PREVIOUS INFLAMMATION ALTERS THE RESPONSE OF THE RAT COLON TO STRESS

Background & Aims: Patients with inflammatory bowel disease have sympt oms of irritable bowel syndrome (IBS) with a higher than expected prev alence, Stress is an important factor in the pathogenesis of IBS, Thus , previous inflammation may predispose to IBS by rendering the bower m ore susceptible to the impact of stress. The aim of this study was to examine the effect of previous colitis on stress-induced responses in rats, Methods: Acute colitis was induced in rats by intrarectal admini stration of trinitrobenzene sulfonic acid (TNBS), and the rats were al lowed to recover for 6 weeks before application of mild restraint stre ss for 3 consecutive days. In vitro measurements included myeloperoxid ase activity, plasma corticosterone levels, interleukin 1 beta messeng er RNA expression, and [H-3]noradrenaline release from the myenteric p lexus, Results: Six weeks after administration of TN BS, stress caused a significant increase in myeloperoxidase activity in TNBS-treated ra ts but not in stressed controls; plasma corticosterone responses were similar, Stress also caused an exaggerated and significant suppression of [H-3]noradrenaline release in TNBS-treated stressed rats compared with stressed controls, This was accompanied by a significant decrease in interleukin 1 beta messenger RNA expression in the colon, Conclusi ons: Previous colitis rendered the colon more susceptible to effects o f stress on enteric nerve function and also increased some parameters of inflammation in response to stress.