OPPOSING ACTIONS OF D-1-DOPAMINE AND D-2-DOPAMINE RECEPTORS ON ARACHIDONIC-ACID RELEASE AND CYCLIC-AMP PRODUCTION IN STRIATAL NEURONS

D-1- and D-2-dopamine receptors exert important physiological actions on striatal neurons, but the intracellufar second messenger pathways a ctivated by these receptors are still incompletely understood. Using p rimary cultures of rat striatal cells, we have examined the effects of activating D-1 or D-2 receptors on arachidonic acid (AA) release and cyclic AMP accumulation. In striatal neurons labeled by incubation wit h [H-3]AA, D-2-receptor stimulation enhanced release of [H-3]AA produc ed by application of the Ca2+ ionophore A23187 or of the purinergic ag onist ATP. By contrast, D-1-receptor stimulation inhibited [H-3]AA rel ease. This inhibitory effect of D-1 receptors was accompanied by stimu lation of adenylyl cyclase activity, measured as accumulation of cycli c AMP, and was mimicked by application of the adenylyl cyclase activat or forskolin. The results indicate the existence of a novel signaling pathway for D-2 and D-1 receptors in striatum, potentiation and inhibi tion, respectively, of Ca2+-evoked AA release.