Pain Free without Numbness – Substance Combination with Chili Peppers
Local anaesthetics are pain killers which are used during
operations whereby patients remain alert during the procedure and thus, do not
require general anaesthesia. “These common analgesics, including lidocaine, affect,
however all neurons in the treated area,” Woolf said. As a result, not only are
pain receptors blocked but also touch receptors, producing numbness. Neurons,
controlling muscles, are silenced as well, producing a temporary paralysis.
In order to specifically block pain receptors and
leave touch sensors and motor function unharmed, the scientists used a normally
inactive positively charged form of the local anaesthetic lidocaine called
QX314. This particular type of lidocaine is special in that it is not able to
pass through the cell membrane of neurons because it is charged. Since local
anesthetics only operate inside neurons, an injection of QX314 alone is ineffective,
unlike lidocaine which passes easily through the membrane of all cells and
therefore blocks all neurons.
As QX314 only enters pain neurons and, thereby, acts
exclusively as a pain killer, the researchers combined it with capsaicin.
Capsaicin binds a membrane receptor which is only present in the membrane of
neurons responsible for pain perception. Thus, the chili pepper substance opens
channels, enabling QX314 to get into the cell and then block the pain
receptors. Using rats, the scientists could show that, when applied to the
animals’ hind paws, the combination of QX314 and capsaicin exclusively blocks
pain receptors. While completely blocking the response to painful stimuli, the
animals could, nevertheless, move normally and were responsive to touch.
There is, however, one disadvantage of this current
strategy, said Woolf. Capsaicin activates the sensors for pain and heat. “Thus,
people’s mouths seem to burn when eating very spicy food,” he said. “To use the
pain killing combination in patients, another way of opening the channel must
be found to allow the QX314 into the cell without capsaicin causing its typical
painful heat sensation until the QX314 gets into the cell and then kills the
pain,” commented Woolf. However, he and his colleagues are working on solving
this problem and have recently found promising new non-painful ways of
targeting QX314 into pain fibers, which they hope will be available soon for
example, for dental patients or for mothers-to-be during labor.“
Barbara
Bachtler
Press
and Public Affairs
MaxDelbrück
Center for Molecular Medicine (MDC)
Berlin-Buch
Robert-Rössle-Straße
10; 13125 Berlin; Germany
Phone:
+49 (0) 30 94 06 — 38 96
Fax: +49 (0) 30 94 06 — 38 33
e‑mail:
presse@mdc-berlin.de
http://www.mdc-berlin.de/en/news
