When Ya-Chieh Hsu, professor of stem cell and regenerative biology at Harvard University and the Harvard Stem Cell Institute, wanted to figure out exactly what makes hair turn grey, she started with an obvious, albeit anecdotal, culprit: stress. There are well-known historical examples of the connection between stress and hair greying—Marie Antoinette’s coif reportedly blanched after she was captured during the French Revolution—and studies have even linked stress in animals to greying hair.
Related Video: Five Foods That Can Actually Prevent Gray HairBut the sympathetic nervous system’s response to stress is generally one of last resort, activated only in a dire emergency when other systems are too slow or have failed. It’s not called into action when you’re behind on a project at work, for example, or are anxious about making an upcoming public presentation.
Story continuesThat’s when Hsu turned to the sympathetic nervous system, and found that it could do permanent damage to a population of cells responsible for coloring hair. “We were really surprised,” she says. “The sympathetic nervous system would have been the last system we thought about. We know it’s activated under stress but you normally think about it as an emergency system, for fight-or-flight responses that are at the very least transient and reversible once the threat is gone.
Hsu found that even during normal stress , the sympathetic nervous system is active, and produces the chemical norepinephrine, which leads to increased muscle contraction, including in the heart. In response to the norepinephrine, the melanocyte stem cells start churning out more than the usual allotment of pigment, misreading the stress-induced cue for the one that signals new hair growth. Eventually, their color reservoir runs dry and they can’t produce pigment any more.
No shit
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