Yukta Kulkarni ’22
Before her execution in 1793, French queen Marie Antoinette noticed that her hair was suddenly turning white. Although this story is just folklore, there may be some truth to it in regards to the Marie Antoinette Syndrome, a condition in which one’s hair abruptly turns white. To further explore this syndrome, Zhang et al. designed an experiment measuring the rate of hair greying in mice after experiencing acute stress in conjunction with the depletion of melanocyte stem cells.
Balanced groups of male and female mice with black coats were used within the experiments, where all mice were also in the same hair cycles (determined by shaving their hair and monitoring qualitative changes) and age ranges. The mice were put through three types of stress to induce hair greying: restraint stress, chronic unpredictable stress, and nociception-induced stress. The research team found that all three of the stressors instigated an increase in grey hair (unpigmented hair) numbers, with restraint stress and chronic unpredictable stress leading to grey-hair production within 3-5 of hair cycles and nociception-induced stress leading to grey-hair production after just one round of hair cycles. By tracking melanocyte stem cell depletion with the injection of RTX (nociception-induced stress) into the mice, it can be reasonably concluded that a lack of these cells is correlated with grey hair. Under stress, sympathetic nerves are activated and the release of norepinephrine (a neurotransmitter) is expedited, causing melanocytes to multiply rapidly. By proliferating, these cells differentiate and migrate, decreasing the number of melanocyte stem cells at the original niche and bringing about grey hair. This effect of melanocyte stem cells on the discoloration of hair was supported by a trial in which stress was applied to the mice, but the proliferation and migration of the melanocyte stem cells were blocked, thus preventing grey, discolored hair from coming about.
Acute stress leads to a permanent depletion of melanocyte stem cells, which can have multiple negative effects, including non-reversible damage to tissue regeneration. This study opens up doors in regards to pigment-producing cells and their connection to the nervous system. This may provide insight into understanding how animals such as octopi or chameleons change the color of their integument in response to stress or danger by coordinating with their nervous system.
- B. Zhang, et al., Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells. Nature 577, 676-681 (2020). Doi: https://doi.org/10.1038/s41586-020-1935-3
- Image retrieved from: https://commons.wikimedia.org/wiki/File:Marie-Antoinette_en_grand_habit_de_cour_-_1778_-_Elisabeth_Louise_Vig%C3%A9e_Le_Brun_(2).jpg