Entomologist Justin Schmidt describes being stung by aSynoeca wasp in his sting pain index, a list that ranks insect stings from least to most painful, as “torture. You are chained in the flow of an active volcano.”
It is perhaps counterintuitive, then, that the venom of onehas discovered that the wasp’s venom contains a previously unknown compound that could treat anxiety. The compound worked as effectively as the “gold standard” anti-anxiety drug diazepam when tested in rats, according to the study.
Márcia Mortari, a professor at the University of Brasília and the team’s lead researcher, said she focused her efforts on anxiety and other neurological diseases and disorders because they were “very prevalent and, unfortunately, there are no efficient treatments for them.” Anxiety disorders affect 18.1% of U.S. adults .
The team isolated the potential drug from extracted venom and tested it using an elevated plus maze (EPM), a common test that evaluates anxiety by seeing how much time rats are willing to spend in raised, open spaces. To rats, it’s the nerve-wracking equivalent of walking across a tall bridge without railings. When the team injected rats with the wasp venom compound, the rats became more willing to explore and linger in open spaces.
The EPM “is one of the best tests to measure acute fear” and has been used to test existing anti-anxiety drugs, so it is a good measure of the compound’s efficacy, said Dr. S.M. Korte, an associate professor of pharmacology at Utrecht University in the Netherlands who was unaffiliated with the study.
Venoms contain hundreds of compounds, so finding one that treats a particular disease is “a bit like finding the needle in the haystack,” said Dr. Volker Herzig, a senior research officer at the University of Queensland in Australia who was also not affiliated with the study.
Mortari’s team made their discovery through trial and error. They tested several compounds in rats for both seizure prevention and anti-anxiety effects and made one positive match, Mortari said. The team has also tested wasp venom in search of treatments for Parkinson’s and Alzheimer’s disease and pain relief.
Mortari said her team was the first to try cataloging the therapeutic effects of venom in this particular wasp species, though researchers have been looking to animal venoms for potential pharmaceuticals for decades. Captopril, released in 1981, is used to treat high blood pressure and cardiac failure and was based on Jararaca pit viper snake venom. However, of the millions of compounds from venom that have been catalogued, very few have ever made it into clinical trials, let alone onto pharmacy shelves.
Herzig and Korte were skeptical that the wasp venom compound would ever become a pharmaceutical drug. Mortari agreed that it would not be effective if taken orally because it would not be absorbed well in the digestive system. The team is working on alternative delivery systems, such as a nanoparticle that would carry the compound with it into the bloodstream or transdermal patches that would deliver the drug through the skin.
However, even if Mortari could coax the compound into the bloodstream, Herzig and Korte both expect it would to be too large to pass the blood-brain barrier, and so would not reach the brain. The problem is shared among many potential drugs for CNS disorders, which is one reason why there are so few effective treatments.
Given the obstacles, the compound may not be the next anti-anxiety wonder drug, but it could still “help us better understand the neurobiology of anxiety,” Mortari said. Korte agreed that the research had value regardless of the clinical results, saying, “It is high-risk fundamental research.”
The research is risky in more ways than one, because in order for Mortari’s lab to continue their work, someone will have to collect more wasps to extract venom from. As Schmidt, the entomologist, can confirm, getting too close to Synoeca wasps can be a painful endeavor: “Any takers?”