Bradykinin Upregulated The Expression of Cyclooxygenase-2 in The Submucosal Plexus of Enteric Nervous System of Guinea Pig*

Objective Bradykinin and bradykinin B2 receptors (B2R) play important roles in the enteric nervous system. Bradykinin is usually involved in inflammation and neuroprotection, dependent on the bradykinin-induced formation of prostaglandins (PGs). Cyclooxygenase-1 (COX1) and cyclooxygenase-2 (COX2) catalyze the conversion of arachidonic acid to PGs. This study aimed to investigate the effect and the signaling mechanism of bradykinin stimulation on the release of prostaglandin E2 (pGE2) and the expression of COX2 in the enteric nervous system of guinea pigs. Methods Immunofluorescence was used to detecting the colocalization of COX2 with neural markers Anti-Hu and chAT in the primary cultured ileal submucosal plexus of guinea pigs. PCR and Western blot were used to detecting the effect of bradykinin evoking COX2 expression. Bradykinin B1 receptor (B1R) antagonist Leu-8 and B2R antagonist HOE-140 were preincubated before bradykinin stimulation. COX2 antagonist NS398 and COX1 antagonist FR12207 were used to observing the effect of bradykinin-induced pEG2 release. Results The results showed that COX2 was co-localized with neural markers Anti-Hu and chAT on ileal submucosal plexuses. Bradykinin induced COX2 expression was blocked by the B2R antagonist. The release of pGE2 by bradykinin stimulation in ileal submucosal plexuses was significantly decreased when incubating with the COX2 antagonist. Conclusion COX2 expression evoked by B2R signaling as an excitatory neurotransmitter in bradykinin stimulated pGE2 secretion, which provides a reasonable explanation for the role of bradykinin in intestinal inflammatory diseases.