Vasoactive Intestinal Peptide (VIP), a 28 amino acid peptide originally isolated from porcine duodenum, is present not only in gastrointestinal tissues but also in neural tissues, possibly as a neurotransmitter, and exhibits a wide variety of biological actions. It belongs to the glucagon family, and in the duodenum is known to stimulate myocardial contractility, cause vasodilation, increase glycogenolysis, lower arterial blood pressure and relax the smooth muscle of trachea, stomach and gall bladder. Ectopic endocrine tumors secreting VIP (VIPomas) give rise to raised plasma levels of VIP and are associated with watery diarrhea, hypokalemia and achlorhydria syndrome. This antibody detects ganglion cells in both the superficial and deep plexus of the wall of the small bowel in human. The VIP producing tumors are usually neuroblastomas of endocrine tumors in the pancreas. It is also a modulator of joint pain.
Image: VIP Staining of rat brain.