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Insulin-like growth factor-I partially attenuates colonic damage in rats with experimental colitis induced by oral
G S Howarth1, C J Xian, L C Read
1Cooperative Research Centre for Tissue Growth and Repair and Child Health Research Institute, North Adelaide, South Australia.
Background:
Administration of insulin-like growth factor-I (IGF-I) results in selective growth of the gastrointestinal tract. We investigated the effects of IGF-I on the colonic damage induced by oral dextran sulphate sodium (DSS) in the rat.
Methods:
Rats consumed 2% DSS in the drinking water for 10 days to induce colitis. Pumps were implanted on day 3 to deliver IGF-I for 7 days. Colonic histopathology and immunolocalization of transforming growth factor-beta1 (TGF-beta1) were assessed on day 10.
Results:
Compared with the colon of vehicle-treated rats consuming DSS, IGF-I increased the numbers of goblet cells by 76%, reduced the proportion of lamina propria cells expressing TGF-beta1, and reduced the thickness of submucosal and muscularis externa layers by 26% and 20%, respectively.
Conclusions:
We conclude that the effects of IGF-I treatment on the colonic epithelium may be mediated directly, whereas the reduced inflammation in the mucosa and submucosa may be mediated by a mechanism other than up-regulation of TGF-beta1-mediated immunosuppression.