Differences in receptor density between genotypes is line specific. (A–D) Autoradiography images (A, C) and quantification (B, D) of h5-HT1A expression in rs6295 GG and CC animals from line A at P21 (A, B) and in adulthood (C, D). No significant differences in h5-HT1A levels were detected in any brain region at either time point. (E–H) Autoradiography images (E, G) and quantification (F, H) of h5-HT1A expression in rs6295 GG and CC animals from line B at P21 (E, F) and in adulthood (G, H). At P21, GG mice have higher levels of h5-HT1A in the dorsal hippocampus (DHpc) (p = 0.001) and the claustrum (p = 0.001), but no difference in the ventral hippocampus (VHpc) (p = 0.5290). In adulthood, GG animals have higher h5-HT1A expression in the DHpc (p = 0.0001), VHpc (p = 0.0350), and claustrum (p = 0.0070). Group sizes and statistical analyses available in Supplementary Table 4.