Figure 6. Systemic cort administration immediately after a strong footshock training is sufficient to produce PTSD-like phenotype. A, Plasma cort levels at 30–45 min after training (TR) elicited with a 0.6, 1.5, or 3 mA footshock. B, Systemic injection of cort, compared with vehicle (Veh), immediately after training with 1.5 or 3 mA footshock leads to opposite effects on IA latency (in seconds) tested 2 d later. C, Latency of the groups of rats described in B exposed to a new context (ctx) 2 d after TR. D–G, Open-field test (OFT) performed on the groups of rats described in B and compared with naive rats. Data are expressed as the mean ± SEM of total activity, center activity, center time, and center/total activity. Total activity in the arena (D), activity in the center of the arena (E), time spent in the center of the arena (F), and ratio of center activity over total activity (G). H, Extinction curves after TR with 1.5 or 3 mA shock and vehicle or cort injection Data are expressed in latency (in seconds). I, Extinction curves of memory first tested 2 d after training (T1) with either 1.5 or 3 mA footshock, injected 1 d later with cort (0.5, 3.0, or 10.0 mg/kg) or vehicle (Veh), and, starting 1 d later, undergone extinction for 5 consecutive days (E1–E5). One day after E5, an RS was given and memory was tested 24 h later (T2). Data are expressed in latency (in seconds). p < 0.001, E5 versus T2 for all groups except for cort at 0.5 mg/kg in the 3 mA group at p < 0.01. J, Plasma cort levels were measured at 45–60 min after RS or a second training trial (TR2) delivered 1 d after the original training and compared with those of naive animals. *p < 0.05, **p < 0.01, ***p < 0.001.