title: Stress resilience and vulnerability: the association with rearing conditions, endocrine function, immunology, and anxious behavior.
abstract: BACKGROUND
  The current study explored the underlying behavioral, endocrine, and immune markers of vulnerability to stress-induced depression, and the impact of rearing environments on adult functioning.
  
  
  METHODS
  Adult Sprague-Dawley rats (n=195) were reared in either Maternal Separation (MS), Early Weaning and Isolation (EWI), or Non-Handled (NH) conditions. Anxiety behavior was assessed using the emergence test at mean postnatal day (PND) 60. Stress-induced depressive behavior was measured at mean PND 86 using an intermittent cold water swim stress and swim escape test (SET) paradigm. Immediately following the SET, and in a sample of naïve controls (N=31), trunk blood was collected to assay for serum corticosterone (CORT) and spleens were removed for determination of Concanavalin A (Con-A) stimulated T-cell proliferation.
  
  
  RESULTS
  Stress vulnerable rats (top tertile of SET swim time) were characterised by increased anxiety-like behavior, greater post-stress CORT concentrations, and a significantly higher Con-A induced T-cell proliferative response compared to stress resilient rats (bottom tertile of SET swim time). The EWI rearing condition was a contributing factor in predicting total swim escape time, however MS was not. MS offspring did have double the basal level of CORT than NH offspring, suggestive of a hyperfunctioning HPA axis.
  
  
  CONCLUSIONS
  The swim stress animal model enabled observation of stress vulnerability and resilience; results point towards the existence of distinct behavioral, endocrine, and immunological profiles of the vulnerable and resilient animal, which may have important implications for mental health and stress research.
authors.affiliation: School of Psychological Science, La Trobe University, Bundoora, Victoria 3086, Australia.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Stiller
authors.forename: Robert C
authors.initials: RC
authors.lastname: Drugan
authors.forename: Agnes
authors.initials: A
authors.lastname: Hazi
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Kent
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology*; D000822:Animal Husbandry; D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000209:etiology* / Q000503:physiopathology; D001522:Behavior, Animal / Q000502:physiology; D004703:Endocrine System / Q000502:physiology*; D005260:Female; D006234:Handling, Psychological; D007107:Immune System / Q000502:physiology*; D008297:Male; D008426:Maternal Deprivation; D051381:Rats; D017207:Rats, Sprague-Dawley; D055500:Resilience, Psychological; D013315:Stress, Psychological / Q000276:immunology / Q000503:physiopathology* / Q000523:psychology; D013550:Swimming / Q000502:physiology