Tarantula Venom Tapped for New Kind of Painkiller

The Peruvian green velvet tarantula, whose venom shows promise as an inhibitor of the reception and transmission of pain. Image credit: Tarantuland via Flickr // CC BY-NC 2.0

Most of us fear venomous creatures like spiders and scorpions for good reason—venom delivered straight from the source can cause life-threatening reactions and death. However, within venoms themselves are potentially therapeutic peptides that have been shown to block some pain receptors in mice and humans. This new class of painkillers could be the first real breakthrough in treating drug-resistant chronic pain without addictive side effects.

New research recently presented at the Biophysical Society’s 60th Annual Meeting in Los Angeles revealed the mode of action of the venom derived from the Peruvian green velvet tarantula, Thrixopelma pruriens, which is considered especially potent to inhibit the reception and transmission of pain through voltage-gated sodium channels, such as NaV 1.7, 1.8, and 1.9.

The tarantula venom, called Pro-Tx II, was first identified at Yale in 2014, after culling 100 other spider venoms, for its potential in dulling pain-sensing neurons. “We set out to understand if the cell membrane itself is important in the peptides’ mode of action,” Sonia Troeira Henriques, senior research officer at the University of Queensland Institute for Molecular Bioscience, tells mental_floss.

Using lab-cultivated neuroblastoma cells, which were modified to express the NaV 1.7 pain receptor, researchers obtained a 3D view of the peptides’ structure under nuclear magnetic resonance (NMR) so they could closely observe how and if the toxin was binding to the cell membrane.

“What we found is that the cell membranes of neuronal cells attract the peptides to a close vicinity of pain target receptors and orient the peptides with the right position to bind to the target,” Henriques says. In other words, the peptides have the perfect chemical composition to bind to the phospholipid layer of the cell. Prior research had suggested that the peptides’ ability to bind to the lipid membrane might be responsible for inhibiting the NaV 1.7 pain receptor. “But we are the first one showing that correlation,” she says.

The NaV 1.7 pain channel is one of several subtypes in cell membranes responsible for controlling the ions that come and go from the cell. NaV 1.7 is expressed only in neuronal cells, but, says Henriques, “there are other channels of the same family expressed in the cardiac muscles. Because they are so similar we have to make sure the peptide we are working with is selective to the pain target and not the cardiac muscles, because if you inhibit cardiac muscles, the person won’t survive.”

If it makes it into therapeutic form, Pro-Tx II won’t be the first commercially viable toxin-derived pain reliever; an existing drug called Prialt, designed from the venom of marine snails, is often used as a last resort when morphine doesn’t stop chronic pain. As of yet, making any venom-based painkillers available in a pill form may take a while to develop, because currently these peptide molecules don’t cross the blood-brain barrier, necessitating an injection to the spine.

As to the effectiveness of pain relief provided by the venom-based painkillers, Henriques says, “Some studies have compared the pain behavior of those mice when they are injected with this toxin versus regular painkillers and they are comparable in terms of efficiency and in the way they relieve pain.”

The next stage of research is to try to improve the mode of action so that more pain-blocking peptides can be attracted to a given pain receptor, for greater effectiveness.

Henriques remains hopeful. “What keeps me going, and what I like in this work, is that every single piece of knowledge we bring to this field will be converted into a product that will improve someone else’s life.”

Editor's note: This post has been updated to clarify the pain receptor focused on in the study. It is NaV 1.7, not NaV 1.8.

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Whale Sharks Can Live for More Than a Century, Study Finds
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Some whale sharks alive today have been swimming around since the Gilded Age. The animals—the largest fish in the ocean—can live as long as 130 years, according to a new study in the journal Marine and Freshwater Research. To give you an idea of how long that is, in 1888, Grover Cleveland was finishing up his first presidential term, Thomas Edison had just started selling his first light bulbs, and the U.S. only had 38 states.

To determine whale sharks' longevity, researchers from the Nova Southeastern University in Florida and the Maldives Whale Shark Research Program tracked male sharks around South Ari Atoll in the Maldives over the course of 10 years, calculating their sizes as they came back to the area over and over again. The scientists identified sharks that returned to the atoll every few years by their distinctive spot patterns, estimating their body lengths with lasers, tape, and visually to try to get the most accurate idea of their sizes.

Using these measurements and data on whale shark growth patterns, the researchers were able to determine that male whale sharks tend to reach maturity around 25 years old and live until they’re about 130 years old. During those decades, they reach an average length of 61.7 feet—about as long as a bowling lane.

While whale sharks are known as gentle giants, they’re difficult to study, and scientists still don’t know a ton about them. They’re considered endangered, making any information we can gather about them important. And this is the first time scientists have been able to accurately measure live, swimming whale sharks.

“Up to now, such aging and growth research has required obtaining vertebrae from dead whale sharks and counting growth rings, analogous to counting tree rings, to determine age,” first author Cameron Perry said in a press statement. ”Our work shows that we can obtain age and growth information without relying on dead sharks captured in fisheries. That is a big deal.”

Though whale sharks appear to be quite long-lived, their lifespan is short compared to the Greenland shark's—in 2016, researchers reported they may live for 400 years. 

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Animal Welfare Groups Are Building a Database of Every Cat in Washington, D.C.
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There are a lot of cats in Washington, D.C. They live in parks, backyards, side streets, and people's homes. Exactly how many there are is the question a new conservation project wants to answer. DC Cat Count, a collaboration between Humane Rescue Alliance, the Humane Society, PetSmart Charities, and the Smithsonian Conservation Biology Institute, aims to tally every cat in the city—even house pets, The New York Times reports.

Cities tend to support thriving feral cat populations, and that's a problem for animal conservationists. If a feline is born and grows up without human contact, it will never be a suitable house cat. The only options animal control officials have are to euthanize strays or trap and sterilize them, and release them back where they were found. If neither action is taken, it's the smaller animals that belong in the wild who suffer. Cats are invasive predators, and each year they kill billions of birds in the U.S. alone.

Before animal welfare experts and wildlife scientists can tackle this problem, they need to understand how big it is. Over the next three years, DC Cat Count will use various methods to track D.C.'s cats and build a feline database for the city. Sixty outdoor camera traps will capture images of passing cats, relying on infrared technology to sense them most of the time.

Citizens are being asked to help as well. An app is currently being developed that will allow users to snap photos of any cats they see, including their own pets. The team also plans to study the different ways these cats interact with their environments, like how much time pets spend indoors versus outdoors, for example. The initiative has a $1.5 million budget to spend on collecting data.

By the end of the project, the team hopes to have the tools both conservationists and animal welfare groups need to better control the local cat population.

Lisa LaFontaine, president and CEO of the Humane Rescue Alliance, said in a statement, “The reality is that those in the fields of welfare, ecology, conservation, and sheltering have a common long-term goal of fewer free-roaming cats on the landscape. This joint effort will provide scientific management programs to help achieve that goal, locally and nationally."

[h/t The New York Times]

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