Researchers have found a chemical that can be a real pain to people with migraines. According to findings published in the journal Pain, the hypersensitivity to pain that people experience during a migraine may be linked to a certain protein — rats given a drug to absorb that protein were less sensitive to stimuli that typically trigger the severe headaches.

“Between attacks, migraine patients are otherwise normal but are sensitized to non-noxious events known as triggers,” the study says. And previous research has shown that people who get migraines have higher levels of a protein called brain-derived neurotrophic factor, also known as BDNF. The University of Texas at Dallas neuroscience professor Greg Dussor and his colleagues were seeking to learn more about this as a possible mechanism behind migraines.

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In the scientific community, the membranes around the brain and spinal cord called the meninges are a prime suspect in migraines as a co-conspirator, potentially sending pain information through the brain stem and into the brain, according to the university. The researchers in this study first gave the rats a human substance involved in transmitting information about pain and inflammation through those membranes, and then injected a drug into their brain stems that “soaks up” the protein in question, the BDNF. “The result was that the animals became desensitized to migraines” when the researchers tried to stimulate them to bring on a migraine.

“There's something that BDNF has done, and potentially is continuing to do, that is keeping migraine patients sensitized,” Dussor said in the university statement.

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In addition to searing pain, people with migraines can experience nausea and become sensitive to lights and sounds, among other symptoms that can last for hours or days. Scientists seeking to better understand how migraines start are also trying to determine why certain triggers like stress, not enough sleep, or even bright lights can induce migraines in some people, but are practically harmless for others. Dussor said in the statement that he plans to keep investigating the cause of migraines and what role BDNF plays, and expressed hope that one day targeting that protein could be a treatment for some people who get migraines.

“We have a lot of work to do” to understand fully how BDNF works and “how we can target the pain system while not impacting learning and memory, emotion and movement,” he said. “We are still working on solving the puzzle.”

Source: Dussor G, Burgos-Vega CC, Quigley LD, Avona A, Price T. Dural stimulation in rats causes BDNF-dependent priming to subthreshold stimuli including a migraine trigger. Pain. 2016.