Scientists working with mouse models have identified a sensory pathway that links fine, touch-sensitive hairs to itching. The study describes a previously unrecognized class of hairs in mice, called vellus-like hairs, and a specialized population of neurons that connect to them.
In experiments with mice that had chronic skin inflammation, which is similar to eczema in humans, animals with the touch-sensitive neurons scratched normally. Mice that lacked those neurons or in which the neurons were inactive showed a much reduced scratching response. The team stroked the vellus-like hairs with a small loop of thread and also made the neurons sensitive to blue light; light alone then triggered scratching.
Researchers found proteins that help send the itch signal from hairs to the spinal cord, and human neurons grown in culture responded to the same proteins. The team suggests that targeting the mechanical itch pathway could better treat chronic itch that does not respond to existing therapies.
Difficult words
- sensory — related to feeling or physical sensations
- pathway — a route that signals or information travel along
- vellus-like hairs — thin, fine body hairs on mammals
- neuron — a nerve cell that sends signals in the bodyneurons
- chronic — continuing for a long time, not short
- inflammation — a body's response that causes redness or pain
- spinal cord — the nerve bundle that connects brain and body
- therapy — medical treatment to help an illness or conditiontherapies
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Discussion questions
- How could a treatment that targets the mechanical itch pathway help people with chronic itch?
- Do you think findings from mouse studies about skin and nerves can apply to humans? Why or why not?
- If a medicine reduced scratching, what everyday activities might improve for someone with chronic itch?
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