title: Exercise and intestinal polyp development in APCMin mice.
abstract: OBJECTIVE
  Epidemiological evidence suggests that physical activity protects against colon cancer. We previously used a mouse predisposed to intestinal polyps (APCMin) to evaluate this association and found the suggestion of fewer polyps in exercised males but not females. The present study was designed to further explore the potential exercise x sex interaction on polyp development and to begin to look at potential mechanisms.
  
  
  METHODS
  Six-week-old APCMin mice (N = 60 males; 60 females) were randomly assigned to one of two groups by sex: treadmill running at 20 m.min-1, 5% grade, 45 min.d-1, 5 d.wk-1 (EX) or nonrunning controls (CON) (N = 30 per group). EX mice ran in running wheels while in quarantine (weeks 0-3), followed by treadmill running weeks 3-8. Body weights were measured weekly. Urine was collected at 5 wk and fasting blood at 7.5 wk. Body composition was measured, serum was frozen, and polyp number and size were measured at sacrifice.
  
  
  RESULTS
  EX resulted in lower body weights (P < 0.01) and reduced fat mass (P < 0.01). Fasting glucose was lower in EX (P < 0.01), and leptin was lower in EX (P = 0.05) compared with CON. EX did not affect serum insulin-like growth factor-1 or urinary corticosterone. Total polyp number and size were not statistically different between groups; however, there were fewer jejunal polyps in EX (3.6 +/- 0.7, mean +/- SE) versus CON males (5.2 +/- 0.8; P = 0.04) and an even larger difference when only the consistent runners were kept in the analysis (2.7 +/- 0.5 in EX; P = 0.01).
  
  
  CONCLUSIONS
  Despite favorable changes in body composition, blood glucose, and leptin, 8 wk of running resulted in only minor changes related to polyp development in male but not female APCMin mice.
authors.affiliation: National Institute on Aging/NIH, Bethesda, MD 20892, USA.
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Colbert
authors.forename: Volker
authors.initials: V
authors.lastname: Mai
authors.forename: Susan N
authors.initials: SN
authors.lastname: Perkins
authors.forename: David
authors.initials: D
authors.lastname: Berrigan
authors.forename: Jackie A
authors.initials: JA
authors.lastname: Lavigne
authors.forename: Heather H
authors.initials: HH
authors.lastname: Wimbrow
authors.forename: W Gregory
authors.initials: WG
authors.lastname: Alvord
authors.forename: Diana C
authors.initials: DC
authors.lastname: Haines
authors.forename: Pothur
authors.initials: P
authors.lastname: Srinivas
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Hursting
mesh_terms: D000818:Animals; D001823:Body Composition; D001835:Body Weight; D004195:Disease Models, Animal; D005260:Female; D006728:Hormones / Q000097:blood; D007417:Intestinal Polyps / Q000517:prevention & control*; D020738:Leptin / Q000097:blood; D008297:Male; D051379:Mice; D012420:Running; D012727:Sex Characteristics
chemical_list: D006728:Hormones; D020738:Leptin