Parallel increase in substance P and VIP in rat duodenum in response to irradiation

Irradiation was administered to the upper abdomen of rats, whereupon the du odenum was examined. Numerous vasoactive intestinal peptide (VIP)- and subs tance P (SP)-like immunoreactive nerve fibers were seen in the damaged muco sa, often in close association to each other. The intensity of the SP- and VIP-like immunoreaction was increased in several of the tissue compartments and, as measured with radioimmunoassay, the contents of SP- and VIP-like m aterials were increased after 30 Gray. The results show that SP and VIP lev els increase after irradiation and suggest that SP and VIP are involved in interactive reactions in the reorganization and inflammatory processes in t he gut after abdominal irradiation. (C) 2000 Elsevier Science Inc. All righ ts reserved.