Vagally dependent protective action of calcitonin gene-related peptide on colitis

This work evaluates the mechanism of action of calcitonin gene-related peptide (CGRP) on colitis. Firstly, Wistar rats were intracolonically instilled with trinitrobenzenesulfonic acid (TNBS) and IV treated by either αCGRP, or hCGRP(8–37), or by vehicle. The inflammatory level was evaluated 8 h and 4 days after TNBS. Secondly, intracerebroventricular αCGRP was assessed on the 4-day group with colitis. Finally, IV αCGRP was administered in vagotomized animals, and tested on the 4-day group with colitis. Colitis was aggravated by hCGRP(8–37), and decreased by peripheral but not central αCGRP. αCGRP was inactive on inflammatory parameters in vagotomized colitic rats. This suggests that endogenous peripheral CGRP has an anti-inflammatory role in TNBS-induced colitis, depending upon the integrity of the vagus.