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When Marie Antoinette was captured during the French Revolution, her hair reportedly turned white overnight. In more recent history, John McCain experienced severe injuries as a prisoner of war during the Vietnam War -- and lost color in his hair.
For a long time, anecdotes have connected stressful experiences with the phenomenon of hair graying. Now, for the first time, Harvard University scientists have discovered exactly how the process plays out: stress activates nerves that are part of the fight-or-flight response, which in turn cause permanent damage to pigment-regenerating stem cells in hair follicles.
The study, published in Nature, advances scientists' knowledge of how stress can impact the body.
"Everyone has an anecdote to share about how stress affects their body, particularly in their skin and hair -- the only tissues we can see from the outside," said senior author Ya-Chieh Hsu, the Alvin and Esta Star Associate Professor of Stem Cell and Regenerative Biology at Harvard. "We wanted to understand if this connection is true, and if so, how stress leads to changes in diverse tissues. Hair pigmentation is such an accessible and tractable system to start with -- and besides, we were genuinely curious to see if stress indeed leads to hair graying. "
Bing Zhang, Sai Ma, Inbal Rachmin, Megan He, Pankaj Baral, Sekyu Choi, William A. Gonçalves, Yulia Shwartz, Eva M. Fast, Yiqun Su, Leonard I. Zon, Aviv Regev, Jason D. Buenrostro, Thiago M. Cunha, Isaac M. Chiu, David E. Fisher, Ya-Chieh Hsu. Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells. Nature, 2020; DOI: 10.1038/s41586-020-1935-3
(Score: 2, Informative) by Anonymous Coward on Friday January 31 2020, @02:18PM (8 children)
Here is an extract of the abstract: "hair greying results from activation of the sympathetic nerves that innervate the melanocyte stem-cell niche. Under conditions of stress, the activation of these sympathetic nerves leads to burst release of the neurotransmitter noradrenaline (also known as norepinephrine). This causes quiescent melanocyte stem cells to proliferate rapidly, and is followed by their differentiation, migration and permanent depletion from the niche."
(Score: 2) by ikanreed on Friday January 31 2020, @03:10PM
Also the latest skeptic's guide to the universe did a good common language breakdown of the research.
(Score: 0) by Anonymous Coward on Friday January 31 2020, @04:33PM (6 children)
It's amazing how little these people know about biology. The behavior of the cell is controlled by the glutathione redox potential:
Quiescent at ~ -240 mV
Proliferating at ~ -270 mV
Differentiating at ~ -200 mV
Apotosing/Necrosing at ~ > -170 mV
The exact values may differ depending on the cell and environment but basically the GSSG/GSH ratio and/or pH in these cells is fluctuating.
So what is clearly happening is first the stress response reduces the intracellular glutathione of these cells, probably to prepare them for some kind of free radical deluge during flight or fight repsonse. This deluge doesn't come so the redox potential remains more negative, which triggers proliferation. However, over time the repeated, chronic stress depletes the ability to recycle glutathione in some way. At this point the GSSG/GSH ratio goes more positive (and/or the equivalent pH change to more acidic happens) and the cells differentiate, attempt to migrate away from the problem or die.
(Score: 4, Funny) by Osamabobama on Friday January 31 2020, @05:30PM (3 children)
I agree; it is amazing that journalists don't understand glutathione redox potential.
Appended to the end of comments you post. Max: 120 chars.
(Score: 0) by Anonymous Coward on Friday January 31 2020, @05:33PM (2 children)
I didn't read what the journalists said, I read the paper written by people getting paid to be experts who clearly are unfamiliar with basic cell biology.
(Score: 0) by Anonymous Coward on Saturday February 01 2020, @09:08AM (1 child)
Appreciate your expert opinion. Biology is not my forte, but it's fascinating, much more so when, as you did, phrased to describe mechanisms but with a bit of hand waving over the too-complex interactions (how does the cell become overstressed/less responsive to repeated similar stimulus, etc. is *incredibly* interesting but also so broad that more detail than you provided would've not really fit).
So yeah, thanks for participating in this discussion as a knowledgeable person. It adds a lot of value for some of us.
(Score: 0) by Anonymous Coward on Saturday February 01 2020, @10:38AM
Thank you. But really it is not so much handwaving as glossing over an aspect that can and will be achieved in any of a dozen different redundant ways.
(Score: 0) by Anonymous Coward on Friday January 31 2020, @09:03PM (1 child)
Is that in the paper, or is this your going in assumption, which is why it would be so clear to you?
(Score: 0) by Anonymous Coward on Friday January 31 2020, @10:10PM
Its an assumption that explains the observed progression in melanocyte activity.