Vasoactive Intestinal Peptide

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Vasoactive Intestinal Peptide

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VIP is a 28-amino acid peptide structurally related to secretin. It was

originally isolated from intestinal extracts and shown to be a potent

vasodilator. Subsequent work demonstrated that VIP is very widely distributed in

the peripheral and central nervous systems, and probably should not be

considered a true GI hormone.

A huge number of biological effects have been attributed to VIP. With

respect to the digestive system, VIP seems to induce smooth muscle relaxation

(lower esophageal sphincter, stomach, gallbladder), stimulate secretion of water

into pancreatic juice and bile, and cause inhibition of gastric acid secretion

and absorption from the intestinal lumen.

Certain tumors arising from the pancreatic islets or nervous tissue

(called VIPomas) secrete excessive quantities of VIP, and are associated with

chronic, watery diarrhea.