Editor's note: On December 14, 2020, the international journal Nature announced the top ten major scientific discoveries in 2020. One of these ten major scientific discoveries is " Harvard University team discovered the mechanism of white hair overnight."
For a long time, scientists have not known what mechanism is causing human haircuts overnight. Everyone believes that stress is the cause of nightly white haircuts overnight, but there is no scientific evidence to prove that stress is the cause of nightly white haircuts.
Queen Mary's haircut overnight Photo: Wikipedia
The most famous person who has white haircut overnight in Chinese history and clearly recorded in history books is Wu Zixu . The most famous person who has white haircut overnight in Europe is the king of France Louis XVI Queen of Marie Antoinette . She has white haircut overnight because of her abolished queen. To this day, she has white haircut overnight in Europe is also called "Mary Antoinette's disease".
On January 22, 2020, the research team at Harvard University released a related research report on one night of white hair in the international journal Nature, which pointed out that their research team has found the physiological operating mechanism of "one night of white hair".
The general research process is as follows:
First, the research team took black mice as the experimental subject. They first need to confirm whether the hair color fading of the black mice used in the experiment is related to the pressure they are under. To confirm the relationship between the two, the researchers exposed black mice to various stressors set by the experiment, including tethering pressure, chronic unpredictable pressure and nociceptive pressure, such as: tilting the cage, turning on the lights all night, etc. The final results show that under pressure, the hair color of black mice becomes significantly lighter with time. The results prove that mice, like humans, will have a hair color fading after they are under pressure of a certain intensity and length.
Subsequently, researchers from the research team injected capsaicin (Resiniferatoxin) as the source of nociceptive induction stress . A few days later, the researchers found through immunofluorescence staining: the number of melanin stem cells in the hair follicles of the experimental mice was greatly reduced, and the result of shows that the decrease in melanin stem cells will make the hair color fade.
At this point, researchers speculate that the reason for the fading of the coat color after under stress is related to the immune system? Therefore, the researchers injected capsaicin (Resiniferatoxin) into experimental mice lacking immune B cells and T cells and . found that the coat color of the experimental mice would also fade, which shows that the mechanism of coat color fade has nothing to do with the immune system.
What mechanism does pressure affect the coat color?
In order to find the answer to this question, the researchers conducted another experiment. They first performed a series of physiological stimulations on the experimental mice, and then tested the hormone content in the blood of the experimental mice. They found that the concentration of corticosterone (a substance produced by the cortex of the adrenal gland) and norepinephrine (also known as "non-adrenaline") in the blood of the experimental mice increased significantly.
Therefore, the researchers used technical means to prevent the experimental mice from secreting corticosterone and injected capsaicin into their bodies. The final results showed that the coat color of the experimental mice was still fading; subsequently, the researchers increased the concentration of the corticosterone in the experimental mice, but the hair color fading phenomenon of the experimental mice did not change. The experimental results of show that corticosterone, known as the stress hormone, is not the main reason for the fading of the coat.
At the same time, the researchers used the same method to prevent the experimental mice from secreting "norepinephrine", and then injected capsaicin into their bodies. A magical phenomenon occurred: the hair color fading phenomenon of the experimental mice disappeared! Subsequently, the researchers injected "norepinephrine" into the bodies of experimental mice, and the hair color around the injected "norepinephrine" was significantly faded, which proved that overnight white hair was related to "norepinephrine"!
Researchers found through in-depth research that when the body feels stress, the sympathetic nerve of melanin stem cells will be activated. The activated sympathetic nerve will cause the sudden release of "norepinephrine". This mechanism will cause melanin stem cells to proliferate rapidly abnormally, then differentiate and migrate, and finally permanently lose, resulting in fading of the hair color.
This article is a submission to the first Zhengzhou Children's Science Popularization Essay Competition selected works
Author: Yifa
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