The findings demonstrate that some plants and animals have evolved the same molecular strategy to deter predators -- triggering pain by activating a specific receptor on sensory nerves. The research provides new tools to understand how these pain- and heat-sensing neurons work, and to help develop drugs that ease persistent pain, the scientists report.
Their finding, based on studies of mice cells in culture and live mice, is published in the November 9 issue of the journal Nature. The senior author is David Julius, professor and chair of physiology at UCSF.
The tarantula venom targets the heat sensor on nerve cells known as the capsaicin receptor, first cloned in 1997 in the Julius laboratory. In the last 10 years, Julius and his colleagues have demonstrated that this and related receptors trigger nerves to fire pain signals when exposed to Death Valley-like heat or the fiery properties of peppery food, mustard oil and other compounds. Human pain-sensing neurons also have these receptors on their surface, and some pain treatments have been developed that target them.
The capsaicin receptor acts as a channel on the nerve surface. When certain compounds bind to it, the receptor channel opens, allowing a stream of charged sodium and calcium molecules to rush into the nerve cell. This generates an electrical signal that travels to the brain to produce pain.
The researchers examined venoms from 22 spider and scorpion species whose bites are known to cause pain. Venom from the tarantula Psalmopoeus cambridgei activated the capsaicin receptor, also called TRPV1, and the researchers identified three protein subunits or peptides in the venom that targeted the receptor to cause pain. They also showed that venom from a second spider activated TRPV1, but they did not pinpoint which peptides were responsible.
The fact that a second spider venom triggered a capsaicin receptor suggests that a variety of spider species may have evolved the ability to use such toxins to target heat- and pain-sensing neuron receptors, the scientists conclude.
"It is fascinating that plants and animals have evolved the same anti-predatory mechanism to generate noxious sensations," Julius said. "These toxins are incredibly useful for understanding how ion channels of the nervous system work. They give us clues as to how specific activators or blockers on these channels can be designed to treat persistent pain – from arthritis, bladder infections, or other diseases."
The researchers determined the venom peptides' effect in neuron cell cultures, measuring the tell-tale rush of calcium ions when the venom peptides contacted the TRPV1 capsaicin receptor. They also showed that synthetic versions of the venom peptides activated the receptor. In studies with mice, they found that normal animals flinched when their paws were exposed to the peptides, which they call vanillotoxins. Mice genetically engineered to lack capsaicin receptors did not respond.
Wallace Ravven | EurekAlert!
The birth of a new protein
20.10.2017 | University of Arizona
Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research