Featured Research

from universities, journals, and other organizations

Grasshopper mice are numb to the pain of the bark scorpion sting

Date:
October 24, 2013
Source:
University of Texas at Austin
Summary:
The painful, potentially deadly stings of bark scorpions are nothing more than a slight nuisance to grasshopper mice, which voraciously kill and consume their prey with ease. When stung, the mice briefly lick their paws and move in again for the kill.

A grasshopper mouse (O. torridus) attacks a bark scorpion (C. sculpturatus).
Credit: Ashlee Rowe, Michigan State University

The painful, potentially deadly stings of bark scorpions are nothing more than a slight nuisance to grasshopper mice, which voraciously kill and consume their prey with ease. When stung, the mice briefly lick their paws and move in again for the kill.

The grasshopper mice are essentially numb to the pain, scientists have found, because the scorpion toxin acts as an analgesic rather than a pain stimulant.

The scientists published their research this week in Science.

Ashlee Rowe, lead author of the paper, previously discovered that grasshopper mice, which are native to the southwestern United States, are generally resistant to the bark scorpion toxin, which can kill other animals.

It is still unknown why the toxin is not lethal to the mice.

"This venom kills other mammals of similar size," said Rowe, Michigan State University assistant professor of neuroscience and zoology. "The grasshopper mouse has developed the evolutionary equivalent of martial arts to use the scorpions' greatest strength against them."

Rowe, who conducted the research while at The University of Texas at Austin, and her colleagues ventured into the desert and collected scorpions and mice for their experiments.

To test whether the grasshopper mice felt pain from the toxin, the scientists injected small amounts of scorpion venom or nontoxic saline solution in the mice's paws. Surprisingly, the mice licked their paws (a typical toxin response) much less when injected with the scorpion toxin than when injected with a nontoxic saline solution.

"This seemed completely ridiculous," said Harold Zakon, professor of neuroscience at The University of Texas at Austin. "One would think that the venom would at least cause a little more pain than the saline solution. This would mean that perhaps the toxin plays a role as an analgesic. This seemed very far out, but we wanted to test it anyway."

Rowe and Zakon discovered that the bark scorpion toxin acts as an analgesic by binding to sodium channels in the mouse pain neurons, and this blocks the neuron from firing a pain signal to the brain.

Pain neurons have a couple of different sodium channels, called 1.7 and 1.8, and research has shown that when toxins bind to 1.7 channels, the channels open, sodium flows in and the pain neuron fires.

By sequencing the genes for both the 1.7 and 1.8 sodium channels, the scientists discovered that channel 1.8 in the grasshopper mice has amino acids different from mammals that are sensitive to bark scorpion stings, such as house mice, rats and humans. They then found that the scorpion toxin binds to one of these amino acids to block the activation of channel 1.8 and thus inhibit the pain response.

"Incredibly, there is one amino acid substitution that can totally alter the behavior of the toxin and block the channel," said Zakon.

The riddle hasn't been completely solved just yet, though, Rowe said.

"We know the region of the channel where this is taking place and the amino acids involved," she said. "But there's something else that's playing a role, and that's what I'm focusing on next."

Some resistance to prey toxins in mammals has been found in other species. The mongoose, for example, is resistant to the cobra. And naked mole rats' eyes do not burn in pain when carbon dioxide builds up in their underground tunnels.

This study, however, is the first to find that an amino acid substitution in sodium channel 1.8 can have an analgesic effect.

Rowe said studies such as this could someday help researchers target these sodium channels for the development of analgesic medications for humans.


Story Source:

The above story is based on materials provided by University of Texas at Austin. Note: Materials may be edited for content and length.


Journal Reference:

  1. Ashlee H. Rowe, Yucheng Xiao, Matthew P. Rowe, Theodore R. Cummins, and Harold H. Zakon. Voltage-Gated Sodium Channel in Grasshopper Mice Defends Against Bark Scorpion Toxin. Science, October 213

Cite This Page:

University of Texas at Austin. "Grasshopper mice are numb to the pain of the bark scorpion sting." ScienceDaily. ScienceDaily, 24 October 2013. <www.sciencedaily.com/releases/2013/10/131024143422.htm>.
University of Texas at Austin. (2013, October 24). Grasshopper mice are numb to the pain of the bark scorpion sting. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2013/10/131024143422.htm
University of Texas at Austin. "Grasshopper mice are numb to the pain of the bark scorpion sting." ScienceDaily. www.sciencedaily.com/releases/2013/10/131024143422.htm (accessed September 2, 2014).

Share This




More Plants & Animals News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Sharks Off the Menu and on the Tourist Trail in Palau

Sharks Off the Menu and on the Tourist Trail in Palau

AFP (Sep. 2, 2014) Tourists in Palau clamour to dive with sharks thanks to a pioneering conservation initiative -- as the island nation plans to completely ban commercial fishing in its vast ocean territory. 01:15 Video provided by AFP
Powered by NewsLook.com
We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Washington Wildlife Center Goes Nuts Over Baby Squirrels

Washington Wildlife Center Goes Nuts Over Baby Squirrels

Reuters - US Online Video (Aug. 30, 2014) An animal rescue in Washington state receives an influx of orphaned squirrels, keeping workers busy as they nurse them back to health. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Newsy (Aug. 29, 2014) In a new study, a promising experimental treatment for Ebola managed to cure a group of infected macaque monkeys. 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