Researchers have discovered an unknown way to sense touch
A mechanism has been found in hair follicles that allows you to feel light touches.It's not just nerve endings located in the skin that can sense touch. Researchers from Imperial College London have shown that cells within hair follicles - organs located in the skin and surrounding the hair - are also involved in touch.
The researchers sequenced the RNA of individual cells in human skin and hair follicles and found that the latter have a higher percentage of sensory receptors than the skin. To study the role of these receptors, the researchers grew artificial structures from hair follicle cells and sensory nerves. Stimulating the follicle cells, the scientists recorded the activation of neighboring nerve endings - low-threshold mechanoreceptors responsible for the recognition of light touch.
Further analysis showed that hair follicle cells release the neurotransmitters serotonin and histamine in response to touch. When the researchers blocked the receptor for these neurotransmitters on the touch neurons, the neurons no longer responded to hair follicle cell stimulation. Similarly, when synaptic vesicles in follicles were blocked, the signal stopped being transmitted to sensory nerves.
The researchers performed the same experiments with skin cells instead of hair follicle cells. The cells responded to light touch by releasing histamine, but not serotonin. This suggests a unique mechanism that hair follicle cells use.
"This is interesting because histamine in the skin contributes to inflammatory skin diseases such as eczema, and it has always been assumed that immune cells called mast cells release all the histamine. Our work reveals a new role for skin cells in histamine release, with potential applications for eczema research," Claire Higgins, co-author of the study.
The scientists note that the study was conducted on "in vitro" grown cell cultures and will need to be repeated on living organisms to confirm the results. Further analysis will help to better understand how follicle sensitivity to touch works and why they play such a role.