Mice engineered with enhanced CGRP signaling showed increased motion sensitivity and resistance to migraine treatments, modeling vestibular migraine.
Resistant to migraine blockersMice with enhanced CGRP signaling did not respond as expected to standard anti-CGRP migraine treatments
What the researchers found
The nestin/hRAMP1 mice showed heightened sensitivity to CGRP's effects at lower doses compared to normal mice. They exhibited increased motion-induced thermoregulation changes (a surrogate for nausea) and greater postural sway (a measure of balance dysfunction). Male nestin/hRAMP1 mice specifically showed increased sway not seen in male controls.
Migraine blocker experiments were challenging to interpret, but the data suggests olcegepant (a CGRP receptor antagonist) could not reverse CGRP-induced or endogenous changes in these mice. Rizatriptan (a triptan) was ineffective in both the engineered mice and controls.
The authors propose this mouse model represents treatment-resistant migraine with vestibular features.
Why it matters
Vestibular migraine (migraine with dizziness and motion sensitivity) affects about 1% of the general population and is poorly understood. Many patients do not respond well to standard migraine treatments. A mouse model that mimics treatment-resistant vestibular migraine could help researchers understand why some patients fail therapy and test new drug candidates.
The numbers in context
- nestin/hRAMP1 mice: enhanced sensitivity to CGRP at lower doses
- Increased motion-induced thermoregulation changes (nausea surrogate)
- Greater postural sway dynamic range
- Male mice showed increased sway vs male controls
- Olcegepant: unable to reverse CGRP-related symptoms
- Rizatriptan: ineffective in both groups
How the study worked
Researchers used nestin/hRAMP1 transgenic mice that express elevated human RAMP1 in the nervous system, enhancing CGRP signaling. They measured motion sensitivity using motion-induced thermoregulation (a nausea surrogate) and postural sway using center of pressure assays. They tested olcegepant (CGRP receptor antagonist) and rizatriptan (5-HT1B/1D agonist) as migraine treatments.
Who was studied
nestin/hRAMP1 transgenic mice with enhanced CGRP signaling and wild-type littermate controls
What this study cannot tell us
Mouse behavioral surrogates for nausea and dizziness are imperfect. The authors note the migraine blocker experiments were challenging to interpret. RAMP1 overexpression is a genetic model that may not match the complex neurobiology of human vestibular migraine. Sample sizes for behavioral assays are typically small. Sex differences were observed but not fully explained.
How to read the evidence
Rated preliminary: transgenic mouse model providing mechanistic insights, but mouse behavioral surrogates for nausea and dizziness are imperfect.
When this study was published
Published in 2024. Adds to a growing body of research on CGRP's role in vestibular migraine.
The bigger picture
Vestibular migraine (migraine with dizziness) affects about 1% of the population and is poorly understood. This mouse model could help researchers develop targeted treatments for patients who don't respond to standard CGRP-blocking drugs.
Questions still open
- Why are standard CGRP blockers less effective in this enhanced signaling model?
- Could higher doses of CGRP antibodies overcome the resistance?
Common questions
What is vestibular migraine?
Why don't some migraine drugs work for vestibular migraine?
Read the original research
Human RAMP1 overexpressing mice are resistant to migraine therapies for motion sensitivity.
PloS one, 19(12), e0313482
Citation
Rahman, Shafaqat M; Guo, Linda Jia; Minarovich, Carissa; Moon, Laura; Guo, Anna; Luebke, Anne E. (2024). Human RAMP1 overexpressing mice are resistant to migraine therapies for motion sensitivity.. PloS one, 19(12), e0313482. https://doi.org/10.1371/journal.pone.0313482