Research published January 23 in the journal Neuron studied the responses to painful stimuli in the trigeminal nerve of mice. The study found that 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 the pain-activating protein TRPV1 hyperactive throughout its branches, even causing some non-pain-sensing nerve cells to start responding to pain. Understanding the relation of these molecules to pain may be of value in identifying new targets to block to reduce chronic pain. Read a news report here.