Meanwhile, pERK1/ERK1 ratio was not significantly different among the groups, despite showing a strong trend toward a decrease with age (For pERK1/ERK1: F (2,17) = 3.01; P = 0.076; For pERK2/ERK2: F (2,17) = 8.87; P = 0.002) ( Fig. 3 ).
As shown in Figure 2 , one-way ANOVA followed by Newman–Keuls post hoc tests revealed that PN17 rat mPFC had a significantly higher level of c-Fos ( F (2,20) = 4.36; P = 0.027) compared to adult rats ( P < 0.05) with a decreasing trend from PN17 to PN24 and an even stronger decreasing trend from PN24 to adult age, both of which, however, did not reach statistical significance ( P > 0.05) ( Fig. 2 ).