Abstract

The dopamine transporter (DAT) is a key mediator of dopaminergic neurotransmission and a major target for amphetamine. We found previously that protein kinase C (PKC) β regulates amphetamine-mediated dopamine efflux. Here, using PKCβ wild-type (WT) and knockout (KO) mice, we report a novel role for PKCβ in amphetamine-induced regulation of DAT trafficking and activity. PKCβ KO mice have less striatal surface DAT, [³H]dopamine uptake, and amphetamine-stimulated dopamine efflux, yet higher novelty-induced locomotor activity than WT mice. Although a short exposure (≤90 s) to amphetamine rapidly increases striatal surface DAT and [³H]dopamine uptake in WT mice, this treatment decreases surface DAT and [³H]dopamine uptake in KO mice. Increases in surface DAT and [³H]dopamine uptake are not evident in KO mice until a longer exposure (60 min) to amphetamine, by which time WT mice exhibit decreased surface DAT and dopamine uptake. The slowness of amphetamine-induced striatal DAT trafficking in PKCβ KO mice was mimicked by the use of a specific PKCβ inhibitor, LY379196, in WT mice. Furthermore, PKCβ KO mice exhibit reduced locomotor responsiveness to amphetamine compared with WT, which could be explained by reduced surface DAT and delayed amphetamine-induced DAT trafficking in KO mice. Our results indicate that PKCβ is crucial for proper trafficking of DAT to the surface and for functioning of DAT and amphetamine signaling, providing new insight into the role of PKCβ as an important regulator of dopaminergic homeostasis.