title: [External validity of a relevant model for Irritable Bowel Syndrome (IBS) using chronic stress by water avoidance in Wistar rats].
abstract: BACKGROUND
  Development of animal models has been one of the most remarkable achievements for Irritable Bowel Syndrome (IBS) research. These models need to exhibit face validity, construct and predictive validity, as well as internal (replicability) and external validity (generalizability). Among these models, chronic stress induced by water avoidance exposure (WA) has been validated in rats through increasing visceral hypersensitivity, motility impairment, anxiety and, colonic immune activity, all related to IBS.
  
  
  OBJECTIVE
  To assess the external validity of WA indirectly on colonic motility in Wistar rats.
  
  
  METHODS
  Ten male-Wistar rats were exposed to WA and compared with ten Wistar rats not exposed (controls). At the end of each exposure, the quantity of fecal pellets were determined and considered as a sign of autonomic regulation of colonic motility. Data was analyzed with a general linear model for repeated measures.
  
  
  RESULTS
  Rats exposed to WA had higher number or pellets than controls: 7.46 ± 0.45 (95%CI: 6.51, 8.41) vs. 2.88 ± 0.45 (1.93, 3.83), p < 0.001. The higher number of pellets was related to WA exposure as there were no other significant interactions. In both groups, the number of pellets was higher during the first day and then decreased progressively.
  
  
  CONCLUSIONS
  Chronic stress induced through WA in Wistar rats, exhibits external validity as an experimental model for IBS research and our findings of increased number of fecal pellets coincide with the appearance hypermotility related to IBS. The model is optimum for research studies on this disorder.
authors.affiliation: Laboratorio de Hígado, Páncreas y Motilidad (HIPAM), Departamento de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM).
authors.forename: V
authors.initials: V
authors.lastname: Rojas-Macías
authors.forename: O
authors.initials: O
authors.lastname: Rodríguez-Fandiño
authors.forename: F
authors.initials: F
authors.lastname: Jiménez-Ponce
authors.forename: J A
authors.initials: JA
authors.lastname: Saldivar-González
authors.forename: E
authors.initials: E
authors.lastname: Melendro-Lozano
authors.forename: J C
authors.initials: JC
authors.lastname: López-Alvarenga
authors.forename: S B
authors.initials: SB
authors.lastname: Raya-Santoyo
authors.forename: A D
authors.initials: AD
authors.lastname: Santana-Vargas
authors.forename: M
authors.initials: M
authors.lastname: Schmulson
mesh_terms: D000818:Animals; D001362:Avoidance Learning; D004195:Disease Models, Animal; D043183:Irritable Bowel Syndrome / Q000209:etiology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D013315:Stress, Psychological; D014867:Water
chemical_list: D014867:Water