“…Indeed, in this work we also see a down-regulation of genes associated with dopaminergic neuron development and function, including the genes traditionally associated with dopamine synthesis (DDH and TH) and transport (SLC6A3), consistent with findings from human cocaine abusers. Previous studies have observed decreases in the dopamine transporter in post-mortem studies from human cocaine abusers (Bannon et al, 2014; Bannon et al, 2015; Little et al, 1998; Zhou et al, 2014a) as well as in rats following extended cocaine exposure (Cerruti et al, 1994; Letchworth et al, 1997; Letchworth et al, 1999; Zhang et al, 2012). The parallels between these studies and previous human studies extend to a reduced expression of tyrosine hydroxylase in the VTA (Bannon et al, 2014; Bannon et al, 2015), although rat studies have been more ambiguous (Freeman et al, 2000; Rodriguez-Espinosa and Fernandez-Espejo, 2015; Vrana et al, 1993).…”