SLC6A2 and Parkinson disease: In the striatum, however, noradrenergic innervations as well as norepinephrine reuptake transporter levels are low [18,52,53], which is in line with previous published observation, showing that, in the striatum, the NET is responsible for dopamine uptake only when DAT levels reach critically low levels, as observed in Parkinson’s disease [54,55].