Jan 23, 2020 15:00:00

Elucidation of the mechanism by which stress creates gray hair

By

Julim6

Many stories have been told that `` stress makes hair white '', like an anecdote that Marie Antoinette , who was executed in the French Revolution, turned gray hair overnight the day before the execution, but the mechanism is It was unknown for a long time. A joint research team at Harvard University in the United States and the University of Sao Paulo in Brazil has elucidated the mechanism through animal experiments using mice.

Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells | Nature
https://www.nature.com/articles/s41586-020-1935-3

How the stress of fight or flight turns hair white
https://www.nature.com/articles/d41586-019-03949-8

Scientific evidence found for role of stress in hair whitening | EurekAlert! Science News
https://www.eurekalert.org/pub_releases/2020-01/fda-sef012120.php

Stress speeds up hair greying process, science confirms | Science | The Guardian
https://www.theguardian.com/science/2020/jan/22/stress-speeds-up-hair-greying-process-science-confirms

An experiment conducted by the research team was to stress mice and measure their effects on body hair. The mice used in the experiment were `` pain '', which stimulates pain sensation scientifically by injection, `` psychological stress '', which can tilt the cage, quickly change the light on / off, wet the bed, and one day He was given three types of pain, 'restraint', which fixed his body for four hours. The lower side of the image below is the mouse after the experiment. It is clear that the hair is whiter than the mice that did not undergo the upper stress experiment.

Initially, the research team 'stress is a cell that produce the hair dye

melanin cells had carried out the experiment is estimated to cause an immune attack against (melanocytes)'. However, even in mice without immune cells, cases where the hair turned white after the experiment were confirmed, and this theory was rejected. The next suggested theory was that `` cortisol whose secretion is enhanced by stress is related to gray hair '', but this theory was also denied because the hair of mice without cortisol also became white it was done.

After some twists and turns, the team came to the conclusion that ' noradrenaline released by the sympathetic nervous system under stress affects melanocytes'. In the hair follicle that produces hair , there are stem cells that work to produce other cells. Every time new hair is made, some of the stem cells change into melanocytes, and the newly created melanocytes change the color of the hair.

However, when guanethidine , which has a function of inhibiting neurotransmission to the sympathetic nervous system, is administered to mice, it has been found that the color of the mouse hair remains the same even after the 'pain' experiment in which the hair normally becomes white. Researchers have found that noradrenaline is the cause of gray hair. In addition, a follow-up test of injecting noradrenaline into the skin confirmed that the hair around the injection site became white.

Researchers say that a large number of stem cells are converted to melanocytes when noradrenaline flows into the hair follicles. The excess melanocytes produced during this process will begin to collapse immediately after being released from the hair follicles. Since the number of stem cells that turn into melanocytes decreases but does not increase, after `` wasting '' melanocytes as described above, the hair follicles are depleted of stem cells to make new melanocytes, and thereafter The hair that grows on the skin becomes white.

By XiXinXing

When an animal is under stress such as fear, a series of reactions, the fight and flight response, occur. When this reaction occurs, it produces noradrenaline, which increases sensitivity to attention and impulsivity, raises heart rate and releases energy from fat cells. Researchers argue that stress and gray hair are linked by noradrenaline in humans as well, since the production of melanocytes and the sympathetic nervous system in mice and humans are similar. The researchers also speculate that age-related gray hair is also a result of stem cell depletion.

`` I believe that this study will lead to a new light on the way to understand how stem cell loss affects aging, '' said Ya-Chieh Hsu, who led the study. . `` Individuals with blunted hair have a higher social status in the group than normal, '' said Christopher Deppman, who studies the relationship between stress and hair discoloration at the University of Virginia . 'Because gray hair is often age-related, gray hair tends to be more experienced, leadership, and appear to be more reliable. I have experienced a great deal of stress ”, and that stress experience could enhance your social status.”