title: Maternal separation as a model of brain-gut axis dysfunction.
abstract: BACKGROUND
  Early life stress has been implicated in many psychiatric disorders ranging from depression to anxiety. Maternal separation in rodents is a well-studied model of early life stress. However, stress during this critical period also induces alterations in many systems throughout the body. Thus, a variety of other disorders that are associated with adverse early life events are often comorbid with psychiatric illnesses, suggesting a common underlying aetiology. Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that is thought to involve a dysfunctional interaction between the brain and the gut. Essential aspects of the brain-gut axis include spinal pathways, the hypothalamic pituitary adrenal axis, the immune system, as well as the enteric microbiota. Accumulating evidence suggest that stress, especially in early life, is a predisposing factor to IBS.
  
  
  OBJECTIVE
  The objective of this review was to assess and compile the most relevant data on early life stress and alterations at all levels of the brain gut axis.
  
  
  RESULTS
  In this review, we describe the components of the brain-gut axis individually and how they are altered by maternal separation. The separated phenotype is characterised by alterations of the intestinal barrier function, altered balance in enteric microflora, exaggerated stress response and visceral hypersensitivity, which are all evident in IBS.
  
  
  CONCLUSIONS
  Thus, maternally separated animals are an excellent model of brain-gut axis dysfunction for the study of disorders such as IBS and for the development of novel therapeutic interventions.
authors.affiliation: Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork, Cork, Ireland. somahony@ucc.ie
authors.forename: Siobhain M
authors.initials: SM
authors.lastname: O'Mahony
authors.forename: Niall P
authors.initials: NP
authors.lastname: Hyland
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Dinan
authors.forename: John F
authors.initials: JF
authors.lastname: Cryan
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D004195:Disease Models, Animal; D041981:Gastrointestinal Tract / Q000503:physiopathology; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000209:etiology* / Q000503:physiopathology; D008016:Life Change Events; D008426:Maternal Deprivation; D012377:Rodentia; D013315:Stress, Psychological / Q000503:physiopathology*