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Morphometric Analyses of Longitudinal and Circular Smooth Muscle and Lacteals of the Small Intestine of Zucker Lean and Obese Rats
Author(s) -
Burgess Andrea R,
Trujillo Andrea N,
Barter Micaela,
Breslin Jerome W
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.726.8
Subject(s) - ileum , medicine , endocrinology , biology , anatomy
Lymph lacteals are the entry point of absorbed fats and cholesterol in the villi of the small intestine. In a recent study, lacteals and the leakiness of the submucosal lympahtic network was implicated as a source for adult‐onset obesity (Harvey et al. 2005). The purpose of this study was to determine what structural differences may exist in the lacteals, submucosa, and other layers of the ileum between lean and obese Zucker rats using histochemistry (H&E) and immunofluorescence microscopy. We hypothesized that due to increased food intake and levels of digested fats in the obese Zucker rat, the lacteals and the smooth muscle layers of the ileum will modify from their normal appearance to accommodate the increased intake of fats and volume of food respectively. Ileum from lean and obese Zucker rats was harvested, fixed in buffered formalin overnight, processed and embedded in paraffin. Cross sections (2–3 μm) of the ileum were mounted on slides and stained with H&E to measure longitudinal and circular smooth muscle layer thickness. Similar sections were incubated with a LYVE‐1 antibody to identify lymphatic endothelial cells of the lacteals and a smooth muscle actin (SMA) antibody to label smooth muscle cells extending into the villi. Layers of longitudinal and circular smooth muscle, identified in the ileum with H&E staining, were significantly thicker in obese Zucker rats compared to lean rats. Preliminary immunolabeling with LYVE‐1 identified positive endothelial cells in crypts of the sub mucosae and SMA‐positive smooth muscle cells that extended into the villi (lamina propria). SMA was also detected in the circular and longitudinal muscle layers and the muscularis muscosae as predicted. Histological data obtained from the ileum support the hypothesis that increased food intake increases intestinal smooth muscle layer thickness in obese Zucker rats. Support or Funding Information This work was supported by an APS/NHLBI STRIDE Undergraduate Summer Research Fellowship (NIH R25HL115473) and NIH grant L40HL097863.