This is how stress affects hair growth

Science corroborates what was already suspected: the stress negatively affects our hair. Researchers from Harvard University (USA) have discovered in mice how stress hormones suppress hair growth through regulation of the stem cells of the hair follicle.

This story also appeared in SINC

Hair follicles, the cavities in the skin where hair growth occurs, alternate between growth and rest phases. Previous studies in rodents and humans indicated that stress can affect the Hair growth, but until now it was not known exactly how the two are related.

When corticosterone levels are high, the hair follicles remain in a prolonged resting phase and do not regenerate. But if this hormone is reduced, the stem cells of the hair follicle are activated and the growth of new hair occurs.

Now, the team led by Ya-Chieh Hsu shows how in mice the corticosterone (a hormone released during times of stress, equivalent to cortisol in humans) regulates the activity of hair follicles. The results are published this week in the journal Nature.

“Although stress has been anecdotally associated with many tissue variations, including some hair problems, it was not clear whether it actually caused these damaging changes and, more importantly, the mechanisms underlying these changes remain poorly understood.” , explains to SINC Hsu.

“Last year we discovered that stress depletes the stem cells of melanocytes (the stem cells that give our hair its distinctive color) through changes in the nervous system, which is the basis for stress-induced graying of hair ”, adds the expert.

“In the new work we have identified a completely different mechanism by which stress affects the stem cells of the hair follicle, which are important for regulating the regeneration of these follicles and hair growth,” he continues.

When corticosterone levels are high, hair follicles remain in a prolonged resting phase and do not regenerate. On the contrary, if this hormone is reduced, the stem cells of the hair follicle are activated and the growth of new hair occurs.

“Chronic stress, through corticosterone upregulation, inhibits an activation signal in cells surrounding hair follicle stem cells, which normally promote hair growth,” says Hsu. “Although stress can be detrimental to different skin stem cells, the mechanisms by which changes are triggered in tissues can be diverse, and much remains to be learned.”

GAS6 protein: lejos of its application in humans

According to the authors, corticosterone inhibits the activation of hair follicle stem cells by suppressing the production of a protein called GAS6, which has been shown to promote the proliferation of these stem cells in the absence of corticosterone. Thus, the restoration of GAS6 expression could overcome the inhibition induced by stress and favor the regeneration of hair growth.

“These findings lay the foundation for exploring treatments for hair loss caused by chronic stress,” he says. Rui Yi, researcher at Northwestern University (USA), in an attached article. However, Yi insists that several issues need to be addressed before the results can be translated to humans.

Like any therapy, additional validation steps and rigorous testing will need to be taken to assess both safety and efficacy. Our discovery is only the first step, more work still needs to be done before it can be applied to humans.

For example, corticosterone is the rodent equivalent of human cortisol, but it is not known whether cortisol produces effects identical to those seen in this work in humans. What’s more, hair growth phases differ between mice and humans, which could influence the efficacy of approaches to reverse stress-induced hair follicle stem cell inhibition.

“Like any therapy, there will be many additional validation steps and rigorous testing to evaluate both safety and efficacy. Our discovery is only the first step, there is still more work to be done before it can be applied to humans ”, Hsu points out. “However, these discoveries provide an important molecular pathway that needs to be further explored,” he concludes.