A newly discovered communication pathway connecting distant nerve centers in the brain and skull with the rest of the body may provide a new target for quickly stopping migraine pain.
Researchers have long tried to determine where in the brain a migraine begins and how it occurs. Unilateral headache accompanied by nausea It causes pain and other symptoms like vomiting, and understanding this can help us find new ways to prevent migraines or at least relieve the intense pain when they start.
A third of people who experience a migraine experience an aura – or flashing lights or blurred vision – preceded by waves of abnormal brain activity. Spreads through the cortexthe outer layer of the brain.
But how this activity inside the brain affects pain-sensing neuronal receptors outside the brain remains unclear.
The brain is surrounded by a protective layer Blood-brain barrierThe spinal cord removes potentially harmful substances and pathogens from the central nervous system (CNS). Unique cocoon This also prevents larger molecules from passing through.
It is an important neural hub that connects the central nervous system with the external nervous system. Peripheral nervous system – it is Trigeminal ganglionIt has already been suggested to be related to migraines, headacheThis bean-shaped nerve mass is located at the base of the skull. From the face and jaw to the brain.
The researchers found that the trigeminal ganglion Sat outside That means the blood-brain barrier could be conveniently simpler. Drug TargetsPromising new types of migraine medications, such as CGRP inhibitors.
However, this placement meant that the trigeminal ganglion was not exposed to the cerebrospinal fluid (CSF) that irrigates the brain and spinal cord.
A new study in mice shows just the opposite: The cerebrospinal fluid carries signaling molecules directly to cells in the trigeminal ganglion, bypassing the slower known pathways. MeningesA three-layered membrane that surrounds the brain and spinal cord.
“We have identified a communication pathway between the central and peripheral nervous systems that may explain the relationship between migraine aura and headache,” said biologist Martin Kaag Rasmussen of the University of Copenhagen and his colleagues. Explained in published paper.
In a series of real-time imaging experiments, the researchers tracked the flow of cerebrospinal fluid from the visual cortex (where migraine aura most commonly occurs) to the trigeminal ganglion in mouse brains.
The fluid rapidly penetrated into the base of the trigeminal ganglion, and further dissection revealed that there was no tightly wrapped sheath preventing the dissolved molecules from penetrating further along the thin portion of the trigeminal nerve.
Furthermore, molecules dissolved in the cerebrospinal fluid from one cortical hemisphere flow primarily to the trigeminal ganglion on the same side of the head, which may explain why migraines tend to be unilateral.
Rasmussen and his colleagues also found that after the aura, the contents of the animals’ cerebrospinal fluid changed: it contained CGRP (calcitonin gene-related peptide) and other molecules that had been released from the cortex after the wave of abnormal brain activity had passed, activating trigeminal ganglion neurons.
“Our observations indicate that trigeminal cerebrospinal fluid uptake causes immediate migraine headaches,” Rasmussen and colleagues said. writeHowever, “we also found that the composition of cerebrospinal fluid quickly normalized, suggesting that other processes may be causing the headaches at a later stage.”
There are clear differences between mouse and human brains and migraines. Hope Identifying this new signaling pathway “may enable new discoveries.” [drug] This will benefit the large proportion of patients who do not respond adequately to currently available treatments.”
Their findings already suggest that cerebrospinal fluid is more than just a fluid that flushes the body’s “waste clearance systems” — it’s actually an important signaling agent. But there’s still a lot we don’t know about how fluid moves through the brain.
“These findings provide a new mechanism linking the central and peripheral nervous systems,” say neuroscientists Andrew Russo of the University of Iowa and Jeffrey Iliff of the University of Washington. Write from a perspective Accompanying research.
“Similarly, this mechanism may explain the complex clinical associations between traumatic brain injury, sleep disorders, and post-traumatic headache.”
This study Science.
