GM mice used in study to understand why some people can't feel pain
Anew study from researchers at the UK's University College London(UCL) has examined a rare condition that makes people unable to feelpain, known as congenital insensitivity to pain (CIP). While previous projects have had little success in fully understanding the condition, the new effort represents a big breakthrough,pinpointing the key elements that cause it.
Previousresearch has shown that people that suffer from CIP have anon-functional sodium channel, known as Nav1.7 – a pathwaythat's known to be important in passing along pain signals to thebrain. With that knowledge, scientists have developed drugs thatblock Nav1.7 in an attempt to replicate the condition, but theresults haven't been promising, having very little effect.
Forthe new study, the researchers decided to examine whether a secondfactor might be playing a part in the condition, namely naturalopioid peptides – short sequences of amino acids produced in thecentral nervous system and throughout the body.
Theresearchers worked with laboratory mice with a similar lack of Nav1.7to CIP sufferers, introducing an opioid blocker known as naloxoneinto their systems. The results were immediately positive, with themice able to feel pain after the treatment. Encouraged by thedevelopment, the team then gave the blocker to a 39-year-old womanCIP. Once again, the effect was significant, with the womanexperiencing pain for the first time in her life.
Opioidpainkillers, such as morphine, are commonly used, but they're not suitable for long-term use, as they canbe addictive, become less effective over time, and eventually stophaving any effect at all. However, the required dose when used in combinationwith Nav1.7 blockers is very small, making it a viable way ofpreventing pain. Looking forward, the researchers hope that their work will lead to thedevelopment of drug that can be used to treat chronic pain patients.
Anotherimportant aspect of the study is its use of transgenic mice –creatures modified to carry the genetic material of other organisms,in this case the mutation that causes CIP patients to feel no pain.The researchers believe that the study makes a good case for thecontinued use of the modified rodents.
"Studyingthe mice showed us what was going on in the nervous system that ledto painlessness and our findings were directly translatable tohumans, as confirmed by the painless patient," says UCL's ProfessorJohn Wood. "Without the work in transgenic mice, none of this wouldhave been possible and we still wouldn't know how to replicate theeffects to help people suffering from chronic pain."
Thefindings of the research were published in the journal Nature Communications.