01 November 2013

Painkiller Venom

Welcome back. When my wife Vicki arrived home after a 24-hour EMT shift, she mentioned that the only call they received was for a bee sting. I knew she wasn’t up for any of my bee attack stories, so I kept them to myself…well, until now.

The worst assault I ever suffered occurred during the engineering student summer survey camp I described in Gone Camping. Swinging a machete to clear a line through the brush, I smacked open a nest, leaving the nest’s residents quite perturbed and disinclined to accept my apology. I was dressed for the field, but my face was uncovered. A few retribution-seeking worker bees got tangled in my beard, which is to say Ouch! multiple times.

Stings and bites can get nasty, but the flip side is that research keeps making headway on deriving beneficial drugs from insect or reptile venom. For example, a recent study by collaborators from China’s Kunming Institute of Zoology, the Graduate School of Chinese Academy of Sciences, and Australia’s University of Queensland found that centipede venom may provide a major breakthrough in treating chronic pain.

Running low on a popular painkiller.

Centipedes

After I denigrated centipedes as “millipede wannabes” in my blog post, Millipede Fluorescence, I thought it only fair to review the research; especially after reading that the annual cost of chronic pain in the US tops the combined annual cost of cancer, heart disease and diabetes.

Centipedes can have many more or fewer than 100 legs; however, they’re unique among arthropods in having pincer-link forcipules near their head that are used to grab prey and inject a paralyzing venom.

Scolopendra_subspinipes centipede (photo
from opencage.info/pics.e/large_6626.asp)
Although the researchers worked with only one of the thousands of centipede species found worldwide, Scolopendra subspinipes, it's likely that similar results will be found with other centipede species.

Human Pain Transmission

Humans have proteins referred to as “voltage-gated sodium (Nav) channels” that serve a critical role in electrical signaling in our nerve, muscle and neuroendocrine cells. In fact, we’ve got nine different Nav channels, one of which, labeled “Nav1.7,” is key to pain transmission to the brain.

Research to develop drugs to control pain by inhibiting the Nav1.7 channel has a problem. Drugs that affect one Nav channel normally affect the other channels to varying degrees, and those channels have roles in other critical body functions. Pain control is thus usually accomplished with analgesics that treat a broad range of conditions.

Centipede Research Findings

Centipede venom may open the door to drugs that inhibit the Nav1.7 channel--control pain--without affecting the other Nav channels. The investigators found that a peptide molecule from the venom of the centipede species studied had a 150-fold selectivity for Nav1.7 over all but one Nav channel, and it exhibited a 32-fold selectivity for Nav1.7 relative to that other Nav channel.

As a painkiller, the centipede venom peptide proved to be at least as potent as morphine in tests with mice, and the mice showed no blood pressure or heart rate side effect.

Wrap Up

Rather than make this blog post more of a cringing read for those who don’t care to associate with creepy, crawly or slithery creatures, I’ll just list a few papers (below) that report medical research making use of the cone snail, deathstalker scorpion, South American rattlesnake, Malayan pit viper… ok, I understand. Thanks for stopping by.

P.S.

Centipede research report in Proceedings of the National Academy of Sciences:
-www.pnas.org/content/early/2013/09/25/1306285110
Example articles on centipede research report:
-www.abc.net.au/science/articles/2013/10/01/3859315.htm
-www.latimes.com/science/sciencenow/la-sci-centipede-venom-pain-relief-20130930,0,68952.story
Example articles on medical research using toxins:
-www.popularmechanics.com/science/health/breakthroughs/the-positive-power-in-deadly-poison#slide-1
-ngm.nationalgeographic.com/2013/02/125-venom/holland-text
-www.economist.com/news/science-and-technology/21569015-snake-venom-being-used-cure-rather-kill-toxic-medicine


P.P.S.

C'mon! Why wait? Enter the Retired--Now What? Blog contests now!

- Write about a goal that you, someone close to you or your pet accomplished or failed to accomplish – see Goal-Setting Writing Contest, 18 Oct 2013
- Photograph humans or whatever accomplishing or failing to accomplish a goal – see Goal-Setting Photo Contest, 22 Oct 2013

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