Vasoactive Intestinal Peptide (VIP) is a 28 amino acid neuropeptide member of the secretin/glucagon superfamily, discovered by Said and Mutt in 1970. VIP is widely distributed in the central and peripheral nervous systems, gastrointestinal tract, and immune tissues, signaling through VPAC1 (VIPR1) and VPAC2 (VIPR2) receptors coupled to cAMP/PKA signaling cascades.
Smooth Muscle and Autonomic Research
VIP's characterization as a vasodilatory and smooth muscle relaxant peptide has generated extensive research into its interactions with vascular, bronchial, and gastrointestinal smooth muscle tone regulation through nitric oxide synthase activation and cAMP-mediated signaling.
Immunomodulatory Signaling Research
A significant area of VIP research involves its immunomodulatory properties. Studies have examined VPAC receptor expression on T-cells, macrophages, and dendritic cells, and VIP's effects on cytokine production and Th1/Th2 balance in experimental immune models.
Circadian Rhythm and Suprachiasmatic Nucleus Research
VIP plays an established role in circadian rhythm regulation through its expression in suprachiasmatic nucleus (SCN) neurons. Research has examined VIP's function in synchronizing SCN neuronal oscillations and coordinating light-entrained circadian timing.
• Said SI & Mutt V (1970). Polypeptide with broad biological activity: isolation from small intestine. Science, 169(3951), 1217–1218.
• Delgado M et al. (2004). Vasoactive intestinal peptide: a neuropeptide with pleiotropic immune functions. Journal of Immunology, 173(8), 4985–4992.
