Female and R2KO mice display reduced SERT levels in hippocampus and prefrontal cortex. SERT levels were examined by autoradiography in the DG (A and D), area CA1 (B and E), and area CA3 (C and F) in the dorsal and ventral hippocampus (dHpc and vHpc, respectively), the prefrontal cortex (PFC) (G), and basolateral amygdala (BLA) (H). Significant sex by genotype interaction effects were observed in the DG and CA3 areas in the dorsal hippocampus where WT females displayed decreased SERT compared with males. Significant effect of genotype was detected in the prefrontal cortex, where R2KO mice SERT was reduced compared with WT. Representative autoradiogram images of i) PFC, ii) dHPC, and iii) vHPC are displayed, outlining regions sampled for analysis, accompanied by cytoarchitectural schematics (adapted from Ref. 65). Data are presented as mean ± sem. *, Significant effect of genotype, P < 0.05; +, significant effect of sex, P < 0.05; ++, significant effect of sex, P < 0.01.