Vasoactive intestinal peptide was named for its presence in neurons in the gastrointestinal tract, where it stimulates pancreatic secretions. Based on its vasodilatory effects, VIP found its first therapeutic use in erectile function, and is marketed in some countries by Senetek Plc (SNTKY, Napa, Calif.) as Invicorp, a combination of VIP and phentolamine. But VIP has other functions, including modulation of immunity and inflammatory responses, and new research indicates it may have utility in rheumatoid arthritis.

Scientists at Complutense University (Madrid, Spain) reported in last week's Nature Medicine that VIP reduced both the incidence and severity of arthritis in a mouse model of RA