Neuroendocrine responses to acute restraint. The day following the second FST, a subset of rats was placed in a well-ventilated, size-adjusted Plexiglas restraint tube and subjected to a 30-min restraint (shown in the dark bar). Results for ACTH indicated a significant effect of stress at baseline (0 min) with defeated rats showing lower levels of ACTH compared to naïve rats regardless of the age at which they were stressed. There was a significant effect at 60 min with rats stressed earlier in adulthood displaying lower concentrations of ACTH and corticosterone compared to rats stressed as adolescents. Group sizes for ACTH: Adolescent Naïve: n=6–7; Adolescent Defeat: n=9–10; Adult Naïve: n=6–7; Adult Defeat: n=10–11. Group sizes for Corticosterone: Adolescent Naïve: n=6–7, Adolescent Defeat: n=8–11, Adult Naïve: n=7–8, Adult Defeat: n=10–11.
* p ≤ .05 indicates a significant Stress effect with a significant difference between defeated rats compared to age matched counterparts
# p≤ .05 indicates a significant Age effect with a significant difference between adolescent and adult female rats