Colonic muscle enhances the production of interleukin-1 beta messenger RNA in experimental colitis

Background-Inflammatory bowel diseases are accompanied by alterations in the contractile function of colonic muscle. Whether these changes are also accompanied by the production of interleukin-1 beta (IL-1 beta) mRNA remains unknown. Aims-To investigate the profile of IL-1 beta mRNA in the colonic muscle of rats with acetic acid induced colitis. Methods-Colitis was induced by intra-rectal administration of 1 ml of 4% acetic acid 8 cm from anal margin. Myeloperoxidase activity was used as a marker of inflammation in the colon. RNA was extracted from colonic muscle and was used to amplify the level of IL-1 beta mRNA with a reverse transcription coupled polymerase chain reaction (RT-PCR) method developed in this study. Results-Colonic muscle exhibited constitutive expression of IL-1 beta mRNA. The level was enhanced significantly, one, two, and five days after acetic acid administration. On day 7 after treatment, the level of IL-1 beta mRNA had returned baseline values. This profile of IL-1 beta mRNA was consistent with myeloperoxidase activity. Conclusions-IL-1 beta is a putative mediator of the changes in muscle function in this model of colitis.