title: Blunted HPA axis response to stress influences susceptibility to posttraumatic stress response in rats.
abstract: BACKGROUND
  Posttraumatic stress disorder (PTSD) is associated with low levels of circulating cortisol, and recent studies suggest that cortisol administration may reduce PTSD symptoms. This study investigated the role of cortisol in the manifestation of anxiety- and fear-like symptoms in an animal model of PTSD.
  
  
  METHODS
  Magnitude of changes in prevalence of anxiety-like behaviors on the elevated plus-maze and nonhabituated exaggerated startle reaction were compared in three strains of rats exposed to predator stress, with and without prior corticosterone treatment. Extreme behavioral changes in both paradigms implied an extreme behavioral response (EBR), representing PTSD-like symptoms.
  
  
  RESULTS
  Lewis rats exhibited greater baseline anxiety-like behaviors and greater stress-induced increases in anxiety-like behaviors than Fischer F344 or Sprague-Dawley rats, with only minor corticosterone increases following stress. Prevalence of EBR was 50% among Lewis rats compared with 10% of Fischer F344 and 25% of Sprague-Dawley rats. Administering corticosterone 1 hour before stress exposure reduced the prevalence of EBR from 50% to 8% in the Lewis rats.
  
  
  CONCLUSIONS
  These results suggest that a blunted HPA response to stress may play a causal role in this model of PTSD and that this susceptibility may be prevented by administration of cortisol before stress exposure.
authors.affiliation: Ministry of Health Mental Health Center, Anxiety and Stress Research Unit, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel. hagitc@bgu.ac.il
authors.forename: Hagit
authors.initials: H
authors.lastname: Cohen
authors.forename: Joseph
authors.initials: J
authors.lastname: Zohar
authors.forename: Yori
authors.initials: Y
authors.lastname: Gidron
authors.forename: Michael A
authors.initials: MA
authors.lastname: Matar
authors.forename: Dana
authors.initials: D
authors.lastname: Belkind
authors.forename: Uri
authors.initials: U
authors.lastname: Loewenthal
authors.forename: Nitsan
authors.initials: N
authors.lastname: Kozlovsky
authors.forename: Zeev
authors.initials: Z
authors.lastname: Kaplan
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D004195:Disease Models, Animal; D004198:Disease Susceptibility / Q000097:blood / Q000523:psychology; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System; D008297:Male; D018782:Maze Learning / Q000502:physiology; D010913:Pituitary-Adrenal System; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D017207:Rats, Sprague-Dawley; D013216:Reflex, Startle / Q000502:physiology; D013313:Stress Disorders, Post-Traumatic / Q000097:blood* / Q000523:psychology*; D013315:Stress, Psychological / Q000097:blood* / Q000523:psychology*; D013997:Time Factors
chemical_list: D006854:Hydrocortisone