Not all itches go away with a simple scratch. Roughly 15% of people suffer relentless, long-term itchiness.
Researchers have identified a particular neurotransmitter that is responsible for passing itchy sensations from the skin to the brain, and found a new subset of neurons in the spinal cord that transmits those signals, according to a study published this week in Science. The findings suggest that itchiness has a neural pathway distinct from the one that mediates pain sensation.
Itchiness is triggered by the activation of sensory neurons called TRPV1 cells but these neurons also respond to heat and pain, so researchers were unsure if the sensation of itchiness might be a low level form of pain. That’s made it difficult to develop treatments that target itch without affecting other sensory systems.
Long-term itch can often caused by diseases and medications; terminally ill cancer patients, for example, often experience such severe whole-body itch in response to morphine that many choose to live in pain rather than take the medication.
For more on skin, goto: Psoriasis.
Reference: The Cells and Circuitry for Itch Responses in Mice. DOI: 10.1126/science.1233765