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There is now a scientific explanation for the term “graying hair”. According to Harvard researchers, stress triggers an excessive transformation of stem cells into cells that produce the pigments in our hair. Too much stress would exhaust their number, and with it the number of colored hair or hairs on our bodies.

Le docteur Emmett Brown, le savant (un peu) fou des films Retour Vers Le Futur (Crédits : Amblin Entertainment / Universal Pictures).

Dr. Emmett Brown, the (slightly) mad scientist from the films Back to the Future (Credits: Amblin Entertainment / Universal Pictures).

Science now knows how a stressed person can literally turn gray, even at a young age. Stress does play a role in this. Researchers at Harvard University now have proof of this and point it out in a publication in the journal Nature. Their initial question was about the observable form that the effect of stress on our bodies can take. In response, they wanted to demonstrate how stress can actually make our hair grey or gray – that is, hair without pigmentation.

American scientists have conducted several experiments on laboratory mice. To put them in stressful situations, they physically restrained them against their will or caused them pain. They then observed how the stress thus induced translated into different physiological changes. Suppressing the rodent’s immune defences did not prevent the bleaching of its hair. The removal of their adrenal glands – which synthesize one of the main stress hormones, cortisol – was again not enough to stop the phenomenon. However, by preventing the synthesis of another hormone, norepinephrine (or norepinephrine), the scientists also stopped the bleaching of the hair of the mice studied. This hormone plays a major role in the sympathetic nervous system, which is activated when the body is in action, and, more specifically, in a response called “fight-flight. “The latter, identified in a large number of animals, is the natural reaction to external threats and initiates a fight or flight.

When stress takes its toll

Later, the researchers found that this norepinephrine secretion triggered the differentiation of an abnormally high number of stem cells in the body. In the case of hair, these are transformed into pigment-producing cells. Excessive stress will, by force, exhaust the “reservoir” of stem cells that our body has and therefore of cells capable of giving colour to our hair. This depletion of “pigment cells” occurs gradually with age but is therefore accentuated with stress. By accurately identifying the physiological consequences of stress, we are paving the way to a broader understanding of the effects of stress on our bodies,” said Ya-Chieh Hsu, one of the study’s authors and a Harvard stem cell specialist. This is a first step towards an eventual treatment capable of stopping or reversing the negative impact of stress. »

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Back to The Future :…

  • Universal Pictures France (10/02/2018)
  • DVD, All audiences
  • Operating time: 328 minutes
  • Michael J. Fox, Christopher Lloyd, James Tolkan, Lea Thompson, Crispin Glover