Spiders have helped researchers from Australia and the US discover a new target for irritable bowel syndrome pain.
In the research – published today in the journal Nature – the international team used spider venom to identify a specific protein involved in transmitting mechanical pain, which is the type of pain experienced by patients with irritable bowel syndrome.
One in five Australians suffer from irritable bowel syndrome, with symptoms including abdominal pain, diarrhoea and constipation.
"Irritable bowel syndrome places a large burden on individuals and on the health system, but there are currently no effective treatments. Instead, sufferers are advised to avoid triggers that will cause their symptoms to flare up," says co-leader of the study Associate Professor Stuart Brierley, currently Head of the University of Adelaide's Visceral Pain Group, based at the South Australian Health and Medical Research Institute (SAHMRI), and soon to be a Matthew Flinders Fellow at Flinders University.
The work was also led by Professor Glenn King from the University of Queensland's Institute for Molecular Bioscience (IMB) Centre for Pain Research, Professor David Julius from the University of California San Francisco, and Dr Frank Bosmans from Johns Hopkins University.
The team found that an ion channel (a protein in nerves and muscles) called NaV1.1, previously implicated in epilepsy, was activated by the spider venom, suggesting it also played a significant role in sensing and transmitting pain.
Further investigation revealed that NaV1.1 was present in pain-sensing nerves in the gut and underlies pathological levels of abdominal pain, such as that felt by irritable bowel syndrome patients.
"Identifying the crucial role NaV1.1 makes in signalling of chronic pain is the first step in developing novel treatments," Associate Professor Brierley says.
A total of 109 spider, scorpion and centipede venoms were investigated as part of the study. Venom from a species of tarantula native to West Africa, Heteroscodra maculate, produced the strongest result.
Professor King says spider venom is an effective tool for investigating pain signalling in the human body.
"Spiders make toxins to kill prey and defend themselves against predators, and the most effective way to defend against a predator is to make them feel excruciating pain," he says.
"Spider venom should therefore be full of molecules that stimulate the pain-sensing nerves in our body, allowing us to discover new pain pathways by examining which nerves are activated when exposed to spider toxins."
The team is now developing molecules that will block NaV1.1 and alleviate irritable bowel syndrome pain.
This research has been supported by the National Health and Medical Research Council (NHMRC).