PET-based neuropharmacology: state of the art.

Positron emission tomography (PET) enables the study of neuropharmacological variables, such as regional receptor densities, alterations in receptor occupancy from endogenous neurotransmitters and exogenous drugs, and receptor plasticity in living human subjects. The purpose of this paper is to review the procedures currently used to study brain pharmacology based on the use of radioactive tracers and PET, and to identify open issues in this field. In particular, the article reviews methodology for tracer validation, including essential biochemistry and kinetic modeling, as well as present clinical applications of tracers used to study dopamine, opioid, benzodiazepine, and cholinergic receptors.