Dopamine D-1 and D-2 Receptor-mediated Inhibition and Excitation of Caudate Neurons Induced by Respective High and Low Concentrations of Dopamine in vitro

Abstract

Recent biochemical studies have demonstrated that the D-1 receptor in the caudate nucleus (CN) has low affinity (micromolar range) to dopamine, while the D-2 receptor exhibits high affinity (nanomolar range) to the amine (Creese et al., 1983). Our previous studies using an iontophoretic technique with selective D-1 or D-2 receptor agonists and antagonists suggested that D-1 and D-2 receptors mediated the inhibitory and excitatory responses of the neurons, respectively (Ohno et al., 1987). Therefore, the present study using an intracellular recording technique in vitro was performed to examine whether or not dopamine at low and high concentrations produces excitatory and inhibitory effects on CN neurons, respectively.