Lexington, Ky. –
University of Kentucky researcher Bradley Taylor recently received a five-year, $3 million research grant from the National Institute on Drug Abuse (NIDA) to better understand the physiological mechanisms of chronic pain.
For many patients recovering from an injury, pain disappears after the injury heals, but for others, pain persists for months, years or even decades. Until recently doctors and scientists had few insights as to why the body’s natural mechanisms of pain relief failed in these patients.
Understanding why chronic pain occurs is crucial in Kentucky, where the condition has contributed to high rates of opioid abuse. The Institute of Medicine recently reported that chronic pain affects more Americans than heart disease, cancer, and diabetes combined, costing over $600 billion each year in lost productivity, medications and other medical treatments.
In 2013, Taylor, a professor of physiology in the UK College of Medicine, and his laboratory group made an important discovery concerning the body’s ability to control chronic pain. The results of this study, reported in Science magazine, suggested that mu opioid receptors (MORs), or receptors in the body that disrupt the transmission of chronic pain signals to the brain and are key targets of opioid painkillers, remain activated, or “turned on,” after an injury.
Taylor coined the termed “MORCA,” for mu opioid receptor constitutive activity, and demonstrated that it provides lasting pain relief in mice. When Taylor and colleagues “switched off” MORCA with a drug called naltrexone, they found signs of pain and symptoms of opioid withdrawal, similar to what doctors observe in patients suffering from chronic pain or withdrawal from heroin in the clinic. The results raised the idea that the body can become dependent on its own mechanism of pain control.
This new grant awarded to Taylor’s laboratory will help his team at UK (Suzanne Doolen, Renee Donahue, Ghanshyam Sinha and Weisi Fu) further investigate the body’s communication pathways for alleviating pain. Understanding how these signals travel from an injured site through the spinal cord to the brain will help doctors and scientists figure out why some patients suffer from chronic pain and why others do not. More importantly, Taylor hopes this grant will help physicians prevent or reverse chronic pain so these patients will not have to resort to potentially addictive painkillers.
“I want to understand endogenous opioid receptor analgesia, that is, how the body can control its own pain, because with that understanding, we can either mimic it using non-opioid pain medications or alternative therapies, and prevent chronic pain from developing in the first place,” Taylor said.
A preliminary study funded by the new grant has already shown that the endogenous opioid receptor analgesia observed in mice also occurs in humans. Future work will delve deeper into the molecular mechanisms governing this pathway.