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

- Colitis manifests with diarrhea, hypoproteinemia and malabsorption of nutrients.
- A novel model of localized colonic injury induced by bipolar electro-cautery has been described.
- In this model, up-regulation of proinflammatory cytokines protein and mRNA occurs in the whole gut.
- A decreased jejunal amino acid absorption swiftly follows localized colonic injury.
- The spreading effects of colitis to non-inflamed intestines may involve neuro-humoral pathways.

BackgroundColitis 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.MethodsA 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.ResultsThe 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.ConclusionsElectrically 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.