connected stress to hair color. They eliminated a possible immune attack as the culprit and then turned to the hormone cortisol, which also resulted in a dead-end. They had removed the adrenals from the mice and established that cortisol couldn’t be the primary factor because stress still resulted in the greying of the mice’s hair. They then turned to the sympathetic nervous system because these nerves branch out to each hair follicle on the skin. What they found was norepinephrine triggered excessive pigment-producing cells which, in turn, burned up the reservoir prematurely and resulted in permanent damage to pigment-regenerating cells.
"Acute stress, particularly the fight-or-flight response, has been traditionally viewed to be beneficial for an animal's survival. But in this case, acute stress causes permanent depletion of stem cells," said postdoctoral fellow Bing Zhang, the lead author of the study. Pinpointing the exact system that was involved didn’t come easily. It required the collaboration of a wide range of scientists from many disciplines. Now that we have information on how stress can alter stem cell function, the foundations have been laid to find a process to revert the detrimental impacts of stress.
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