Alkaline Phosphatase, Sucrase, and Insulin-like Growth Factor Receptors are Present in Atrophied Small Bowel 14 Years after Jejunoileal Bypass

Abstract

The authors obtained atrophied and hypertrophied small intestinal tissue from a patient undergoing jejunolleal (JI) bypass reversal. Tissue from both segments was examined for insulin, insulin-like growth factor-I (IGF-1) and IGF-11 receptors, and alkaline phosphatase and sucrase. We were interested in the potential of the atrophied segment to respond to luminal stimulation once the food train was re-established. Within the atrophic segment, flow cytometric evaluation of the receptors revealed (expressed as percent positive staining cells): insulin, 17.1%; IGF-1, 33.6%; and IGF-11, 60.8%, while the immunoreactive sucrase was 87.7% and alkaline phosphatase was 88.6%. Actual sucrase activity (expressed as glucose generated) in this segment was 17.9 ng/minl,ug protein and alkaline phosphatase was 28.0 U/L/µg protein as assessed by conventional methods. Receptor evaluation in the hypertrophic segment demonstrated 9.7% positive staining cells for insulin, 26.6% for IGF-I and 70.2% for IGF-11. Immunoreactive sucrase was 91.2% and alkaline phosphatase was 91.4%. Enzyme activity for sucrase was 10.4 ng/min/µg protein and for alkaline phosphatase was 59.4 U/L/µg protein. This data suggests that even in atrophied bowel insulin and IGF receptors as well as sucrase and alkaline phosphatase enzymes are present and may assist in the rapid recovery of the atrophied portion following reversal of the JI bypass.

The Role of Insulin-Like Growth Factors in Small Intestinal Cell Growth and Development

“…We obtained biopsies of the segments of intestine that had been exposed to systemic but not lumenal nutrients (bypass tissue) and the active intestine which had undergone significant compensatory hyperplasia. Similar IGF-I and IGF-II receptor densities in the bypassed and hypertro-phied segments, as well as disaccharidase activity, were observed, indicating that these aspects of intestinal function can be maintained without lumenal nutrition for extended periods of time [9].…”