Why You Have To Scratch That Itch | WAMU 88.5 - American University Radio
Filed Under:

Why You Have To Scratch That Itch

Play associated audio

Everybody itches. Sometimes itch serves as a useful warning signal — there's a bug on your back! But sometimes itch arises for no apparent reason, and can be a torment.

Think of the itchy skin disorder eczema, or the constant itching caused by some cancers. "A very high percentage of people who're on dialysis for chronic kidney disease develop severe itch that's very difficult to manage," says Dr. Ethan Lerner, an associate professor of dermatology at Harvard Medical School.

Scientists now say they've got a much better clue as to how itch happens.

For a long time, the thought was that itch piggybacked on the nerves that feel pain or temperature. But it now looks like itch has its own dedicated highway from skin to brain.

And the molecule that makes itch happen comes as a surprise; it usually hangs out in the heart, where it helps control blood pressure.

It's a neurotransmitter called natriuretic polypeptide B, or Nppb.

Researchers at the National Institute of Dental and Craniofacial Research wondered what it was doing in nerve cells. To find out, they created a mouse that didn't make Nppb in its body.

Things that made a normal mouse scratch like crazy had no effect on mice with no Nppb. But when those mice were injected with the substance, they scratched, too.

Nppb seems to be working sort of like an itch-molecule. Take it away and the mice don't itch. Put it back and the itch returns.

The researchers also found a small group of nerves in skin that produce and use this molecule to send an itch message to the spinal cord.

This research hasn't been replicated in humans, so it doesn't prove that human itch works the same way. But the researchers are confident that the molecule is a key clue in defining the long-elusive itch pathway.

The study was published in the journal Science.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

NPR

College Life Doesn't Have To Mean Crummy Cuisine, Says Dorm Room Chef

Sick of dining hall pizza, public health student Emily Hu taught herself how to cook — even with no oven. Now she's hoping to inspire her peers to pick up cooking skills and healthier eating habits.
NPR

College Life Doesn't Have To Mean Crummy Cuisine, Says Dorm Room Chef

Sick of dining hall pizza, public health student Emily Hu taught herself how to cook — even with no oven. Now she's hoping to inspire her peers to pick up cooking skills and healthier eating habits.
NPR

What Romney's Retreat Means For GOP Hopefuls

NPR's Scott Simon speaks with senior Washington editor Ron Elving about the narrowing Republican presidential field for 2016 and what we've seen so far in the first month of the new Congress.
NPR

The Infinite Whiteness Of Public Radio Voices

The hashtag #publicradiovoices, about the "whiteness" of public radio, trended on Twitter this week. NPR's Scott Simon speaks with Gene Demby of NPR's Code Switch team about the conversation.

Leave a Comment

Help keep the conversation civil. Please refer to our Terms of Use and Code of Conduct before posting your comments.