An interaction between two proteins in the nerve cells that carry pain information from the head and neck to the brain has been discovered, according to an article in the December issue of Journal of Neurochemistry.
Head pain is signaled to the brain by the trigeminal nerve, which also conveys other types of sensation, such as touch and temperature, from structures of the face, including skin, temporomandibular joints (TMJs) and teeth. The trigeminal nerve provides the signaling pathway for pain associated with migraines, TMJ disorder, dental surgery, head and neck cancer, and other neuropathic and inflammatory pain conditions.
Researchers at Oregon Health & Science University’s (OHSU) School of Dentistry conducted a study in which they focused on two trigeminal nerve cell proteins: calcitonin gene-related peptide (CGRP) and brain-derived neurotrophic factor (BDNF). During a migraine attack, the stimulation of trigeminal nerve cells releases CGRP at the peripheral end of the cells, widening blood vessels in the brain coverings called "meninges." This increases the flow of blood through the meninges and initiates an inflammatory process that may contribute to the pain experience. Blocking CGRP helps alleviate migraine pain.
The research team—led by Agnieszka Balkowiec, MD, PhD, OHSU School of Dentistry—found that the stimulation of trigeminal nerve cells, such as during a migraine attack, leads to the release of both CGRP and BDNF. They also found that BDNF is released by CGRP when trigeminal nerve cells are not stimulated. In fact, said Dr. Balkowiec, CGRP’s role at the central end of the trigeminal nerve cells may be what facilitates BDNF release. BDNF has been shown to play an important role in pain signaling from other parts of the body, but this is the first time it has been considered to be a factor in head pain, say researchers.
"What we now need to better understand is how the interaction between CGRP and BDNF affects pain signaling to the brain in various disorders," said Dr. Balkowiec.
The study was funded by grants from the National Institutes of Health, the Medical Research Foundation of Oregon, the American Association for Dental Research and the OHSU School of Dentistry.
