VIP

Vasoactive Intestinal Peptide (VIP): Comprehensive Research Guide

Vasoactive intestinal peptide (VIP) is a naturally occurring 28-amino-acid neuropeptide and signaling molecule studied across neurobiology, gastrointestinal physiology, pulmonary biology, circadian regulation, endocrine signaling, and immunology. Although its historical name emphasizes the intestine, VIP is distributed broadly in the central and peripheral nervous systems and is released by multiple neuronal and immune-cell populations. It is a member of the secretin/glucagon peptide family and signals mainly through the class B G-protein-coupled receptors VPAC1 and VPAC2.

Hanpro Peptides supplies VIP as a lyophilized research material for controlled laboratory, analytical, in-vitro, and appropriately authorized preclinical work. The page summarizes established research concepts while carefully distinguishing receptor biology and model-system observations from clinical claims. This material is not approved for human or veterinary use, is not a medicine, and must not be used for self-experimentation, diagnosis, treatment, or prevention of disease.

Molecular structure and physicochemical properties

• Common name: vasoactive intestinal peptide or vasoactive intestinal polypeptide (VIP).
• Human sequence: HSDAVFTDNYTRLRKQMAVKKYLNSILN-NH2.
• Peptide length: 28 amino acids.
• Approximate molecular mass: about 3.3 kDa; verify the exact salt form and lot-specific identity on the certificate of analysis.
• Format: lyophilized research material in labeled vial configurations.
• Specifications offered: refer to the selected variation and label; current catalog options include 5mg × 10 vials and 10mg × 10 vials.
• Quality control: lot-specific chromatographic purity assessment and mass-spectrometric identity confirmation.
• Solubility and stability: must be established for the specific buffer, concentration, container, temperature, and assay conditions used by the laboratory.

VIP is susceptible to proteolytic degradation and may show concentration-dependent adsorption or loss in experimental systems. Its relatively short biological persistence is an important variable in time-course design. Researchers should not assume that a concentration measured immediately after preparation remains unchanged throughout an experiment. Stability-indicating HPLC or LC-MS measurements, appropriate recovery controls, and carefully documented sample handling are valuable when quantitative interpretation matters.

Mechanisms of action studied in research

1. VPAC1 and VPAC2 receptor binding

VIP binds with high affinity to VPAC1 and VPAC2, two family B GPCRs that are also activated by pituitary adenylate cyclase-activating polypeptide (PACAP). Receptor distribution differs by tissue and cell state, so the same peptide can produce different outcomes in different models. PAC1 is comparatively selective for PACAP and is not normally treated as the principal VIP receptor. Experiments should characterize receptor expression rather than infer it from tissue name alone.

2. Adenylyl cyclase, cAMP, and PKA signaling

VPAC receptors preferentially couple to Gαs, activating adenylyl cyclase, increasing intracellular cyclic AMP, and engaging protein kinase A. Downstream consequences may include altered transcription-factor activity, ion transport, secretory behavior, smooth-muscle tone, and cytokine production. Researchers commonly use cAMP assays, receptor antagonists, knockdown strategies, and phosphoprotein measurements to determine whether a response is VPAC-dependent.

3. Alternative signaling and receptor regulation

VIP receptor biology is not limited to one linear pathway. Depending on the model, VPAC activation can intersect with phospholipase C, calcium signaling, protein kinase C, ERK/MAPK, β-arrestin recruitment, receptor internalization, and desensitization. Exposure duration and receptor density can therefore change the apparent potency or direction of an effect. This makes kinetic experiments and matched controls more informative than a single endpoint.

4. Neuroimmune communication

VIP has been investigated as a messenger between neuronal and immune systems. In cellular and animal models, researchers have reported changes in macrophage behavior, T-cell polarization, cytokine release, and inflammatory transcription programs. For example, published pulmonary models have examined VIP-associated modulation of TNF-α, IL-10, IL-17A, PKA, and PKC pathways. These findings are model-dependent and do not establish treatment efficacy in people.

5. Smooth-muscle and vascular signaling

The peptide was initially isolated and characterized in relation to vasodilation. VIP receptor signaling has since been studied in vascular, airway, and gastrointestinal smooth-muscle preparations. Experimental endpoints may include relaxation, resistance, pressure, calcium flux, or contractility. Because cardiovascular and smooth-muscle effects can be profound, VIP must be handled only within appropriate laboratory safety and ethics frameworks.

6. Epithelial secretion and gastrointestinal regulation

VIP participates in experimental models of intestinal ion and water secretion, nutrient absorption, motility, epithelial function, and enteric neuronal communication. Both genetic models and receptor-focused pharmacology have been used to separate physiological signaling from disease-associated overexpression. The peptide’s name should not be interpreted as evidence that its activity is restricted to the gut.

7. Circadian and neuronal network research

VIP is an important signaling molecule in the suprachiasmatic nucleus and has been studied in the synchronization of circadian neuronal networks. VIP/VPAC2 experiments may quantify clock-gene expression, phase relationships, neuronal firing, sleep-wake timing, or responses to altered light schedules. These studies typically rely on carefully controlled genetic, electrophysiological, and imaging methods.

8. Endocrine and metabolic signaling

VIP and VPAC2 are studied in pancreatic islet signaling, glucose-responsive insulin secretion, and endocrine-cell communication. Reviews note that broad receptor distribution and short peptide persistence complicate translation, motivating research into receptor-selective agonists and stabilized analogues. A native VIP research material should therefore not be treated as interchangeable with an engineered VPAC-selective compound.

Research applications

Receptor pharmacology: determine VPAC1/VPAC2 potency, selectivity, desensitization, internalization, or antagonist sensitivity using receptor-expression systems and appropriate positive and negative controls.

Immunology and inflammation models: examine cytokine panels, transcriptional responses, macrophage or lymphocyte phenotypes, and pathway activation in stimulated cells. Include vehicle, untreated, receptor-blockade, and viability controls so that a change is not mistakenly attributed to cytotoxicity or assay interference.

Pulmonary research: VIP has been evaluated in airway smooth-muscle, inflammatory, vascular-remodeling, and lung-injury models. Published findings include cell and mouse data, but they must remain explicitly labeled as preclinical. Experimental design should distinguish direct receptor effects from secondary hemodynamic or immune changes.

Gastrointestinal physiology: study epithelial secretion, motility, enteric-neuronal signaling, mucosal immune interactions, and receptor expression. Investigators may compare wild-type and receptor-deficient systems or combine functional assays with transcript and protein measurements.

Neuroscience and circadian biology: examine neuronal synchronization, clock-gene output, neuroendocrine communication, and stress-related signaling. Because VIP signaling is network- and timing-dependent, circadian phase, sampling time, and culture synchronization should be documented.

Analytical and formulation development: establish peptide identity, recovery, degradation kinetics, adsorption, buffer compatibility, and temperature sensitivity. Analytical work is essential when comparing native VIP with analogues, delivery systems, or receptor-selective ligands.

Product specification

Product name	Vasoactive Intestinal Peptide (VIP)
Sequence	HSDAVFTDNYTRLRKQMAVKKYLNSILN-NH2
Peptide length	28 amino acids
Approximate molecular mass	Approximately 3.3 kDa; confirm lot-specific form on COA
Available catalog specifications	5mg × 10 vials and 10mg × 10 vials; verify selected variation
Appearance	Lyophilized research material; appearance may vary by lot and salt form
Quality-control methods	HPLC/UPLC purity assessment and mass-spectrometric identity verification
Storage	Follow the current product label and lot-specific COA; protect from moisture and light
Intended use	Laboratory research and analytical use only

Laboratory reconstitution and handling

Review the product label, safety documentation, and COA before opening. Use a qualified laboratory procedure that defines the solvent or buffer, target concentration, pH, container, mixing method, temperature, and sampling schedule. VIP can be sensitive to proteases and surface adsorption; use clean low-protein-binding equipment where the validated method calls for it, and include recovery controls.

Prepare only the quantity needed for the approved experiment. Add the validated solvent gently and avoid harsh agitation unless a method has demonstrated that it does not affect recovery or integrity. Record the preparation time, operator, lot, solvent lot, concentration calculation, container type, and storage condition. Aliquoting may reduce repeated freeze-thaw exposure, but an acceptable number of cycles and a post-reconstitution stability period must be established experimentally for the actual matrix.

This page intentionally provides no human or animal dose, injection route, or self-administration instructions. Any in-vivo study must be designed and approved by qualified personnel under applicable institutional and legal requirements. A catalog amount is not a recommended experimental concentration or dose.

Frequently asked questions

What is VIP and how does it work?

VIP is a 28-amino-acid endogenous neuropeptide. It primarily activates VPAC1 and VPAC2 receptors, commonly increasing cAMP and PKA signaling while also engaging model-dependent calcium, PKC, MAPK, receptor-internalization, and transcriptional pathways. The resulting response depends on receptor expression, cell type, exposure time, peptide stability, and experimental context.

What research concentration or dose is recommended?

Hanpro Peptides does not recommend doses for humans or animals. Laboratories should select in-vitro concentration ranges from peer-reviewed model-specific literature, run pilot concentration-response and viability experiments, and operate under approved protocols. Catalog vial content must never be interpreted as a dosing recommendation.

What side effects can VIP cause?

This is not a clinical product, so the relevant laboratory concern is biological hazard rather than consumer “side effects.” VIP can influence vascular tone, secretion, smooth muscle, immune signaling, and endocrine pathways. Risk assessments, suitable personal protective equipment, exposure controls, and institution-approved handling procedures are required.

Is VIP legal for research use?

Research legality varies by country, institution, intended use, and experimental system. This material is sold only for lawful laboratory and analytical research. The purchaser is responsible for procurement rules, import requirements, ethics review, controlled access, storage, and disposal. It is not approved by the FDA for diagnosis or treatment.

Can VIP be combined with other peptides or compounds?

Only within a justified research design. First test chemical compatibility, analytical interference, and stability. Use individual-compound, vehicle, and combination arms to distinguish additive, antagonistic, or synergistic effects. Do not assume that sharing a pathway or research area makes two materials physically or biologically compatible.

What are the shelf-life and storage requirements?

Follow the current label and the lot-specific COA. Store unopened lyophilized material protected from moisture and light under the stated conditions. Once a solution is prepared, its stability depends on buffer, concentration, pH, container, temperature, protease exposure, and freeze-thaw history; establish those conditions experimentally.

How should VIP activity be validated?

Combine chemical identity and purity data with a fit-for-purpose functional assay. Depending on the research question, this could include VPAC receptor binding, cAMP generation, PKA activation, receptor internalization, calcium signaling, or a validated downstream transcriptional readout. Always include vehicle, positive, negative, and viability controls.

Related research products

• Humanin – mitochondrial-derived peptide for cellular stress and signaling research.
• SS-31 – mitochondria-targeted research peptide.
• MOTS-c – mitochondrial signaling research material.
• Thymosin Alpha-1 – peptide studied in immune-signaling models.
• LL-37 – antimicrobial host-defense peptide for controlled research.
• KPV – short melanocortin-related peptide studied in inflammatory models.
• NAD+ – research material for redox and cellular metabolism studies.
• Cerebrolysin research product – complex peptide preparation for analytical and neuroscience research.

Selected scientific references

• IUPHAR review of VIP/PACAP receptor pharmacology and function.
• Review of VIP physiology and gastrointestinal research.
• Review of VPAC receptor activation and regulation.
• Preclinical study of VIP signaling in a murine lung-injury model.

Quality assurance and disclaimer

Hanpro Peptides supports lot-specific review through chromatographic purity testing, mass-spectrometric identity analysis, and certificate-of-analysis documentation. Researchers should retain the applicable COA and independently determine suitability for their method. VIP is supplied strictly for laboratory research and analytical purposes. It is not for human or animal consumption, administration, diagnosis, treatment, or prevention of disease and has not been approved by the FDA for therapeutic use.