PACAP-38
A 38-amino acid pituitary peptide with extraordinary neuroprotective potency - 1,000x more potent than VIP - and roles in migraine pathophysiology, stress response, and neuronal survival.
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⚠ Research & Educational Use Only. PACAP-38 is a research chemical documented here for scientific education. All information references peer-reviewed literature and preclinical/clinical study data. Not for human consumption. Not medical advice. Consult a licensed researcher or healthcare professional before any laboratory use.
- Activates adenylyl cyclase with 1,000x the potency of VIP - among the most potent neuroprotective peptides known
- Protects neurons against multiple forms of death: excitotoxicity, oxidative stress, ischemia, and amyloid toxicity
- Promotes adult neurogenesis in the hippocampus via BDNF upregulation and Wnt/beta-catenin signalling
- PACAP-38 is not FDA-approved for human use. It is a research chemical for scientific study only.
Research At a Glance
- Activates adenylyl cyclase with 1,000x the potency of VIP - among the most potent neuroprotective peptides known
- Protects neurons against multiple forms of death: excitotoxicity, oxidative stress, ischemia, and amyloid toxicity
- Promotes adult neurogenesis in the hippocampus via BDNF upregulation and Wnt/beta-catenin signalling
- Reduces neuroinflammation by suppressing microglial NF-kappaB activation and pro-inflammatory cytokines
What is PACAP-38?
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Pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) is a member of the vasoactive intestinal peptide (VIP)/secretin/glucagon superfamily of neuropeptides. Named for its original discovery as a potent activator of adenylyl cyclase in pituitary cells, PACAP-38 has since been identified as one of the most biologically active and evolutionarily conserved neuropeptides in vertebrate biology - the sequence is 97-98% identical between fish and humans, suggesting extreme functional importance across 500 million years of evolution.
PACAP exists in two forms: the full-length 38-amino acid form (PACAP-38) and a C-terminally truncated 27-amino acid form (PACAP-27). Both are derived from the same prepro-PACAP precursor by differential proteolytic processing. PACAP-38 is the predominant form in the brain (comprising ~90% of total PACAP), while PACAP-27 predominates in the gut. Both activate three G-protein-coupled receptors: PAC1R (PACAP-specific, mediating most CNS effects) and VPAC1/VPAC2 (shared with VIP). The PAC1 receptor activates multiple intracellular pathways including adenylyl cyclase, phospholipase C, and MAP kinase cascades.
The neuroprotective activity of PACAP-38 has been demonstrated across virtually every in vitro and in vivo model of neuronal death investigated. In excitotoxicity models (glutamate, NMDA exposure), PACAP-38 dramatically reduces neuronal death via PKA-dependent inhibition of caspase-3 and upregulation of anti-apoptotic Bcl-2 family proteins. In ischemia models, PACAP-38 administered before or immediately after the ischemic insult reduces infarct volume by 40-60% in multiple studies. The mechanisms include reduced glutamate release, enhanced activity of antioxidant enzymes, anti-inflammatory cytokine modulation, and direct mitochondrial protection.
The relationship between PACAP-38 and migraine is one of the most clinically important and scientifically complex aspects of this peptide. PACAP-38 levels in cranial venous blood are elevated during migraine attacks, and IV infusion of PACAP-38 triggers delayed migraine attacks in 60-70% of susceptible individuals (migraine without aura patients) - one of the most reliable experimental triggers known. Paradoxically, PACAP-38 has also been proposed as a neuroprotective treatment in migraine prevention. The resolution of this apparent contradiction lies in the temporal dynamics: acute PACAP release during attacks drives dural vasodilation and pain signalling through PAC1R on trigeminal neurons, while preventive approaches targeting PACAP or its receptors could suppress this cascade.
The development of PACAP antibodies and receptor antagonists for migraine prevention represents one of the most active areas of headache medicine research. Several anti-PACAP antibodies and PAC1R antagonists are in clinical development, positioning PACAP biology as the next major therapeutic frontier after the anti-CGRP antibodies.
Key Research Benefits
Documented effects observed in preclinical and clinical studies on PACAP-38. See all Cognitive Enhancement peptides for comparison.
Side Effects & Risks
Adverse effects reported in the research literature. All data sourced from preclinical and clinical study reports. View all peptides' side effects →
Dosing Data from the Literature
Doses referenced below are sourced from published preclinical and clinical studies. Use the peptide dose calculator to convert these values to injection volume.
PACAP-38 research dosing is primarily in preclinical models; human studies have been limited to IV infusion challenges:
Migraine trigger research (IV infusion): 10 pmol/kg/min for 20 minutes - reliably triggers migraine attacks in susceptible individuals
Neuroprotection research (animal models): 1-100 nmol/kg IV, IM or intracerebroventricularly
The practical research challenge with PACAP-38 is its 5-10 minute plasma half-life, which has driven development of stable analogues (maxadilan, PACAP6-38 antagonist) for mechanistic studies.
Administration in Research Settings
Standard reconstitution and administration methodology for laboratory research use.
IV infusion for human migraine research protocols: dissolve in normal saline, infuse at specified picomolar/kg/min rate. Monitoring required for blood pressure and heart rate changes.
For preclinical neuroprotection research: IV bolus or slow infusion. Intracerebroventricular administration in rodent models achieves direct CNS delivery and is the gold standard route for dose-response studies.
Many research groups use stable PACAP analogues or receptor-selective agonists to circumvent the half-life limitation while studying downstream signalling pathways.
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This information is for educational research purposes only. This is not medical advice. Consult a qualified healthcare professional.