We've all endured some kind of physical pain, more or less intense. When you hit your finger while hammering, for example, the pain is really intense, but passes away (at least mostly) in just a few moments. So scientists were trying to find out why is it that some intense pains pass so quickly and why some have to be endured for more time.
Researchers from the University of Texas Medical Branch of Galveston believe they have, at least partially, found the answer, which is, believe it or not, in a group of compounds that include cannabinoids, the active ingredients in marijuana, or weed, as anybody under 40 (and not only) knows it as. This proves to be very interesting, given the recent research and interest in medical use of marijuana for pain relief. According to this study, the results are the exact opposite, as endocannabinoids, which are produced by human body (and not only) prolong pain istead of damping it down.
"In the spinal cord there's a balance of systems that control what information, including information about pain, is transmitted to the brain," said UTMB professor Volker Neugebauer, one of the authors of the Science article, along with UTMB senior research scientist Guangchen Ji and collaborators from Switzerland, Hungary, Japan, Germany, France and Venezuela. "Excitatory systems act like a car's accelerator, and inhibitory ones act like the brakes. What we found is that in the spinal cord endocannabinoids can disable the brakes."
In order to get to this conclusion they applied a 'biochemical mimic' to the inhibitory neurons on slices they took from mouse spinal cord. Electrical signals that should have produced an inhibitory response were ignored. They then proceeded to analyze spinal cord slices taken from genetically engineered mice that lacked receptors for the endocannabinoid molecules and they found that the so called 'brakes' work.
"To sum up, we've discovered a novel mechanism that can transform transient normal pain into persistent chronic pain," Neugebauer said. "Persistent pain is notoriously difficult to treat, and this study offers insight into new mechanisms and possibly a new target in the spinal cord."