VIP (Vasoactive Intestinal Peptide)
A reference guide to the 28-amino-acid neuropeptide studied for immune modulation, gut physiology and chronic inflammatory response research. Supplied in Australia for laboratory and research use only.
What is vasoactive intestinal peptide?
Vasoactive intestinal peptide (VIP) is a 28-amino-acid neuropeptide that belongs to the secretin and glucagon superfamily, a group that also includes PACAP, secretin, glucagon, GHRH and GLP-1. It was first isolated from mammalian intestine by Said and Mutt in the early 1970s and was named for the vasodilatory activity it produced on gut blood vessels and smooth muscle.
Although it was discovered in the digestive tract, VIP is now recognised as a widely distributed signalling molecule. It is expressed throughout the central and peripheral nervous systems, the enteric nervous system of the gut, the pancreas, the respiratory tract and cells of the immune system, where it acts as a neurotransmitter, neuromodulator and paracrine messenger. This broad distribution is a large part of why the peptide attracts research interest across so many separate fields.
This page describes what VIP is studied for in laboratory and preclinical research. It is not a description of effects in people and contains no dosing or usage guidance.
Mechanism and receptor targets
VIP signals through class B G-protein-coupled receptors. Its principal targets are the VPAC1 (VIPR1) and VPAC2 (VIPR2) receptors, which bind VIP and the closely related peptide PACAP with roughly equal affinity. A third receptor, PAC1, preferentially binds PACAP but is often discussed alongside VIP because of the shared biology.
Receptor targets studied in the literature
- VPAC1 (VIPR1), broadly expressed in the gut, liver, lung and immune tissue and studied in relation to epithelial and immune signalling.
- VPAC2 (VIPR2), enriched in the suprachiasmatic nucleus, smooth muscle and immune cells and studied in circadian and vascular research.
- PAC1 (ADCYAP1R1), the PACAP-preferring receptor frequently examined in the same experiments as VIP.
Activation of VPAC1 and VPAC2 couples mainly to the Gs protein, which stimulates adenylyl cyclase, raises intracellular cyclic AMP (cAMP) and activates protein kinase A. Additional coupling to phospholipase C and other second-messenger pathways has also been reported. Downstream of cAMP, VIP has been studied for its influence on cytokine transcription, smooth muscle tone and neuronal firing.
Native VIP has an extremely short plasma half-life, commonly reported at only one to two minutes, because it is rapidly broken down by peptidases. This instability is central to how the peptide is handled and studied, and it is why so much research effort has gone into analogues and delivery methods.
What VIP is studied for
VIP is one of the most studied anti-inflammatory neuropeptides, and the research literature spans several distinct areas. In every case the work is preclinical or clinical research, not established human use.
Principal research areas
- Immune modulation. VIP has been investigated in laboratory models for its ability to shift immune responses, reduce pro-inflammatory cytokines such as TNF-alpha, IL-6 and IL-12, increase anti-inflammatory signals such as IL-10, and promote regulatory T cell populations.
- Gut and gastrointestinal physiology. As an enteric neurotransmitter, VIP is studied in relation to intestinal motility, epithelial secretion of water and electrolytes, smooth muscle relaxation and gut barrier function.
- Chronic inflammatory response syndrome (CIRS). In the CIRS and biotoxin research literature, VIP levels have been examined as a marker of interest, and VIP has featured in investigational protocols studied by researchers in that field.
- Circadian biology. VIP and the VPAC2 receptor are central to synchronising the master clock in the suprachiasmatic nucleus, and genetic models lacking VIP or VPAC2 show disrupted circadian rhythms.
- Vascular and pulmonary research. Reflecting its original vasodilatory description, VIP is studied in models of smooth muscle relaxation, pulmonary vascular tone and airway biology.
Chronic inflammatory response syndrome is an active and debated area of research. References to VIP in that context describe how the peptide is measured and investigated by researchers, and are not claims that it treats or manages any condition in people.
The research landscape
Interest in VIP has grown steadily since its discovery, and a synthetic form of the peptide, aviptadil, has been produced for research and investigational purposes. Aviptadil has been the subject of clinical research in respiratory and pulmonary settings, which illustrates the level of scientific attention the molecule attracts.
Across preclinical work, VIP has been evaluated in a range of animal models of inflammation and autoimmunity, including models of colitis, arthritis, experimental autoimmune encephalomyelitis and sepsis, as well as in circadian and vascular studies. These models are how researchers characterise the peptide's receptor pharmacology and signalling.
Why VIP remains an active research subject
- It sits at the intersection of the nervous, immune, vascular and digestive systems, so findings in one field inform another.
- Its receptor family (VPAC1, VPAC2 and PAC1) is a target of ongoing medicinal chemistry and analogue design.
- Its short half-life poses a formulation and delivery challenge that continues to drive method development.
How VIP is handled in a laboratory context
In a laboratory setting, VIP is typically supplied as a lyophilised (freeze-dried) powder because the peptide is more stable in dry form than in solution. Research handling reflects the peptide's known fragility.
Handling considerations documented in peptide research
- Reconstitution is generally performed with a suitable sterile diluent such as bacteriostatic water, prepared according to the requirements of the specific experiment.
- Peptide solutions are prone to degradation, so reconstituted material is usually kept cold and lyophilised stock is stored frozen.
- VIP can adsorb to glass and plastic surfaces and is sensitive to repeated freeze-thaw cycles, both of which are controlled for in careful experimental design.
- Purity and identity are confirmed by analytical methods before use, so that results can be attributed to the intended compound.
The points above describe general laboratory practice reported in the peptide research literature. They are not instructions, a protocol or dosing guidance, and VIP is supplied strictly for laboratory and research use.
Sourcing and verification
Because VIP is fragile, and because peptide quality varies widely between suppliers, verification is a core part of responsible research sourcing. A Certificate of Analysis (COA) is the primary document researchers rely on to confirm what is actually in a vial.
What a peptide Certificate of Analysis typically reports
- Purity, usually measured by high performance liquid chromatography (HPLC) and expressed as a percentage of the main peak.
- Identity and molecular weight, confirmed by mass spectrometry against the expected sequence.
- Batch or lot identification, so that a specific vial can be traced back to its analysis.
- Appearance and, where relevant, tests for residual solvents or contaminants.
Every NovaPeptides batch is supplied with a verified Novagen Certificate of Analysis, so the purity and identity of the material can be checked rather than assumed.
Why researchers source VIP from NovaPeptides
NovaPeptides is an Australian owned business based on the Gold Coast that has supplied research peptides to Australian researchers for over three years. That track record matters in a field where consistency, correct storage and reliable documentation separate usable research material from unusable stock.
What NovaPeptides provides
- A verified Novagen Certificate of Analysis on every batch, covering purity and identity.
- Australian ownership and Gold Coast dispatch, with distribution to researchers across Australia.
- More than three years of experience supplying the Australian research community.
- Clear research-use-only labelling and documentation on every product.
Researchers can request the Certificate of Analysis for a specific batch before ordering. All enquiries are handled as research supply, never as advice on personal use.
Research use status
VIP supplied by NovaPeptides is intended for laboratory and research use only. It is not a medicine and is not approved by the Therapeutic Goods Administration (TGA) for use in humans.
Status at a glance
- Not TGA approved for human use.
- Supplied for laboratory and research use only.
- Not for human or animal consumption, and not for diagnostic or therapeutic use.
- All descriptions on this page refer to research findings, not effects in people.
Nothing on this page is medical advice or a recommendation to use VIP in any person or animal. It is provided to help researchers understand what the compound is and what it is studied for.
Frequently asked questions
What is VIP (vasoactive intestinal peptide)?+
VIP is a 28-amino-acid neuropeptide in the secretin and glucagon family, first isolated from intestine in the early 1970s. It is widely distributed in the nervous system, gut, pancreas, lungs and immune tissue, where it acts as a signalling molecule. It is supplied here for research use only.
What receptors does VIP act on?+
VIP binds the class B G-protein-coupled receptors VPAC1 and VPAC2 with high affinity, and is discussed alongside the PACAP-preferring PAC1 receptor. Activation mainly raises intracellular cyclic AMP through the Gs protein and protein kinase A.
What is VIP studied for in research?+
In laboratory and preclinical research, VIP is studied for immune modulation, gut and gastrointestinal physiology, circadian rhythm regulation, vascular and pulmonary biology, and as a marker of interest in chronic inflammatory response syndrome research. These are research areas, not established uses in people.
How is VIP connected to CIRS research?+
In the chronic inflammatory response syndrome and biotoxin literature, VIP levels have been examined as a biomarker of interest and the peptide has featured in investigational research protocols. CIRS is a debated field, and these references describe research, not treatment of any condition.
How is VIP related to PACAP?+
VIP and PACAP (pituitary adenylate cyclase-activating polypeptide) are closely related peptides that share a large part of their sequence and both act on the VPAC1 and VPAC2 receptors. PACAP also has its own preferred receptor, PAC1, so the two are frequently studied together.
What is aviptadil?+
Aviptadil is a synthetic form of vasoactive intestinal peptide produced for research and investigational purposes. It has been the subject of clinical research, particularly in respiratory and pulmonary settings, which reflects the scientific interest in the molecule.
Why does VIP have such a short half-life?+
Native VIP is rapidly broken down by peptidases in the body, giving it a plasma half-life commonly reported at only one to two minutes. This instability is a major reason researchers study analogues, formulations and delivery methods, and it also shapes how the peptide is handled in the laboratory.
How is VIP handled and stored in a laboratory?+
VIP is usually supplied as a lyophilised powder because it is more stable when dry. Research handling described in the literature involves reconstitution with a sterile diluent, cold storage of solutions, frozen storage of stock, and care to avoid repeated freeze-thaw cycles and surface adsorption. This is general research practice, not a protocol or usage instruction.
Is VIP approved for human use in Australia?+
No. VIP is not approved by the Therapeutic Goods Administration for human use. It is supplied by NovaPeptides for laboratory and research use only and is not for human or animal consumption.
What is a Certificate of Analysis and why does it matter?+
A Certificate of Analysis, or COA, is a laboratory document that reports a peptide's purity, usually by HPLC, and confirms its identity by mass spectrometry, along with batch details. Because peptide quality varies between suppliers, a COA lets researchers verify what is in a vial. NovaPeptides supplies a verified Novagen COA on every batch.
Does NovaPeptides supply VIP to researchers across Australia?+
Yes. NovaPeptides is an Australian owned, Gold Coast based business that has supplied research peptides to Australian researchers for over three years and distributes across Australia, with a verified Novagen Certificate of Analysis on every batch. All supply is for research use only.
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