Protective Effect of Proteinase-Activated Receptor 2 Activation on Motility Impairment and Tissue Damage Induced by Intestinal Ischemia/Reperfusion in Rodents

We hypothesized that proteinase-activated receptor-2 (PAR2) modulates intestinal injuries induced by ischemia/reperfusion. Ischemia (1 hour) plus reperfusion (6 hours) significantly delayed gastrointestinal transit (GIT) compared with sham operation. Intraduodenal injection of PAR2-activating peptide SLIGRL-NH2 significantly accelerated transit in ischemia/reperfusion but not in sham-operated rats. GIT was significantly delayed in ischemia/reperfusion and sham-operated PAR2−/− mice compared with PAR2+/+. SLIGRL-NH2 significantly accelerated transit in ischemia/reperfusion in PAR2+/+ but not in PAR2−/− mice. Prevention of mast cell degranulation with cromolyn, ablation of visceral afferents with capsaicin, and antagonism of calcitonin gene-related peptide (CGRP) and neurokinin-1 receptors with CGRP8–37 and RP67580, respectively, abolished the SLIGRL-NH2-induced stimulatory effect on transit in ischemia/reperfusion. Tissue damage was significantly reduced by SLIGRL-NH2; this effect was not observed in cromolyn-, capsaicin-, or RP67580-treated rats but was detected following CGRP8–37. Intestinal PAR2 mRNA levels were not affected by SLIGRL-NH2 in ischemia/reperfusion. We propose that PAR2 modulates GIT and tissue damage in intestinal ischemia/reperfusion by a mechanism dependent on mast cells and visceral afferents. PAR2 effect on transit might be mediated by CGRP and substance P, whereas the effect on tissue damage appears to involve substance P but not CGRP. PAR2 might be a signaling system in the neuroimmune communication in intestinal ischemia/reperfusion.