Towards Understanding the Process of Intestinal Adaptation

Abstract

When bowel is lost due to disease or surgery, the residual bowel increases its functional capacity in order to compensate for the loss of absorptive capacity. The success and extent of this adaptive process is critical to recovery. This article reviews the current understanding of the intestinal adaptation. Adaptation is a complex process which as yet is poorly understood and thus it is difficult to develop strategies to enhance the outcome of the adaptation phase. Extensive loss of bowel brings about functional as well as morphologic changes in the remaining intestine. The exact relationship between histologic changes and function is still unknown and some studies show that histologic changes may precede functional changes. Both nonnutritive and nutritive factors have been identified as major stimuli to the adaptive process. The importance of oral intake as a positive stimulus has been demonstrated and the role of diet composition rather than diet complexity being recognized. Recent studies attempt to understand the molecular basis of intestinal adaptation by seeking to characterize the nature of humoral factors involved and to establish alterations in the patterns of gene expression. These new approaches may facilitate the identification of both nutritional and pharmacological methods to manipulate the intestinal adaptation process.

Adult zebrafish intestine resection: a novel model of short bowel syndrome, adaptation, and intestinal stem cell regeneration

“…Whereas IGF-2 is primarily involved in growth during the fetal period (18), IGF-1 is thought to be one of the primary effectors of growth hormone; IGF-1 stimulates duodenal crypt cell proliferation in humans and increased intestinal adaptation when administered to rats after massive small bowel resection (18,23,47,54,56). IGF is preserved across vertebrate species.…”

Structural, neuronal, and functional adaptive changes in atrophic rat ileum

“…Changes in activity lead to both functional and structural adaptive adjustments in most organ systems, including the gastrointestinal tract (for reviews see Dowling1 and Wolvekamp and colleagues2). In the intestine hypertrophy can be experimentally induced by partial obstruction of the ileum of rat or guinea pig 3-5.…”

Epidermal growth factor and bombesin act synergistically to support intestinal adaptation in rats with massive small bowel resection

“…A considerable amount of evidence indicates that the initial stimulus for intestinal adaptation is an increase in undigested nutrients distally [28]. Several studies have shown that this leads to an increase in the release of gut hormones, including peptide YY, substance P, cholecystokinin, and glucagon-like peptide 2 [31][32][33]. Growth hormone, neurotensin, insulin-like growth factor 1, and EGF have also been reported to be associated with mucosal proliferation [7][8][9][10][11][12][13].…”