ELECTROPHYSIOLOGY OF DOPAMINE D-1 RECEPTORS IN THE BASAL GANGLIA - OLD FACTS AND NEW PERSPECTIVES

1. The dopamine (DA) D1-receptor family is highly represented in the m ammalian brain and particularly in the nigrostriatal system, whose int egrity is crucial for the execution of motor performances. 2. In the l ast decade, our understanding of the electrophysiology of D1 receptors on caudate-putamen neurons has greatly improved. The effects of the a ctivation of striatal DI receptors were studied by extracellular singl e unit recordings in the intact animal as well as by intracellular rec ordings in rat brain slice preparation. More recently, whole-cell reco rdings on isolated striatal neurons have further addressed this issue and confirmed the inhibitory modulatory role of D1 receptor on the ele ctrical activity of striatal neurons. 3. Several important questions, however, concerning the functional effects of D1 receptor activation i n the basal ganglia are still debated: the cellular segregation of the distribution of D1-D2-like receptors, their synergistic or opposite f unctional roles at the second messenger level, the effects of D1 recep tor activation on the transmitter release and the modifications of D1 receptor pharmacology in dopamine-denervated striata. 4. A different p erspective will also be discussed: the involvement of D1 receptors in long-term changes of synaptic efficacy in the striatum as a possible c orrelate of motor learning.