US boffins discover 'super' pain treatment

A potentially “groundbreaking” natural pain treatment has been discovered whose effects last eight time longer than morphine.

The new agent is a protein which for nearly 50 years has been used to identify pain-sensitive neurons.

Under a different name, it is also routinely used to diagnose prostate cancer that has spread throughout the body.

Scientists demonstrated that both were identical by “knocking out” the gene for the protein in mice.

They found that the mutant mice were more sensitive to inflammatory and neuropathic pain than normal animals.

Both are common forms of chronic pain in humans.

The mice became less vulnerable to pain when the researchers injected the prostate diagnostic marker, PAP (prostatic acid phosphatase) into their spinal cords.

PAP suppressed pain effectively as morphine but for almost eight times longer. One dose of PAP lasted for up to three days, compared with about five hours with a single dose of morphine.

Study leader Dr Mark Zylka, from the University of North Carolina at Chapel Hill, US, said: “This protein has the potential to be a groundbreaking treatment for pain and has previously not been studied in pain-sensing neurons.

“We were really blown away that a simple injection could have such a potent effect on pain. Not only that, but it appeared to work much better than the commonly used drug morphine.”

The protein is thought to convert nerve cell chemical that cause pain into ones that suppress it.

Dr Zylka, whose research is reported in the journal Neuron, is now searching for other proteins that have a similar effect.

He added: “It is entirely possible that PAP itself could be used as a treatment for pain, through an injection just like morphine. But we would like to modify it to be taken in pill form.

“By taking this field in a new direction, we are encouraged and hopeful that we will be able to devise new treatments for pain.”