and subsequent DA release in their terminal fields (Barnes et al., 1990; West and Michael, 1991), increases locomotor activity (Barnes et al., 1990; Eison et al., 1982; Elliott et al., 1992; Kelley et al., 1979; Placenza et al., 2004), and induces conditioned place preference (Boix et al., 1995; Nikolaus et al., 1999). The relative contribution of NK receptor subtypes to the effects of SP in the VTA and substantia nigra remains unclear. Another subset of SPergic MSNs of the ventral striatum project to the ventral pallidum (Lu et al., 1998), a brain region involved in drug seeking as part of a final common pathway for relapse [see (Kalivas and Volkow, 2005)]. The NK1R is also located throughout the striatum, where it is found on dendrites of cholinergic interneurons as well as terminals projecting into this region (Commons and Serock, 2009; Murtra et al., 2000; Pickel et al., 2000).
