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Blocking the Negative Emotions of Pain

Research Suggests Possible Advance to Less Addictive Pain Medications

Working with rodent models, researchers at Washington University School of Medicine, St. Louis have demonstrated that receptors in the brain that trigger emotional responses to pain including lethargy and depression can be blocked. The discovery may be a step toward the realization of less addictive pain killers that can reduce negative emotions associates with pain while not inducing euphoria. Senior investigator Jose Moron-Concepcion, PhD, associate professor of anesthesiology, neuroscience, and psychiatry, commented, “We’re in the midst of an opioid epidemic, and the euphoria associated with opioids is a major driver of opioid dependence. By targeting the emotional aspects of pain, we hope to make pain less debilitating so that patients won’t crave the emotional high they get from opioids.” Conclusions from the work were published earlier this week in the journal Neuron.

The work builds on a discovery by Kooresh Shoghi, PhD, associate professor of radiology, in which positron emission tomography (PET) imaging of rodent brains showed that pain caused heightened activity in the kappa opioid receptors in the nucleus accumbens, a brain region linked to emotion. The research team injected the paws of rats with a substance that causes painful inflammation. They then assessed the effect on rats’ motivation to push a lever to obtain sugar. First author Nicolas Massaly, PhD, instructor in anesthesiology, explained, “When the animals experienced pain, they were less motivated to work to obtain the reward. It’s often the same for people in pain who don’t get as much pleasure from daily activities they usually enjoy.” When the treated rats were then given a compound that blocks the release of dynorphin, a stimulator of the kappa opioid receptor, their motivation to work for the reward returned to the same level as a control group of untreated rats. The authors indicate that the findings may suggest a path to the development of substances that can address the emotional properties of pain in people, thereby improving functionality and quality of life without addictive potential.

Read about the findings.

The journal abstract may be read here.