report they have pinpointed two molecules involved in perpetuating chronic pain in mice. The molecules, they say, also appear to have a role in the phenomenon that causes uninjured areas of the body to be more sensitive to pain when an area nearby has been hurt.
This is a frightening discovery, and only adds to the urgency of treating pain. In some situations, when pain is left untreated for too long it can increase and spread instead of getting better. Those of us with chronic pain are familiar with this phenomenon, where the pain keeps getting worse instead of winding down and decreasing.
We found that persistent pain doesn’t always originate in the brain, as some had believed, which is important information for designing less addictive drugs to fight it.
This spreading of pain to uninjured areas is typical of those experiencing chronic pain, but it can also be experienced during acute injuries, as when a thumb is hit with a hammer and the whole hand throbs with pain
Says Dong: “Chronic pain seems to cause serotonin to be released by the brain into the spinal cord. There, it acts on the trigeminal nerve at large, making TRPV1 hyperactive throughout its branches, even causing some non-pain-sensing nerve cells to start responding to pain. Hyperactive TRPV1 causes the nerves to fire more frequently, sending additional pain signals to the brain.“
nerves that don’t normally respond to pain can modify themselves during prolonged injury, adding to the pain signals being sent to the brain.
Chronic pain is proving to be ever more complicated. We know there is some central sensitization happening, but this research shows that chemical changes also occur in the painful area, and that these chemicals can spread out to affect a larger area.