Fig. 2

Effect of acute immobilization stress after contextual fear conditioning (Experiment 2). a Experimental protocol for contextual fear conditioning training followed by stress and behavior tests. b Quantification of freezing behavior 24 h after the contextual fear conditioning training followed by immobilization stress (n = 10). c Quantification of BDNF/GAPDH mRNA ratio in the hippocampus (n = 5–8). The samples of naïve mice were collected the same day as the other groups. Naïve mice were not exposed to the training apparatus or immobilization stress. Data are expressed as mean ± SEM. *P < 0.05 compared with training group. ^# P < 0.05 compared with training + stress group (90–120 min)