Morphine? Nope. Centipede venom a much less addictive way to kill pain, says Chinese team after some impressive reverse-engineering
Scientists say a compound in the Chinese red-headed centipede can turn pain on and off like a switch, and it isn’t addictive like morphine.
Chinese scientists have found a new chemical compound in the venom of a centipede native to China that can act as a painkiller with no negative side effects like those associated with morphine.
The discovery could potentially help a country’s military reduce its reliance on morphine for battleground injuries, or even create an army of soldiers with the ability to fight on after sustaining wounds in combat, pundits say.
“It is completely different from morphine,” said Professor Lai Ren, the lead scientist of the study.
“Morphine is only intended for emergency use. It has many side effects and can lead to addiction over the longer-term,” added Lai, who works with the Chinese Academy of Sciences’ Kunming Institute of Zoology in southern Yunnan province.
Lai said the ultimate goal of their research was to develop a painkiller for long-term use that does not compromise the health of the subject. He said the centipede’s venom serves as a beacon of hope in this quest.
A centipede’s venom can cause pain and swelling in the area of the bite but is not usually life-threatening, although there are exceptions.
Lai’s team isolated a chemical called RhTx from a complex toxin found in the Chinese red-headed centipede, which is native to East Asia and Australasia.
The chemical has the ability to act like a switch turning pain on and off, they said.
Although morphine has been widely used in military operations since the start of the first world war and is still the most important pain-relieving drug for field medics, there are risks involved.
For example, its use can negatively impact the way patients breathe and also interfere with their blood pressure - both of which could prove lethal in some cases.
A more serious problem is how addictive the drug is. Derived from opium, it generates feelings of calm or even euphoria due to the way it interacts with the central nervous system. As such, most countries impose tight limits on its usage even in medical fields.
Yet the importance of painkillers cannot be overstated, whether it be cancer patients or combat veterans with postwar trauma. Combat injuries that lead to chronic pain have even led some veterans to take their own lives, reports show.
To find an alternative to drugs like morphine or codeine, Lai’s team decided to investigate some deadly and less dangerous poisons.
This approach was based on the logic that if a chemical can activate pain, the same mechanism could theoretically be reversed to achieve the opposite effect.
Centipedes rank among the planet’s oldest predators. The earliest known fossils date back some 460 million years - making them twice as old as some dinosaurs.
Although most species are relatively harmless, some kinds of centipedes have a bite deadly enough to kill a human.
Their “extremely sharp pain ... has an instant onset and lasts from half an hour up to two to three days,” reported the research team in their paper, which was published recently in the journal Nature Communications.
Lai’s team studied the venom from the Chinese red head, an aggressive centipede known for its bright colouring that averages 20 centimetres in length when fully grown.
The researchers found that the venom had many sophisticated chemical components, and it took years of effort to identify the pain related compound RhTx, they said.
Using various observational methods such as nuclear magnetic resonance and fluorescence imaging, Lai and his colleagues found that RhTx causes pain by triggering a “false alert” on the host’s central nervous system.
The compound did this by binding to TRPV1, a heat-sensing protein commonly found in animals and humans.
The RhTx was able to dupe the so-called sentry protein into believing that the external temperature had suddenly shot up above its true reading, thus causing feelings of pain similar to being scalded in boiling water.
But if the same compound was programmed to work in the opposite direction, the test animal could be persuaded to swim in boiling water without realising the damage it was subjecting itself to, the team said.
As such, it is little wonder that the TRPV1 protein has become a popular research subject in the development of next-generation painkillers.
Some drug companies have used capsaicin, an active component of chili peppers, to suppress the pain alerts generated by this protein.
The Chinese researchers said their study “opens the door for the molecular modification” of the centipede venom to reverse its effect from pain generator to painkiller.
“But there are still long roads ahead,” said Lai.
“Pain is a very complex scientific issue, with lots of questions remaining about its underlying mechanisms,” he said.
“It is still too early to say whether the centipede toxin will replace morphine and become the ultimate painkiller.”