DOPAMINE AND GAMMA-AMINOBUTYRIC-ACID TRANSPORTERS - DIFFERENTIAL REGULATION BY AGENTS THAT PROMOTE PHOSPHORYLATION

Treatment of striatal synaptosomes with the protein phosphatase inhibi tor okadaic acid significantly decreased gamma-aminobutyric acid (GABA ) uptake, indicating that the GABA transporter may be regulated by pho sphorylation. Forskolin and 8-bromoadenosine-3,5-cyclic monophosphate (8-br-cAMP) inhibited GABA uptake to the same extent as okadaic acid, suggesting the involvement of protein kinase A in GABA transporter reg ulation. In contrast, the same treatments did not alter dopamine (DA) uptake into striatal synaptosomal preparations. The results suggest th at the structurally related GABA and DA transporters may be subject to different post-translational regulation.