Low magnification photomicrographs illustrating TrpOH/c-Fos-immunostained sections from different rostrocaudal levels of the DR from a control (CO) rat. TrpOH-immunopositive neurons and dendrites can be identified by the brown/orange precipitate within subdivisions of the DR. The subdivisions of the DR analyzed are illustrated by dashed lines (adapted from a standard stereotaxic atlas of the rat brain [42]). Abbreviations: Aq, cerebral aqueduct; 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; mlf, medial longitudinal fasciculus; xscp, decussation of the superior cerebellar peduncle. Scale bar, 500μm.