CGRP in the amygdala reduced cold pain sensitivity in neuropathic mice but had no effect on mechanical pain, with effects varying by brain hemisphere, injury type, and which paw was tested.
Cold sensitivity reduced, mechanical unaffectedCGRP in the amygdala selectively modulated cold but not mechanical pain sensitivity in neuropathic mice — revealing a pain-modality-specific role that challenges the simple view of CGRP as purely pain-promoting.
What the researchers found
CGRP in the amygdala — a brain region critical for pain processing — selectively modulated cold sensitivity but not mechanical sensitivity in two mouse models of neuropathic pain. Infusing CGRP into the amygdala reduced cold sensitivity in nerve injury (SNI) and chemotherapy-induced (paclitaxel) neuropathy models, while blocking CGRP with the antagonist CGRP 8-37 increased cold sensitivity. Notably, the effects were complex: they depended on which side of the brain was injected, which paw was tested, and whether the neuropathy was caused by nerve injury or chemotherapy. CGRP had no effect on mechanical pain sensitivity in either model.
Why it matters
CGRP is well-known as a pain mediator in migraine, but its role in neuropathic pain (chronic pain from nerve damage) is much less understood. This study reveals that CGRP in the amygdala actually reduces cold pain sensitivity — the opposite of what might be expected from a pain-promoting peptide. This suggests CGRP plays different, even opposing, roles depending on where in the nervous system it acts and what type of pain is involved. Understanding these nuances is critical for developing CGRP-based therapies that don't inadvertently worsen certain types of chronic pain.
The numbers in context
2 neuropathy models (SNI + paclitaxel) · CGRP and CGRP 8-37 tested · Left and right amygdala injections · Cold sensitivity modulated · Mechanical sensitivity unchanged
How the study worked
Researchers used two mouse models of neuropathic pain: spared nerve injury (SNI, surgical) and chemotherapy-induced peripheral neuropathy (CIPN, paclitaxel). They infused CGRP or the CGRP receptor antagonist CGRP 8-37 directly into the left or right central nucleus of the amygdala (CeA). Mechanical sensitivity was measured using von Frey filaments and cold sensitivity using the topical acetone drop assay on both hindpaws.
Who was studied
Mice with nerve injury (SNI) or chemotherapy-induced (paclitaxel) neuropathic pain, with CGRP or its antagonist infused into the amygdala
What this study cannot tell us
This is a mouse study using direct brain infusion — a technique that doesn't translate to practical clinical drug delivery. The effects were complex and hemisphere/model-dependent, making interpretation challenging. Sample sizes per group are not specified. The study only examined acute effects of CGRP infusion, not chronic administration. The two neuropathy models may not fully represent the diversity of human neuropathic pain conditions.
How to read the evidence
This is a well-designed preclinical study testing multiple conditions (two neuropathy models, two brain hemispheres, two pain modalities, agonist and antagonist). The complexity of the results is itself informative, but the findings are limited to mice with direct brain infusion.
When this study was published
Published in 2026, this is a very recent study at the frontier of understanding CGRP's diverse roles beyond migraine. The findings are directly relevant to ongoing discussions about expanding anti-CGRP therapy to other pain conditions.
The bigger picture
Anti-CGRP drugs (like erenumab and fremanezumab) are revolutionizing migraine treatment, but there's growing interest in whether they could help other pain conditions. This study adds a crucial nuance: in the amygdala, CGRP appears to be pain-protective for cold sensitivity in neuropathic pain — meaning anti-CGRP therapy could theoretically worsen cold allodynia (a common neuropathic pain symptom). This highlights the danger of assuming a drug's effects in one pain condition will transfer directly to another, and underscores the need for careful evaluation before expanding anti-CGRP drugs to neuropathic pain indications.
Questions still open
- If blocking CGRP in the amygdala worsens cold sensitivity, could anti-CGRP migraine drugs inadvertently exacerbate cold allodynia in patients who also have neuropathic pain?
- Why does amygdalar CGRP selectively affect cold but not mechanical sensitivity in neuropathic pain models?
- How do the pain-promoting effects of CGRP in migraine reconcile with its pain-protective effects in the amygdala during neuropathic pain?
Common questions
Isn't CGRP supposed to cause pain? Why did it reduce it here?
Could anti-CGRP migraine drugs make neuropathic pain worse?
Read the original research
Amygdalar calcitonin gene-related peptide driven effects of cold sensitivity induced by peripheral neuropathy in mice.
The journal of pain, 41, 106199
Citation
Trail, Alexis D; Allen, Heather N; Paul, Blesson; Nelson, Tyler S; Widner, James A; Lewter, Lakeisha; Tack, See H; Neilan, Rachael Miller; Kolber, Benedict J. (2026). Amygdalar calcitonin gene-related peptide driven effects of cold sensitivity induced by peripheral neuropathy in mice.. The journal of pain, 41, 106199. https://doi.org/10.1016/j.jpain.2026.106199