Habaneros and Tarantulas Prove to Be Partners in Pain

Air Date: 11/08/2006
Source:
Scientific American
Creator:
Alison Snyder
Air/Publish Date:
11/08/2006
Event Date:
11/08/2006
Resource Type:
Article
Copyright:
n/a
Copyright Date:
2006
Clip Length:
-

This 2006 "Scientific American" article reports on research into how spider and scorpion venom and chili peppers both, in different ways, activate pain response in humans. Source: Scientific American, November 8, 2006

Habaneros and Tarantulas Prove to Be Partners in Pain

By Alison Snyder November 8, 2006

As painful as a spider bite may feel, the molecular mechanism that underlies how venom produces that sensation isn't well understood. Little is known about the molecular channels through which ions flow across the membrane of sensory neurons and thereby trigger a firing of electrical signals perceived as pain. Now researchers examining arachnid venom may have discovered a new tool to probe deeper into how ion channels work to produce pain.

David Julius and his colleagues at the University of California, San Francisco, screened 22 different species of spiders and scorpions in search of molecules that activate sensory neurons and produce pain sensation. The researchers identified and purified three molecules in the venom of a West Indian tarantula species, Psalmopoeus cambridgei, that do so. When the researchers injected the toxins into the paws of mice, their limbs became inflamed and the animals reacted by licking them and flinching. Mice genetically engineered not to express the receptor, however, did not react when the toxin was administered, according to the study appearing in the November 9 issue of Nature.

The peptides isolated from the tarantula species target the same receptor as capsaicin, the fiery compound in hot chili peppers. The pepper molecule and the tarantula toxins activate the same channel but in different ways: capsaicin binds the receptor from inside the cell whereas the tarantula peptides target the receptor from the outside. "One can achieve the same, or very similar, molecular consequences by tickling this channel in two different places," says Mike Catarina, a biochemist at Johns Hopkins University. This unusual situation may prove a powerful laboratory tool, he adds. Because the tarantula toxins target the outside of sensory neurons, the peptides could be used to study neurons without destroying them. And unlike similar peptides that inhibit other ion channels, this new class of "vanillotoxins" excites channels when it binds to the receptors. This characteristic may aid in developing analgesic drugs based on channel structure.

"The plant and the spider, through evolution, have come up with the same general molecular strategy for averting predators by activating this same receptor," Julius says. Capsaicin helps the pepper to scare off mammals but does not affect birds that could spread the pepper seeds. But the tarantula toxins identified in the study activate both bird and mammal channels, suggesting that spiders evolved a toxin to defend themselves against many different predators. Sensory systems are a great way to understand how organisms interact, Julius says. "They define how we perceive our world."

Close NBC Learn

FILTERING

If you are trying to view the videos from inside a school or university, your IT admin may need to enable streaming on your network. Please see the Internet Filtering section of our Technical Requirements page.

DVDs AND OTHER COPIES

Videos on this page are not available on DVD at this time due to licensing restrictions on the footage.

DOWNLOADING VIDEOS

Subscribers to NBC Learn may download videos and play them back without an internet connection. Please click here to find out more about subscribing or to sign up for a FREE trial (download not included in free trial).

Still have questions?
Click here to send us an email.

Close NBC Learn

INTERNATIONAL VISITORS

The Science of the Olympic Winter Games videos are only available to visitors inside the United States due to licensing restrictions on the Olympics footage used in the videos.

FILTERING

If you are trying to view the videos from inside a school or university, your IT admin may need to enable streaming on your network. Please see the Internet Filtering section of our Technical Requirements page.

DVDs AND OTHER COPIES

The Science of the Olympic Winter Games is not available on DVD at this time due to licensing restrictions on on Olympic footage.

DOWNLOADING VIDEOS

Subscribers to NBC Learn may download videos and play them back without an internet connection. Please click here to find out more about subscribing or to sign up for a FREE trial (download not included in free trial).

Still have questions?
Click here to send us an email.

Close NBC Learn

Choose your product

NBC Learn K-12 product site
NBC Learn Higher Ed product site

For NBC Learn in Blackboard™ please log in to your institution's Blackboard™ web site and click "Browse NBC Learn"

Close NBC Learn

If you have received a new user registration code from your institution, click your product below and use the "Register now" link to sign up for a personal account.

NBC Learn K-12 product site
NBC Learn Higher Ed product site

For further assistance, please contact our NBC Learn Support Team and we'll be happy to assist you.

Start Your Free
day
Day Trial!