VIP
Neuropeptide hormone
Vasoactive intestinal peptide, a 28-amino-acid neuropeptide studied across vascular and neurological research.
Also referenced as: Vasoactive Intestinal Peptide
Overview
Vasoactive intestinal peptide (VIP) is a 28-amino-acid endogenous neuropeptide of the secretin/glucagon peptide family, first isolated from intestinal tissue. It is widely distributed in the nervous system and peripheral tissues.
At a glance
What VIP does
Vasoactive intestinal peptide (VIP) is a 28-amino-acid neuropeptide of the secretin/glucagon superfamily that acts as a signaling molecule across the nervous, vascular, gastrointestinal, respiratory, and immune systems. What it does is best understood through its receptors: VIP binds the class B G-protein-coupled receptors VPAC1 and VPAC2 (and, with lower affinity, PAC1), which couple to Gs, activate adenylate cyclase, and raise intracellular cAMP. That single upstream event drives its two headline actions - relaxing smooth muscle and dampening inflammation.
Through cAMP-driven smooth-muscle relaxation, VIP produces vasodilation of blood vessels, bronchodilation in the airways, and relaxation of gastrointestinal smooth muscle, and it stimulates secretion of water and electrolytes in the gut (the reason VIP-secreting tumors cause profuse watery diarrhea). In the immune compartment, VIP is a well-characterized anti-inflammatory mediator: acting mainly through VPAC1 on macrophages, dendritic cells, and T cells, it suppresses pro-inflammatory cytokines such as TNF-alpha, IL-6, and IL-12, promotes a shift toward regulatory/Th2 responses, and reduces production of inflammatory mediators.
The evidence spans strong basic physiology and animal models - VIP is protective in rodent models of endotoxemia/sepsis, arthritis, and autoimmune inflammation - but its therapeutic use in humans is limited by a very short circulating half-life and rapid degradation. Human clinical experience is narrow (for example inhaled VIP explored in pulmonary hypertension and sarcoidosis, with modest results). Overall VIP's actions are well established mechanistically; its practical translation is constrained by pharmacokinetics.
Effects reported in research
- Raises intracellular cAMP by activating VPAC1/VPAC2 (Gs-coupled) receptors, the shared upstream event for its downstream actions (well established).
- Relaxes vascular smooth muscle to produce vasodilation and lower vascular tone (established physiology; animal and isolated-tissue studies).
- Relaxes airway smooth muscle (bronchodilation), studied as a rationale for inhaled VIP in pulmonary vascular and airway disease (animal + limited human trials).
- Suppresses pro-inflammatory cytokines including TNF-alpha, IL-6, and IL-12 in macrophages and dendritic cells (in-vitro and animal models).
- Promotes regulatory T-cell / Th2-skewed immune responses, reducing autoimmune-type inflammation in rodent models of arthritis and colitis (animal).
- Protects against lethality in rodent endotoxemia/sepsis models by blunting the systemic inflammatory response (animal).
- Stimulates intestinal secretion of water and electrolytes - the mechanism behind the watery diarrhea of VIP-secreting tumors (VIPomas) (human clinical observation).
- Has a very short plasma half-life and is rapidly degraded, which limits systemic therapeutic use (established pharmacokinetics).
Effects listed reflect findings reported in the research literature — many in animal or in-vitro models. Listing an effect is not a claim of efficacy or a therapeutic indication in humans.
Mechanism of action
VIP signals through the class B G-protein-coupled receptors VPAC1 and VPAC2, activating adenylate cyclase and raising intracellular cAMP. Its physiological actions include smooth-muscle relaxation and vasodilation, modulation of secretion, and immunomodulatory/anti-inflammatory signaling. These broad receptor-mediated effects underlie its study across vascular, pulmonary, and inflammatory contexts.
Mechanistic description reflects published research-literature understanding. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.
What it's studied for
Research contexts in which VIP appears in the literature. Listing a research area is not a claim of efficacy or a therapeutic indication.
Key characteristics
- Endogenous 28-residue neuropeptide of the secretin/glucagon family.
- Acts via VPAC1 and VPAC2 GPCRs, elevating cAMP.
- Physiological roles include vasodilation and smooth-muscle relaxation.
- Studied for immunomodulatory and anti-inflammatory signaling.
- Investigational as a therapeutic; not a broadly approved peptide drug.
Reported research dosing reference only
Educational reference, not dosing guidance. The figures below summarize amounts reported in published research and research-community protocols, provided for educational and research context only. They are not medical advice, not a recommendation, and not instructions for human use. VIP is a research compound.
Because native VIP is cleared within minutes, research literature does not define a single standardized dosing protocol; exposures are context-specific to the model and often delivered by infusion or repeated administration.
- Preclinical infusion/administration studies: microgram-scale amounts scaled to model, reported per study
- In vitro: nanomolar-to-micromolar receptor-activation concentrations reported
These are reference figures for research context only, not dosing guidance for humans. The ~1-2 minute half-life dominates any practical handling consideration.
How it compares
VIP is a broadly acting endogenous neuropeptide signaling through VPAC receptors, unrelated to the melanocortin, gonadotropin, and myostatin-pathway mechanisms elsewhere in this set.
Compare and calculate
Side-by-side pages for the pairings the literature already documents for VIP, plus the unit-conversion reference for a reconstituted vial. Factual comparisons of documented characteristics — not a recommendation to combine or use any compound.
VIP reconstitution calculator → Concentration, volume per measured amount and syringe units for a stated vial mass and diluent volume. A unit-conversion reference, not a dosing recommendation.
Handling & Stability
Lyophilized peptides are stored cold, protected from light, and reconstituted only at the time of intended in-vitro work.
- Avoid repeated freeze-thaw cycles
- Verify supplier lot and Certificate of Analysis
- Follow institutional lab-safety protocols
Analytical & COA Concepts
Reputable research suppliers publish a third-party Certificate of Analysis per batch. Key analytical concepts referenced in COAs include:
Category Context
VIP sits in the Specialty & Research area of the PeptiDex library.
- Entry type: Research compound reference
- Specialty & Research category hub →
- Browse the full library →
- Glossary of terms →
Where researchers source VIP
For researchers studying VIP, third-party suppliers such as Practically Natty Peptides offer research-grade material, third-party tests every batch and provides Certificates of Analysis on request, and ship from the US. This specific listing is currently marked out of stock — check the supplier site for current availability.
View research-supplier listing →
Outbound link to a third-party research supplier. Inclusion does not constitute endorsement; all editorial content is developed independently.
Frequently asked questions
What is VIP (vasoactive intestinal peptide)?
VIP is a 28-amino-acid neuropeptide belonging to the glucagon/secretin superfamily and acts as a ligand at class II G-protein-coupled receptors (VPAC1 and VPAC2). It is a naturally occurring signaling peptide found in the nervous system and gut. In research it is examined for roles in vasodilation, immune modulation, and neuroprotection.
What is VIP studied for in research?
VIP is investigated in models of inflammation, immune regulation, circadian signaling, pulmonary and vascular biology, and chronic inflammatory conditions. Interest in a research-community context has centered on inflammatory and neuroimmune models. It is a research and reference compound, not an approved general-use therapeutic in this form.
Why does VIP's very short half-life matter for research design?
Native VIP has a plasma half-life on the order of only ~1-2 minutes because it is rapidly degraded by peptidases. This extremely short duration means native VIP is difficult to maintain at stable concentrations, which is why much research explores analogs, sustained-delivery formats, or frequent administration. Study design must account for this rapid clearance.
How is VIP handled and stored?
VIP is typically supplied as a lyophilized powder, reconstituted before use, and is sensitive to degradation. Lyophilized peptide is kept frozen and protected from light; reconstituted solution is refrigerated and used quickly given the peptide's instability. A COA with HPLC purity and mass-spec identity is standard to expect.
Is VIP an approved drug?
Native VIP itself is not a broadly approved therapeutic in the research-peptide context, though VIP biology has informed drug development. Reported uses are research- and reference-oriented, and material sold in this space is intended for laboratory research rather than human use.
Answers are educational summaries of research-literature context and do not constitute medical advice. See the Research Library, COA guide, and Storage & Handling guide for more.
References
Primary literature indexed in PubMed for VIP. Listing a study records that it exists and is indexed — it is not a claim of efficacy, a therapeutic indication, or an endorsement of its conclusions. Much of this literature is preclinical (in-vitro or animal-model).
- Pituitary adenylate cyclase-activating polypeptide/vasoactive intestinal peptide [Part 1]: biology, pharmacology, and new insights into their cellular basis of action/signaling which are providing new therapeutic targets
- Vasoactive intestinal peptide/pituitary adenylate cyclase activating polypeptide, and their receptors and cancer
Each reference was checked against its PubMed record on 2026-07-28: the PMID resolves and the title, journal and year match. Where no indexed literature exists for a compound, PeptiDex says so rather than substituting a citation about a different molecule. See the editorial policy.