**5.3 LC altered dopaminergic behavior**

There have been several studies to indicate the ability of LC noradrenergic neurons to modulate dopamine-induced behavior, especially when LC noradrenergic neurons are reduced (Antelman & Caggiula, 1977; Archer & Fredriksson, 2006**;** Chopin et al., 1999; Grimbergen et al., 2009; Mavridis et al., 1991; Rommelfanger et al., 2007; Taylor et al., 2009; Villegier et al., 2003; Wang et al., 2010). In addition, reducing LC function alone by lesioning LC neurons can produce motor symptoms that are observed in PD (Grimbergen et al., 2009; Wang et al., 2010). In support of the LC lesion studies and the consequence of reduced NE content, DBH knockout mice, which do not synthesize NE, also exhibit PD motor symptoms with age (Rommelfanger et al., 2007). These data suggest the loss of LC noradrenergic function observed in PD may contribute to the motor symptoms of PD.
