Signals from the spinal cord drive chronic pain. Scientists may have found a way to stop them
Chronic pain often lingers long after the original injury has healed. Scientists have discovered that the spinal cord develops its own pain memory through a mechanism that operates independently of the brain -- and one that could open the door to targeted treatment.
Neuropathic pain -- the burning, shooting pain people experience long after a nerve injury or surgery has supposedly "healed" -- is one of the most treatment-resistant conditions in medicine. Worldwide, one in five people lives with some form of chronic pain. Existing treatments too often fall short, or come with serious side effects. Research published in eLife now shows that the chronic phase of neuropathic pain in the spinal cord is driven largely by changes in how genes are read out -- not through the genetic code itself, but through the control of which proteins get made.
That mechanism is called translational control: the regulation of protein production based on a genetic intermediate that has already been produced (mRNA). In mice with chronic neuropathic pain, the genes altered in the spinal cord during the chronic phase turned out to be regulated not so much at the level of transcription (the production of mRNA) but at the level of translation -- which mRNA actually gets converted into protein. It is a subtle distinction, but a crucial one.
Why that distinction matters for pain treatment
Much existing pain research focuses on blocking the production of pain-related mRNA molecules. But if the critical regulation happens one step later, at the level of protein production, those therapies are missing the mark. The finding suggests that during chronic pain the spinal cord actively switches to a different regulatory circuit, one in which translational mechanisms take over from transcriptional ones.
More specifically, the researchers identified proteins that drive this translational programme, including components of the eIF4F complex -- a molecular machine that initiates protein production. When those components were blocked in mouse models, pain sensitivity during the chronic phase dropped significantly. The pain did not disappear entirely, but the hypersensitivity -- the phenomenon in which even a light touch causes pain -- was measurably reduced.
Chronic pain as a disease in its own right, not just a symptom
What the research fundamentally shows is that chronic pain is more than a continuous signal of tissue damage. The spinal cord develops its own molecular state that keeps the pain going, independently of what is happening in the originally injured tissue or in the brain. That also has implications for how you think about pain treatment: not as switching off a signal, but as breaking a self-reinforcing state within the spinal cord's nervous system.
Whether the targets identified can be safely and effectively targeted in humans remains unknown. Translational regulation is a fundamental cellular process active in virtually every tissue, so achieving a targeted intervention without side effects elsewhere is a considerable challenge. But the finding does shift the search area for future pain medications toward a layer that has received little attention until now.