Molecular Neurobiology of Dopaminergic Receptors

Publisher Summary The chapter discusses dopamine receptors that are divided into two major subtypes referred to as D 1 and D 2 . D 1 receptors activate the enzyme adenylylcyclase and increase intracellular levels of cAMP, whereas D 2 receptors exert an inhibitory influence on this enzyme. D 2 receptors may also be linked to additional second messenger systems including activation of K + channels and inhibition of Ca 2+ channels and phosphatidylinositol turnover. With the advent of molecular cloning techniques, however, and their application to the dopamine receptor family, it has become clear that the D 1 /D 2 classification scheme will need to undergo expansion. Five pharmacologically distinct dopamine receptors are defined through molecular cloning methods. Two of these cloned receptors exhibit the functional and pharmacological properties expected for a classical D 1 receptor, while the other three receptors exhibit the pharmacological characteristics of a D 2 receptor. The recent cloning work for the different dopamine receptor subtypes and the current state of knowledge concerning their molecular biological characteristics also discussed.