Excitation-mediating and inhibition-mediating dopamine-receptors: a new concept towards a better understanding of electrophysiological, biochemical, pharmacological, functional and clinical data.

A great number of earlier reported experimental data dealing with the role of dopamine in dopamine-loaded structures within the mammalian brain have raised questions concerning the concept of dopamine as an inhibitory agent acting on one type of receptor. A critical review of the anatomical, histochemical, electrophysiological, pharmacological and functional studies reveals that the dopamine-loaded structures are marked by an internal differentiation at various levels. It is attempted to demonstrate that this is due to a heterogeneous distribution of two distinct types of dopamine-receptors, each characterized by their own properties: DAe and DAi-receptors. Furthermore, the experimental and clinical implications are discussed in view of the hypothesis that balance between both types of receptors is essential for normal psychomotor functioning.