Electrocautery-induced localized colonic injury elicits increased levels of pro-inflammatory cytokines in small bowel and decreases jejunal alanine absorption

Abstract

Background: Colitis is associated with functional abnormalities in proximal non-inflamed gut areas, but animal models to study small bowel dysfunction in colitis have limitations. This study aims to determine small intestinal alanine absorption and cytokine expression in a novel model of colonic ulceration induced by electro-cautery. Methods: A descending colon ulcer was induced in rats by a bipolar electro-cautery probe. Ulcer score was determined using Satoh's criteria. Jejunal alanine absorption was measured immediately and at different time intervals post ulcer induction. Levels of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) protein and m-RNA were determined in mucosal scrapings obtained from the colon, duodenum, jejunum and ileum at various time intervals after colonic ulcer induction. Results: The mean ulcer score was 3 up to 48. h, followed by healing by 96. h post ulcer induction. Small bowel histology was normal throughout. Jejunal alanine absorption was reduced by 12-34% immediately and up to 72. h after cautery and returned to normal at 96. h. IL-1 and TNF-α mRNA increased significantly in the colon, duodenum, jejunum and ileum 3. h post electro-cautery and returned to normal at 48. h, while that of IL-6 increased significantly at 48. h post ulcer induction. Similarly, IL-1, IL-6 and TNF-α protein levels increased in the duodenum, jejunum, ileum and colon up to 48. h post ulcer induction. Conclusions: Electrically induced localized colonic injury increased production of pro-inflammatory cytokines in non-inflamed segments of the small intestine and was associated with derangements of jejunal absorptive function. © 2014 Elsevier Ltd.