INSULIN-LIKE GROWTH-FACTOR-I PARTIALLY ATTENUATES COLONIC DAMAGE IN RATS WITH EXPERIMENTAL COLITIS INDUCED BY ORAL DEXTRAN SULFATE SODIUM

Background: Administration of insulin-like growth factor-I (IGF-I) res ults in selective growth of the gastrointestinal tract. We investigate d the effects of IGF-I on the colonic damage induced by oral dextran s ulphate 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 immunolo calization of transforming growth factor-beta(1) (TGF-beta(1)) were as sessed 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-beta(1 ), and reduced the thickness of submucosal and muscularis externa laye rs by 26% and 20%. respectively. Conclusions: We conclude that the eff ects of IGF-I treatment on the colonic epithelium may be mediated dire ctly, whereas the reduced inflammation in the mucosa and submucosa may be mediated by a mechanism other than upregulation of TGF-beta(1)-med iated immunosuppression.