Mechanism of Action
CGRP Receptor Complex
CGRP signals through a heterodimeric receptor complex consisting of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1). This Gs-coupled complex activates adenylyl cyclase, increasing cAMP and activating PKA. In vascular smooth muscle, cAMP-mediated relaxation produces potent vasodilation. CLR/RAMP1 is the canonical CGRP receptor; CLR/RAMP2 and CLR/RAMP3 are adrenomedullin receptors with lower CGRP affinity.
Trigeminal Pain and Neurogenic Inflammation
CGRP is co-stored with substance P in trigeminal sensory fibers innervating meningeal blood vessels. Activation of trigeminal afferents releases CGRP, producing meningeal vasodilation, plasma protein extravasation, and mast cell degranulation, the triad of neurogenic inflammation central to migraine pain. CGRP sensitizes trigeminal neurons to subsequent stimuli, amplifying and sustaining migraine pain.
Research Summary
Migraine Pathophysiology
HumanIV CGRP infusion triggers migraine in susceptible individuals within 30-90 minutes. CGRP levels are elevated in jugular venous blood during migraine attacks and normalize following sumatriptan treatment. These findings established CGRP as a validated migraine target, leading to four FDA-approved monoclonal antibodies and two classes of gepants (olcegepant, ubrogepant, rimegepant) that block the CGRP receptor.
Cardiovascular Effects
HumanIV CGRP infusion produces dose-dependent facial flushing, palpitations, and reduced systemic vascular resistance in healthy volunteers and heart failure patients. These hemodynamic effects initially motivated CGRP as a heart failure therapy before the migraine application became the primary focus.
Wound Healing and Bone
AnimalCGRP promotes wound healing through vasodilation-mediated nutrient delivery and direct fibroblast stimulation. In bone, CGRP from sensory nerve endings regulates osteoblast activity and bone formation. These peripheral actions support broad investigation of the CGRP system beyond migraine.
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Research Protocols
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Migraine research | 1.5-2 mcg/kg | Single IV infusion over 20 min | Intravenous |
| Vasodilation studies | 0.3-3 mcg/kg/min | Infusion | Intravenous |
Exogenous CGRP research focuses on pathophysiology. Therapeutic development uses CGRP-blocking antibodies and receptor antagonists rather than CGRP itself.
Interactions
Safety Profile
Native CGRP infusion in humans causes predictable vasodilatory effects including flushing, palpitations, and headache at higher doses. The very short plasma half-life (~7 min) limits duration of any adverse effects. CGRP pathway blocking drugs (antibodies, gepants) used clinically have demonstrated excellent long-term safety in migraine prevention trials with minimal serious adverse events.
References
- [1]Amara SG, et al. Alternative RNA processing in calcitonin gene expression generates mRNAs encoding different polypeptide products. Nature. 1982;298(5871):240-244.
- [2]Goadsby PJ, et al. A controlled trial of erenumab for episodic migraine. N Engl J Med. 2017;377(22):2123-2132.
- [3]Edvinsson L, et al. CGRP as the target of new migraine therapies, successful translation from bench to clinic. Nat Rev Neurol. 2018.