Summary: A groundbreaking study conducted by Imperial College London has revealed a previously unknown mechanism within hair follicles that enables us to perceive touch. Contrary to previous beliefs that sensation was solely attributed to nerve endings in the skin, this study demonstrates that cells within hair follicles can also detect touch. These cells release neurotransmitters, including histamine and serotonin, in response to touch. This discovery has the potential to enhance our understanding of inflammatory skin conditions such as eczema.
Key Facts:
- Hair follicle cells, not just nerve endings in the skin, are capable of detecting touch.
- Upon stimulation by touch, hair follicle cells release the neurotransmitters histamine and serotonin.
- This newfound understanding has the potential to reshape our perspective on the role of histamine in inflammatory skin diseases like eczema.
Source: Imperial College London
Imperial College London researchers have made a groundbreaking discovery, uncovering a hidden mechanism within hair follicles that allows us to perceive touch.
Traditionally, touch was thought to be detected solely by nerve endings present within the skin and surrounding hair follicles. However, this new research from Imperial College London has found that cells within hair follicles – the structures that encompass the hair fiber – possess the ability to detect touch in cell cultures.
The researchers also discovered that these hair follicle cells release the neurotransmitters histamine and serotonin in response to touch, which could be instrumental in deepening our comprehension of histamine’s role in inflammatory skin conditions like eczema.
Dr Claire Higgins, the lead author of the study from Imperial’s Department of Bioengineering, expressed her surprise at the findings, stating, “This is a surprising finding as we don’t yet know why hair follicle cells have this role in processing light touch. Since the follicle contains many sensory nerve endings, we now want to determine if the hair follicle is activating specific types of sensory nerves for an unknown but unique mechanism.”
A Complex Sensory Process
Multiple mechanisms contribute to our sense of touch. Sensory nerve endings in the skin detect touch and transmit signals to the brain, while highly innervated hair follicles detect hair fiber movement. Additionally, specialized sensory nerves called C-LTMRs, found exclusively in hairy skin, process “feel-good” or emotional touch.
However, this study reveals a previously unrecognized process within hair follicles. To conduct their research, the scientists analyzed single-cell RNA sequencing data from human skin and hair follicles, discovering that hair follicle cells contain a higher percentage of touch-sensitive receptors compared to equivalent skin cells.
The researchers created co-cultures of human hair follicle cells and sensory nerves, mechanically stimulating the hair follicle cells and observing the subsequent activation of nearby sensory nerves.
They then investigated how hair follicle cells communicate with sensory nerves. Employing a technique known as fast scan cyclic voltammetry, they analyzed the cultured cells and found that hair follicle cells release the neurotransmitters serotonin and histamine in response to touch.
When they blocked the receptors for these neurotransmitters on the sensory neurons, the neurons no longer responded to stimulation from the hair follicle cells. Similarly, when they blocked synaptic vesicle production by hair follicle cells, they were unable to signal to the sensory nerves.
Consequently, the researchers concluded that hair follicle cells release activating signals that impact nearby sensory neurons when stimulated by touch.
The scientists replicated the same experiments using cells from the skin instead of hair follicles. While the skin cells released histamine in response to light touch, they did not release serotonin.
Dr. Higgins commented, “This is interesting, as histamine in the skin contributes to inflammatory skin conditions such as eczema, and it has always been presumed that immune cells release all the histamine. Our work uncovers a new role for skin cells in the release of histamine, with potential applications for eczema research.”
The researchers acknowledge that their experiments were performed on cell cultures and that further research on living organisms is necessary to confirm their findings. They also expressed interest in determining whether hair follicles activate specific types of sensory nerves.
Given that C-LTMRs are exclusively present in hairy skin, the researchers are curious to investigate whether hair follicles have a unique mechanism for signaling to these particular nerves.
Funding: This project received funding from the Engineering and Physical Research Council (EPSRC), Proctor & Gamble, Wellcome Trust, and Biotechnology and Biological Sciences Research Council (BBSRC).
About this Tactile Perception Research News
Author: Caroline Brogan
Source: Imperial College London
Contact: Caroline Brogan – Imperial College London
Image: The image is credited to Neuroscience News
Original Research: Open access.
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