COLONIC VASOACTIVE INTESTINAL POLYPEPTIDE IN ULCERATIVE-COLITIS

Vasoactive intestinal polypeptide (VIP) is a 28 amino acid peptide whi ch is localised in both the central and peripheral nervous system. In the human colon VIP is found in all layers and the highest concentrati ons have been found in the myenteric plexus. It is known that VIP has various effects on intestinal functions: i) it is a potent stimulant o f mucosal water and electrolyte secretion: ii) it is involved in the p eristaltic reflex; and iii) plays an inhibitory role on immune cell fu nction. Based on these biological effects it has been hypothesized tha t the intestinal mucosal immune system and inflammation may be influen ced by alterations in the tissue concentrations of VIP. Some authors h ave demonstrated no changes in the VIP colonic content of patients wit h ulcerative colitis. whereas others have demonstrated a reduction. Ou r results. using specific radioimmunoassay, showed that there is a sig nificant decrease of VIP in both rectal and colonic mucosa of patients with ulcerative colitis as compared to controls. The VIP decrease is selective since substance P and calcitonin gene-related peptide were u nchanged in the mucosal tissue of ulcerative colitis patients and furt hermore the VIP alteration is correlated to the degree of mucosal infl ammation. These findings suggest that the reduction of VIP mucosal con tent, even if it represents a non-specific event. could influence loca l inflammatory response and the activity of the disease.