Altered hippocampal function before emotional trauma in rats susceptible to PTSD-like behaviors

Rebecca Nalloor, Kristopher M. Bunting, Almira Ivanova Vazdarjanova

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Posttraumatic stress disorder (PTSD) is an anxiety disorder that occurs after experiencing a traumatic event. Susceptibility to PTSD exists, as only some trauma-exposed individuals develop this condition. Investigating susceptibilities in animal models can contribute to understanding the etiology of the disorder. We previously reported an animal model which allows reliable pre-classification of rats as susceptible (Sus) or resistant (Res) to developing a PTSD-like phenotype after a later trauma. Here we report that Sus, compared to Res, rats have altered hippocampal function, along the septo-temporal axis, prior to experiencing a traumatic event. In Experiment I, Res and Sus rats explored a novel box twice. Using a cellular imaging method for assessing plasticity-related immediate-early gene expression in large neuronal ensembles, Arc/Homer1a catFISH, we show that Sus rats have smaller vCA3 ensembles during the second exploration. This suppressed vCA3 activation in Sus rats was not due to a difference in exploratory behavior, or to a difference in Arc/Homer1a expression in the basolateral amygdala (BLA). BLA is a main source of inputs to vCA3, but both the ensemble size and overlap of BLA ensembles activated during the two explorations was similar to that of Res rats. Additionally, Sus rats had significant 'infidelity' in their dorsal hippocampal representations of the second event: a lower overlap, compared to Res rats, of Arc/Homer1a-expressing ensembles activated during the two explorations (the size of the ensembles were similar to those of Res rats). These differences were revealed only in conditions of relatively low stress, because they were not observed when Sus and Res rats experienced fear conditioning (Experiment II). Combined, the findings show that altered hippocampal function exists before experiencing emotional trauma in susceptible rats and suggest that this is a risk factor for PTSD.

Original languageEnglish (US)
Pages (from-to)158-167
Number of pages10
JournalNeurobiology of Learning and Memory
Volume112
DOIs
StatePublished - Jan 1 2014

Fingerprint

Post-Traumatic Stress Disorders
Wounds and Injuries
Animal Models
Exploratory Behavior
Immediate-Early Genes
Anxiety Disorders
Fear
Phenotype
Gene Expression

Keywords

  • Arc
  • CatFISH
  • Hippocampus
  • Homer
  • IEG
  • PTSD
  • Rats
  • Susceptibility

ASJC Scopus subject areas

  • Behavioral Neuroscience
  • Cognitive Neuroscience
  • Experimental and Cognitive Psychology
  • Medicine(all)

Cite this

Altered hippocampal function before emotional trauma in rats susceptible to PTSD-like behaviors. / Nalloor, Rebecca; Bunting, Kristopher M.; Vazdarjanova, Almira Ivanova.

In: Neurobiology of Learning and Memory, Vol. 112, 01.01.2014, p. 158-167.

Research output: Contribution to journalArticle

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