James C Y Dunn1, Mandy M Lam, Edward Lee. 1. Division of Pediatric Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA. jdunn@mednet.ucla.edu
Abstract
INTRODUCTION: A segment of the jejunum could double its length by the application of an axial mechanical force. We hypothesize that this growth is correlated with an increased expression of insulin-like growth factor (IGF-I) in the jejunum. METHODS: Adult Sprague-Dawley rats underwent the isolation of a 1.5-cm segment of the jejunum. The isolated jejunal segment was either lengthened using mechanical force or left alone for 3 weeks. The jejunal segments were analyzed by quantitative polymerase chain reaction and immunofluorescence for the expression of IGF-I. RESULTS: Whereas jejunal segments that underwent isolation alone did not change their length, isolated jejunal segments that were stretched by applying a gradual mechanical force doubled their initial length. Both groups increased their muscular thickness 5 folds as compared to the normal jejunum. The mRNA level of IGF-I in the lengthened jejunum was 6 folds higher than that in the normal jejunum, but the IGF-I mRNA level in the isolated jejunum without mechanical lengthening was unchanged. By immunofluorescence, the increased IGF-I expression in the lengthened jejunum was localized to the intestinal smooth muscle cells. CONCLUSIONS: Insulin-like growth factor I may be an important signal induced by the applied axial force that mediates longitudinal intestinal growth.
INTRODUCTION: A segment of the jejunum could double its length by the application of an axial mechanical force. We hypothesize that this growth is correlated with an increased expression of insulin-like growth factor (IGF-I) in the jejunum. METHODS: Adult Sprague-Dawley rats underwent the isolation of a 1.5-cm segment of the jejunum. The isolated jejunal segment was either lengthened using mechanical force or left alone for 3 weeks. The jejunal segments were analyzed by quantitative polymerase chain reaction and immunofluorescence for the expression of IGF-I. RESULTS: Whereas jejunal segments that underwent isolation alone did not change their length, isolated jejunal segments that were stretched by applying a gradual mechanical force doubled their initial length. Both groups increased their muscular thickness 5 folds as compared to the normal jejunum. The mRNA level of IGF-I in the lengthened jejunum was 6 folds higher than that in the normal jejunum, but the IGF-I mRNA level in the isolated jejunum without mechanical lengthening was unchanged. By immunofluorescence, the increased IGF-I expression in the lengthened jejunum was localized to the intestinal smooth muscle cells. CONCLUSIONS:Insulin-like growth factor I may be an important signal induced by the applied axial force that mediates longitudinal intestinal growth.
Authors: Nhan Huynh; Genia Dubrovsky; Joshua D Rouch; Andrew Scott; Elvin Chiang; Tommy Nguyen; Benjamin M Wu; Shant Shekherdimian; Thomas M Krummel; James C Y Dunn Journal: PLoS One Date: 2018-07-12 Impact factor: 3.240