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PACAP, short for pituitary adenylate cyclase-activating polypeptide, is a naturally occurring neuropeptide that acts as a hormone, neurotransmitter, and neuromodulator. Encoded by the ADCYAP1 gene and closely related to vasoactive intestinal peptide, it signals through G protein-coupled receptors to raise cellular cAMP and takes part in the stress response, circadian timing, and neuroprotection. It has become a prominent target in migraine research, since infusing PACAP can trigger migraine-like attacks in susceptible people.
- Neuroprotective signaling
- Involved in circadian regulation
- Neurotrophic support in models
- Experimental infusion can trigger headache or migraine-like attacks
- Facial flushing and a sensation of warmth
- Transient fall in blood pressure with a faster heart rate
Overview
PACAP (pituitary adenylate cyclase-activating polypeptide) is a neuropeptide, first isolated in 1989 from ovine hypothalamic tissue through its ability to stimulate adenylate cyclase in pituitary cells, that belongs to the vasoactive intestinal peptide (VIP) family [2]. In humans it is encoded by the ADCYAP1 gene and occurs in two bioactive lengths, a 38-residue form and a shorter 27-residue form, the longer of which predominates in tissues. Its close structural kinship with VIP means the two peptides share several receptors and overlapping actions [2].
PACAP is broadly distributed through the nervous system and endocrine tissues, where it functions as a hormone, neurotransmitter, and neuromodulator [2]. It acts on three G protein-coupled receptors: the PAC1 receptor, which it binds with high affinity, together with the VPAC1 and VPAC2 receptors, which respond to both PACAP and VIP [4]. Through these receptors it participates in a wide range of processes, including the body's response to stress, regulation of circadian rhythm, control of hormone release, and protection of neurons from injury [2][4].
A major focus of PACAP research is its role in headache. Experimental infusion of PACAP can provoke migraine-like attacks in people prone to migraine, and the peptide is present throughout the trigeminovascular system that carries craniofacial pain [3][4]. This has made PACAP and its PAC1 receptor targets for migraine prevention; monoclonal antibodies directed against the peptide or its receptor have been studied, with antibodies that neutralize PACAP showing more consistent promise than blockade of the PAC1 receptor alone [1]. PACAP is a naturally occurring signaling molecule rather than a marketed drug, and interest in it also extends to post-traumatic stress and inflammatory conditions [2].
Mechanism
PACAP acts mainly by activating class B G protein-coupled receptors, chiefly the PAC1 receptor along with the shared VPAC1 and VPAC2 receptors [4]. Receptor binding stimulates adenylate cyclase and raises intracellular cyclic AMP, which sets off downstream signaling that can change neuronal excitability, promote cell survival, and drive the release of other hormones and transmitters [2]. In the vasculature and the trigeminovascular system these actions produce and activation of pain-signaling pathways, a sequence thought to underlie the 's ability to set off migraine-like attacks [3][4]. Its neuroprotective and stress-related roles are attributed to the same -linked signaling operating in neurons and endocrine cells [2].
receptor fingerprint
PAC1 receptoragonist
Cyclic AMP signalingincreases
VPAC1/VPAC2 receptorsagonist
Trigeminovascular systemactivates
Dosingtypical ranges, not medical advice
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Safetyrisks and cautions, not medical advice
Infused PACAP reliably causes flushing, headache, and can trigger migraine in susceptible people, along with drops in blood pressure. There is no safe, validated supplement form or dose. Any consumer PACAP product deserves real skepticism.
Resources
This entry is here for reference.
Research
- 2011first citedNeuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) slows down Alzheimer's…
- 2023most recentShared and independent roles of CGRP and PACAP in migraine pathophysiology
- 1.Targeting pituitary adenylate cyclase-activating polypeptide (PACAP) with monoclonal antibodies in migraine prevention: a brief review
- 2.Pituitary adenylate cyclase-activating polypeptide/vasoactive intestinal peptide (Part 2): biology and clinical importance in central nervous system and inflammatory disorders
- 3.Shared and independent roles of CGRP and PACAP in migraine pathophysiology
- 4.Pituitary adenylate cyclase-activating polypeptide receptors in the trigeminovascular system: implications for migraine
- 5.Intranasal administration of PACAP: uptake by brain and regional brain targeting with cyclodextrins.
- 6.Intranasal Administration of PACAP Is an Efficient Delivery Route to Reduce Infarct Volume and Promote Functional Recovery After Transient and Permanent Middle Cerebral Artery Occlusion.
- 7.Neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) slows down Alzheimer's disease-like pathology in amyloid precursor protein-transgenic mice.
- 8.Intranasal application of PACAP and β-cyclodextrin before the "critical period of proestrous stage" can block ovulation.
8 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
Why is PACAP linked to migraine?
Infusing PACAP provokes migraine-like attacks, so blocking it is being developed as a migraine treatment.
Is there a PACAP supplement worth taking?
No; there is no validated oral or safe consumer form.
Is it neuroprotective?
In animal models yes, but that has not translated into a usable human therapy for neuroprotection.
How is it different from VIP?
They are related peptides sharing receptors, but PACAP has its own PAC1 receptor and distinct roles in stress and migraine.
Limitations of the evidence
- Studied mainly in research settings rather than as an approved treatment
Adverse effects
- Experimental infusion can trigger headache or migraine-like attacks
- Facial flushing and a sensation of warmth
- Transient fall in blood pressure with a faster heart rate
Notes and cautions
- Intranasal PACAP is established in animals and nowhere else. Radiolabelled PACAP-38 given into the nose reached the brain, with occipital cortex and striatum taking up roughly 2 to 4 percent of the injected dose per gram of tissue [5]. In mice with middle cerebral artery occlusion, intranasal PACAP cut infarct volume and improved functional recovery, and did so far better than intravenous dosing while intraperitoneal dosing did nothing [6]. Other rodent work gave it daily to amyloid precursor protein transgenic mice and saw shifted APP processing [7], and blocked ovulation in proestrous rats [8]. No human intranasal PACAP study was found, so nothing is known about a human nasal dose, a human safety profile, or whether the rodent uptake figures carry across.