“…Of the many classifications available, the simplest system, based essentially on adenylate cyclase, holds the greatest sway at the present time for the mammalian central nervous system (Kebabian & Calne, 1979;Creese et al, 1983). In this system, DI-receptors mediate adenylate cyclase stimulation, and there is abundant evidence that SKF 38393 and SCH 23390, are, respectively, selective agonists and antagonists at DI-receptors (Setler et al, 1978;Stoof & Kebabian, 1981;Cross et al, 1983;lorio et al, 1983;O'Boyle & Waddington, 1984); in contrast, D2-receptor activation has either no effect or inhibits adenylate cyclase, and there is evidence that the compound LY 141865 is a selective agonist at this receptor site (Tsuruta et al, 1981;Stoof & Kebabian, 1981;Scatton, 1982).…”