Rapid delivery of the dopamine transporter to the plasmalemmal membrane upon amphetamine stimulation

The dopamine transporter, DAT, is a primary regulator of dopamine (DA) signaling at the synapse. Persistent stimulation with the substrate amphetamine (AMPH) promotes DAT internalization. AMPH rapidly elicits DA efflux, yet its effect on DAT trafficking at short times is unknown. We examined the rapid effect of AMPH on DAT trafficking in rat striatal synaptosomes using biotinylation to label surface DAT. Within 30 s of treatment with 3 μM AMPH, synaptosomal DAT surface expression increased to 163% of control and remained elevated through at least 1 min before returning to control levels at 2.5 min. The increase in surface DAT was cocaine-sensitive but was not produced by DA itself. A 1-min preincubation with AMPH did not alter [ 3H]DA uptake, but did result in a higher basal DA efflux and efflux elicited in the presence of AMPH as compared to vehicle pretreatment. Reversible biotinylation experiments demonstrated that the AMPH-stimulated rise in surface DAT is due to an increase in the delivery of DAT to the plasmalemmal membrane rather than a reduction of the endocytic process. These studies suggest that AMPH has a biphasic effect on DAT trafficking and acts rapidly to regulate DAT in the plasmalemmal membrane.