Neuropeptide

VIP

Vasoactive intestinal peptide (VIP) is a 28-amino-acid neuropeptide involved in smooth muscle relaxation, immune modulation, and circadian biology research.

By The Peptides Codex Editorial TeamReviewed July 10, 2026

Length

28 aa

Class

Neuropeptide

Function

Vasodilation, smooth muscle, immune and circadian signaling

Context

Physiology research; related analogs in drug development

Classic 28-aa neuropeptide with wide receptor distribution.

Also known as: vasoactive intestinal peptide

Part of the Foundational & therapeutic peptides cluster

Overview

Vasoactive intestinal peptide (VIP) is a 28-amino-acid neuropeptide involved in smooth muscle relaxation, immune modulation, and circadian biology research.

Source & context

Biological / chemical source: Endogenous neuropeptide

Primary research or clinical context: Physiology research; related analogs in drug development

Receptor systems

VIP acts primarily through VPAC1 and VPAC2 receptors (shared pathways with PACAP). Structure–activity studies inform analog design.

FAQ about VIP

What is VIP?+

Vasoactive intestinal peptide (VIP) is a 28-amino-acid neuropeptide involved in smooth muscle relaxation, immune modulation, and circadian biology research.

Is VIP an approved medicine?+

VIP is discussed here as a research / educational topic. Physiology research; related analogs in drug development. This is not medical advice.

What is the typical length of VIP?+

VIP is commonly described as approximately 28 amino acids (Neuropeptide).

Related peptides

Oxytocin

Neuropeptide

Oxytocin is a nine-amino-acid neuropeptide and hormone involved in labor, lactation, and social behavior. It is a classic model of cyclic peptide structure.

Selank

Research peptide

Selank is a synthetic analog of the immunomodulatory peptide tuftsin, studied in models related to anxiety and cognitive function. Regulatory status varies by country.

Semax

Research peptide

Semax is a synthetic peptide analog of ACTH(4-10) studied for neurological and cognitive research applications. Status and availability differ by jurisdiction.

Substance P

Neuropeptide

Substance P is an 11-amino-acid neuropeptide of the tachykinin family involved in pain signaling and neurogenic inflammation research.

References & further reading

Disclaimer: Educational content only. Not medical advice. Not instructions for human use. Research peptides and unapproved products may be restricted or illegal to market for human consumption in your jurisdiction. Consult qualified professionals and applicable law.

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Cite this: Peptides Codex — VIP educational profile.

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