VIP

Vasoactive Intestinal Peptide (VIP) is a naturally occurring peptide composed of 28 amino acids. It was initially isolated from porcine duodenum due to its potent vasodilatory effects. VIP belongs to the glucagon–secretin family of peptides, a group characterized by their structural similarities and diverse biological functions. Beyond its role in vasodilation, VIP is widely distributed throughout the body, acting as a hormone, neurotransmitter, and neuromodulator. It is found in significant concentrations in the central and peripheral nervous systems, the gastrointestinal tract, and the immune system. VIP exerts its effects by binding to specific G protein-coupled receptors, primarily VPAC1 and VPAC2, which are expressed on cell surfaces across various tissues. The widespread distribution of VIP and its receptors underscores its involvement in a broad spectrum of physiological processes, including the regulation of blood flow, digestion, inflammation, immune responses, and neuronal activity, as noted by research cited in PubMed Central articles and review articles on peptide hormones.