The age of stressor exposure can determine its neurobehavioral impact. For example, exposure of adolescent male rats to resident-intruder stress impairs cognitive flexibility in adulthood. The current study examined the impact of this stressor in female rats. Rats were exposed to resident-intruder stress during early adolescence (EA), mid-adolescence (MA) or adulthood (Adult). They were tested in an operant strategy-shifting task for side discrimination (SD), reversal learning (REV) and strategy set-shifting (SHIFT) the following week. Performance varied with age, stress and coping style. MA and EA rats performed SD and SHIFT better than other ages, respectively. Social stress impaired performance in rats depending on their coping strategy as determined by a short (SL) or long (LL) latency to become subordinate. SL rats were impaired in SD and REV, whereas EA-LL rats were impaired in SHIFT. These impairing effects of female adolescent stress did not endure into adulthood. Strategy set-shifting performance for female adolescents was positively correlated with medial prefrontal cortex (mPFC) activation as indicated by c-fos expression suggesting that this region is engaged during task performance. This contrasts with the inverse relationship between these indices reported for male adolescent rats. Together, the results demonstrate that social stress produces cognitive impairments for female rats that depend on age and coping style but unlike males, the impairing effects of female adolescent social stress are immediate and do not endure into adulthood. Sex differences in the impact of adolescent social stress on cognition may reflect differences in mPFC engagement during the task.
Keywords: Development; Prefrontal cortex; Resident-intruder; Reversal learning; Sex difference; Strategy shifting.
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