2023-09-01 11:40:00
As soon as the start of the school year begins, the benefits of the holidays already seem distant. A survey by Protime even reveals that one out of six Belgian employees finds themselves overwhelmed with work on their return from vacation. Stress is often associated with the appearance of white hair, so much so that it has become an expression to say that we are worried. But is it really justified?
Scientists at Harvard University wanted to find out if stress could really change our hair color. Because stress affects the entire body, the researchers first had to determine which body system was responsible for the link between stress and hair color. Although they initially suspected an immune attack on pigment-producing cells, they then turned to the hormone cortisol (which plays a critical role in blood glucose balance and sugar release). “Stress always raises cortisol levels in the body, so we thought cortisol might play a role,” said study lead author Ya-Chieh Hsu, a professor of regenerative biology at Harvard. “But surprisingly, when we removed the adrenal glands from the mice so they couldn’t produce cortisol-like hormones, their hairs turned gray from the stress.”
After eliminating various possibilities, the researchers turned to the sympathetic nervous system. They found that stress causes sympathetic nerves to release norepinephrine, which is taken up by nearby stem cells that regenerate pigment.
Irreversible damage
In the hair root, certain stem cells act as a reservoir of pigment-producing cells. Because of stress, all hair stem cells turn into pigment-producing cells. In the long term, the hair prematurely exhausts its reservoir of pigment, and it remains white. “When we first started researching this question, I expected stress to be bad for the body – but the negative impact of stress we found exceeded what I had imagined,” Hsu commented. . “After only a few days, all pigment-regenerating stem cells were lost. Once they have disappeared, the pigment can no longer be regenerated. The damage is permanent.”
The results can help shed light on the broader effects of stress on various organs and tissues. This discovery will pave the way for further studies aimed at modifying or blocking the harmful effects of stress. “Understanding how our tissues change under stress is the critical first step towards a possible treatment that can halt or reverse the damaging effects of stress. We still have a lot to learn in this area.”
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