American scientists from Harvard University, together with colleagues from Taiwan, conducted a study that found that goosebumps and hair growth have a common link. The results of the study were published in the journal Cell.
Goosebumps on the skin are traditionally thought to be the body’s protective response to cold. But it turns out that this reflex is inherent in all mammals, including humans. The researchers found that the muscles that cause goosebumps are connected by a sympathetic nerve to the stem cells of the hair follicle. That is, every time goosebumps occur, new hair growth is stimulated.
To study the interaction of different cells when reacting to changes in the environment, scientists conducted experiments on mice. They found that nerve fibers wrap around the stem cells of the hair follicle, creating a kind of synapse-like structure. This allows nerve activity to constantly keep the stem cells ready to regenerate.
Interestingly, severe cooling activates the sympathetic nerve at a higher level, resulting in rapid stem cell activation and new hair growth. When the muscle connected to the hair follicle was removed, the nerve connection to the stem cells was lost.
Thus, the scientists identified a two-component system that regulates hair follicle stem cells. The nerve is the signaling component that activates stem cells through neurotransmitters, and the muscle is the structural component that connects nerve fibers to stem cells.
In addition, the scientists found that the signal comes from the hair follicle itself. It secretes a protein that activates the smooth muscle associated with the sympathetic nerve. Thus, there is a reverse interaction – the nerve through the muscle controls the stem cells of the hair follicle, stimulating the growth of new hair.
This discovery is of great importance for understanding the processes of hair regeneration and may help in the development of new methods of treatment for baldness. Scientists hope that further research will help uncover all the mechanisms underlying hair growth and the possibility of hair regeneration.