Amphetamine induces accumulation of the norepinephrine transporter into Rab4- and Rab11-positive compartments

Abstract

The norepinephrine transporter (NET) clears norepinephrine (NE) from the synapse after vesicular release. NET is a target of the psychostimulant amphetamine (AMPH). We have recently shown that AMPH alters trafficking of the transporter, causing a net decrease in surface NET in the monoaminergic CAD cell line. In this study we demonstrate, by confocal imaging of immunostained superior cervical ganglion (SCG) neurons, that AMPH causes an increase in NET levels inside terminal boutons. Further, the intracellular compartment in which NET accumulates upon AMPH exposure is not known; such information would inform investigation of the mechanism by which the drug affects NET’s cellular distribution. We show that after AMPH treatment, NET co-fractionates with both Rab4 and Rab11, and that AMPH increases co-localization of NET with these endosomal markers as indicated by the intensity correlation quotient (ICQ). Finally, we show that the functions of both GTPases are involved in AMPH-regulated NET trafficking by transfection of dominant negative (DN) constructs followed by cell-surface biotinylation. Our results support the conclusion that AMPH-regulated NET trafficking occurs through endosomes.