28-amino acid neuropeptide VIP (Vasoactive Intestinal Peptide) is a neurotransmitter and a neuromodulator. VIP is broadly distributed in the peripheral and central nervous systems. It has an amino acid sequence identity of 68% with pituitary adenylate cyclase-activating polypeptide (PACAP). VIP and PACAP inhibit TNF-a, IL-1ß, IL-6, and NO production by lipopolysaccharide (LPS)-activated microglia. Both regulate the production of proinflammatory factors at a transcriptional level by inhibiting p65 nuclear translocation and nuclear factor-kB-DNA binding. As well, VIP relaxes the smooth muscle of the respiratory, gastrointestinal and reproductive tracts, stimulates exocrine and endocrine secretion, increases the survival time of neurons, and promotes the proliferation of untransformed and cancer cells.