VIP (Vasoactive Intestinal Peptide)
VIP is a 28-residue neuropeptide first isolated from hog small intestine for its broad vasodilator activity, now studied as a ligand of the VPAC1, VPAC2 and PAC1 receptors and as an immune-modulating signal in rodent inflammation models; the research catalog lists it at https://onesourcepeptides.com/product/vip.
The peptide was found through its vascular effects. Said and Mutt, Science, 1970 (PMID 5450698) isolated a 28-amino-acid polypeptide from hog small intestine with potent and diverse actions in animal experiments, including systemic vasodilation, lowered blood pressure, increased cardiac output, respiratory stimulation and raised blood glucose, and showed it was chemically distinct from the kinins, substance P, glucagon and secretin.
Its receptor biology is now well mapped. The IUPHAR review by Harmar et al., British Journal of Pharmacology, 2012 (PMID 22289055) describes how VIP and the related peptide PACAP act through three class B G protein-coupled receptors, VPAC1, VPAC2 and PAC1, and summarizes their pharmacology, tissue distribution and roles across the nervous, immune, cardiovascular and digestive systems. That shared receptor family is why VIP shows up in such a wide range of research models.
The standout animal finding is in immunology. In a collagen-induced arthritis model, Delgado et al., Nature Medicine, 2001 (PMID 11329057) reported that VIP treatment significantly reduced the incidence and severity of arthritis, completely abrogating joint swelling and cartilage and bone destruction, with both the inflammatory and autoimmune components of the disease turned down. Related notes cover DSIP, KPV and Selank, and lot identity belongs on the certificate of analysis for the vial in hand (see Are research peptides third-party tested?). VIP on the catalog is laboratory research supply only. This note summarizes published animal and receptor research and is not dosing, reconstitution, or human-use guidance.