Chapter Twelve - Dopamine Receptors and Dopamine Release

Abstract

Dopamine (DA) signaling in the brain is mediated by two major classes of DA receptors, DA D1-type receptors which include DA D1 and DA D5 receptors and DA D2-type receptors which include DA D2-, DA D3-, and DA D4-type receptors. These receptors have differing distributions in brain and differing intracellular signaling pathways which are briefly reviewed. Because of the importance of DA signaling in a number of disease states including schizophrenia, drug abuse, movement disorders, attention deficit hyperactivity disorder, and likely depression and obesity, there has been great interest and considerable research efforts into development of methods for delineating regional levels of cerebral DA receptors and DA release in striatum, substantia nigra, limbic regions, and cortex over the past three decades. This chapter will examine the strengths and weaknesses of the currently available positron emission tomography and single-photon emission computed tomography radioligands for DA D1- and DA D2-type receptors, the methods of quantitation of receptor levels using these radioligands, and the ability of these radioligands to assess both psychostimulant-induced DA release and basal extracellular levels of DA as well as provide a limited review of their clinical research applications.