Dopamine transporter in vitro binding and in vivo imaging in the brain

Much research interest has lately been focused on the dopamine transporter function in brain. Recent findings indicate that dopamine reuptake is more like a highly regulated than a constitutive determinant of dopamine clearan ce. Positron emission tomography (PET) and single-photon emission tomograph y (SPET) offer unique methods to study dopamine transporter function. Resul ts from in vivo PET and SPET studies correspond well with in vitro studies performed on post mortem human brain tissue. Considering some of the varian ces between in vitro and in vivo receptor binding phenomena it may be that the role of a compound to alter binding to monoamine uptake sites in vitro does not indicate its potential to affect monoamine transporters after admi nistration in vivo. This discrepancy may be better understood taking into a ccount recant studies indicating the possibility of a rapid regulation of t ransporter function and surface expression. Furthermore, the dopamine trans porter is a fruitful target for CNS drug discovery Fundamental nature of dr ug actions in vivo may be studied using demonstrated in vitro and in vivo i maging methods.