Supplementary Material 1: Supplementary Fig. 1. Atlases of serotonergic gene expression. (a) Atlas of rat tryptophan hydroxylase 2 (tph2) mRNA expression, (b) atlas of rat 5-HT1A receptor (htr1a) mRNA expression, and (c) atlas of rat serotonin transporter (slc6a4) mRNA expression in the midbrain and pontine raphe complex (84 μm intervals) used for analysis of subregions of the dorsal raphe nucleus (DR), median raphe nucleus (MnR), pontomesencephalic reticular formation (PMRF) and B9 serotonergic cell group (B9) with a high level of neuroanatomical resolution. Photographs are autoradiographic images of tph2, htr1a, and slc6a4 mRNA expression. The levels chosen for analysis ranged from (A) − 7.412 mm bregma through (P) − 8.672 mm bregma. Dotted lines delineate different subdivisions of the DR analyzed in this study, based on a stereotaxic atlas of the rat brain [39]. Abbreviations: B9, supralemniscal serotonergic cell group; MnR, median raphe nucleus; DRC, dorsal raphe nucleus, caudal part; DRD, dorsal raphe nucleus, dorsal part; DRI, dorsal raphe nucleus, interfascicular part; DRV, dorsal raphe nucleus, ventral part; DRVL, dorsal raphe nucleus, ventrolateral part; PMRF, pontomesencephalic reticular formation; VLPAG, ventrolateral periaqueductal gray. Numbers in the upper right of each panel indicate the rostrocaudal coordinates relative to bregma (in mm). Numbers in the lower right of each panel indicate the rostrocaudal level of each DR. Scale bar, 1 mm. The rostrocaudal levels and matrices defining subregions of the DR that were defined using tph2 autoradiograms were also used in the analysis of htr1a and slc6a4 to ensure sampling of the same anatomical regions for each gene