Time-dependent fluctuation of CREB, αCaM kinase II, MAPK/Erk1/2 in PFC/FC nuclei. Modulation by chronic agomelatine. Expression levels of CREB (A), αCaM kinase II (C), MAPK/Erk1 (E) and MAPK/Erk2 (G) and phosphorylation levels of CREB at Ser133(B), αCaM kinase II at Thr286(D), MAPK/Erk1 at Thr202/204(F) and MAPK/Erk2 at Thr202/204(H) in nuclear fraction of PFC/FC from rats chronically treated with vehicle (VEH, black bar) or agomelatine (AGO, white bar) and sacrificed 1 or 16 h after the last injection. Data are expressed as % intensity units/mm2 (mean ± S.E.M.). Bonferroni post-hoc test (following 2-way ANOVA): *p < 0.05 VEH treated rats sacrificed 16 h after last injection vs. VEH treated rats sacrificed 1 h after last injection; § p < 0.05 AGO 16 h after last injection vs. AGO 1 h after last injection; §§ p < 0.01 AGO 16 h after last injection vs. AGO 1 h after last injection (n =8 rats/group).