University College London researchers have discovered the recipe for painlessness.
According to a report on the UCL website, people born with a non-functioning Nav1.7 do not feel pain. Sodium channel Nav1.7 is particularly important for signalling in pain pathways.
Interestingly, drugs that block Nav1.7 have since been developed but they had disappointingly weak effects.
The new study, published in Nature Communications, reveals that mice and people who lack Nav1.7 also produce higher than normal levels of natural opioid peptides.
To examine if opioids were important for painlessness, the researchers gave naloxone, an opioid blocker, to mice lacking Nav1.7 and found that they started to feel pain. They then gave naloxone to a 39-year-old woman with the rare mutation and she felt pain for the first time in her life, the report has said.
A senior author, Professor John Wood of UCL Medicine, was pleased that after several years of trying to develop drugs that would combat pain, the secrete ingredient had finally been found.
He said, “After a decade of rather disappointing drug trials, we now have confirmation that Nav1.7 really is a key element in human pain.
“The secret ingredient turned out to be good old-fashioned opioid peptides, and we have now filed a patent for combining low dose opioids with Nav1.7 blockers.
“This should replicate the painlessness experienced by people with rare mutations, and we have already successfully tested this approach in unmodified mice.”
Broad-spectrum sodium channel blockers are used as local anaesthetics, but they are not suitable for long-term pain management as they cause complete numbness and can have serious side-effects over time.
By contrast, people born without working Nav1.7 still feel non-painful touch normally and the only known side-effect is the inability to smell.
The findings were made possible by the use of ‘transgenic’ mice, meaning they were modified to carry genetic material from another organism – in this case, the mutation that prevents humans from feeling pain.
Precise physiological experiments showed that the nervous systems of the transgenic mice contained around twice the levels of naturally-produced opioids as unmodified mice from the same litter.
Source: www.ucl.ac.uk, www.nature.com
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