title: Morphological changes in the small intestinal smooth muscle layers of horses suffering from small intestinal strangulation. Is there a basis for predisposition for reduced contractility?
abstract: BACKGROUND
  Intestinal strangulation often leads to enterectomy after which ileus can develop. This has prompted research to look into possible pathophysiological processes triggering equine ileus. However, morphological changes of the small intestinal smooth muscle in relation to equine colic have not yet been studied.
  
  
  OBJECTIVE
  The presence of some smooth muscle proteins was morphologically assessed and quantified in control and colic horses. In addition, the up- or down-regulation of heat shock proteins (HSP20 and HSP27) influencing the contractility of smooth muscles was studied.
  
  
  METHODS
  Cranial resection margins of 18 strangulated small intestinal samples were collected. Small intestinal control samples were collected from 11 horses subjected to euthanasia for other than gastrointestinal-related reasons. Formaldehyde-fixed tissue was paraffin-embedded and processed for conventional staining and immunohistochemistry. Snap-frozen full-thickness biopsies were collected for western blot analyses.
  
  
  RESULTS
  Evaluating the muscle layer microscopically, colic samples showed significantly more signs of degradation than controls (P = 0.026) of which vacuolar degeneration was most prominent (P = 0.009). In colic samples, myosin protein levels were decreased (P = 0.022) whereas desmin (P = 0.049) and HSP20 protein levels (P = 0.005) were elevated.
  
  
  CONCLUSIONS
  In colic samples, microscopic lesions at the level of the muscle layer indicate a stress response. In addition, modified amounts of structural proteins such as myosin and desmin together with increased HSP20 levels could perhaps provide a basis for explaining the malfunctioning of the intestinal muscle layer.
  
  
  CONCLUSIONS
  Post operative ileus, following small intestinal strangulation and resection, could be related in part to a dysfunctional muscle layer. In addition to microscopic signs of degeneration, myosin and HSP20 were affected. Pharmacological interventions might alter HSP20 expressions and thus serve a protective effect.
authors.affiliation: Department of Veterinary Sciences, Laboratory of Veterinary Anatomy, Embryology and Pathology, University of Antwerp, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: De Ceulaer
authors.forename: C
authors.initials: C
authors.lastname: Delesalle
authors.forename: R
authors.initials: R
authors.lastname: Van Elzen
authors.forename: L
authors.initials: L
authors.lastname: Van Brantegem
authors.forename: A
authors.initials: A
authors.lastname: Weyns
authors.forename: C
authors.initials: C
authors.lastname: Van Ginneken
mesh_terms: D000818:Animals; D001706:Biopsy / Q000662:veterinary; D015153:Blotting, Western; D003085:Colic / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D005260:Female; D050886:HSP20 Heat-Shock Proteins / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006734:Horse Diseases / Q000378:metabolism / Q000473:pathology*; D006736:Horses; D007150:Immunohistochemistry / Q000662:veterinary; D007410:Intestinal Diseases / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D007421:Intestine, Small / Q000378:metabolism / Q000473:pathology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D009218:Myosins / Q000378:metabolism; D018709:Statistics, Nonparametric
chemical_list: D050886:HSP20 Heat-Shock Proteins; D055551:HSP27 Heat-Shock Proteins; D009218:Myosins