A University of Iowa study may provide an explanation for why some people get migraine headaches while others do not. The researchers found that too much of a small protein called RAMP1 appears to "turn up the volume" of a nerve cell receptor's response to a neuropeptide thought to cause migraines.
The neuropeptide is called CGRP (calcitonin gene-related peptide) and studies have shown that it plays a key role in migraine headaches. In particular, CGRP levels are elevated in the blood during migraine, and drugs that either reduce the levels of CGRP or block its action significantly reduce the pain of migraine headaches. Also, if CGRP is injected into people who are susceptible to migraines, they get a severe headache or a full migraine.
"We have shown that this RAMP protein is a key regulator for the action of CGRP," said Andrew Russo, Ph.D., UI professor of molecular physiology and biophysics. "Our study suggests that people who get migraines may have higher levels of RAMP1 than people who don't get migraines."
RAMP1 is a normal, required subunit of the CGRP receptor. Russo and his colleagues found that overexpression of RAMP1 protein in nerve cells increased the sensitivity and responsiveness of CGRP receptors to the neuropeptide -- more RAMP1 made CGRP receptors react to much lower concentrations of CGRP than usual and caused the receptors to respond more vigorously to the neuropeptide.