Key Brain Cells Identified in Persistent Pain

Scientists have discovered a small set of often-overlooked brain cells that are activated during persistent pain—the kind that lasts long after an injury. This research, performed in mice, could lead to new therapies for chronic pain, a condition affecting about one in five people globally.

As biologist Nicholas Betley, a co-author of the study, puts it, "Pain is in your head. But it is very real."

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The Persistent-Pain Neuron

The study, published in Nature, focused on the parabrachial nucleus, a brain region that processes sensory information. Researchers identified a subset of neurons in this nucleus that switched on after a painful stimulus (like a nerve cut) and remained active long after the insult.

These "persistent-pain neurons" carry receptors for the signaling molecule neuropeptide Y (NPY).

• Activation: When scientists artificially activated these neurons (called 'Y1R' neurons), mice displayed pain-associated behaviors.
• Suppression: When the activity of these neurons was blocked, the animals' persistent pain decreased, while their normal, short-lived pain responses (like recoiling from a hot surface) remained intact.

Betley clarified that while these Y1R neurons don't cause the feeling of pain by themselves, they form a crucial part of the network "that leads to the sensation that we refer to as pain."

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The Brain's Innate Pain-Killing Mechanism

The experiments also revealed that the brain has an innate pain-killing mechanism. The researchers found that the release of NPY into the parabrachial nucleus can dampen the activity of these persistent-pain neurons.

This NPY was released by neurons in other brain areas that became active when the mice were subjected to urgent needs, such as being deprived of food or water or exposed to a frightening stimulus (like the smell of bobcat urine). In these situations, the mice's pain-associated behaviors and neural activity decreased. For instance, hungry mice with a nerve injury ignored a poke to their paws that would normally cause them to recoil.

"In the wild, we think this would allow them to shift focus from their pain to go out and seek food," Betley suggested.

Co-author Ann Kennedy, a neuroscientist, summarized the finding: "Something more important than pain came along." The research highlights that the sensation of pain is "a lot more malleable, and it's changed by our experiences."

Disclaimer: This content is published only for health awareness and informational purposes. It's not a substitute for your professional medical advice. You must consult a doctor/healthcare professional regarding your specific health concerns.