Irradiation induces marked immunohistochemical expression of vasoactive intestinal peptide in colonic mucose of man

Vasoactive intestinal peptide (VIP) is known to modulate inflammatory react ions, to have trophic effects, and to contribute to diarrhea and has been i mplicated as an important factor in several inflammatory conditions in the human gut. The aim of the present study was to investigate the effects of i rradiation on the expression of VIP in the colon of patients operated on fo r adenocarcinoma. Some of the patients had received preoperative irradiatio n (25 Gy) within one week before the operation. Specimens of sigmoideum, 10 cm cranial to the margin of the cancer, were examined, by using antiserum against VIP and immunohistochemistry. There were numerous nerve fibers show ing VIP-like immunoreactivity in the damaged mucosa, including the regions showing ulcerations. There was a higher degree of expression of VIP in the ganglion cells in the submucous plexuses in irradiated than nonirradiated p atients. The study shows that there is a marked immunohistochemical express ion of VIP concomitant with the occurrence of inflammatory and repair proce sses in the irradiation-damaged human colonic mucosa.