About half of itch-responsive neurons projecting from the parabrachial nucleus to the central amygdala express CGRP, and activating them triggers scratching behavior in mice.
~50% are CGRP+About half of itch-responsive neurons projecting from the parabrachial nucleus to the amygdala express calcitonin gene-related peptide
What the researchers found
Approximately half of itch-responsive PBN-CeA projecting neurons are CGRP+, and optogenetic stimulation of these neurons elicits scratching behavior without enhancing anxiety in mice.
Why it matters
Chronic itch is a debilitating symptom affecting millions. Understanding the exact brain circuits involved could lead to targeted therapies, and the CGRP connection is particularly interesting given that anti-CGRP drugs are already available for migraine.
The numbers in context
Approximately half of serotonin-responsive PBN-CeA neurons are CGRP+. Optogenetic stimulation elicited scratching. Inhibition in chronic itch model significantly reduced spontaneous scratching. No effect on anxiety-like behaviors.
How the study worked
Mouse study using Targeted Recombination in Active Populations (TRAP) for labeling, retrograde tracing, and optogenetic stimulation to characterize CGRP+ PBN-CeA itch circuits.
Who was studied
Mice with acute and chronic itch models
What this study cannot tell us
Mouse study — itch circuits in human brains may differ. Optogenetic activation is artificial and may not fully replicate natural itch processing. The study examined acute responses, not chronic itch.
How to read the evidence
Preclinical mouse study using advanced neuroscience techniques. Provides important mechanistic insight but requires human validation before clinical translation.
When this study was published
Published in 2025, advancing our understanding of how CGRP functions in brain itch circuits.
The bigger picture
The finding that CGRP is involved in brain itch circuits raises the intriguing possibility that anti-CGRP therapies already used for migraine might also have applications for chronic itch conditions.
Questions still open
- Could anti-CGRP antibodies used for migraine also help patients with chronic itch conditions?
- What distinguishes the CGRP+ itch neurons from the CGRP- neurons in this pathway?
Common questions
What is CGRP and why does it matter for itch?
Could migraine drugs help with chronic itch?
Read the original research
A subpopulation of projections from the parabrachial nucleus to the central amygdala mediates itch.
Scientific reports, 15(1), 26432
Citation
Pavlenko, Darya; Ishida, Hirotake; Markan, Anika; Akiyama, Tasuku. (2025). A subpopulation of projections from the parabrachial nucleus to the central amygdala mediates itch.. Scientific reports, 15(1), 26432. https://doi.org/10.1038/s41598-025-08612-z