Dopamine transporter: biochemistry, pharmacology and imaging.

In recent years, there has been substantial progress in studying the dopamine transporter, a unique component of the functioning dopaminergic nerve terminal. The transporter has been studied by direct binding techniques using a variety of ligands which function as inhibitors of transport. Analogues of these ligands have been used as photoaffinity labels to solubilize and further characterize the transporter. While a variety of drugs bind to the transporter, it is clear that the transporter may serve as an important drug receptor, particularly for the reinforcing properties of some psychostimulants such as cocaine. An extension of the in vitro ligand-binding studies reveals that it is possible to preferentially label the transporter in vivo. The success of in vivo labeling has lead to successful positron emission tomographic scanning studies of the transporter. These studies in turn have revealed the usefulness of imaging the transporter, a measure of the presence of dopaminergic nerve terminals, as a potential diagnostic tool in Parkinson's disease.