Giant spider promises IBS relief

Molecules from the venom of one of the world’s largest spiders are helping researchers tailor pain blockers for people with irritable bowel syndrome (IBS).

Researchers screened 28 spiders, with the venom of the Venezuelan Pinkfoot Goliath tarantula – which has a leg-span of up to 30 centimetres – showing the most promise.

The team led by Professor Richard Lewis from the University of Queensland in collaboration with Flinders University’s Professor Stuart Brierley and the South Australian Health and Medical Research Institute (SAHMRI) hopes to find effective pain relief for chronic intestinal pain.

“All pains are complex but gut pain is particularly challenging to treat, and affects around 20 per cent of the world’s population,” Professor Lewis said.

“Current drugs are failing to produce effective pain relief in many patients before side effects limit the dose that can be administered.”

Professor Brierley says IBS and other gastrointestinal and bladder disorders cause chronic visceral pain – pain which affects the internal organs.

“Internal organs have a complex network of sensory nerves that have a wide array of voltage-gated ion channels and receptors to detect stimuli,” he says.

“The hypersensitivity of these nerves in disease often contributes to the development of pain.”

Voltage-gated ion channels open and close in response to changes across the cell membrane, with their dysfunction identified as a cause of chronic visceral pain.

Professor Lewis says spider venoms contain hundreds of mini-proteins known as peptides that can inhibit voltage-gated ion channels from opening.

“Unfortunately these peptides aren’t completely selective for pain targets,” he said.

“Our goal was to find more specialised pain blockers that are potent and target pain sodium channels for chronic visceral pain, but not those that are active in the heart and other channels.”

The team found two peptides isolated from the tarantula venom inhibited the most important ion channels underlying pain, with one particularly potent at reducing the sensory nerves of the bladder and colon and nearly stopping chronic visceral pain in a model of IBS.

The research was published in the journal Pain and funded by the National Health and Medical Research Council.

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