Effect of ileocolonic transposition on gut morphology, gene expression, and function

Intestinal morphology and expression of brush border enzymes can be dramatically altered by nutrient composition and position along the longitudinal gut axis. In contrast, endocrine gene expression appears to be relatively "imprinted" and is not significantly altered by positional changes. The purpose of our study was to assess the effects of transposing the ileum into the colonic position on intestinal morphology, gene expression, and enzyme activity. For this study, male Sprague-Dawley rats underwent either transposition of an approximately 8-cm segment of distal ileum into the colonic position or sham operation. Rats were sacrificed 2 months after operation and transposed or sham ileum was assessed. We found that transposition of the ileum to the colonic position resulted in no change in the ileal mucosal architecture. Furthermore, no change in the expression of the endocrine genes neurotensin and PYY or the apoptotic genes was detected. Although sucrase-isomaltase activity was decreased in the transposed ileum, this decrease did not achieve statistical significance. These results demonstrate that the ileum can be successfully interposed into the colonic position. In this location, the ileum functions normally without changes in the villus morphology or gene expression pattern despite the change in position and composition of the luminal content.