Featured Research

from universities, journals, and other organizations

New Understanding Of Pain Sensitivity: Heat Sensing Regulator Identified

Date:
May 14, 2008
Source:
Johns Hopkins Medical Institutions
Summary:
Neuroscientists are a step closer to understanding pain sensitivity -- specifically why it's variable instead of constant -- having identified a gene that regulates a heat-activated molecular sensor.

Neuroscientists at Johns Hopkins are a step closer to understanding pain sensitivity - specifically why it's variable instead of constant - having identified a gene that regulates a heat-activated molecular sensor. Their description of the function of a membrane protein called Pirt appears in the May 2 issue of Cell.

"Pain sensitivity increases during inflammation or injury and we want to know what molecules are involved in pain sensation when sensitivity is elevated," says Xinzhong Dong, Ph.D., an assistant professor of neuroscience at Hopkins.

The ability to sense temperature heat and spice is controlled by the TRPV1 protein channel found on the surface of certain nerve cells. In an inactive state, TRPV1 channels remain closed-there is no pain sensation. However, when noxious heat-temperatures above 108 degrees Fahrenheit-or capsaicin-the main ingredient in "hot" peppers-activates a TRPV1 channel, ions flow through, depolarizing the nerve to create an electrical current that sends pain signals to the brain.

"The interesting thing about this channel is it's not always constant," says Dong, whose team set out to find proteins that modulate TRPV1's action. They found the Pirt protein,phosphoinositide interacting regulator of TRP, and named it for its ability to regulate the TRPV1 channel.

To better understand how Pirt works, the researchers made mice that lacked Pirt and tested their ability to respond to heat. The mice were placed on a hot surface and monitored for how long it took them to scurry off. Mice lacking Pirt responded significantly slower than normal mice.

The team then exposed one hind paw to capsaicin and found that mice lacking Pirt did not lick their paws as long as normal mice, suggesting that without Pirt, they were compromised in their ability to sense the spice of capsaicin. The researchers also tried mustard oil on the hind paw and found mice lacking Pirt licked for about the same amount of time as normal mice. These observations suggest that Pirt's action is specific to capsaicin and not other chemicals.

To figure out whether Pirt directly affects TRPV1 channel action, the researchers measured electrical currents generated by TRPV1 in single nerve cells with or without Pirt. They exposed some nerves to noxious heat-108 degrees Fahrenheit-and some nerves to capsaicin and compared currents generated in each cell. Cells containing Pirt generated stronger currents in heat and spice than cells lacking Pirt, leading the researchers to conclude that Pirt is required for a full pain response to both heat and spice.

Further research revealed that Pirt interacts with yet another molecule in the cell, a so-called acidic phospholipid, allowing access to TRPV1. According to Dong, through this phospholipid Pirt somehow changes the TRP channel, perhaps by opening it wider, or maybe by causing it to stay open longer. And the result is elevated pain sensitivity.

Exactly how Pirt regulates the TRPV1 channel isn't yet clear, says Dong. "The goal is to find molecules that specifically affect the pain pathway, but not other nerves," he says. "We're looking for genes specifically turned on in pain-sensing neurons. If we find them and can target them with new drugs, we will be able to treat pain without unfavorable side effects."

The research was funded by the National Institute of Neurological Disorders and Stroke.

Authors on the paper are Andrew Y. Kim, Zongxiang Tang, Qin Liu, Kush N. Patel, David Maag, and Yixun Geng and Dong, all of Hopkins.


Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins Medical Institutions. "New Understanding Of Pain Sensitivity: Heat Sensing Regulator Identified." ScienceDaily. ScienceDaily, 14 May 2008. <www.sciencedaily.com/releases/2008/05/080513101552.htm>.
Johns Hopkins Medical Institutions. (2008, May 14). New Understanding Of Pain Sensitivity: Heat Sensing Regulator Identified. ScienceDaily. Retrieved August 21, 2014 from www.sciencedaily.com/releases/2008/05/080513101552.htm
Johns Hopkins Medical Institutions. "New Understanding Of Pain Sensitivity: Heat Sensing Regulator Identified." ScienceDaily. www.sciencedaily.com/releases/2008/05/080513101552.htm (accessed August 21, 2014).

Share This




More Plants & Animals News

Thursday, August 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Possible Ebola Patient in Isolation at California Hospital

Possible Ebola Patient in Isolation at California Hospital

Reuters - US Online Video (Aug. 20, 2014) — A patient who may have been exposed to the Ebola virus is in isolation at the Kaiser Permanente South Sacramento Medical Center. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) — Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. Video provided by Reuters
Powered by NewsLook.com
Unsustainable Elephant Poaching Killed 100K In 3 Years

Unsustainable Elephant Poaching Killed 100K In 3 Years

Newsy (Aug. 20, 2014) — Poachers have killed 100,000 elephants between 2010 and 2012, as the booming ivory trade takes its toll on the animals in Africa. Video provided by Newsy
Powered by NewsLook.com
Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) — Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins