Most Fearsome Platypi
Platypi pack a nasty punch
By Damon Shorter
Despite its cute and cuddly public image, an angry platypus can do a lot of damage.
The males have a single spur on each hind leg carrying a venom that causes swelling, redness and excruciating pain in anyone unlucky enough to be jabbed, and the side-affects of a spurring can last for up to three months.
Now, an ANU PhD student studying the venom has shown it contains a specific pain-causing ingredient that directly stimulates the nerve cells that register pain.
Greg de Plater, from the John Curtin School of Medical Research, says the discovery helps explain the ruthless effectiveness of the venom and may eventually lead to new treatments for chronic pain sufferers.
"This venom is a highly refined chemical cocktail whose single purpose, it seems, is to cause pain," Mr de Plater explained.
Digestive enzymes in the venom (peptidases and hyaluronidases) dissolve connective tissues joining cells together, other proteins dilate blood vessels, helping the poison to spread and stimulate histamine release and inflammation. The slight natural acidity of the venom adds further sting.
However the new protein isolated by Mr de Plater (he is coy about its exact identity until the work is published) works by directly stimulating nociceptors, the nerve cells that register pain.
Mr de Plater said the protein works in a similar manner to capsacin - the active ingredient in chillis that makes them taste "hot" - by stimulating electrical activity in nerve cells. But unlike capsacin, whose affects pass quickly, a single 10 second exposure of the new compound affects electrical activity in nerve cells growing in culture for up to 20 minutes.
"This is an example of a natural toxin acting directly on pain receptors, and that has never been found in a venom before," Mr de Plater said.
Pain caused by the venom can not be treated with morphine or other common pain-killers, and spurred patients' only relief comes through anaesthetising nerves running away from the spur site.
Ultimately, Mr de Plater hopes a better understanding of how the new protein works will lead to treatments for other sorts of morphine-resistant pain - common in cancer patients and those with neuropathic pain.
Mr de Plater, who was supervised by Dr Rosemary Martin and Dr Peter Milburn, faced some unusual problems during his project such as how to best extract venom from an irate monotreme.
"It takes three people to hold onto them because they are so incredibly strong," he said.
Once the animal is safely constrained the venom is "carefully" collected from the spurs using a micro-pipette.
Unprovoked, the platypus rarely attacks and Mr de Plater said the females are almost affectionate.
"You can pick them up by the tail and give them a cuddle and they don't seem to mind at all. It's a bit like cuddling a cat."
By Damon Shorter
Despite its cute and cuddly public image, an angry platypus can do a lot of damage.
The males have a single spur on each hind leg carrying a venom that causes swelling, redness and excruciating pain in anyone unlucky enough to be jabbed, and the side-affects of a spurring can last for up to three months.
Now, an ANU PhD student studying the venom has shown it contains a specific pain-causing ingredient that directly stimulates the nerve cells that register pain.
Greg de Plater, from the John Curtin School of Medical Research, says the discovery helps explain the ruthless effectiveness of the venom and may eventually lead to new treatments for chronic pain sufferers.
"This venom is a highly refined chemical cocktail whose single purpose, it seems, is to cause pain," Mr de Plater explained.
Digestive enzymes in the venom (peptidases and hyaluronidases) dissolve connective tissues joining cells together, other proteins dilate blood vessels, helping the poison to spread and stimulate histamine release and inflammation. The slight natural acidity of the venom adds further sting.
However the new protein isolated by Mr de Plater (he is coy about its exact identity until the work is published) works by directly stimulating nociceptors, the nerve cells that register pain.
Mr de Plater said the protein works in a similar manner to capsacin - the active ingredient in chillis that makes them taste "hot" - by stimulating electrical activity in nerve cells. But unlike capsacin, whose affects pass quickly, a single 10 second exposure of the new compound affects electrical activity in nerve cells growing in culture for up to 20 minutes.
"This is an example of a natural toxin acting directly on pain receptors, and that has never been found in a venom before," Mr de Plater said.
Pain caused by the venom can not be treated with morphine or other common pain-killers, and spurred patients' only relief comes through anaesthetising nerves running away from the spur site.
Ultimately, Mr de Plater hopes a better understanding of how the new protein works will lead to treatments for other sorts of morphine-resistant pain - common in cancer patients and those with neuropathic pain.
Mr de Plater, who was supervised by Dr Rosemary Martin and Dr Peter Milburn, faced some unusual problems during his project such as how to best extract venom from an irate monotreme.
"It takes three people to hold onto them because they are so incredibly strong," he said.
Once the animal is safely constrained the venom is "carefully" collected from the spurs using a micro-pipette.
Unprovoked, the platypus rarely attacks and Mr de Plater said the females are almost affectionate.
"You can pick them up by the tail and give them a cuddle and they don't seem to mind at all. It's a bit like cuddling a cat."