(A) Experimental timeline showing fluoxetine treatment and behavioral testing. Fluoxetine effect on (B) NOR task, L/D box, OFT and the forced swim test (FST) (N = 6–8), (C) corticosterone levels in serum (N = 11–13), and hippocampal GR, MR and (D) Arc mRNA expression levels (N = 4–10); (E) tryptophan levels in serum (N = 11–20), brain stem (N = 3–6) and hippocampus (N = 4–5) detected by LC/MS; (F) hippocampal 5HT1ra, Tph2 and Sert mRNA expression levels (N = 6–7). Data are presented as mean ± SEM. (*P < 0.05; **P < 0.01, unpaired Student’s t-test and 2-way ANOVA).