title: Resistant starch alters colonic contractility and expression of related genes in rats fed a Western diet.
abstract: OBJECTIVE
  Dietary fiber shortens gut transit time, but data on the effects of fiber components (including resistant starch, RS) on intestinal contractility are limited. We have examined RS effects in male Sprague-Dawley rats fed either a high-amylose maize starch (HAMS) or a wholemeal made from high-amylose wheat (HAW) on ileal and colonic contractility ex vivo and expression of genes associated with smooth muscle contractility.
  
  
  METHODS
  Rats were fed diets containing 19 % fat, 20 % protein, and either low-amylose maize starch (LAMS), HAMS, wholemeal low-amylose wheat (LAW) or HAW for 11 week. Isolated ileal and proximal colonic sections were induced to contract electrically, or by receptor-independent (KCl) or receptor-dependent agents. Colonic gene expression was assessed using an Affymetrix microarray.
  
  
  RESULTS
  Ileal contractility was unaffected by treatment. Maximal proximal colonic contractility induced electrically or by angiotensin II or carbachol was lower for rats fed HAMS and LAW relative to those fed LAMS (P < 0.05). The colonic expression of genes, including cholinergic receptors (Chrm2, Chrm3), serotonin receptors (Htr5a, Htr7), a protease-activated receptor (F2r), a prokineticin receptor (Prokr1), prokineticin (Prok1), and nitric oxide synthase 2 (Nos2), was altered by dietary HAMS relative to LAMS (P < 0.05). HAW did not significantly affect these genes or colonic contractility relative to effects of LAMS.
  
  
  CONCLUSIONS
  RS and other fiber components could influence colorectal health through modulation of stool transit time via effects on muscular contractility.
authors.affiliation: CSIRO Animal, Food and Health Sciences, Kintore Avenue, PO Box 10041, Adelaide BC, SA, 5000, Australia, glen.patten@csiro.au.
authors.forename: Glen S
authors.initials: GS
authors.lastname: Patten
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Kerr
authors.forename: Robert A
authors.initials: RA
authors.lastname: Dunne
authors.forename: Janet M
authors.initials: JM
authors.lastname: Shaw
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Bird
authors.forename: Ahmed
authors.initials: A
authors.lastname: Regina
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Morell
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Lockett
authors.forename: Peter L
authors.initials: PL
authors.lastname: Molloy
authors.forename: Mahinda Y
authors.initials: MY
authors.lastname: Abeywardena
authors.forename: David L
authors.initials: DL
authors.lastname: Topping
authors.forename: Michael A
authors.initials: MA
authors.lastname: Conlon
mesh_terms: D000818:Animals; D066273:Diet, Western; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000235:genetics*; D015870:Gene Expression; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects* / Q000235:genetics*; D009130:Muscle, Smooth / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013213:Starch / Q000494:pharmacology*; D003313:Zea mays
chemical_list: D013213:Starch