Relief from itch seen in nerves; may aid treatment

Apr 06, 2009 By MALCOLM RITTER , AP Science Writer

(AP) -- Scratch an itch and you get ... aaaaaah. Now scientists have watched spinal nerves transmit that relief signal to the brain in monkeys, a possible step toward finding new treatments for persistent itching in people.

More than 50 conditions can cause serious itching, including AIDS, Hodgkin's disease and the side effects of treatment, said Glenn J. Giesler, Jr., a neuroscientist at the University of Minnesota in Minneapolis. Some terminal cancer patients even cut back on just to reduce the itch, he said.

Scratching can lead to serious skin damage and infections in people with chronic itch, he said. So scientists want to find ways for such people to relieve their distress "without tearing up their skin," he said.

While medications can relieve some kinds of itch, other cases resist current treatments.

Nobody knows just how scratching relieves itch. But the federally funded monkey study, reported Monday on the Web site of the journal by Giesler and colleagues, takes a step in unraveling the mystery.

The scientists focused on a kind of spinal nerve that transmits the "itch" signal to the brain. These nerves reach into the brain from near the bottom of the rib cage.

The researchers sedated long-tailed for the experiment and placed recording electrodes on their spinal nerves. They injected a chemical into the skin of a leg to produce itching. The nerves fired in response.

Then the researchers scratched the leg with a hand-held metal device that simulates three monkey fingers. The firing rate dropped - the apparent signature of the "relief" signal.

In contrast, when researchers scratched the leg without causing an itch first, the firing rate jumped. So the nerves somehow "know" to react much differently if there's an itch to be relieved than if there isn't.

"It's like there's a little brain" in the spinal cord, Giesler said. "We really want to understand that, because then we think we'll understand how to relieve itch."

Maybe scientists can identify signals that tell these nerves to provide the relief response, and then try to mimic that action with drugs or some kind of stimulator, he said.

Dr. Gil Yosipovitch of the Wake Forest University Baptist Medical Center in Winston-Salem, N.C., who didn't participate in the study, said in an e-mail that his own work shows that particular brain circuits also play a role in how scratching quells itch.

He called the new study "very important" and said it opens further research on the nervous system and itching.

---

On the Net:

Nature Neuroscience: http://www.nature.com/neuro

©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Explore further: Researchers explore new possibilities for the treatment of epilepsy

add to favorites email to friend print save as pdf

Related Stories

Research suggests why scratching is so relieving

Jan 31, 2008

In the first study to use imaging technology to see what goes on in the brain when we scratch, researchers at Wake Forest University Baptist Medical Center have uncovered new clues about why scratching may be so relieving ...

Scratch no more: Gene for itch sensation discovered

Jul 25, 2007

Itching for a better anti-itch remedy? Your wish may soon be granted now that scientists at Washington University School of Medicine in St. Louis have identified the first gene for the itch sensation in the central nervous ...

The pepperoni pizza hypothesis

Oct 08, 2008

What's the worst that could happen after eating a slice of pepperoni pizza? A little heartburn, for most people.

Recommended for you

Obama's BRAIN initiative gets more than $300 million

2 hours ago

President Barack Obama's initiative to study the brain and improve treatment of conditions like Alzheimer's and autism was given a boost Tuesday with the announcement of more than $300 million in funds.

US aims for traumatic brain injury clinical trial success

15 hours ago

An unprecedented, public-private partnership funded by the Department of Defense (DoD) is being launched to drive the development of better-run clinical trials and may lead to the first successful treatments for traumatic ...

User comments : 0