Many experts had previously thought that the receptors for pain and itching were linked.
However, the team from Johns Hopkins university found that certain nerve cells, called mrgpra3+, are specialized to detect itchy sensations and those receptors don’t detect painful sensations.
‘Itch-specific neurons have been sought for decades, the researchers says in their paper, published in nature neuroscience.
The existence of such neurons has been doubted recently as a result of the observation that itch-mediating neurons also respond to painful stimuli.
To identify cells that sense itching, xinzhong dong, a neuroscientist at Johns Hopkins university, genetically engineered mice whose nerve cells glowed fluorescent green when they fired.
The researchers then exposed the mice to a series of irritating compounds, such as histamine and the active ingredient in itching powder, and looked for nerves that glowed green. The researchers then burnt out the nerves that lit up, and found the mice scratched a lot less. Researchers now hope they can silence those cells to develop better anti-itch treatments.
Our study opens new avenues for studying itch and developing antipruritic therapies,’they say.
The newly discovered itch nerves sit inside the spine, near the spinalcord, and only innervate locations within the skin. That explains why people feel the urge to scratch their skin, but don’t feel itchy in internal organs, dong told live science. ‘You can’t have an itchy pancreas,’he said.