Vasoactive intestinal peptide got its name from the first thing anyone noticed about it: it widened blood vessels. Isolated from pig intestine in 1970, it turned out to be much more than a gut hormone. It is also a neurotransmitter, an immune regulator and part of the brain’s daily clock.
This guide explains what VIP is, the peptide family it belongs to, the receptors it acts on, what it does across the body, why it has been hard to turn into a drug, and what to check before ordering research-grade VIP in Canada.
The short answer
- VIP is a 28-amino-acid peptide isolated in 1970 by Sami Said and Viktor Mutt from pig small intestine, on the strength of its ability to widen blood vessels.
- Its sequence is identical in humans, pigs, cows, rats and several other mammals, a sign of strong evolutionary pressure to keep it unchanged.
- It acts through two receptors, VPAC1 and VPAC2, which it shares with its close relative PACAP. Both are class B G protein-coupled receptors.
- VIP relaxes smooth muscle, drives fluid secretion in the gut, modulates immune cells and helps synchronize the brain’s circadian clock.
- A synthetic version, aviptadil, has been tested in clinical trials, including in COVID-19 respiratory failure, but it is not an approved medicine in Canada. Research-grade VIP is a laboratory reagent.
Vasoactive intestinal peptide (VIP)
28 amino acids with a C-terminal amide. Synthetic human VIP is also known as aviptadil.
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- NH₂
Highlighted: methionine 17, the residue most prone to oxidation during storage.
- Mass
- About 3,326 g/mol
- Family
- Secretin–glucagon superfamily, with PACAP, secretin, glucagon, GLP-1 and GHRH
- Receptors
- VPAC1 and VPAC2 (class B GPCRs)
- Discovered
- 1970, Sami Said and Viktor Mutt
- Research themes
- Gut secretion and motility, airway and vascular tone, immunity, circadian rhythm
Where the evidence stands
- Cell studies
- Animal studies
- Human studies
- Controlled clinical trials
Trials of synthetic VIP have had mixed results, and it is not approved in Canada.
A vasodilator found in the gut
In the late 1960s Sami Said was looking for substances that widen blood vessels, and he noticed vasodilating activity in extracts of lung. Working with Viktor Mutt, a biochemist at the Karolinska Institute in Stockholm who had already purified secretin, he isolated the responsible peptide from pig small intestine and published it in Science in 1970. They named it for what it did and where it came from: vasoactive intestinal polypeptide.
VIP turned out to be made mainly by nerve cells rather than gut hormone cells, which is why it is now usually described as a neuropeptide. It is found throughout the nervous system, in the gut wall, airways, blood vessels and brain.
A family resemblance
VIP belongs to a family of peptide hormones that share a recognizable opening sequence. Line up their first ten amino acids and the pattern jumps out:
| Peptide | Residues 1 to 10 | Our guide |
|---|---|---|
| VIP | H S D A V F T D N Y | This page |
| PACAP | H S D G I F T D S Y | — |
| Secretin | H S D G T F T S E L | — |
| Glucagon | H S Q G T F T S D Y | GLP-1 map |
| GLP-1 | H A E G T F T S D V | GLP-1 map |
| GHRH | Y A D A I F T N S Y | Sermorelin |
Phenylalanine at position 6 and threonine at position 7 are shared by every member shown, and most start with histidine and serine. Their receptors are related too: all belong to class B of the G protein-coupled receptors, sometimes called the secretin receptor family. It is a useful reminder that the growth hormone, GLP-1 and VIP stories in our library are chapters of one larger family history.
VPAC1, VPAC2 and PACAP
VIP acts through two receptors, named VPAC1 and VPAC2 because they bind both VIP and its relative PACAP (pituitary adenylate cyclase-activating polypeptide) with high affinity. A third receptor, PAC1, binds PACAP strongly but VIP only weakly. All three mainly signal by raising cyclic AMP inside the cell.
The two VIP receptors are distributed differently. In the immune system, VPAC1 is constantly present on T cells, monocytes and macrophages, while VPAC2 appears when those cells are activated. That pattern is one reason VIP is studied as a brake on inflammation.
Research-grade VIP with a batch-matched COA.
View VIPWhat VIP does
- Gut. VIP drives water and electrolyte secretion and relaxes intestinal smooth muscle. Rare VIP-secreting tumours, called VIPomas, cause severe watery diarrhea, a vivid demonstration of how powerful the signal is.
- Blood vessels and airways. It widens blood vessels and relaxes airway smooth muscle, which led to research interest in lung conditions.
- Immune system. In cell and animal studies, VIP dampens inflammatory signalling by macrophages and T cells.
- Brain clock. In the suprachiasmatic nucleus, the brain’s master circadian clock, VIP and VPAC2 help keep thousands of clock neurons in sync. Mice lacking them show disrupted daily rhythms.
Why VIP is hard to use as a drug
Like many natural peptides, VIP is broken down within minutes in the bloodstream, and because its receptors are everywhere, it is hard to target one tissue without effects in others. Researchers have explored stabilized analogues and inhaled delivery to the lungs. Synthetic human VIP, aviptadil, was tested in trials during the COVID-19 pandemic for respiratory failure, with mixed results, and it is not an approved medicine in Canada. Our guide to how peptides are made to last explains the stability problem in more depth.
Reasonably well established
- VIP is a 28-residue neuropeptide acting through VPAC1 and VPAC2.
- It drives intestinal secretion and relaxes smooth muscle.
- It is essential for synchronizing the circadian clock in mice.
Open questions
- Whether VIP-based treatments can deliver consistent clinical benefit.
- How to target one tissue without effects elsewhere.
- How its immune effects translate from animal models to people.
Related immune research peptides
Thymosin alpha-1Thymic immune peptideView product and COA
LL-37The human cathelicidinView product and COA
KPVAlpha-MSH-derived tripeptideView product and COA
Sourcing VIP in Canada
Before ordering VIP from any supplier, check that:
- The mass matches, at about 3,326 g/mol for the amidated peptide. An extra 16 g/mol usually means oxidized methionine. See our HPLC testing guide.
- Purity is reported by HPLC and the COA matches your lot. Our peptide COA guide walks through it.
- You understand net content. VIP is strongly basic, so counter-ions can make up a meaningful share of the powder. See our net peptide content guide.
- Storage is cold, dry and dark, to protect the methionine. See our peptide storage guide.
Research use only. VIP from Pure Peptides Canada is a laboratory reagent. It is not an approved drug, it is not for human or veterinary use, and nothing in this article is dosing or medical guidance.
Frequently asked questions
What is vasoactive intestinal peptide?
Vasoactive intestinal peptide (VIP) is a 28-amino-acid neuropeptide first isolated from pig intestine in 1970. It widens blood vessels, relaxes smooth muscle, drives intestinal secretion, modulates immune cells and helps synchronize the brain’s circadian clock.
Why is it called vasoactive intestinal peptide?
Its discoverers named it for its first known effect, widening blood vessels (vasoactive), and the tissue they isolated it from, the small intestine. It was later found mainly in nerve cells throughout the body.
What receptors does VIP act on?
VIP acts on VPAC1 and VPAC2, class B G protein-coupled receptors that it shares with PACAP. A third receptor, PAC1, binds PACAP strongly but VIP only weakly.
What is the difference between VIP and PACAP?
They are closely related peptides from the same family and both activate VPAC1 and VPAC2. PACAP also has its own receptor, PAC1, and exists in 27- and 38-amino-acid forms; the shorter form shares 68% of its sequence with VIP.
Is VIP an approved medicine in Canada?
No. Synthetic VIP, called aviptadil, has been tested in clinical trials, including for COVID-19 respiratory failure, but it is not approved in Canada. Pure Peptides Canada sells VIP strictly as a laboratory research reagent.
Does Pure Peptides Canada ship VIP across Canada?
Yes. Orders ship tracked and discreetly across Canada, usually arriving by Xpresspost in 3–7 days, or free in 4–12 days on orders over $299, with free shipping on orders over $299.
VIP, tested batch by batch
Lyophilized VIP with an independent COA for every batch, tracked delivery across Canada and pricing in Canadian dollars.
References
- Said SI, Mutt V. Polypeptide with broad biological activity: isolation from small intestine. Science. 1970;169:1217–1218.
- Iwasaki M, et al. Recent advances in vasoactive intestinal peptide physiology and pathophysiology: focus on the gastrointestinal system. F1000Research. 2019. PubMed Central
- Langer I. Mechanisms involved in VPAC receptors activation and regulation. Front Endocrinol. 2012. PubMed Central
For laboratory research use only. Not for human or veterinary use. This article summarizes published research for educational purposes and is not medical advice.